Neuralink

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Neuralink 

 

Neuralink Corporation

Type	Private
Industry	Brain-computer interface Neuroprosthetics
Founded	July 2016
Founder	Elon Musk
Headquarters	Pioneer Building, San Francisco, California, U.S. (as of 2020)
Key people	Max Hodak (President) Elon Musk (CEO)
Owner	Elon Musk
Number of employees	Around 100 (08/2020)
Website	neuralink.com

Neuralink Corporation is a neurotechnology company founded by Elon Musk and others, developing implantable brain–machine interfaces (BMIs). The company's headquarters is in San Francisco; it was started in 2016 and was first publicly reported in March 2017.

Since its founding, the company has hired several high-profile neuroscientists from various universities. By July 2019, it had received $158 million in funding (of which $100 million was from Musk) and was employing a staff of 90 employees. At that time, Neuralink announced that it was working on a "sewing machine-like" device capable of implanting very thin (4 to 6 μm in width) threads into the brain, and demonstrated a system that read information from a lab rat via 1,500 electrodes, they had anticipated starting experiments with humans in 2020; but have since moved that projection to 2021.

Some claims made by Musk in relation to the technology have been criticized by several neuroscientists and publications, including the MIT Technology Review.

Overview

The Pioneer Building in San Francisco, housing the offices of Neuralink and OpenAI

Neuralink was founded in 2016 by Elon Musk and eight partners; Ben Rapoport, Dongjin Seo, Max Hodak, Paul Merolla, Philip Saps, Tim Gardner, Tim Hanson and Vanessa Tolosa, a group of experts in different areas.

In April 2017, the blog Wait But Why reported that the company was aiming to make devices to treat serious brain diseases in the short-term, with the eventual goal of human enhancement, sometimes called transhumanism. Musk said his interest in the idea partly stemmed from the science fiction concept of "neural lace" in the fictional universe in The Culture, a series of 10 novels by Iain M. Banks.

Musk defined the neural lace as a "digital layer above the cortex" that would not necessarily imply extensive surgical insertion but ideally an implant through a vein or artery. Musk explained that the long-term goal is to achieve "symbiosis with artificial intelligence", which he perceives as an existential threat to humanity if it goes unchecked. As of 2017, some neuroprosthetics can interpret brain signals and allow disabled people to control their prosthetic arms and legs. Musk spoke of aiming to link that technology with implants that, instead of actuating movement, can interface at broadband speed with other types of external software and gadgets.

As of 2020, Neuralink is headquartered in San Francisco's Mission District, sharing the former Pioneer Trunk Factory building with OpenAI, another company co-founded by Musk. Musk was the majority owner of Neuralink as of September 2018, but did not hold an executive position. Jared Birchall was listed as CEO, CFO and president of Neuralink in 2018; his role has been described as formal. An August 2020 tweet confirmed past reports that Musk is the current CEO. The trademark "Neuralink" was purchased from its previous owners in January 2017.

Members

The company is made up of a group of experts in different areas such as neuroscience, biochemistry, robotics, applied mathematics, machinery, among others. It is currently looking for experts in different scientific areas to shape his team.

Its founding members are:

• Elon Musk.
• Max Hodak, president of the company. He previously worked on the development of brain-computer interfaces at Duke University.
• Matthew MacDougall, Head of Neurosurgery at Neuralink and neurosurgeon at California Pacific Medical Center. He was previously working at Stanford where he worked in labs that implemented and designed brain-computer interfaces.
• Vanessa Tolosa, Director of Neural Interfaces. She previously led a neurotechnology team at the Lawrence Livermore National Laboratory that worked with a wide variety of technology on technology prostheses that were used in clinical and academic settings.
• DJ Seo, director of the Implantation System. He was the co-inventor of "neural dust" a technology he developed while studying at UC Berkeley.
• Philip Sabes, senior scientist. He was a professor of physiology at UC San Francisco and led a lab that studied how the brain processed sensorial and motor signals.
• Tim Gardner, professor of biology at Boston University, in which they have worked on the implementation of brain-computer interfaces in birds.
• Ben Rapoport, neurosurgeon with a PhD in electrical engineering and computer science from MIT.
• Tim Hanson, researcher at the Berkeley Sensor and Acuator Center.

By August 2020, only three of the eight founding scientists remained at the company, according to an article by Stat News which reported that Neuralink had seen "years of internal conflict in which rushed timelines have clashed with the slow and incremental pace of science."

Technology

By 2018, the company had "remained highly secretive about its work since its launch", although public records showed that it had sought to open an animal testing facility in San Francisco; it subsequently started to carry out research at the University of California, Davis. In 2019, during a live presentation at the California Academy of Sciences, the Neuralink team revealed to the public the technology of the first prototype they had been working on. It is a system that involves ultra-thin probes that will be inserted into the brain, a neurosurgical robot that will perform the operations and a high-density electronic system capable of processing information from neurons.

Probes

The probes, composed mostly of polyamide, a biocompatible material, and coated in a thin gold thread, will be inserted into the brain through an automated process performed by a surgical robot.

Each probe consists of an area of wires that contains electrodes capable of locating electrical signals in the brain, and a sensory area where the wire interacts with an electronic system that allows amplification and acquisition of the brain signal.

Each of the probes contains 48 or 96 wires, each of which contains 32 independent electrodes; achieving this way a system of up to 3072 electrodes per formation.

Robot

Studies involving the insertion of probes in the brain have shown that, due to their rigidity, the body recognizes them as an unknown material and, consequently, generates tissue to get rid of them, which, in turn, long term, makes them unusable.

For this reason, Neuralink has developed a robot capable of inserting flexible probes, allowing the rapid insertion of multiples of these to minimize trauma that can trigger a bounce reaction.

This robot has an insertion head with a 40 μm diameter needle made of tungsten-rhenium designed to attach to the insertion loops, made to transport and insert individual probes, and to penetrate the meninges and tissue cerebral. The robot is capable of inserting up to six probes (192 electrodes) per minute.

Electronics

Elon Musk discussing the Neuralink

Neuralink has developed an Application-Specific Integrated Circuit (ASIC) to create a 1,536-channel recording system.

This system consists of 256 amplifiers capable of being individually programmed ("analog pixels"), analog-to-chip converters within the chip ("ADCs") and a peripheral circuit control to serialize the digitized information obtained.

