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Thursday, October 12, 2023

Gender-affirming surgery

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Gender-affirming_surgery

Gender-affirming surgery
is a surgical procedure, or series of procedures, that alters a person's physical appearance and sexual characteristics to resemble those associated with their identified gender. The phrase is most often associated with transgender health care and intersex medical interventions, however many such treatments are also pursued by cisgender and non-intersex individuals. It is also known as sex reassignment surgery, gender confirmation surgery, and several other names.

Professional medical organizations have established Standards of Care, which apply before someone can apply for and receive reassignment surgery, including psychological evaluation, and a period of real-life experience living in the desired gender.

Feminization surgeries are surgeries that result in anatomy that is typically gendered female, such as vaginoplasty and breast augmentation, whereas masculinization surgeries are those that result in anatomy that is typically gendered male, such as phalloplasty and breast reduction.

In addition to gender-affirming surgery, patients may need to follow a lifelong course of masculinizing or feminizing hormone replacement therapy.

Sweden became the first country in the world to allow transgender people to change their legal gender after "reassignment surgery" and provide free "reassignment" treatment in 1972. Singapore followed soon after in 1973, being the first in Asia.

Terminology

Gender-affirming surgery is known by numerous other names, including gender-affirmation surgery, sex reassignment surgery, gender reassignment surgery, and gender confirmation surgery. Top surgery and bottom surgery refer to surgeries on the chest and genitals respectively. It is sometimes called a sex change, though this term is usually considered offensive.

Some transgender people who desire medical assistance to transition from one sex to another identify as "transsexual".

Trans women and others assigned male at birth may undergo one or more feminizing procedures which result in anatomy that is typically gendered female. These include genital surgeries such as penectomy (removal of the penis), orchiectomy (removal of the testes), vaginoplasty (construction of a vagina), as well as breast augmentation, tracheal shave (reduction of the Adam's apple), facial feminization surgery, and voice feminization surgery among others.

Trans men and others assigned female at birth seeking surgery may undergo one or more masculinizing procedures, which include chest reconstruction, breast reduction, hysterectomy (removal of the uterus), oophorectomy (removal of the ovaries). A penis can be constructed through metoidioplasty or phalloplasty, and a scrotum through scrotoplasty.

As knowledge of non-binary genders expands in the medical community, more surgeons are willing to tailor operations to individual needs. Bigenital operations allow individuals to construct a penis or vagina and retain their original organs. Gender nullification is the removal of all external genitalia except the urethral opening, typically pursued by people assigned male at birth.

Gender-affirming surgery can also refer to operations pursued by cisgender people, such as mammaplasty, penile implant, or testicular implants following orchiectomy.

Gender-affirming surgery is often sensationalized and misrepresented by anti-trans activists through terminology such as Genital-mutilation surgery.

Surgical procedures

Genital surgery

For trans women, genital reconstruction usually involves the surgical construction of a vagina, by means of penile inversion or the sigmoid colon neovagina technique; or, more recently, non-penile inversion techniques that make use of scrotal tissue to construct the vaginal canal. For trans men, genital reconstruction may involve construction of a penis through either phalloplasty or metoidioplasty.

Non-binary people often pursue genital surgeries, including the same operations as binary trans people of the same sex assignment, as well as bigenital or gender nullification surgeries. Bigenital operations include androgynoplasty, a procedure that retains the penis, or vagina-preserving phalloplasty.

Genital surgery may also involve other medically necessary ancillary procedures, such as orchiectomy, penectomy, mastectomy or vaginectomy. Complications of penile inversion vaginoplasty are mostly minor; however, rectoneovaginal fistulas (abnormal connections between the neovagina and the rectum) can occur in about 1–3% of patients. These require additional surgery to correct and are often fixed by colorectal surgeons.

Other surgeries

As underscored by WPATH, a medically assisted transition from one gender to another may entail any of a variety of non-genital surgical procedures which change primary and/or secondary sex characteristics, any of which are considered "gender-affirming surgery" when undertaken to affirm a person's gender identity. For trans men, these may include mastectomy (removal of the breasts) and chest reconstruction (the shaping of a male-contoured chest), or hysterectomy and bilateral salpingo-oophorectomy (removal of ovaries and Fallopian tubes). For some trans women, facial feminization surgery, hair implants, and breast augmentation are also aesthetic components of their surgical treatment.

Scope and procedures

The best known of these surgeries are those that reshape the genitals, which are also known as genital reassignment surgery or genital reconstruction surgery - or bottom surgery (the latter is named in contrast to top surgery, which is surgery to the breasts; bottom surgery does not refer to surgery on the buttocks in this context). However, the meaning of "sex reassignment surgery" has been clarified by the medical subspecialty organization, the World Professional Association for Transgender Health (WPATH), to include any of a larger number of surgical procedures performed as part of a medical treatment for "gender dysphoria" or "transsexualism". According to WPATH, medically necessary sex reassignment surgeries include "complete hysterectomy, bilateral mastectomy, chest reconstruction or augmentation ... including breast prostheses if necessary, genital reconstruction (by various techniques which must be appropriate to each patient ...)... and certain facial plastic reconstruction." In addition, other non-surgical procedures are also considered medically necessary treatments by WPATH, including facial hair electrolysis.

Voice feminizing surgery is a procedure in which the overall pitch range of the patients voice is reduced.

Adam's Apple Reduction surgery (chondrolaryngoplasty) or tracheal shaving is a procedure in which the most prominent part of the thyroid cartilage is reduced.

There is also Adam's Apple Enhancement therapy, in which cartilage is used to bring out the Adam's apple in female to male patients.

History

Reports of people seeking gender-confirming surgery (vaginoplasty) go back to the 2nd century, such as the Roman Emperor Elagabalus. The first modern gender-confirming surgery was performed in the 20th century.

20th century

In the US in 1917, Alan L. Hart, an American tuberculosis specialist, became one of the first trans men to undergo hysterectomy and gonadectomy as treatment of what is now called gender dysphoria.

Dora Richter is the first known trans woman to undergo complete male-to-female genital surgery. She was one of several transgender people in the care of sexologist Magnus Hirschfeld at Berlin's Institute for Sexual Research. In 1922, Richter underwent orchiectomy. In early 1931, a penectomy, followed in June by vaginoplasty. Richter is presumed to have died in May 1933, when Nazis attacked the institute and destroyed its records, but her exact fate is not known.

Between 1930 and 1931, Lili Elbe underwent four sex reassignment surgeries, including orchiectomy, an ovarian transplant, and penectomy. In June 1931, she underwent her fourth surgery, including an experimental uterine transplant and vaginoplasty, which she hoped would allow her to give birth. However, her body rejected the transplanted uterus, and she died of post-operative complications in September, at age 48.

A previous sex reassignment surgery (SRS) patient was Magnus Hirschfeld's housekeeper, but their name has not been discovered.

Elmer Belt may have been the first U.S. surgeon to perform gender affirmation surgery, in about 1950.

