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Polyoxymethylene (POM), also known as acetal, polyacetal, and polyformaldehyde, is an engineering
thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...
used in precision parts requiring high stiffness, low
friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...
, and excellent dimensional stability. As with many other synthetic
polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s, it is produced by different chemical firms with slightly different formulas and sold variously by such names as Delrin, Kocetal, Ultraform, Celcon, Ramtal, Duracon, Kepital, Polypenco, Tenac and Hostaform. POM is characterized by its high strength, hardness and rigidity to −40 °C. POM is intrinsically opaque white because of its high crystalline composition but can be produced in a variety of colors. POM has a density of 1.410–1.420g/cm3. Typical applications for
injection-molded Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...
POM include high-performance engineering components such as small gear wheels, eyeglass frames,
ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...
s,
ski binding A ski binding is a device that connects a ski boot to the ski. Before the 1933 invention of ski lifts, skiers went uphill and down and cross-country on the same gear. As ski lifts became more prevalent, skis—and their bindings—became increasin ...
s, fasteners,
gun A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch projectiles. The projectiles are typically solid, but can also be pressurized liquid (e.g. in water guns/cannons, spray guns for painting or pressure washing, p ...
parts, knife handles, and lock systems. The material is widely used in the automotive and
consumer electronics Consumer electronics or home electronics are electronic ( analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usuall ...
industry. POM's electrical resistivity is 14×1015 Ω⋅cm making it a dielectric with a 19.5 MV/m breakdown voltage.


Development

Polyoxymethylene was discovered by Hermann Staudinger, a German chemist who received the 1953
Nobel Prize in Chemistry ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then "M ...
. He had studied the
polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...
and structure of POM in the 1920s while researching
macromolecules A macromolecule is a very large molecule important to biophysical processes, such as a protein or nucleic acid. It is composed of thousands of covalently bonded atoms. Many macromolecules are polymers of smaller molecules called monomers. The ...
, which he characterized as polymers. Due to problems with
thermostability In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature. ...
, POM was not commercialized at that time. Around 1952, research chemists at DuPont synthesized a version of POM, and in 1956 the company filed for patent protection of the
homopolymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic an ...
. DuPont credits R. N. MacDonald as the inventor of high-molecular-weight POM. Patents by MacDonald and coworkers describe the preparation of high-molecular-weight
hemiacetal A hemiacetal or a hemiketal has the general formula R1R2C(OH)OR, where R1 or R2 is hydrogen or an organic substituent. They generally result from the addition of an alcohol to an aldehyde or a ketone, although the latter are sometimes called hemi ...
-terminated (~O−CH2OH) POM, but these lack sufficient thermal stability to be commercially viable. The inventor of a heat-stable (and therefore useful) POM homopolymer was Stephen Dal Nogare, who discovered that reacting the hemiacetal ends with acetic anhydride converts the readily depolymerizable hemiacetal into a thermally stable, melt-processable plastic. In 1960, DuPont completed construction of a plant to produce its own version of acetal resin, named ''Delrin'', at Parkersburg, West Virginia. Also in 1960,
Celanese Celanese Corporation, formerly known as Hoechst Celanese, is an American technology and specialty materials company headquartered in Irving, Texas. A Fortune 500 corporation, the company is the world’s leading producer of acetic acid, prod ...
completed its own research. Shortly thereafter, in a limited partnership with the
Frankfurt Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...
firm
Hoechst AG Hoechst AG () was a German chemicals then life-sciences company that became Aventis Deutschland after its merger with France's Rhône-Poulenc S.A. in 1999. With the new company's 2004 merger with Sanofi-Synthélabo, it became a subsidiary of th ...
, a factory was built in
Kelsterbach Kelsterbach () is a town in Groß-Gerau district in Hessen, Germany and part of the Frankfurt Rhein-Main urban area. It is located on Frankfurt's southwestern outskirts at a bend on the left bank of the river Main, right where a small brook, ca ...
,
Hessen Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are Darms ...
; from there, ''Celcon'' was produced starting in 1962, with ''Hostaform'' joining it a year later. Both remain in production under the auspices of
Celanese Celanese Corporation, formerly known as Hoechst Celanese, is an American technology and specialty materials company headquartered in Irving, Texas. A Fortune 500 corporation, the company is the world’s leading producer of acetic acid, prod ...
and are sold as parts of a product group now called 'Hostaform/Celcon POM''.


Production

Different manufacturing processes are used to produce the homopolymer and copolymer versions of POM.