It aims to convert information obtained from neurons into an understandable binary code in order to achieve greater understanding of brain function and the ability to stimulate these neurons back.

Currently, electrodes are still too big to record the firing of individual neurons, so they can record only the firing of a group of neurons; Neuralink representatives believe this issue might get mitigated algorithmically, but it's computationally expensive and does not produce exact results.

In July 2020, according to Musk, Neuralink obtained a FDA breakthrough device designation which allows limited human testing under the FDA guidelines for medical devices.

Reception

Several neurology scientists have commented on the intention of Musk and members of Neuralink to build a brain-computer interface. The response from the scientific community has been mixed.

At a live demonstration in August 2020, Musk described one of their early devices as "a Fitbit in your skull" which could soon cure paralysis, deafness, blindness, and other disabilities. Many neuroscientists and publications criticized these claims. For example, MIT Technology Review described them as "highly speculative" and "neuroscience theater".

Mary Lou Jepsen, founder of Openwater, a company that also works in the area of brain-computer interfaces, with the goal of creating a telepathy system, has expressed concern about the rejection reactions that probes can cause.

Thomas Oxley, MD, PhD, CEO of Synchron, an Australian company that is also developing a system to insert brain probes via blood-vessel-borne catheters that avoid any direct penetration of brain tissue, and therefore do not cause trauma, says no efficacy results from Neuralink are expected soon, as the technology is not advanced enough to achieve this. However, he believes that because Musk is willing to invest large sums of money in his company, it will be "exciting to see what he will develop."

Criticism

Neuralink tests their devices by surgically implanting them in the brains of live monkeys, pigs and other animals. These methods have been criticized by groups such as PETA.

Carbon fiber reinforced polymer

From Wikipedia, the free encyclopedia

 

Tail of a radio-controlled helicopter, made of CFRP

Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (Commonwealth English), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, also known as carbon fiber, carbon composite, or just carbon), is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.

The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used. The properties of the final CFRP product can be affected by the type of additives introduced to the binding matrix (resin). The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used.

Carbon fiber is sometimes referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer (GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer).

Properties

CFRP are composite materials. In this case the composite consists of two parts: a matrix and a reinforcement. In CFRP the reinforcement is carbon fiber, which provides its strength. The matrix is usually a polymer resin, such as epoxy, to bind the reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements.

Reinforcement gives CFRP its strength and rigidity, measured by stress and elastic modulus respectively. Unlike isotropic materials like steel and aluminum, CFRP has directional strength properties. The properties of CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer. The two different equations governing the net elastic modulus of composite materials using the properties of the carbon fibers and the polymer matrix can also be applied to carbon fiber reinforced plastics. The following equation,

${\displaystyle E_{c}=V_{m}E_{m}+V_{f}E_{f}}$

is valid for composite materials with the fibers oriented in the direction of the applied load. ${\displaystyle E_{c}}$ is the total composite modulus, ${\displaystyle V_{m}}$ and ${\displaystyle V_{f}}$ are the volume fractions of the matrix and fiber respectively in the composite, and ${\displaystyle E_{m}}$ and ${\displaystyle E_{f}}$ are the elastic moduli of the matrix and fibers respectively. The other extreme case of the elastic modulus of the composite with the fibers oriented transverse to the applied load can be found using the following equation:

${\displaystyle E_{c}=\left({\frac {V_{m}}{E_{m}}}+{\frac {V_{f}}{E_{f}}}\right)^{-1}}$

The fracture toughness of carbon fiber reinforced plastics is governed by the following mechanisms: 1) debonding between the carbon fiber and polymer matrix, 2) fiber pull-out, and 3) delamination between the CFRP sheets. Typical epoxy-based CFRPs exhibit virtually no plasticity, with less than 0.5% strain to failure. Although CFRPs with epoxy have high strength and elastic modulus, the brittle fracture mechanics present unique challenges to engineers in failure detection since failure occurs catastrophically. As such, recent efforts to toughen CFRPs include modifying the existing epoxy material and finding alternative polymer matrix. One such material with high promise is PEEK, which exhibits an order of magnitude greater toughness with similar elastic modulus and tensile strength. However, PEEK is much more difficult to process and more expensive.

Despite its high initial strength-to-weight ratio, a design limitation of CFRP is its lack of a definable fatigue limit. This means, theoretically, that stress cycle failure cannot be ruled out. While steel and many other structural metals and alloys do have estimable fatigue or endurance limits, the complex failure modes of composites mean that the fatigue failure properties of CFRP are difficult to predict and design against. As a result, when using CFRP for critical cyclic-loading applications, engineers may need to design in considerable strength safety margins to provide suitable component reliability over its service life.

Environmental effects such as temperature and humidity can have profound effects on the polymer-based composites, including most CFRPs. While CFRPs demonstrate excellent corrosion resistance, the effect of moisture at wide ranges of temperatures can lead to degradation of the mechanical properties of CFRPs, particularly at the matrix-fiber interface. While the carbon fibers themselves are not affected by the moisture diffusing into the material, the moisture plasticizes the polymer matrix. This led to significant changes in properties that are dominantly influenced by the matrix in CFRPs such as compressive, interlaminar shear, and impact properties. The epoxy matrix used for engine fan blades is designed to be impervious against jet fuel, lubrication, and rain water, and external paint on the composites parts is applied to minimize damage from ultraviolet light.

The carbon fibers can cause galvanic corrosion when CRP parts are attached to aluminum.

Carbon Fiber Reinforced Plastics are very hard to machine, and causes significant tool wear. The tool wear in CFRP machining is dependent on the fiber orientation and machining condition of the cutting process. In order to reduce tool wear various types of coated tools are used in machining CFRP and CFRP-metal stack.

Manufacture

Carbon fiber reinforced polymer

The primary element of CFRP is a carbon filament; this is produced from a precursor polymer such as polyacrylonitrile (PAN), rayon, or petroleum pitch. For synthetic polymers such as PAN or rayon, the precursor is first spun into filament yarns, using chemical and mechanical processes to initially align the polymer chains in a way to enhance the final physical properties of the completed carbon fiber. Precursor compositions and mechanical processes used during spinning filament yarns may vary among manufacturers. After drawing or spinning, the polymer filament yarns are then heated to drive off non-carbon atoms (carbonization), producing the final carbon fiber. The carbon fibers filament yarns may be further treated to improve handling qualities, then wound on to bobbins. From these fibers, a unidirectional sheet is created. These sheets are layered onto each other in a quasi-isotropic layup, e.g. 0°, +60°, or −60° relative to each other.