In 1951, Harold Gillies, a plastic surgeon active in World War II, worked to develop the first technique for female-to-male SRS, producing a technique that has become a modern standard, called phalloplasty. Phalloplasty is a cosmetic procedure that produces a visual penis out of grafted tissue from the patient.

Following phalloplasty, in 1999, the procedure for metoidioplasty was developed for female-to-male surgical transition by the doctors Lebovic and Laub. Considered a variant of phalloplasty, metoidioplasty works to create a penis out of the patient's present clitoris. This allows the patient to have a sensation-perceiving penis head. Metoidioplasty may be used in conjunction with phalloplasty to produce a larger, more "cis-appearing" penis in multiple stages.

21st century

On 12 June 2003, the European Court of Human Rights ruled in favor of Carola van Kück, a German trans woman whose insurance company denied her reimbursement for sex reassignment surgery as well as hormone replacement therapy. The legal arguments related to the Article 6 of the European Convention on Human Rights as well as the Article 8. This affair is referred to as van Kück vs Germany.

In 2011, Christiane Völling won the first successful case brought by an intersex person against a surgeon for non-consensual surgical intervention described by the International Commission of Jurists as "an example of an individual who was subjected to sex reassignment surgery without full knowledge or consent".

As of 2017, some European countries require forced sterilization for the legal recognition of sex reassignment. As of 2020, Japan also requires an individual to undergo sterilization to change their legal sex.

The early history of sex reassignment surgery in transgender people has been reviewed by various authors.

Prevalence

The prevalence of transgender-related surgeries is difficult to measure and likely underestimated. In 2015, the largest survey of transgender people in the United States reported that 25% of respondents reported having undergone such a surgery.

Prior to surgery

Medical considerations

Some transgender persons present with health conditions including diabetes, asthma, and HIV, which can lead to complications with future therapy and pharmacological management. Typical SRS procedures involve complex medication regimens, including sex hormone therapy, throughout and after surgery. Typically, a patient's treatment involves a healthcare team consisting of a variety of providers including endocrinologists, whom the surgeon may consult when determining if the patient is physically fit for surgery. Health providers including pharmacists can play a role in maintaining safe and cost-effective regimens, providing patient education, and addressing other health issues including smoking cessation and weight loss.

People with HIV or hepatitis C may have difficulty finding a surgeon able to perform successful surgery. Many surgeons operate in small private clinics that cannot treat potential complications in these populations. Some surgeons charge higher fees for HIV and hepatitis C-positive patients; other medical professionals assert that it is unethical to deny surgical or hormonal treatments to transgender people solely on the basis of their HIV or hepatitis status.

Fertility is also a factor considered in SRS, as patients are typically informed that if an orchiectomy or oöphoro-hysterectomy is performed, it will make them irreversibly infertile.

Gender dysphoric children

Sex reassignment surgery is generally not performed on children under 18, though in rare cases may be performed on adolescents if health care providers agree there is an unusual benefit to doing so or risk to not performing it. Preferred treatments for children include puberty blockers, which are thought to have some reversible physical changes, and sex hormones, which reduce the need for future surgery. Medical protocols typically require long-term mental health counseling to verify persistent and genuine gender dysphoria before any intervention, and consent of a parent or guardian or court order is legally required in most jurisdictions.

Intersex children and cases of trauma

Infants born with intersex conditions might undergo interventions at or close to birth. This is controversial because of the human rights implications.

There can be negative outcomes (including PTSD and suicide) that occur when the surgically assigned gender does not match the individual's gender identity, which will only be realized by the individual later in life. Milton Diamond at the John A. Burns School of Medicine, University of Hawaii recommended that physicians do not perform surgery on children until they are old enough to give informed consent and to assign such infants in the gender to which they will probably best adjust. Diamond believed introducing children to others with differences of sex development could help remove shame and stigma. Diamond considered the intersex condition as a difference of sex development, not as a disorder.

Standards of care

Sex reassignment surgery can be difficult to obtain due to financial barriers, insurance coverage, and lack of providers. An increasing number of surgeons are now training to perform such surgeries. In many regions, an individual's pursuit of SRS is often governed, or at least guided, by documents called Standards of Care for the Health of Transgender and Gender Diverse People (SOC). The most widespread SOC in this field is published and frequently revised by the World Professional Association for Transgender Health (WPATH, formerly the Harry Benjamin International Gender Dysphoria Association or HBIGDA). Many jurisdictions and medical boards in the United States and other countries recognize the WPATH Standards of Care for the treatment of transgender individuals. Some treatment may require a minimum duration of psychological evaluation and living as a member of the target gender full-time, sometimes called the real life experience (RLE) (sometimes mistakenly referred to as the real life test (RLT)) before sex reassignment surgeries are covered by insurance.

Standards of Care usually give certain very specific "minimum" requirements as guidelines for progressing with treatment, causing them to be highly controversial and often maligned documents among transgender patients seeking surgery. Alternative local standards of care exist, such as in the Netherlands, Germany, and Italy. Much of the criticism surrounding the WPATH/HBIGDA-SOC applies to these as well, and some of these SOCs (mostly European SOC) are actually based on much older versions of the WPATH SOC. Other SOCs are entirely independent of the WPATH. The criteria of many of those SOCs are stricter than the latest revision of the WPATH-SOC. Many qualified surgeons in North America and many in Europe adhere almost unswervingly to the WPATH SOC or other SOCs. However, in the United States many experienced surgeons are able to apply the WPATH SOC in ways which respond to an individual's medical circumstances, as is consistent with the SOC.

Many surgeons require two letters of recommendation for sex reassignment surgery. At least one of these letters must be from a mental health professional experienced in diagnosing gender identity disorder (now recognized as gender dysphoria), who has known the patient for over a year. Letters must state that sex reassignment surgery is the correct course of treatment for the patient.

Many medical professionals and numerous professional associations have stated that surgical interventions should not be required for transsexual individuals to change sex designation on identity documents. However, depending on the legal requirements of many jurisdictions, transsexual and transgender people are often unable to change the listing of their sex in public records unless they can furnish a physician's letter attesting that sex reassignment surgery has been performed. In some jurisdictions legal gender change is prohibited in any circumstances, even after genital or other surgery or treatment.

Insurance

A growing number of public and commercial health insurance plans in the United States now contain defined benefits covering sex reassignment-related procedures, usually including genital reconstruction surgery (MTF and FTM), chest reconstruction (FTM), breast augmentation (MTF), and hysterectomy (FTM). For patients to qualify for insurance coverage, certain insurance plans may require proof of the following:

  • a written initial assessment by a qualified licensed mental health professional
  • persistent, well-documented gender dysphoria
  • months of prior physician-supervised hormone therapy

In June 2008, the American Medical Association (AMA) House of Delegates stated that the denial to patients with gender dysphoria or otherwise covered benefits represents discrimination, and that the AMA supports "public and private health insurance coverage for treatment for gender dysphoria as recommended by the patient's physician." Other organizations have issued similar statements, including WPATH, the American Psychological Association, and the National Association of Social Workers.