Homopolymer

To make polyoxymethylene
homopolymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic an ...
, anhydrous
formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
must be generated. The principal method is by reaction of the aqueous formaldehyde with an alcohol to create a hemiformal, dehydration of the hemiformal/water mixture (either by extraction or
vacuum distillation Vacuum distillation is distillation performed under reduced pressure, which allows the purification of compounds not readily distilled at ambient pressures or simply to save time or energy. This technique separates compounds based on differences i ...
) and release of the formaldehyde by heating the hemiformal. The formaldehyde is then polymerized by anionic catalysis, and the resulting polymer stabilized by reaction with acetic anhydride. Due to the manufacturing process, large-diameter cross-sections may have pronounced centerline porosity. A typical example is DuPont's Delrin.


Copolymer

The polyoxymethylene
copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...
replaces about 1–1.5% of the −CH2O− groups with −CH2CH2O−. To make polyoxymethylene
copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...
, formaldehyde is generally converted to
trioxane Trioxane refers to any of three isomeric organic compounds composed of a six-membered ring with three carbon atoms and three oxygen atoms, having the molecular formula C3H6O3. The three isomers are: * 1,2,3-trioxane, a hypothetical compound rela ...
(specifically
1,3,5-trioxane 1,3,5-Trioxane, sometimes also called trioxane or trioxin, is a chemical compound with molecular formula CHO. It is a white, highly water-soluble solid with a chloroform-like odor. It is a stable cyclic trimer of formaldehyde, and one of the th ...
, also known as trioxin). This is done by
acid catalysis In acid catalysis and base catalysis, a chemical reaction is catalyzed by an acid or a base. By Brønsted–Lowry acid–base theory, the acid is the proton (hydrogen ion, H+) donor and the base is the proton acceptor. Typical reactions catalyze ...
(either sulfuric acid or acidic
ion-exchange resins An ion-exchange resin or ion-exchange polymer is a resin or polymer that acts as a medium for ion exchange. It is an insoluble matrix (or support structure) normally in the form of small (0.25–1.43 mm radius) microbeads, usually white or ye ...
) followed by purification of the trioxane by distillation and/or extraction to remove water and other active hydrogen-containing impurities. Typical copolymers are Hostaform from
Celanese Celanese Corporation, formerly known as Hoechst Celanese, is an American technology and specialty materials company headquartered in Irving, Texas. A Fortune 500 corporation, the company is the world’s leading producer of acetic acid, prod ...
and Ultraform from
BASF BASF SE () is a German multinational chemical company and the largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The BASF Group comprises subsidiaries and joint ventures in more than 80 countries ...
. The
co-monomer In polymer chemistry, a comonomer refers to a polymerizable precursor to a copolymer aside from the principal monomer. In some cases, only small amounts of a comonomer are employed, in other cases substantial amounts of comonomers are used. Furthe ...
is typically
dioxolane Dioxolane is a heterocyclic acetal with the chemical formula (CH2)2O2CH2. It is related to tetrahydrofuran by interchange of one oxygen for a CH2 group. The corresponding saturated 6-membered C4O2 rings are called dioxanes. The isomeric 1,2-diox ...
, but
ethylene oxide Ethylene oxide is an organic compound with the formula . It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sw ...
can also be used. Dioxolane is formed by reaction of
ethylene glycol Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...
with aqueous formaldehyde over an acid catalyst. Other diols can also be used. Trioxane and dioxolane are polymerized using an acid catalyst, often boron trifluoride etherate, BF3OEt2. The polymerization can take place in a non-polar solvent (in which case the polymer forms as a slurry) or in neat trioxane (e.g. in an extruder). After polymerization, the acidic catalyst must be deactivated and the polymer stabilized by melt or solution hydrolysis to remove unstable end groups. Stable polymer is melt-compounded, adding thermal and oxidative stabilizers and optionally lubricants and miscellaneous fillers.


Fabrication

POM is supplied in a granulated form and can be formed into the desired shape by applying heat and pressure. The two most common forming methods employed are injection molding and
extrusion Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...
.
Rotational molding Rotational molding (BrE: moulding) involves a heated mold which is filled with a charge or shot weight of material. It is then slowly rotated (usually around two perpendicular axes), causing the softened material to disperse and stick to the ...
and
blow molding Blow molding (or moulding) is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes. In general, there are three main types of blow molding: extrusion blow molding, injectio ...
are also possible. Typical applications for injection-molded POM include high-performance engineering components (e.g. gear wheels, ski bindings,
yoyo A yo-yo (also spelled yoyo) is a toy consisting of an axle connected to two disks, and a string looped around the axle, similar to a spool. It is an ancient toy with proof of existence since 500 BCE. The yo-yo was also called a bandalore in ...
s, fasteners, lock systems). The material is widely used in the automotive and consumer electronics industry. There are special grades that offer higher mechanical toughness, stiffness or low-friction/wear properties. POM is commonly extruded as continuous lengths of round or rectangular section. These sections can be cut to length and sold as bar or sheet stock for machining.