From the elementary fiber, a bidirectional woven sheet can be created, i.e. a twill with a 2/2 weave. The process by which most CFRPs are made varies, depending on the piece being created, the finish (outside gloss) required, and how many of the piece will be produced. In addition, the choice of matrix can have a profound effect on the properties of the finished composite.

Many CFRP parts are created with a single layer of carbon fabric that is backed with fiberglass. A tool called a chopper gun is used to quickly create these composite parts. Once a thin shell is created out of carbon fiber, the chopper gun cuts rolls of fiberglass into short lengths and sprays resin at the same time, so that the fiberglass and resin are mixed on the spot. The resin is either external mix, wherein the hardener and resin are sprayed separately, or internal mixed, which requires cleaning after every use. Manufacturing methods may include the following:

Molding

One method of producing CFRP parts is by layering sheets of carbon fiber cloth into a mold in the shape of the final product. The alignment and weave of the cloth fibers is chosen to optimize the strength and stiffness properties of the resulting material. The mold is then filled with epoxy and is heated or air-cured. The resulting part is very corrosion-resistant, stiff, and strong for its weight. Parts used in less critical areas are manufactured by draping cloth over a mold, with epoxy either preimpregnated into the fibers (also known as pre-preg) or "painted" over it. High-performance parts using single molds are often vacuum-bagged and/or autoclave-cured, because even small air bubbles in the material will reduce strength. An alternative to the autoclave method is to use internal pressure via inflatable air bladders or EPS foam inside the non-cured laid-up carbon fiber.

Vacuum bagging

For simple pieces of which relatively few copies are needed (1–2 per day), a vacuum bag can be used. A fiberglass, carbon fiber, or aluminum mold is polished and waxed, and has a release agent applied before the fabric and resin are applied, and the vacuum is pulled and set aside to allow the piece to cure (harden). There are three ways to apply the resin to the fabric in a vacuum mold.

The first method is manual and called a wet layup, where the two-part resin is mixed and applied before being laid in the mold and placed in the bag. The other one is done by infusion, where the dry fabric and mold are placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with holes or something similar to evenly spread the resin throughout the fabric. Wire loom works perfectly for a tube that requires holes inside the bag. Both of these methods of applying resin require hand work to spread the resin evenly for a glossy finish with very small pin-holes.

A third method of constructing composite materials is known as a dry layup. Here, the carbon fiber material is already impregnated with resin (pre-preg) and is applied to the mold in a similar fashion to adhesive film. The assembly is then placed in a vacuum to cure. The dry layup method has the least amount of resin waste and can achieve lighter constructions than wet layup. Also, because larger amounts of resin are more difficult to bleed out with wet layup methods, pre-preg parts generally have fewer pinholes. Pinhole elimination with minimal resin amounts generally require the use of autoclave pressures to purge the residual gases out.

Compression molding

A quicker method uses a compression mold. This is a two-piece (male and female) mold usually made out of aluminum or steel that is pressed together with the fabric and resin between the two. The benefit is the speed of the entire process. Some car manufacturers, such as BMW, claimed to be able to cycle a new part every 80 seconds. However, this technique has a very high initial cost since the molds require CNC machining of very high precision.

Filament winding

For difficult or convoluted shapes, a filament winder can be used to make CFRP parts by winding filaments around a mandrel or a core.

Applications

Applications for CFRP include the following:

Aerospace engineering

A composite Airbus A350 with carbon fiber themed livery

The Airbus A350 XWB is built of 52% CFRP including wing spars and fuselage components, overtaking the Boeing 787 Dreamliner, for the aircraft with the highest weight ratio for CFRP, which is 50%. This was one of the first commercial aircraft to have wing spars made from composites. The Airbus A380 was one of the first commercial airliners to have a central wing-box made of CFRP; it is the first to have a smoothly contoured wing cross-section instead of the wings being partitioned span-wise into sections. This flowing, continuous cross section optimises aerodynamic efficiency. Moreover, the trailing edge, along with the rear bulkhead, empennage, and un-pressurised fuselage are made of CFRP. However, many delays have pushed order delivery dates back because of problems with the manufacture of these parts. Many aircraft that use CFRP have experienced delays with delivery dates due to the relatively new processes used to make CFRP components, whereas metallic structures have been studied and used on airframes for years, and the processes are relatively well understood. A recurrent problem is the monitoring of structural ageing, for which new methods are constantly investigated, due to the unusual multi-material and anisotropic nature of CFRP.

In 1968 a Hyfil carbon-fiber fan assembly was in service on the Rolls-Royce Conways of the Vickers VC10s operated by BOAC.

Specialist aircraft designers and manufacturers Scaled Composites have made extensive use of CFRP throughout their design range, including the first private manned spacecraft Spaceship One. CFRP is widely used in micro air vehicles (MAVs) because of its high strength to weight ratio.

Automotive engineering

Citroën SM that won 1971 Rally of Morocco with carbon fiber wheels

 

1996 McLaren F1 – first carbon fiber body shell

 

McLaren MP4 (MP4/1), first carbon fiber F1 car.

CFRPs are extensively used in high-end automobile racing. The high cost of carbon fiber is mitigated by the material's unsurpassed strength-to-weight ratio, and low weight is essential for high-performance automobile racing. Race-car manufacturers have also developed methods to give carbon fiber pieces strength in a certain direction, making it strong in a load-bearing direction, but weak in directions where little or no load would be placed on the member. Conversely, manufacturers developed omnidirectional carbon fiber weaves that apply strength in all directions. This type of carbon fiber assembly is most widely used in the "safety cell" monocoque chassis assembly of high-performance race-cars. The first carbon fiber monocoque chassis was introduced in Formula One by McLaren in the 1981 season. It was designed by John Barnard and was widely copied in the following seasons by other F1 teams due to the extra rigidity provided to the chassis of the cars.