In 2017, the United States Defense Health Agency for the first time approved payment for sex reassignment surgery for an active-duty U.S. military service member. The patient, an infantry soldier who is a transgender woman, had already begun a course of treatment for gender reassignment. The procedure, which the treating doctor deemed medically necessary, was performed on 14 November at a private hospital, since U.S. military hospitals lack the requisite surgical expertise.

Post-procedural considerations

Quality of life and physical health

Several studies have measured quality of life and self-perceived physical health using different scales. Castellano et al. (2015) found similar quality of life compared to a control group for 60 SRS patients two years after surgery. Kuhn et al. (2008), assessing 52 trans women and 3 trans men 15 years after surgery, found quality of life lower than control in domains of health and limitations. De Cuypere et al. (2005), assessing 32 trans women and 23 trans men after surgery, concluded that patients' emotional and social needs were met, but less so their physical and sexual needs. Ainsworth and Spiegel (2010), in a study of 247 trans women, find improvements in mental health after genital reassignment surgery or face feminization surgery.

In 2021, a review published in Plastic And Reconstructive Surgery found that less than 1% of people who undergo gender-affirming surgery regret the decision.

Psychological and social consequences

A 2009 review in the International Journal of Transgenderism found that from 1998 onward, studies have shown that "the whole process of gender reassignment is effective in relieving gender dysphoria and that its positive results greatly outweighed any negative consequences", but noted methodological issues in many studies, particularly older ones. A 2010 meta-analysis in Clinical Endocrinology noted the lack of randomization and control groups and reliance of self-reporting in the studies it reviewed, reaching the conclusion "Very low quality evidence suggests that hormonal therapies given to individuals with GID as a part of sex reassignment are likely to improve gender dysphoria, psychological functioning and comorbidities, sexual function and overall quality of life."

Smith et al. (2001) found that among 20 patients, anxiety, depression and hostility levels were lower after sex reassignment surgery. Wierckx et al. (2011), in a study of 49 trans men, found them in good self-perceived physical and mental health. Dhejne et al. (2011), in a study following 324 transgender people who received sex reassignment surgery from 1973 to 2003, found that they "have considerably higher risks for mortality, suicidal behaviour, and psychiatric morbidity than the general population", concluding that "sex reassignment, although alleviating gender dysphoria, may not suffice as treatment for transsexualism". Lawrence (2003), in a study of 232 trans women who underwent surgery between 1994 and 2000, found "None reported outright regret and only a few expressed even occasional regret."

Risk categories for post-operative regret include being older, having characterised personality disorders with personal and social instability, lacking family support, lacking sexual activity, and expressing dissatisfaction with the results of surgery. During the process of sex reassignment surgery, transsexuals may become victims of different social obstacles such as discrimination, prejudice and stigmatising behaviours. The rejection faced by transgender people is much more severe than what is experienced by lesbian, gay, and bisexual individuals. The hostile environment may trigger or worsen internalized transphobia, depression, anxiety and post-traumatic stress.

Many patients perceive the outcome of the surgery as not only medically but also psychologically important. Social support can help them to relate to their minority identity, ascertain their trans identity and reduce minority stress.

Sexuality

Looking specifically at transsexual people's genital sensitivities, both trans men and trans women are capable of maintaining their genital sensitivities after SRS. However, these are counted upon the procedures and surgical tricks which are used to preserve the sensitivity. Considering the importance of genital sensitivity in helping transsexual individuals to avoid unnecessary harm or injuries to the genitals, allowing trans men to obtain an erection by inserting a penile implant after phalloplasty, the ability for transsexual people to experience erogenous and tactile sensitivity in their reconstructed genitals is one of the essential objectives surgeons want to achieve in SRS. Moreover, studies have also found that the critical procedure for genital sensitivity maintenance and achieving orgasms after phalloplasty is to preserve both the clitoris hood and the clitoris underneath the reconstructed phallus.

Erogenous sensitivity is measured by the capabilities to reach orgasms in genital sexual activities, like masturbation and intercourse. Many studies reviewed that both trans men and trans women have reported an increase of orgasms in both sexual activities, implying the possibilities to maintain or even enhance genital sensitivity after SRS.

The majority of the transsexual individuals have reported enjoying better sex lives and improved sexual satisfaction after sex reassignment surgery. The enhancement of sexual satisfaction was positively related to the satisfaction of new primary sex characteristics. Before undergoing SRS, transsexual patients possessed unwanted sex organs which they were eager to remove. Hence, they were not enthusiastic about engaging in sexual activity. Transsexual individuals who have undergone SRS are more satisfied with their bodies and experienced less stress when participating in sexual activity.

Most of the individuals have reported that they have experienced sexual excitement during sexual activity, including masturbation. The ability to obtain orgasms is positively associated with sexual satisfaction. Frequency and intensity of orgasms are substantially different among trans men and trans women. Almost all female-to-male individuals have revealed an increase in sexual excitement and are capable of achieving orgasms through sexual activity with a partner or via masturbation, whereas only 85% of the male-to-female individuals are able to achieve orgasms after SRS. A study found that both trans men and trans women reported qualitative change in their experience of orgasm. The female-to-male transgender individuals reported that they had been experiencing intensified and stronger excitements and orgasm while male-to-female individuals have been encountering longer and more gentle feelings.

The rates of masturbation have also changed after sex reassignment surgery for both trans women and trans men. A study reported an overall increase of masturbation frequencies exhibited in most transsexual individuals and 78% of them were able to reach orgasm by masturbation after SRS. A study showed that there were differences in masturbation frequencies between trans men and trans women, in which female-to-male individuals masturbated more often than male to female The possible reasons for the differences in masturbation frequency could be associated with the surge of libido, which was caused by the testosterone therapies, or the withdrawal of gender dysphoria.

Concerning trans people's expectations for different aspects of their life, the sexual aspects have the lowest level of satisfaction among all other elements (physical, emotional and social levels). When comparing transgender with cisgender individuals of the same gender, trans women had a similar sexual satisfaction to cis women, but trans men had a lower level of sexual satisfaction to cis men. Moreover, trans men also had a lower sexual satisfaction with their sexual life than trans women.

Intersex rights in Germany

From Wikipedia, the free encyclopedia
 
Intersex rights in Germany
Location of Germany (dark green)

– in Europe (light green & dark grey)
– in the European Union (light green)

Protection of physical integrity and bodily autonomyYes, with loopholes
Protection from discriminationNo
Changing M/F sex classificationsYes
Third gender or sex classificationsYes (since December 2018)
MarriageYes (since 1 October 2017)

Intersex people in Germany have legal recognition of their rights to physical integrity and bodily autonomy, with exceptions, but no specific protections from discrimination on the basis of sex characteristics. In response to an inquiry by the German Ethics Council in 2012, the government passed legislation in 2013 designed to classify some intersex infants as a de facto third category. The legislation has been criticized by civil society and human rights organizations as misguided.