Machining

When supplied as extruded bar or sheet, POM may be machined using traditional methods such as turning, milling, drilling etc. These techniques are best employed where production economics do not merit the expense of melt processing. The material is free-cutting, but does require sharp tools with a high clearance angle. The use of soluble cutting lubricant is not necessary, but is recommended. POM sheets can be cut cleanly and accurately using an infrared laser, such as in a CO2
laser cutter A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...
. Because the material lacks the rigidity of most metals, care should be taken to use light clamping forces and sufficient support for the work piece. As can be the case with many polymers, machined POM can be dimensionally unstable, especially with parts that have large variations in wall thicknesses. It is recommended that such features be "designed-out" e.g. by adding fillets or strengthening ribs. Annealing of pre-machined parts before final finishing is an alternative. A rule of thumb is that in general, small components machined in POM suffer from less warping.


Bonding

POM is typically very difficult to bond, with the copolymer typically responding worse to conventional adhesives than the homopolymer. Special processes and treatments have been developed to improve bonding. Typically these processes involve surface etching, flame treatment, using a specific primer/adhesive system, or mechanical abrasion. Typical etching processes involve
chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixtu ...
at elevated temperatures. DuPont uses a patented process for treating acetal homopolymer called satinizing that creates a surface roughness sufficient for micromechanical interlocking. There are also processes involving oxygen plasma and corona discharge. In order to get a high bond strength without specialized tools, treatments, or roughening, one can use Loctite 401 prism adhesive combined with Loctite 770 prism primer to get bond strengths of ~1700psi. Once the surface is prepared, a number of adhesives can be used for bonding. These include
epoxies The Epoxies were an American new wave band from Portland, Oregon, formed in 2000. Heavily influenced by new wave, the band jokingly described themselves as robot garage rock. Members included FM Static on synthesizers, guitarist Viz Spectrum, ...
,
polyurethanes Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from ...
, and
cyanoacrylates Cyanoacrylates are a family of strong fast-acting adhesives with industrial, medical, and household uses. They are derived from ethyl cyanoacrylate and related esters. The cyanoacrylate group in the monomer rapidly polymerizes in the presenc ...
. Epoxies have shown shear strength. Cyanoacrylates are useful for bonding to metal, leather, rubber, cotton, and other plastics.
Solvent welding Plastic welding is welding for semi-finished plastic materials, and is described in ISO 472 as a process of uniting softened surfaces of materials, generally with the aid of heat (except solvent welding). Welding of thermoplastics is accomplishe ...
is typically unsuccessful on acetal polymers, due to the excellent solvent resistance of acetal. Thermal welding through various methods has been used successfully on both homopolymer and copolymer.