Many supercars over the past few decades have incorporated CFRP extensively in their manufacture, using it for their monocoque chassis as well as other components. As far back as 1971, the Citroën SM offered optional lightweight carbon fiber wheels.

Use of the material has been more readily adopted by low-volume manufacturers who used it primarily for creating body-panels for some of their high-end cars due to its increased strength and decreased weight compared with the glass-reinforced polymer they used for the majority of their products.

Civil engineering

CFRP has become a notable material in structural engineering applications. Studied in an academic context as to its potential benefits in construction, it has also proved itself cost-effective in a number of field applications strengthening concrete, masonry, steel, cast iron, and timber structures. Its use in industry can be either for retrofitting to strengthen an existing structure or as an alternative reinforcing (or pre-stressing) material instead of steel from the outset of a project.

Retrofitting has become the increasingly dominant use of the material in civil engineering, and applications include increasing the load capacity of old structures (such as bridges) that were designed to tolerate far lower service loads than they are experiencing today, seismic retrofitting, and repair of damaged structures. Retrofitting is popular in many instances as the cost of replacing the deficient structure can greatly exceed the cost of strengthening using CFRP.

Applied to reinforced concrete structures for flexure, CFRP typically has a large impact on strength (doubling or more the strength of the section is not uncommon), but only a moderate increase in stiffness (perhaps a 10% increase). This is because the material used in this application is typically very strong (e.g., 3000 MPa ultimate tensile strength, more than 10 times mild steel) but not particularly stiff (150 to 250 GPa, a little less than steel, is typical). As a consequence, only small cross-sectional areas of the material are used. Small areas of very high strength but moderate stiffness material will significantly increase strength, but not stiffness.

CFRP can also be applied to enhance shear strength of reinforced concrete by wrapping fabrics or fibers around the section to be strengthened. Wrapping around sections (such as bridge or building columns) can also enhance the ductility of the section, greatly increasing the resistance to collapse under earthquake loading. Such 'seismic retrofit' is the major application in earthquake-prone areas, since it is much more economic than alternative methods.

If a column is circular (or nearly so) an increase in axial capacity is also achieved by wrapping. In this application, the confinement of the CFRP wrap enhances the compressive strength of the concrete. However, although large increases are achieved in the ultimate collapse load, the concrete will crack at only slightly enhanced load, meaning that this application is only occasionally used. Specialist ultra-high modulus CFRP (with tensile modulus of 420 GPa or more) is one of the few practical methods of strengthening cast-iron beams. In typical use, it is bonded to the tensile flange of the section, both increasing the stiffness of the section and lowering the neutral axis, thus greatly reducing the maximum tensile stress in the cast iron.

In the United States, pre-stressed concrete cylinder pipes (PCCP) account for a vast majority of water transmission mains. Due to their large diameters, failures of PCCP are usually catastrophic and affect large populations. Approximately 19,000 miles (31,000 km) of PCCP have been installed between 1940 and 2006. Corrosion in the form of hydrogen embrittlement has been blamed for the gradual deterioration of the pre-stressing wires in many PCCP lines. Over the past decade, CFRPs have been utilized to internally line PCCP, resulting in a fully structural strengthening system. Inside a PCCP line, the CFRP liner acts as a barrier that controls the level of strain experienced by the steel cylinder in the host pipe. The composite liner enables the steel cylinder to perform within its elastic range, to ensure the pipeline's long-term performance is maintained. CFRP liner designs are based on strain compatibility between the liner and host pipe.

CFRP is a more costly material than its counterparts in the construction industry, glass fiber-reinforced polymer (GFRP) and aramid fiber-reinforced polymer (AFRP), though CFRP is, in general, regarded as having superior properties. Much research continues to be done on using CFRP both for retrofitting and as an alternative to steel as a reinforcing or pre-stressing material. Cost remains an issue and long-term durability questions still remain. Some are concerned about the brittle nature of CFRP, in contrast to the ductility of steel. Though design codes have been drawn up by institutions such as the American Concrete Institute, there remains some hesitation among the engineering community about implementing these alternative materials. In part, this is due to a lack of standardization and the proprietary nature of the fiber and resin combinations on the market.

Carbon-fiber microelectrodes

Carbon fibers are used for fabrication of carbon-fiber microelectrodes. In this application typically a single carbon fiber with diameter of 5–7 μm is sealed in a glass capillary. At the tip the capillary is either sealed with epoxy and polished to make carbon-fiber disk microelectrode or the fiber is cut to a length of 75–150 μm to make carbon-fiber cylinder electrode. Carbon-fiber microelectrodes are used either in amperometry or fast-scan cyclic voltammetry for detection of biochemical signaling.

Sports goods

A carbon-fiber and Kevlar canoe (Placid Boatworks Rapidfire at the Adirondack Canoe Classic)

CFRP is now widely used in sports equipment such as in squash, tennis, and badminton racquets, sport kite spars, high-quality arrow shafts, hockey sticks, fishing rods, surfboards, high end swim fins, and rowing shells. Amputee athletes such as Jonnie Peacock use carbon fiber blades for running. It is used as a shank plate in some basketball sneakers to keep the foot stable, usually running the length of the shoe just above the sole and left exposed in some areas, usually in the arch.

Controversially, in 2006, cricket bats with a thin carbon-fiber layer on the back were introduced and used in competitive matches by high-profile players including Ricky Ponting and Michael Hussey. The carbon fiber was claimed to merely increase the durability of the bats, but it was banned from all first-class matches by the ICC in 2007.

A CFRP bicycle frame weighs less than one of steel, aluminum, or titanium having the same strength. The type and orientation of the carbon-fiber weave can be designed to maximize stiffness in required directions. Frames can be tuned to address different riding styles: sprint events require stiffer frames while endurance events may require more flexible frames for rider comfort over longer periods. The variety of shapes it can be built into has further increased stiffness and also allowed aerodynamic tube sections. CFRP forks including suspension fork crowns and steerers, handlebars, seatposts, and crank arms are becoming more common on medium as well as higher-priced bicycles. CFRP rims remain expensive but their stability compared to aluminium reduces the need to re-true a wheel and the reduced mass reduces the moment of inertia of the wheel. CFRP spokes are rare and most carbon wheelsets retain traditional stainless steel spokes. CFRP also appears increasingly in other components such as derailleur parts, brake and shifter levers and bodies, cassette sprocket carriers, suspension linkages, disc brake rotors, pedals, shoe soles, and saddle rails. Although strong and light, impact, over-torquing, or improper installation of CFRP components has resulted in cracking and failures, which may be difficult or impossible to repair.