Research published in 2016 found no substantive reduction in the numbers of intersex medical interventions for infants and children with intersex conditions in the period from 2005 to 2014. In 2021 the Bundestag (the German parliament) passed legal protections, albeit protections that have been criticized due to exceptions to the law.

History

The 12th-century canon law collection known as the Decretum Gratiani states that "Whether a hermaphrodite may witness a testament, depends on which sex prevails" ("Hermaphroditus an ad testamentum adhiberi possit, qualitas sexus incalescentis ostendit."). On ordainment, Raming, Macy and Cook found that the Decretum Gratiani states, "item Hermafroditus. If therefore the person is drawn to the feminine more than the male, the person does not receive the order. If the reverse, the person is able to receive but ought not to be ordained on account of deformity and monstrosity." Historical accounts of intersex people are scarce, but 19th-century medical journals document Gottlieb Göttlich, a man who made a living from being studied by medical practitioners, and Karl Dürrge. Dürrge also made his living as a medical subject, but his life also illustrates the historical legal tradition. Assigned female at birth, Dürrge changed name and designation to male as an adult, in line with articles Articles 19-24 of the Prussian Code of 1792, which enabled hermaphrodites to choose to live as either male or female from the age of majority.

In the 20th century, the term intersex was coined by the German-born geneticist Richard Goldschmidt. In 1932 gynecologist and obstetrician Hans Naujoks performed what was described as the first complete and comprehensive intersex surgery and hormone treatment on a patient with both ovarian and testicular tissue, at the University of Marburg. The female patient was described as fully functional after surgery and, starting in 1934, spontaneously menstruated.

Nazi Germany

A pseudo-diagnosis from Nazi Germany in 1943. The text reads: "The intersex type is physical and psychologically expressed. There are also sexual intermediate stages, where female characteristics are only weakly developed. Hair growth is excessive and atypical, the features are male, the voice is deep. Puberty occurs with delay, there is frigidity and reduced fertility in the case of hypoplasia of the gonads and hyperfunction of the pituitary gland, sometimes eunuch-like tall stature, also disorders in the function of the thyroid gland. Often dysmenorrhea is observed."

During Nazi rule in Germany many intersex people were either killed or hidden from the public. German athlete Dora Ratjen competed in the 1936 Olympic Games in Berlin, placing fourth in the women's high jump. She later competed and set a world record for the women's high jump at the 1938 European Championships. Raised as a girl, tests by the German police concluded that Ratjen was a man. Ratjen later took the name Heinrich Ratjen following an official registry change. Formal sex verification testing was controversially later introduced in sport. Time magazine later reported that Ratjen tearfully confessed that he had been forced by the Nazis to pose as a woman "for the sake of the honor and glory of Germany".

Post World War II

In the 21st century, legal cases by Christiane Völling and Michaela Raab, provide first and later examples of successful legal action against coercive intersex medical interventions.

Also in this century, Germany introduced what may be the first form of third gender recognition in Europe, albeit controversially as a requirement for some intersex infants and otherwise not available. This was introduced as a measure to prevent early intersex medical interventions, but intersex civil society organizations fear that it will encourage such interventions, and there is no evidence of reductions in surgery numbers.

Civil society organizations, including Intergeschlechtliche Menschen, OII Germany and Zwischengeschlecht, have submitted reports to Land, federal and international human rights institutions.

In the spring of 1999, Heike Bödeker coined the term endosex, as an opposite or antonym for the term intersex.

Physical integrity and bodily autonomy

  Legal prohibition of non-consensual medical interventions
  Regulatory suspension of non-consensual medical interventions

The organization Intersexuelle Menschen first submitted a Shadow Report to the United Nations Committee on the Elimination of All Forms of Discrimination Against Women (CEDAW) in July 2008, detailing human rights violations in medical settings and failures to act in the best interests of the child.

In 2010, the German Ethics Council was instructed to review the situation of intersex people in Germany following a demand by CEDAW to protect the human rights of intersex persons. A 2012 report by the German Ethics Council stated that, "Many people who were subjected to a 'normalizing' operation in their childhood have later felt it to have been a mutilation and would never have agreed to it as adults." Legislation was subsequently passed to assign infants who could not be determined as male or female to a de facto third classification.

Research published by Ulrike Klöppel at the Humboldt University in December 2016 shows that, over the period 2005 to 2014, there were no significant trends in numbers of intersex medical interventions. An average of 99 feminizing surgeries took place each year, with a change only to the types of medical classification adopted. Rising numbers of masculinizing surgeries took place, exceeding 1600 per year. Between 10 and 16% of children diagnosed with hypospadias underwent a plastic reconstruction of the penis.

In a hearing of the United Nations Committee on the Elimination of Discrimination against Women, German government stated that irreversible medical interventions were permissible where they are "a life-saving procedure, or the best interest of the child, for example if a child was suicidal."

In 2017, Amnesty International published a report condemning "non-emergency, invasive and irreversible medical treatment with harmful effects" on children born with variations of sex characteristics in Germany and Denmark. It found that surgeries take place with limited psychosocial support, based on gender stereotypes, but without firm evidence. Amnesty International reported that "there are no binding guidelines for the treatment of intersex children".

Legal protections, 2021

A law that provides for a general ban on operations in children and adolescents with 'variations of sex development' ('Varianten der Geschlechtsentwicklung') was passed in the German parliament on 25 March 2021. According to a report in the Deutsches Ärzteblatt, the law is intended to strengthen the self-determined decision-making of children and adolescents and avoid possible damage to their health. Surgical changes to sex characteristics should only take place - even with the consent of the parents - if the operation cannot be postponed until age 14. The majority of legal scholars and psychologists consulted support the approach. The Federal Chamber of Psychotherapists requires the mandatory participation of a counsellor with experience in intersex in an assessment before a possible intervention. While supportive of progress, the law that was finally passed was criticized by the Organisation Intersex International (OII) Germany, OII Europe, and Intergeschlechtliche Menschen e.V., because they provide too many exceptions. Whether the protection takes hold in an individual case depends on whether the medical professional diagnoses the child with variations of sex development (the German implementation of disorders of sex development) or not.

Remedies and claims for compensation

  Explicit protection from discrimination on grounds of sex characteristics
  Explicit protection on grounds of intersex status
  Explicit protection on grounds of intersex within attribute of sex

Two legal cases seeking compensation for "unwanted, harmful medical interventions" have succeeded, those of Christiane Völling and Michaela Raab. Both were adults at the time of the medical interventions. There appear to be no statutory provisions offering compensation, however, at a hearing of the United Nations Committee on the Elimination of Discrimination against Women in February 2017, the German government said that a compensation fund for victims of intersex genital mutilation is under discussion.

Christiane Völling case

In Germany in 2011, Christiane Völling won what may be the first successful case against non-consensual "normalizing" medical treatment. The surgeon was ordered to pay €100,000 in damages after a legal battle that began in 2007, thirty years after the removal of her reproductive organs.