Usage

* Mechanical
gears A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic p ...
, sliding and guiding elements, housing parts, springs,
chains A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A c ...
, screws, nuts, fan wheels, pump parts, valve bodies. * Electrical engineering:
insulators Insulator may refer to: * Insulator (electricity), a substance that resists electricity ** Pin insulator, a device that isolates a wire from a physical support such as a pin on a utility pole ** Strain insulator, a device that is designed to work ...
, bobbins, connectors, parts for electronic devices such as
televisions Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...
,
telephones A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into ele ...
, etc. * Vehicle: fuel sender unit, light/control stalk/combination switch (including shifter for light, turn signal), power windows, door lock systems, articulated shells. * Model: model railway parts, such as trucks (bogies) and hand rails (handle bars). POM is tougher than ABS, comes in bright translucent colors, and is not paintable. * Hobbies:
radio-controlled helicopter A radio-controlled helicopter (also '' RC helicopter'') is model aircraft which is distinct from a RC airplane because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of w ...
main gear, landing skid,
yo-yo A yo-yo (also spelled yoyo) is a toy consisting of an axle connected to two disks, and a string looped around the axle, similar to a spool. It is an ancient toy with proof of existence since 500 BCE. The yo-yo was also called a bandalore in ...
s, vaping drip tips, 3D printer wheels,
K'Nex K'Nex is a construction toy system founded by Joel Glickman. It was first introduced in America in 1992. K'Nex is designed and produced by K'Nex Industries Inc. of Hatfield, Pennsylvania. K'Nex was purchased by Florida-based company Basic Fun ...
, ball-jointed dolls, etc. * Medical: insulin pen, metered dose inhalers (MDI). * Food industry:
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
has approved some grades of POM for milk pumps, coffee spigots, filter housings and food conveyors. * Furniture: hardware,
locks Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock ...
,
handles A handle is a part of, or attachment to, an object that allows it to be grasped and manipulated by hand. The design of each type of handle involves substantial ergonomic issues, even where these are dealt with intuitively or by following t ...
, hinges., rollers for sliding mechanisms of furnitures * Construction: structural glass - pod holder for point * Packaging: aerosol cans, vehicle tanks. * Pens: used as the material for pen bodies and caps * Sports: paintball accessories. It is often used for machined parts of paintball markers that do not require the strength of aluminium, such as handles and reciprocating bolts. POM is also used in airsoft guns to reduce piston noise. *
Longboarding Longboarding is typically defined as a variation of skateboarding that involves a larger board and softer urethane wheels. Longboards vary in shape and size. Compared to skateboards, longboards are more stable at speed and have more traction, du ...
: puck material for slide gloves help the rider touch the road and lean on their hand to slow down, stop, or perform tricks. * Clothing:
zippers A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding together two edges of fabric or other flexible material. Used in clothing (e.g. jackets and jeans), luggage and other bags, camping ...
. * Music: picks, Irish flutes, bagpipes,
practice chanter A bagpipe practice chanter is a double-reed woodwind instrument, principally used as an adjunct to the Great Highland bagpipe. As its name implies, the practice chanter serves as a practice instrument: firstly for learning to finger the differe ...
s, harpsichord plectra, instrument mouthpieces, tips of some drum sticks. * Dining: fully automatic coffee brewers; knife handles (particularly folding knives). *
Horology Horology (; related to Latin '; ; , interfix ''-o-'', and suffix ''-logy''), . is the study of the measurement of time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clo ...
: mechanical movement parts (e.g. Lemania 5100), watch bracelets (e.g. IWC
Porsche Design Porsche Design is a German product design studio and brand founded in 1972 by F. A. Porsche, the designer of the original Porsche 911, known for its high-end accessories including sunglasses, pens, and watches. The current legal instantiation of ...
3701). * Vapor/e-cigarette accessories: material used in the manufacturing of most "Drip Tips" (Mouthpiece). * Tobacco products: The BIC Group uses Delrin for their lighters. *Keyboard
keycap A keycap is a small cover of plastic, metal, or other material placed over the keyswitch of a computer keyboard. Keycaps are often illustrated to indicate the key function or alphanumeric Alphanumericals or alphanumeric characters are a co ...
s: Cherry uses POM for their G80 and G81 series keyboards.


Degradation

Acetal resins are sensitive to acid
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...
and
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
by agents such as
mineral acid A mineral acid (or inorganic acid) is an acid derived from one or more inorganic compounds, as opposed to organic acids which are acidic, organic compounds. All mineral acids form hydrogen ions and the conjugate base when dissolved in water. Cha ...
and
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
. POM homopolymer is also susceptible to alkaline attack and is more susceptible to degradation in hot water. Thus low levels of chlorine in potable water supplies (1–3 ppm) can be sufficient to cause environmental stress cracking, a problem experienced in both the US and Europe in domestic and commercial water supply systems. Defective mouldings are most sensitive to cracking, but normal mouldings can succumb if the water is hot. Both POM homopolymer and copolymer are stabilized to mitigate these types of degradation. In chemistry applications, although the polymer is often suitable for the majority of glassware work, it can succumb to catastrophic failure. An example of this would be using the polymer clips on hot areas of the glassware (such as a flask-to-column, column-to-head or head-to-condenser joint during distillation). As the polymer is sensitive to both chlorine and acid hydrolysis, it may perform very poorly when exposed to the reactive gases, particularly
hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...
(
HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a spe ...
). Failures in this latter instance can occur with seemingly unimportant exposures from well sealed joints and do so without warning and rapidly (the component will split or fall apart). This can be a significant health hazard, as the glass may open or smash. Here, PTFE or a high-grade stainless steel may be a more appropriate choice. In addition, POM can have undesirable characteristics when burned. The flame is not self-extinguishing, shows little to no smoke, and the blue flame can be almost invisible in ambient light. Burning also releases
formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
gas, which irritates nose, throat, and eye tissues.


See also

* Dalziel Hammick *
Forensic engineering Forensic engineering has been defined as ''"the investigation of failures - ranging from serviceability to catastrophic - which may lead to legal activity, including both civil and criminal".'' It includes the investigation of materials, produc ...
*
Forensic polymer engineering Forensic polymer engineering is the study of failure in polymeric products. The topic includes the fracture of plastic products, or any other reason why such a product fails in service, or fails to meet its specification. The subject focuses on t ...
*
Paraformaldehyde Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraf ...
*
Polymer degradation Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycl ...
*
Resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...


References


External links

* * * * {{Plastics DuPont products Plastics Polyethers Thermoplastics