Other applications

The fire resistance of polymers and thermo-set composites is significantly improved if a thin layer of carbon fibers is moulded near the surface because a dense, compact layer of carbon fibers efficiently reflects heat.

CFRP is being used in an increasing number of high-end products that require stiffness and low weight, these include:

• Musical instruments, including violin bows; guitar picks, necks (carbon fiber rods), and pick-guards; drum shells; bagpipe chanters; and entire musical instruments such as Luis and Clark's carbon fiber cellos, violas, and violins; and Blackbird Guitars' acoustic guitars and ukuleles; also audio components such as turntables and loudspeakers.
• Firearms use it to replace certain metal, wood, and fiberglass components but many of the internal parts are still limited to metal alloys as current reinforced plastics are unsuitable.
• High-performance drone bodies and other radio-controlled vehicle and aircraft components such as helicopter rotor blades.
• Lightweight poles such as: tripod legs, tent poles, fishing rods, billiards cues, walking sticks, and high-reach poles such as for window cleaning.
• Dentistry, carbon fiber posts are used in restoring root canal treated teeth.
• Railed train bogies for passenger service. This reduces the weight by up to 50% compared to metal bogies, which contributes to energy savings.
• Laptop shells and other high performance cases.
• Carbon woven fabrics.
• Archery, carbon fiber arrows and bolts, stock, and rail.
• As a filament for the 3D fused deposition modeling printing process, carbon fiber-reinforced plastic (polyamide-carbon filament) is used for the production of sturdy but lightweight tools and parts due to its high strength and tear length.
• District heating pipe rehabilitation, using CIPP method.

Disposal and recycling

CFRPs have a long service lifetime when protected from the sun. When it is time to decommission CFRPs, they cannot be melted down in air like many metals. When free of vinyl (PVC or polyvinyl chloride) and other halogenated polymers, CFRPs can be thermally decomposed via thermal depolymerization in an oxygen-free environment. This can be accomplished in a refinery in a one-step process. Capture and reuse of the carbon and monomers is then possible. CFRPs can also be milled or shredded at low temperature to reclaim the carbon fiber; however, this process shortens the fibers dramatically. Just as with downcycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not need the strength of full-length carbon fiber reinforcement. For example, chopped reclaimed carbon fiber can be used in consumer electronics, such as laptops. It provides excellent reinforcement of the polymers used even if it lacks the strength-to-weight ratio of an aerospace component.

Carbon nanotube reinforced polymer (CNRP)

In 2009, Zyvex Technologies introduced carbon nanotube-reinforced epoxy and carbon pre-pregs. Carbon nanotube reinforced polymer (CNRP) is several times stronger and tougher than CFRP and is used in the Lockheed Martin F-35 Lightning II as a structural material for aircraft. CNRP still uses carbon fiber as the primary reinforcement, but the binding matrix is a carbon nanotube-filled epoxy.

Fiberglass

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Fiberglass

Fiberglass (American English), or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet (called a chopped strand mat), or woven into a fabric. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinylester—or a thermoplastic.

Cheaper and more flexible than carbon fiber, it is stronger than many metals by weight, is non-magnetic, non-conductive, transparent to electromagnetic radiation, can be molded into complex shapes, and is chemically inert under many circumstances. Applications include aircraft, boats, automobiles, bath tubs and enclosures, swimming pools, hot tubs, septic tanks, water tanks, roofing, pipes, cladding, orthopedic casts, surfboards, and external door skins.

Other common names for fiberglass are glass-reinforced plastic (GRP), glass-fiber reinforced plastic (GFRP) or GFK (from German: Glasfaserverstärkter Kunststoff). Because glass fiber itself is sometimes referred to as "fiberglass", the composite is also called "fiberglass reinforced plastic". This article will adopt the convention that "fiberglass" refers to the complete glass fiber reinforced composite material, rather than only to the glass fiber within it.

History

Glass fibers have been produced for centuries, but the earliest patent was awarded to the Prussian inventor Hermann Hammesfahr (1845–1914) in the U.S. in 1880.

Mass production of glass strands was accidentally discovered in 1932 when Games Slayter, a researcher at Owens-Illinois, directed a jet of compressed air at a stream of molten glass and produced fibers. A patent for this method of producing glass wool was first applied for in 1933. Owens joined with the Corning company in 1935 and the method was adapted by Owens Corning to produce its patented "Fiberglas" (spelled with one "s") in 1936. Originally, Fiberglas was a glass wool with fibers entrapping a great deal of gas, making it useful as an insulator, especially at high temperatures.

A suitable resin for combining the fiberglass with a plastic to produce a composite material was developed in 1936 by du Pont. The first ancestor of modern polyester resins is Cyanamid's resin of 1942. Peroxide curing systems were used by then. With the combination of fiberglass and resin the gas content of the material was replaced by plastic. This reduced the insulation properties to values typical of the plastic, but now for the first time, the composite showed great strength and promise as a structural and building material. Many glass fiber composites continued to be called "fiberglass" (as a generic name) and the name was also used for the low-density glass wool product containing gas instead of plastic.

Ray Greene of Owens Corning is credited with producing the first composite boat in 1937 but did not proceed further at the time due to the brittle nature of the plastic used. In 1939 Russia was reported to have constructed a passenger boat of plastic materials, and the United States a fuselage and wings of an aircraft. The first car to have a fiber-glass body was a 1946 prototype of the Stout Scarab, but the model did not enter production.

Fiber

Glass reinforcements used for fiberglass are supplied in different physical forms: microspheres, chopped or woven.

Unlike glass fibers used for insulation, for the final structure to be strong, the fiber's surfaces must be almost entirely free of defects, as this permits the fibers to reach gigapascal tensile strengths. If a bulk piece of glass were defect-free, it would be equally as strong as glass fibers; however, it is generally impractical to produce and maintain bulk material in a defect-free state outside of laboratory conditions.