Michaela Raab case

In 2015, Michaela Raab sued doctors in Nuremberg, Germany, who failed to properly advise her. Doctors stated that they "were only acting according to the norms of the time - which sought to protect patients against the psychosocial effects of learning the full truth about their chromosomes". On 17 December 2015, the Nuremberg State Court ruled that the University of Erlangen-Nuremberg Clinic must pay damages and compensation.

Identification documents

  Nonbinary / third gender available as voluntary opt-in
  Opt-in for intersex people only
  Mandatory for some born intersex, and opt in
  Mandatory for some born intersex
  Nonbinary / third gender not legally recognized / no data

In November 2013, Germany became the first European country to allow "indeterminate" sex, requiring this where a child may not be assigned male or female. This was criticized by intersex civil society organizations such as OII Germany and Zwischengeschlecht who argued that "if a child's anatomy does not, in the view of physicians, conform to the category of male or the category of female, there is no option but to withhold the male or female labels given to all other children." The German Ethics Council and the Swiss National Advisory Commission also criticized the law, saying that "instead of individuals deciding for themselves at maturity, decisions concerning sex assignment are made in infancy by physicians and parents."

Many intersex advocates in Germany and elsewhere have suggesting that the law might encourage surgical interventions, rather than reduce them. The Council of Europe Issue Paper on intersex restates these concerns:

Human rights practitioners fear that the lack of freedom of choice regarding the entry in the gender marker field may now lead to an increase in stigmatisation and to "forced outings" of those children whose sex remains undetermined. This has raised the concern that the law may also lead to an increase in pressure on parents of intersex children to decide in favour of one sex.

13 October 2018: protest for third gender in front of the Bundeskanzleramt

In June 2016, Germany's High Court ruled that German law would not allow entry of a third option of "inter" or "diverse" in the birth registry. The High Court said it found no violation of the plaintiff's basic rights since intersex people have been able since 2013 to leave the gender entry in German birth registries blank. In November 2017, the German Constitutional Court ruled that civil status law must allow a third gender option. Open sex entries don't "reflect that the complainant does not see themself as a genderless person, but rather perceives themself as having a gender beyond male or female". This ruling was followed in August 2018 by a cabinet decision to create a new sex classification, "diverse", for intersex people only. This has been criticized for failing to address concerns about medical interventions, and for failing to make this non-binary gender category available to non-intersex people. The proposal was approved by the Bundestag in December 2018. On 22 December 2018, the adopted act entered into force, allowing the choice for intersex people (both at birth and at a later age) between "female", "male", "diverse" and no gender marker at all. In case of a change later in life, first names can also be changed. In the meantime, an appeals court had held that a nonbinary status must also be open to non-intersex non-binary people; the adopted act does not address this category of people and their situation therefore remains unclear pending additional case-law.

Marriage

Since 2017, persons classified as neither male nor female (or intersex people) can legally marry another person of any sex/gender within Germany. Since 1 October 2017, same-sex marriage became legal within Germany and registered partnerships that had been legally available since 2001, were abolished. Same-sex step adoption has also been legal since 2005 and was expanded in 2013 to allow someone in a same-sex relationship to adopt a child already adopted by their partner and full adoption rights for same-sex couples has been legally available since 1 October 2017 within Germany.

Polyethylene terephthalate

From Wikipedia, the free encyclopedia

Polyethylene terephthalate
Strukturformel von Polyethylenterephthalat (PET)
PET polymer chain
A short section of a PET polymer chain
Names
IUPAC name
poly(ethylene terephthalate)
Systematic IUPAC name
poly(oxyethyleneoxyterephthaloyl)
Other names
Terylene (trademark); Dacron (trademark).
Identifiers
Abbreviations PET, PETE
ChEBI
ChemSpider
  • None
ECHA InfoCard 100.121.858 Edit this at Wikidata
UNII
Properties
(C10H8O4)n
Molar mass 10–50 kg/mol, varies
Density
Melting point > 250 °C (482 °F; 523 K) 260 °C
Boiling point > 350 °C (662 °F; 623 K) (decomposes)
Practically insoluble
log P 0.94540
Thermal conductivity 0.15 to 0.24 W/(m·K)
1.57–1.58, 1.5750
Thermochemistry
1.0 kJ/(kg·K)
Related compounds
Related Monomers
Terephthalic acid
Ethylene glycol

Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins.

In 2016, annual production of PET was 56 million tons. The biggest application is in fibres (in excess of 60%), with bottle production accounting for about 30% of global demand. In the context of textile applications, PET is referred to by its common name, polyester, whereas the acronym PET is generally used in relation to packaging. Polyester makes up about 18% of world polymer production and is the fourth-most-produced polymer after polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

PET consists of repeating (C10H8O4) units. PET is commonly recycled, and has the digit 1 (♳) as its resin identification code (RIC). The National Association for PET Container Resources (NAPCOR) defines PET as: "Polyethylene terephthalate items referenced are derived from terephthalic acid (or dimethyl terephthalate) and mono ethylene glycol, wherein the sum of terephthalic acid (or dimethyl terephthalate) and mono ethylene glycol reacted constitutes at least 90 percent of the mass of monomer reacted to form the polymer, and must exhibit a melting peak temperature between 225 °C and 255 °C, as identified during the second thermal scan in procedure 10.1 in ASTM D3418, when heating the sample at a rate of 10 °C/minute."

Depending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous (transparent) and as a semi-crystalline polymer. The semicrystalline material might appear transparent (particle size less than 500 nm) or opaque and white (particle size up to a few micrometers) depending on its crystal structure and particle size.

One process for making PET uses bis(2-hydroxyethyl) terephthalate, which can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct (this is also known as a condensation reaction), or by transesterification reaction between ethylene glycol and dimethyl terephthalate (DMT) with methanol as a byproduct. Polymerization is through a polycondensation reaction of the monomers (done immediately after esterification/transesterification) with water as the byproduct.

Young's modulus, E 2800–3100 MPa
Tensile strength, σt 55–75 MPa
Elastic limit 50–150%
Notch test 3.6 kJ/m2
Glass transition temperature, Tg 67–81 °C
Vicat B 82 °C
Linear expansion coefficient, α 7×10−5 K−1
Water absorption (ASTM) 0.16

Uses

Textiles

Polyester fibres are widely used in the textile industry. The invention of the polyester fibre is attributed to J. R. Whinfield. It was first commercialized in the 1940s by ICI, under the brand 'Terylene'. Subsequently E. I. DuPont launched the brand 'Dacron'. As of 2022, there are many brands around the world, mostly Asian.

Polyester fibres are used in fashion apparel often blended with cotton, as heat insulation layers in thermal wear, sportswear and workwear and automotive upholstery.

Rigid packaging

Plastic bottles made from PET are widely used for soft drinks, both still and sparkling. For beverages that are degraded by oxygen, such as beer, a multilayer structure is used. PET sandwiches an additional polyvinyl alcohol (PVOH) or polyamide (PA) layer to further reduce its oxygen permeability.