Production

The process of manufacturing fiberglass is called pultrusion. The manufacturing process for glass fibers suitable for reinforcement uses large furnaces to gradually melt the silica sand, limestone, kaolin clay, fluorspar, colemanite, dolomite and other minerals until a liquid forms. It is then extruded through bushings, which are bundles of very small orifices (typically 5–25 micrometres in diameter for E-Glass, 9 micrometres for S-Glass).

These filaments are then sized (coated) with a chemical solution. The individual filaments are now bundled in large numbers to provide a roving. The diameter of the filaments, and the number of filaments in the roving, determine its weight, typically expressed in one of two measurement systems:

• yield, or yards per pound (the number of yards of fiber in one pound of material; thus a smaller number means a heavier roving). Examples of standard yields are 225yield, 450yield, 675yield.
• tex, or grams per km (how many grams 1 km of roving weighs, inverted from yield; thus a smaller number means a lighter roving). Examples of standard tex are 750tex, 1100tex, 2200tex.

These rovings are then either used directly in a composite application such as pultrusion, filament winding (pipe), gun roving (where an automated gun chops the glass into short lengths and drops it into a jet of resin, projected onto the surface of a mold), or in an intermediary step, to manufacture fabrics such as chopped strand mat (CSM) (made of randomly oriented small cut lengths of fiber all bonded together), woven fabrics, knit fabrics or unidirectional fabrics.

Chopped strand mat

Chopped strand mat or CSM is a form of reinforcement used in fiberglass. It consists of glass fibers laid randomly across each other and held together by a binder.

It is typically processed using the hand lay-up technique, where sheets of material are placed on a mold and brushed with resin. Because the binder dissolves in resin, the material easily conforms to different shapes when wetted out. After the resin cures, the hardened product can be taken from the mold and finished.

Using chopped strand mat gives the fiberglass isotropic in-plane material properties.

Sizing

A coating or primer is applied to the roving to:

• help protect the glass filaments for processing and manipulation.
• ensure proper bonding to the resin matrix, thus allowing for the transfer of shear loads from the glass fibers to the thermoset plastic. Without this bonding, the fibers can 'slip' in the matrix, causing localized failure.

Properties

An individual structural glass fiber is both stiff and strong in tension and compression—that is, along its axis. Although it might be assumed that the fiber is weak in compression, it is actually only the long aspect ratio of the fiber which makes it seem so; i.e., because a typical fiber is long and narrow, it buckles easily. On the other hand, the glass fiber is weak in shear—that is, across its axis. Therefore, if a collection of fibers can be arranged permanently in a preferred direction within a material, and if they can be prevented from buckling in compression, the material will be preferentially strong in that direction.

Furthermore, by laying multiple layers of fiber on top of one another, with each layer oriented in various preferred directions, the material's overall stiffness and strength can be efficiently controlled. In fiberglass, it is the plastic matrix which permanently constrains the structural glass fibers to directions chosen by the designer. With chopped strand mat, this directionality is essentially an entire two-dimensional plane; with woven fabrics or unidirectional layers, directionality of stiffness and strength can be more precisely controlled within the plane.

A fiberglass component is typically of a thin "shell" construction, sometimes filled on the inside with structural foam, as in the case of surfboards. The component may be of nearly arbitrary shape, limited only by the complexity and tolerances of the mold used for manufacturing the shell.

The mechanical functionality of materials is heavily reliant on the combined performances of both the resin (AKA matrix) and fibers. For example, in severe temperature conditions (over 180 °C), the resin component of the composite may lose its functionality, partially due to bond deterioration of resin and fiber. However, GFRPs can still show significant residual strength after experiencing high temperatures (200 °C).

Types of glass fiber used

Composition: the most common types of glass fiber used in fiberglass is E-glass, which is alumino-borosilicate glass with less than 1% w/w alkali oxides, mainly used for glass-reinforced plastics. Other types of glass used are A-glass (Alkali-lime glass with little or no boron oxide), E-CR-glass (Electrical/Chemical Resistance; alumino-lime silicate with less than 1% w/w alkali oxides, with high acid resistance), C-glass (alkali-lime glass with high boron oxide content, used for glass staple fibers and insulation), D-glass (borosilicate glass, named for its low Dielectric constant), R-glass (alumino silicate glass without MgO and CaO with high mechanical requirements as Reinforcement), and S-glass (alumino silicate glass without CaO but with high MgO content with high tensile strength).

Naming and use: pure silica (silicon dioxide), when cooled as fused quartz into a glass with no true melting point, can be used as a glass fiber for fiberglass but has the drawback that it must be worked at very high temperatures. In order to lower the necessary work temperature, other materials are introduced as "fluxing agents" (i.e., components to lower the melting point). Ordinary A-glass ("A" for "alkali-lime") or soda lime glass, crushed and ready to be remelted, as so-called cullet glass, was the first type of glass used for fiberglass. E-glass ("E" because of initial Electrical application), is alkali-free and was the first glass formulation used for continuous filament formation. It now makes up most of the fiberglass production in the world, and also is the single largest consumer of boron minerals globally. It is susceptible to chloride ion attack and is a poor choice for marine applications. S-glass ("S" for "stiff") is used when tensile strength (high modulus) is important and is thus an important building and aircraft epoxy composite (it is called R-glass, "R" for "reinforcement" in Europe). C-glass ("C" for "chemical resistance") and T-glass ("T" is for "thermal insulator"—a North American variant of C-glass) are resistant to chemical attack; both are often found in insulation-grades of blown fiberglass.

Table of some common fiberglass types

Material	Specific gravity	Tensile strength MPa (ksi)	Compressive strength MPa (ksi)
Polyester resin (Not reinforced)	1.28	55 (7.98)	140 (20.3)
Polyester and Chopped Strand Mat Laminate 30% E-glass	1.4	100 (14.5)	150 (21.8)
Polyester and Woven Rovings Laminate 45% E-glass	1.6	250 (36.3)	150 (21.8)
Polyester and Satin Weave Cloth Laminate 55% E-glass	1.7	300 (43.5)	250 (36.3)
Polyester and Continuous Rovings Laminate 70% E-glass	1.9	800 (116)	350 (50.8)
E-Glass Epoxy composite	1.99	1,770 (257)
S-Glass Epoxy composite	1.95	2,358 (342)

Applications

A cryostat made of fiberglass

Fiberglass is an immensely versatile material due to its lightweight, inherent strength, weather-resistant finish and variety of surface textures.

The development of fiber-reinforced plastic for commercial use was extensively researched in the 1930s. It was of particular interest to the aviation industry. A means of mass production of glass strands was accidentally discovered in 1932 when a researcher at Owens-Illinois directed a jet of compressed air at a stream of molten glass and produced fibers. After Owens merged with the Corning company in 1935, Owens Corning adapted the method to produce its patented "Fiberglas" (one "s"). A suitable resin for combining the "Fiberglas" with a plastic was developed in 1936 by du Pont. The first ancestor of modern polyester resins is Cyanamid's of 1942. Peroxide curing systems were used by then.

During World War II, fiberglass was developed as a replacement for the molded plywood used in aircraft radomes (fiberglass being transparent to microwaves). Its first main civilian application was for the building of boats and sports car bodies, where it gained acceptance in the 1950s. Its use has broadened to the automotive and sport equipment sectors. In the production of some products, such as aircraft, carbon fiber is now used instead of fiberglass, which is stronger by volume and weight.

Advanced manufacturing techniques such as pre-pregs and fiber rovings extend fiberglass's applications and the tensile strength possible with fiber-reinforced plastics.

Fiberglass is also used in the telecommunications industry for shrouding antennas, due to its RF permeability and low signal attenuation properties. It may also be used to conceal other equipment where no signal permeability is required, such as equipment cabinets and steel support structures, due to the ease with which it can be molded and painted to blend with existing structures and surfaces. Other uses include sheet-form electrical insulators and structural components commonly found in power-industry products.

Because of fiberglass's lightweight and durability, it is often used in protective equipment such as helmets. Many sports use fiberglass protective gear, such as goaltenders' and catchers' masks.

Storage tanks

Several large fiberglass tanks at an airport

Storage tanks can be made of fiberglass with capacities up to about 300 tonnes. Smaller tanks can be made with chopped strand mat cast over a thermoplastic inner tank which acts as a preform during construction. Much more reliable tanks are made using woven mat or filament wound fiber, with the fiber orientation at right angles to the hoop stress imposed in the sidewall by the contents. Such tanks tend to be used for chemical storage because the plastic liner (often polypropylene) is resistant to a wide range of corrosive chemicals. Fiberglass is also used for septic tanks.

House building

A fiberglass dome house in Davis, California

Glass-reinforced plastics are also used to produce house building components such as roofing laminate, door surrounds, over-door canopies, window canopies and dormers, chimneys, coping systems, and heads with keystones and sills. The material's reduced weight and easier handling, compared to wood or metal, allows faster installation. Mass-produced fiberglass brick-effect panels can be used in the construction of composite housing, and can include insulation to reduce heat loss.

Oil and gas artificial lift systems

In rod pumping applications, fiberglass rods are often used for their high tensile strength to weight ratio. Fiberglass rods provide an advantage over steel rods because they stretch more elastically (lower Young's modulus) than steel for a given weight, meaning more oil can be lifted from the hydrocarbon reservoir to the surface with each stroke, all while reducing the load on the pumping unit.

Fiberglass rods must be kept in tension, however, as they frequently part if placed in even a small amount of compression. The buoyancy of the rods within a fluid amplifies this tendency.

Piping

GRP and GRE pipe can be used in a variety of above- and below-ground systems, including those for:

• desalination
• water treatment
• water distribution networks
• chemical process plants
• water used for firefighting
• hot and cold water
• drinking water
• wastewater/sewage, Municipal waste
• liquified petroleum gas

Examples of fiberglass use

Kayaks made of fiberglass

 

Fiberglass statue, copy of antique Roman bronze statue of winged Victory in the Santa Giulia museum in Brescia.

• DIY bows / youth recurve; longbows
• Pole vaulting poles
• Equipment handles(Hammers, axes, etc.)
• Traffic lights
• Ship hulls
• Rowing shells and oars
• Waterpipes
• Helicopter rotor blades
• Surfboards, tent poles
• Gliders, kit cars, microcars, karts, bodyshells, kayaks, flat roofs, lorries
• Pods, domes and architectural features where a light weight is necessary
• Auto body parts, and entire auto bodies (e.g. Sabre Sprint, Lotus Elan, Anadol, Reliant, Quantum Quantum Coupé, Chevrolet Corvette and Studebaker Avanti, and DMC DeLorean underbody)
• Antenna covers and structures, such as radomes, UHF broadcasting antennas, and pipes used in hex beam antennas for amateur radio communications
• FRP tanks and vessels: FRP is used extensively to manufacture chemical equipment and tanks and vessels. BS4994 is a British standard related to this application.
• Most commercial velomobiles
• Most printed circuit boards consist of alternating layers of copper and fiberglass FR-4
• Large commercial wind turbine blades
• RF coils used in MRI scanners
• Drum Sets
• Sub-sea installation protection covers
• Reinforcement of asphalt pavement, as a fabric or mesh interlayer between lifts
• Helmets and other protective gear used in various sports
• Orthopedic casts
• Fiberglass grating is used for walkways on ships and oil rigs, and in factories
• Fiber-reinforced composite columns
• Water slides
• sculpture making
• Fish ponds or lining cinder block fish ponds.

Construction methods

Filament winding

Filament winding is a fabrication technique mainly used for manufacturing open (cylinders) or closed-end structures (pressure vessels or tanks). The process involves winding filaments under tension over a male mandrel. The mandrel rotates while a wind eye on a carriage moves horizontally, laying down fibers in the desired pattern. The most common filaments are carbon or glass fiber and are coated with synthetic resin as they are wound. Once the mandrel is completely covered to the desired thickness, the resin is cured; often the mandrel is placed in an oven to achieve this, though sometimes radiant heaters are used with the mandrel still turning in the machine. Once the resin has cured, the mandrel is removed, leaving the hollow final product. For some products such as gas bottles, the 'mandrel' is a permanent part of the finished product forming a liner to prevent gas leakage or as a barrier to protect the composite from the fluid to be stored.