Non-oriented PET sheet can be thermoformed to make packaging trays and blister packs. Crystallizable PET withstands freezing and oven baking temperatures. Both amorphous PET and BoPET are transparent to the naked eye. Color-conferring dyes can easily be formulated into PET sheet.

PET is permeable to oxygen and carbon dioxide and this imposes shelf life limitations of contents packaged in PET.

Flexible packaging

Biaxially oriented PET (BOPET) film (often known by one of its trade names, "Mylar") can be aluminized by evaporating a thin film of metal onto it to reduce its permeability, and to make it reflective and opaque (MPET). These properties are useful in many applications, including flexible food packaging and thermal insulation (such as space blankets).

Photovoltaic modules

BOPET is used in the backsheet of photovoltaic modules. Most backsheets consist of a layer of BOPET laminated to a fluoropolymer or a layer of UV stabilized BOPET.

PET is also used as a substrate in thin film solar cells.

Thermoplastic resins

PET can be compounded with glass fibre and crystallization accelerators, to make thermoplastic resins. These can be injection moulded into parts such as housings, covers, electrical appliance components and elements of the ignition system.

Other applications

  • A waterproofing barrier in undersea cables.
  • As a film base.
  • As a fibre, spliced into bell rope tops to help prevent wear on the ropes as they pass through the ceiling.
  • Since late 2014 as liner material in type IV composite high pressure gas cylinders. PET works as a much better barrier to oxygen than earlier used (LD)PE.
  • As a 3D printing filament, as well as in the 3D printing plastic PETG (polyethylene terephthalate glycol). In 3D printing PETG has become a popular material - used for high-end applications like surgical fracture tables to automotive and aeronautical sectors, among other industrial applications. The surface properties can be modified to make PETG self-cleaning for applications like the fabrication of traffic signs for the manufacture of light-emitting diode LED spotlights.
  • As one of three layers for the creation of glitter; acting as a plastic core coated with aluminum and topped with plastic to create a light reflecting surface, although as of 2021 many glitter manufacturing companies have begun to phase out the use of PET after calls from organizers of festivals to create bio-friendly glitter alternatives.
  • Film for tape applications, such as the carrier for magnetic tape or backing for pressure-sensitive adhesive tapes. Digitalization has caused the virtual disappeance of the magnetic audio and videotape application.
  • Water-resistant paper.

History

PET was patented in 1941 by John Rex Whinfield, James Tennant Dickson and their employer the Calico Printers' Association of Manchester, England. E. I. DuPont de Nemours in Delaware, United States, first used the trademark Mylar in June 1951 and received registration of it in 1952. It is still the best-known name used for polyester film. The current owner of the trademark is DuPont Teijin Films.

In the Soviet Union, PET was first manufactured in the laboratories of the Institute of High-Molecular Compounds of the USSR Academy of Sciences in 1949, and its name "Lavsan" is an acronym thereof (лаборатории Института высокомолекулярных соединений Академии наук СССР).

The PET bottle was invented in 1973 by Nathaniel Wyeth and patented by DuPont.

Physical properties

Sailcloth is typically made from PET fibers also known as polyester or under the brand name Dacron; colorful lightweight spinnakers are usually made of nylon.

PET in its most stable state is a colorless, semi-crystalline resin. However it is intrinsically slow to crystallize compared to other semicrystalline polymers. Depending on processing conditions it can be formed into either amorphous or crystalline articles. Its amenability to drawing makes PET useful in fibre and film applications. Like most aromatic polymers, it has better barrier properties than aliphatic polymers. It is strong and impact-resistant. PET is hygroscopic.

About 60% crystallization is the upper limit for commercial products, with the exception of polyester fibers. Transparent products can be produced by rapidly cooling molten polymer below Tg glass transition temperature to form an amorphous solid. Like glass, amorphous PET forms when its molecules are not given enough time to arrange themselves in an orderly, crystalline fashion as the melt is cooled. At room temperature the molecules are frozen in place, but, if enough heat energy is put back into them by heating above Tg, they begin to move again, allowing crystals to nucleate and grow. This procedure is known as solid-state crystallization.

When allowed to cool slowly, the molten polymer forms a more crystalline material. This material has spherulites containing many small crystallites when crystallized from an amorphous solid, rather than forming one large single crystal. Light tends to scatter as it crosses the boundaries between crystallites and the amorphous regions between them, causing the resulting solid to be translucent.

Orientation also renders polymers more transparent. This is why BOPET film and bottles are both crystalline to a degree and transparent.

Amorphous PET crystallizes and becomes opaque when exposed to solvents such as chloroform or toluene.

PET is stoichiometrically a mixture of carbon and H2O, and therefore has been used in an experiment involving laser-driven shock compression which created nanodiamonds and superionic water. This could be a possible way of producing nanodiamonds commercially.

Absorption/scalping

PET has an affinity for hydrophobic flavors, and drinks sometimes need to be formulated with a higher flavor dosage, compared to those going into glass, to offset the flavor taken up by the container. Heavy gauge PET bottles are sometimes returnable for re-use as is practiced in some EU countries, however the propensity of PET to absorb flavors makes it necessary to conduct a "sniffer" test on returned bottles to avoid cross-contamination of flavors.

Intrinsic viscosity

Different applications of PET require different degrees of polymerization, which can be obtained by modifying the process conditions. The molecular weight of PET is measured by solution viscosity. The preferred method is intrinsic viscosity (IV).

IV is a dimensionless measurement. It is found by extrapolating the relative viscosity (measured in (dℓ/g)) to zero concentration.

Shown below are the IV ranges for the main applications:

Fibers
  • 0.40–0.70: textile
  • 0.72–0.98: technical eg tire cord
Films
Bottles
  • 0.70–0.78: general purpose bottles
  • 0.78–0.85: bottles for carbonated drinks
Monofilaments, engineering plastics
  • 1.00–2.00

Copolymers

PET is copolymerized with other diols or diacids to optimize the properties for particular applications.

For example, cyclohexanedimethanol (CHDM) can be added to the polymer backbone in place of ethylene glycol. Since this building block is much larger (six additional carbon atoms) than the ethylene glycol unit it replaces, it does not fit in with the neighboring chains the way an ethylene glycol unit would. This interferes with crystallization and lowers the polymer's melting temperature. In general, such PET is known as PETG or PET-G (polyethylene terephthalate glycol-modified). It is a clear amorphous thermoplastic that can be injection-molded, sheet-extruded or extruded as filament for 3D printing. PETG can be colored during processing.

Replacing terephthalic acid (right) with isophthalic acid (center) creates a kink in the PET chain, interfering with crystallization and lowering the polymer's melting point.

Another common modifier is isophthalic acid, replacing some of the 1,4-(para-) linked terephthalate units. The 1,2-(ortho-) or 1,3-(meta-) linkage produces an angle in the chain, which also disturbs crystallinity.

Such copolymers are advantageous for certain molding applications, such as thermoforming, which is used for example to make tray or blister packaging from co-PET film, or amorphous PET sheet (A-PET/PETA) or PETG sheet. On the other hand, crystallization is important in other applications where mechanical and dimensional stability are important, such as seat belts. For PET bottles, the use of small amounts of isophthalic acid, CHDM, diethylene glycol (DEG) or other comonomers can be useful: if only small amounts of comonomers are used, crystallization is slowed but not prevented entirely. As a result, bottles are obtainable via stretch blow molding ("SBM"), which are both clear and crystalline enough to be an adequate barrier to aromas and even gases, such as carbon dioxide in carbonated beverages.

Production

Polyethylene terephthalate is produced from ethylene glycol (usually referred to in the trade as "MEG", for monoethylene glycol) and dimethyl terephthalate (DMT) (C6H4(CO2CH3)2) but mostly terephthalic acid (known in the trade as "PTA", for purified terephthalic acid). As of 2022, ethylene glycol is made from ethene found in natural gas, while terephthalic acid comes from p-xylene made from crude oil. Typically an antimony or titanium compound is used as a catalyst, a phosphite is added as a stabilizer and a bluing agent such as cobalt salt is added to mask any yellowing.

Dimethyl terephthalate (DMT) process

Polyesterification reaction in the production of PET

In the dimethyl terephthalate (DMT) process, DMT and excess MEG are transesterified in the melt at 150–200 °C with a basic catalyst. Methanol (CH3OH) is removed by distillation to drive the reaction forward. Excess MEG is distilled off at higher temperature with the aid of vacuum. The second transesterification step proceeds at 270–280 °C, with continuous distillation of MEG as well.

The reactions can be summarized as follows:

First step
C6H4(CO2CH3)2 + 2 HOCH2CH2OH → C6H4(CO2CH2CH2OH)2 + 2 CH3OH
Second step
n C6H4(CO2CH2CH2OH)2 → [(CO)C6H4(CO2CH2CH2O)]n + n HOCH2CH2OH

Terephthalic acid (PTA) process

Polycondensation reaction in the production of PET

In the terephthalic acid process, MEG and PTA are esterified directly at moderate pressure (2.7–5.5 bar) and high temperature (220–260 °C). Water is eliminated in the reaction, and it is also continuously removed by distillation:

n C6H4(CO2H)2 + n HOCH2CH2OH → [(CO)C6H4(CO2CH2CH2O)]n + 2n H2O

Bio-PET

Bio-PET is the bio-based counterpart of PET. Essentially in Bio-PET, the MEG is manufactured from ethylene derived from sugar cane ethanol. A better process based on oxidation of ethanol has been proposed, and it is also technically possible to make PTA from readily available biobased furfural.

Degradation

PET is subject to degradation during processing. If the moisture level is too high, hydrolysis will reduce the molecular weight by chain scission, resulting in brittleness.

If the residence time and/or melt temperature are too high, then thermal degradation or thermooxidative degradation will occur resulting in:

Mitigation measures include

Acetaldehyde

Acetaldehyde is a colorless, volatile substance with a fruity smell. Although it forms naturally in some fruit, it can cause an off-taste in bottled water. Acetaldehyde forms by degradation of PET through the mishandling of the material. High temperatures (PET decomposes above 300 °C or 570 °F), high pressures, extruder speeds (excessive shear flow raises temperature), and long barrel residence times all contribute to the production of acetaldehyde. Photo-oxidation can also cause the gradual formation acetaldehyde over the object's lifespan. This proceeds via a Type II Norrish reaction.

When acetaldehyde is produced, some of it remains dissolved in the walls of a container and then diffuses into the product stored inside, altering the taste and aroma. This is not such a problem for non-consumables (such as shampoo), for fruit juices (which already contain acetaldehyde), or for strong-tasting drinks like soft drinks. For bottled water, however, low acetaldehyde content is quite important, because, if nothing masks the aroma, even extremely low concentrations (10–20 parts per billion in the water) of acetaldehyde can produce an off-taste.

Biodegradation

At least one species of bacterium in the genus Nocardia can degrade PET with an esterase enzyme. Esterases are enzymes able to cleave the ester bond. Also, the initial degradation of PET can be esterases expressed by Bacillus and Nocardia.

Japanese scientists have isolated a bacterium Ideonella sakaiensis that possesses two enzymes which can break down the PET into smaller pieces that the bacterium can digest. A colony of I. sakaiensis can disintegrate a plastic film in about six weeks.

French researchers report developing an improved PET hydrolase that can depolymerize at least 90 percent of PET in 10 hours, breaking it down into monomers.

An enzyme based on a natural PET-ase was designed with the help of a machine learning algorithm to be able to tolerate pH and temperature changes by the University of Texas at Austin. The PET-ase was found to able to degrade various products and could break them down as fast as 24 hours.

Environmental concerns

Resource depletion

Compared to the use of petroleum as fuel, however, the amount of crude oil processed into PET is very small. The total production capacity of PET is around 30 million tons, compared to 4.2 billion tons of crude oil production, thus around 0.7% of crude oil is processed into PET.

End of life

Recycle

PET bottles lend themselves well to recycling (see below). In many countries PET bottles are recycled to a substantial degree, for example about 75% in Switzerland. The term rPET is commonly used to describe the recycled material, though it is also referred to as R-PET or post-consumer PET (POSTC-PET).

Energy recovery

PET is a desirable fuel for waste-to-energy plants, as it has a high calorific value which helps to reduce the use of primary resources for energy generation.

Littering

Nevertheless, littering has become a prominent issue in public opinion, and PET bottles are a visible part of that.

Dumping of apparel

A substantial amount of post consumer waste from the textile industry ends up in landfills in developing countries such as Chile and in countries in West Africa such as Ghana. PET being a substantial component of apparel, this waste in landfills contains much PET.

Microfibres from apparel and microplastics

Clothing sheds microfibres in use, during washing and machine drying. Plastic litter slowly forms small particles. Microplastics which are present on the bottom of the river or seabed can be ingested by small marine life, thus entering the food chain. As PET has a higher density than water, a significant amount of PET microparticles may be precipitated in sewage treatment plants. PET microfibers generated by apparel wear, washing or machine drying can become airborne, and be dispersed into fields, where they are ingested by livestock or plants and end up in the human food supply. SAPEA have declared that such particles 'do not pose a widespread risk'. PET is known to degrade when exposed to sunlight and oxygen. As of 2016, scarce information exists regarding the life-time of the synthetic polymers in the environment.

Safety

Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic. Proposed mechanisms include leaching of phthalates as well as leaching of antimony. An article published in Journal of Environmental Monitoring in April 2012 concludes that antimony concentration in deionized water stored in PET bottles stays within EU's acceptable limit even if stored briefly at temperatures up to 60 °C (140 °F), while bottled contents (water or soft drinks) may occasionally exceed the EU limit after less than a year of storage at room temperature.