Filament winding is well suited to automation, and there are many applications, such as pipe and small pressure vessels that are wound and cured without any human intervention. The controlled variables for winding are fiber type, resin content, wind angle, tow or bandwidth and thickness of the fiber bundle. The angle at which the fiber has an effect on the properties of the final product. A high angle "hoop" will provide circumferential or "burst" strength, while lower angle patterns (polar or helical) will provide greater longitudinal tensile strength.

Products currently being produced using this technique range from pipes, golf clubs, Reverse Osmosis Membrane Housings, oars, bicycle forks, bicycle rims, power and transmission poles, pressure vessels to missile casings, aircraft fuselages and lamp posts and yacht masts.

Fiberglass hand lay-up operation

A release agent, usually in either wax or liquid form, is applied to the chosen mold to allow the finished product to be cleanly removed from the mold. Resin—typically a 2-part thermoset polyester, vinyl, or epoxy—is mixed with its hardener and applied to the surface. Sheets of fiberglass matting are laid into the mold, then more resin mixture is added using a brush or roller. The material must conform to the mold, and air must not be trapped between the fiberglass and the mold. Additional resin is applied and possibly additional sheets of fiberglass. Hand pressure, vacuum or rollers are used to be sure the resin saturates and fully wets all layers, and that any air pockets are removed. The work must be done quickly before the resin starts to cure unless high-temperature resins are used which will not cure until the part is warmed in an oven. In some cases, the work is covered with plastic sheets and vacuum is drawn on the work to remove air bubbles and press the fiberglass to the shape of the mold.

Fiberglass spray lay-up operation

The fiberglass spray lay-up process is similar to the hand lay-up process but differs in the application of the fiber and resin to the mold. Spray-up is an open-molding composites fabrication process where resin and reinforcements are sprayed onto a mold. The resin and glass may be applied separately or simultaneously "chopped" in a combined stream from a chopper gun. Workers roll out the spray-up to compact the laminate. Wood, foam or other core material may then be added, and a secondary spray-up layer imbeds the core between the laminates. The part is then cured, cooled, and removed from the reusable mold.

Pultrusion operation

Diagram of the pultrusion process

Pultrusion is a manufacturing method used to make strong, lightweight composite materials. In pultrusion, material is pulled through forming machinery using either a hand-over-hand method or a continuous-roller method (as opposed to extrusion, where the material is pushed through dies). In fiberglass pultrusion, fibers (the glass material) are pulled from spools through a device that coats them with a resin. They are then typically heat-treated and cut to length. Fiberglass produced this way can be made in a variety of shapes and cross-sections, such as W or S cross-sections.

Warping

One notable feature of fiberglass is that the resins used are subject to contraction during the curing process. For polyester this contraction is often 5–6%; for epoxy, about 2%. Because the fibers do not contract, this differential can create changes in the shape of the part during curing. Distortions can appear hours, days, or weeks after the resin has set.

While this distortion can be minimised by symmetric use of the fibers in the design, a certain amount of internal stress is created; and if it becomes too great, cracks form.

Health hazards

In June 2011, the National Toxicology Program (NTP) removed from its Report on Carcinogens all biosoluble glass wool used in home and building insulation and for non-insulation products. However, NTP considers fibrous glass dust to be "reasonably anticipated [as] a human carcinogen (Certain Glass Wool Fibers (Inhalable))". Similarly, California's Office of Environmental Health Hazard Assessment ("OEHHA") published a November, 2011 modification to its Proposition 65 listing to include only "Glass wool fibers (inhalable and biopersistent)." The actions of U.S. NTP and California's OEHHA mean that a cancer warning label for biosoluble fiber glass home and building insulation is no longer required under federal or California law. All fiberglass wools commonly used for thermal and acoustical insulation were reclassified by the International Agency for Research on Cancer (IARC) in October 2001 as Not Classifiable as to carcinogenicity to humans (Group 3).

People can be exposed to fiberglass in the workplace by breathing it in, skin contact, or eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for fiberglass exposure in the workplace as 15 mg/m³ total and 5 mg/m³ in respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 3 fibers/cm³ (less than 3.5 micrometers in diameter and greater than 10 micrometers in length) as a time-weighted average over an 8-hour workday, and a 5 mg/m³ total limit.

The European Union and Germany classify synthetic vitreous fibers as possibly or probably carcinogenic, but fibers can be exempt from this classification if they pass specific tests. Evidence for these classifications is primarily from studies on experimental animals and mechanisms of carcinogenesis. The glass wool epidemiology studies have been reviewed by a panel of international experts convened by the IARC. These experts concluded: "Epidemiologic studies published during the 15 years since the previous IARC monographs review of these fibers in 1988 provide no evidence of increased risks of lung cancer or mesothelioma (cancer of the lining of the body cavities) from occupational exposures during the manufacture of these materials, and inadequate evidence overall of any cancer risk." A 2012 health hazard review for the European Commission stated that inhalation of fiberglass at concentrations of 3, 16 and 30 mg/m3 "did not induce fibrosis nor tumours except transient lung inflammation that disappeared after a post-exposure recovery period." Similar reviews of the epidemiology studies have been conducted by the Agency for Toxic Substances and Disease Registry ("ATSDR"), the National Toxicology Program, the National Academy of Sciences and Harvard's Medical and Public Health Schools which reached the same conclusion as IARC that there is no evidence of increased risk from occupational exposure to glass wool fibers.

Fiberglass will irritate the eyes, skin, and the respiratory system. Potential symptoms include irritation of eyes, skin, nose, throat, dyspnea (breathing difficulty); sore throat, hoarseness and cough. Scientific evidence demonstrates that fiberglass is safe to manufacture, install and use when recommended work practices are followed to reduce temporary mechanical irritation. Unfortunately these work practices are not always followed, and fiberglass is often left exposed in basements that later become occupied. Fiberglass insulation should never be left exposed in an occupied area, according to the American Lung Association.

While the resins are cured, styrene vapors are released. These are irritating to mucous membranes and respiratory tract. Therefore, the Hazardous Substances Ordinance in Germany dictates a maximum occupational exposure limit of 86 mg/m³. In certain concentrations, a potentially explosive mixture may occur. Further manufacture of GRP components (grinding, cutting, sawing) creates fine dust and chips containing glass filaments, as well as tacky dust, in quantities high enough to affect health and the functionality of machines and equipment. The installation of effective extraction and filtration equipment is required to ensure safety and efficiency.