Antimony

Antimony (Sb) is a metalloid element that is used as a catalyst in the form of compounds such as antimony trioxide (Sb2O3) or antimony triacetate in the production of PET. After manufacturing, a detectable amount of antimony can be found on the surface of the product. This residue can be removed with washing. Antimony also remains in the material itself and can, thus, migrate out into food and drinks. Exposing PET to boiling or microwaving can increase the levels of antimony significantly, possibly above US EPA maximum contamination levels. The drinking water limit assessed by WHO is 20 parts per billion (WHO, 2003), and the drinking water limit in the United States is 6 parts per billion. Although antimony trioxide is of low toxicity when taken orally, its presence is still of concern. The Swiss Federal Office of Public Health investigated the amount of antimony migration, comparing waters bottled in PET and glass: The antimony concentrations of the water in PET bottles were higher, but still well below the allowed maximum concentration. The Swiss Federal Office of Public Health concluded that small amounts of antimony migrate from the PET into bottled water, but that the health risk of the resulting low concentrations is negligible (1% of the "tolerable daily intake" determined by the WHO). A later (2006) but more widely publicized study found similar amounts of antimony in water in PET bottles. The WHO has published a risk assessment for antimony in drinking water.

Fruit juice concentrates (for which no guidelines are established), however, that were produced and bottled in PET in the UK were found to contain up to 44.7 μg/L of antimony, well above the EU limits for tap water of 5 μg/L.

Bottle processing equipment

A finished PET drink bottle compared to the preform from which it is made

There are two basic molding methods for PET bottles, one-step and two-step. In two-step molding, two separate machines are used. The first machine injection molds the preform, which resembles a test tube, with the bottle-cap threads already molded into place. The body of the tube is significantly thicker, as it will be inflated into its final shape in the second step using stretch blow molding.

In the second step, the preforms are heated rapidly and then inflated against a two-part mold to form them into the final shape of the bottle. Preforms (uninflated bottles) are now also used as robust and unique containers themselves; besides novelty candy, some Red Cross chapters distribute them as part of the Vial of Life program to homeowners to store medical history for emergency responders.

In one-step machines, the entire process from raw material to finished container is conducted within one machine, making it especially suitable for molding non-standard shapes (custom molding), including jars, flat oval, flask shapes, etc. Its greatest merit is the reduction in space, product handling and energy, and far higher visual quality than can be achieved by the two-step system.

Polyester recycling industry

Resin identification code 1
Alternate 1
Alternate 2

Worldwide, 480 billion plastic drinking bottles were made in 2016 (and less than half were recycled).

While most thermoplastics can, in principle, be recycled, PET bottle recycling is more practical than many other plastic applications because of the high value of the resin and the almost exclusive use of PET for widely used water and carbonated soft drink bottling. The prime uses for recycled PET are polyester fiber, strapping, and non-food containers.

Because of the recyclability of PET and the relative abundance of post-consumer waste in the form of bottles, PET is rapidly gaining market share as a carpet fiber. Mohawk Industries released everSTRAND in 1999, a 100% post-consumer recycled content PET fiber. Since that time, more than 17 billion bottles have been recycled into carpet fiber. Pharr Yarns, a supplier to numerous carpet manufacturers including Looptex, Dobbs Mills, and Berkshire Flooring, produces a BCF (bulk continuous filament) PET carpet fiber containing a minimum of 25% post-consumer recycled content.

PET, like many plastics, is also an excellent candidate for thermal disposal (incineration), as it is composed of carbon, hydrogen, and oxygen, with only trace amounts of catalyst elements (but no sulfur).

When recycling polyethylene terephthalate or PET or polyester, in general three ways have to be differentiated:

  1. The chemical recycling back to the initial raw materials purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) where the polymer structure is destroyed completely, or in process intermediates like bis(2-hydroxyethyl) terephthalate
  2. The mechanical recycling where the original polymer properties are being maintained or reconstituted.
  3. The chemical recycling where transesterification takes place and other glycols/polyols or glycerol are added to make a polyol which may be used in other ways such as polyurethane production or PU foam production In addition, PET can even be recycled chemically into epoxy based products including paints.

Chemical recycling of PET will become cost-efficient only applying high capacity recycling lines of more than 50,000 tons/year. Such lines could only be seen, if at all, within the production sites of very large polyester producers. Several attempts of industrial magnitude to establish such chemical recycling plants have been made in the past but without resounding success. Even the promising chemical recycling in Japan has not become an industrial breakthrough so far. The two reasons for this are: at first, the difficulty of consistent and continuous waste bottles sourcing in such a huge amount at one single site, and, at second, the steadily increased prices and price volatility of collected bottles. The prices of baled bottles increased for instance between the years 2000 and 2008 from about 50 Euro/ton to over 500 Euro/ton in 2008.

Mechanical recycling or direct circulation of PET in the polymeric state is operated in most diverse variants today. These kinds of processes are typical of small and medium-size industry. Cost-efficiency can already be achieved with plant capacities within a range of 5000–20,000 tons/year. In this case, nearly all kinds of recycled-material feedback into the material circulation are possible today. These diverse recycling processes are being discussed hereafter in detail.

Besides chemical contaminants and degradation products generated during first processing and usage, mechanical impurities are representing the main part of quality depreciating impurities in the recycling stream. Recycled materials are increasingly introduced into manufacturing processes, which were originally designed for new materials only. Therefore, efficient sorting, separation and cleaning processes become most important for high quality recycled polyester.

When talking about polyester recycling industry, we are concentrating mainly on recycling of PET bottles, which are meanwhile used for all kinds of liquid packaging like water, carbonated soft drinks, juices, beer, sauces, detergents, household chemicals and so on. Bottles are easy to distinguish because of shape and consistency and separate from waste plastic streams either by automatic or by hand-sorting processes. The established polyester recycling industry consists of three major sections:

  • PET bottle collection and waste separation: waste logistics
  • Production of clean bottle flakes: flake production
  • Conversion of PET flakes to final products: flake processing

Intermediate product from the first section is baled bottle waste with a PET content greater than 90%. Most common trading form is the bale but also bricked or even loose, pre-cut bottles are common in the market. In the second section, the collected bottles are converted to clean PET bottle flakes. This step can be more or less complex and complicated depending on required final flake quality. During the third step, PET bottle flakes are processed to any kind of products like film, bottles, fiber, filament, strapping or intermediates like pellets for further processing and engineering plastics.

Besides this external (post-consumer) polyester bottle recycling, numbers of internal (pre-consumer) recycling processes exist, where the wasted polymer material does not exit the production site to the free market, and instead is reused in the same production circuit. In this way, fiber waste is directly reused to produce fiber, preform waste is directly reused to produce preforms, and film waste is directly reused to produce film.

PET bottle recycling

The only form of PET that is widely recycled in 2022 is the bottle. These are recycled by 'mechanical recycling' increasingly to bottles but still to other forms such as film or fibre. Other forms of polyester are not (as of 2022) collected in significant quantities.

Significant investments were announced in 2021 and 2022 for chemical recycling of PET by glycolysis, methanolysis and enzymatic recycling to recover monomers. Initially these will also use bottles as feedstock but it is expected that fibres will also be recycled this way in future.

 

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