Thermoplastics acetal homopolymer

Classification Thermoplastic polymer Definition Acetal homopolymer with random ethylene oxide throughout chain Formuia [CH20]x[CH2CH0]y Properties Highly cryst. thermoplastic si. char.odor insol. in water dens. 1.250 flash pt. 

Acetal copolymer Acetal homopolymer Polyethylene, ultrahigh m.w. high-density Polyurethane, cast elastomer pPDI-PTMEG rollers, abrasion-resistant Polyurethane elastomer, thermoplastic roofing... 

Acetal, Homopolymer (POM Homopolymer) Nylon 56 (PA 66) Polyamide, Nylon Polyethylene Terephthalate (PET) 9 9 9 g Polystyrene, Impact (IPS) Polyvlnylldene Chloride (PVDC) Rigid Thermoplastic Urethane (RTPU) Styrene Acrylonitrile Copolymer (SAN) 3 8 9 3-9 Polystyrene (PS) Polyvlnylldene Chloride (PVDC) Styrene Acrylonitrile Copolymer (SAN) Trifluoroethanol 5 5-7 7... 

Polyacetals prepared from formaldehyde are engineering thermoplastics, which have found use in traditional metal applications. Some trade names of these polymers are Delrin acetal homopolymer (DuPont) Celcon acetal copolymer (Celanese/Hoechst) Duracon acetal copolymer (Celanese and Diacel—joint venture) Tenac acetal homopolymer by Asahi Chemical in Japan and Ultraform acetal copolymer jointly by BASF and Degussa, in Germany. The polymers have the basic structure shown below ... 

Acetal homopolymer is a highly crystalline thermoplastic manufactured by polymerization of formaldehyde and capping the two ends of the polymer chain with acetate groups (Table 6.2). It is called polyoxymethylene (POM) and has a backbone consisted of repeating —CH2O—units. Acetal copolymers are produced by copolymerization of trioxane and small amounts of a comonomer. The comonomer randomly distributes carbon—carbon bonds in the polymer chain, which stabilizes the resin against environmental degradation. The low cost of acetals compared to other polymers with similar performance and their mechanical, chemical, and electrical properties, allows them to replace metal and other structural materials in many applications. 

RESINS (Acetal). These are thermoplastic resins, obtainable both as homopolymers and copolymers, and produced principally from formaldehyde or formaldehyde derivative. Acetal resins have the highest fatigue endurance of commercial thermoplastics. A variety of ionic initiators, such as tertiary amines and quaternary ammonium salts, are used to effect polymerization of formaldehyde. Chain transfer, shown by the following reactions, controls the molecular weight of resulting resins ... 

Adhesive Emulsions. Thermoplastic, synthetic polymers can be prepared as emulsions for use as adhesives. For example, while EVAc hot-melt adhesives described in the previous section contain less than 40% VAc, when the content of VAc in the copolymer is increased to 60%, and the copolymer is prepared in the form of aqueous emulsions, a very useful and versatile adhesive polymer is obtained. Although the VAc homopolymer, poly(vinyl acetate), is a brittle solid, with a Tg = 28 °C, the ethylene units present in the EVAc copolymer act as an internal plasticizer, and lower the Tg to below room temperature. The plasticization results from the reduction of interchain interaction of the VAc polymer chains by the ethylene units interspersed among the strongly interacting VAc units. This reduction of the Tg has important consequences because the formation of a flexible adhesive film from the emulsion depends upon the Tg of the polymer. 

Polyoxymethylene polymers, POM, commonly known as polyacetals or Acetal resins are linear thermoplastic polymers containing predominantly the -CH -O- repeat unit in their backbone. There are two types of acetal resins available commercially (1) homopolymers made by the polymerization of formaldehyde, followed by endcapping, (2) copolymers derived from the ring opening polymerization of trioxane (a cyclic trimer of formaldehyde), and a small amount of a comonomer such as ethylene oxide. Acetal resins are... 

The polymerization of allyl esters of saturated monobasic acids, e.g., allyl acetate and allyl laurate, yields linear thermoplastic polymers containing 5-20 monomer units per molecule. These homopolymers and copolymers with vinyl monomers such as vinyl acetate, vinyl chloride, and vinylidene cliloride have been used as thermoplastic adhesives and plasticizers. 

EVA copolymers represent the largest-volume segment of ethylene copolymer market and are the products of low-density polyethylene (LDPE) technology. Commercial preparation of EVA copolymer is based on the same process as LDPE with the addition of controlled comonomer stream into the reactor. EVA copolymers are thermoplastic materials consisting of an ethylene chain incorporating 5-20 mol% vinyl acetate (VA), in general. The VA produces a copolymer with lower crystallinity than conventional ethylene homopolymer. 

Vinyl Acetate Copolymers. Copolymerization of vinyl acetate with other monomers allows specific improvement of certain properties. Copolymers generally exhibit a broader compatibility than the homopolymer. For example, softer, permanently flexible polymers with a lower water uptake and higher alkali resistance are obtained by polymerizing vinyl acetate with vinyl laurate. On account of their thermoplastic properties these copolymers are used in heat-sealable finishes on paper, cardboard, and aluminum foil. In cellulose nitrate lacquers they increase adhesion, lightfastness, and the body fullness of the paint film. They can also be used for priming coats and for stabilizing porous or absorbent substrates. 

Most thermoplastics begin with poly and then this term, which means many is followed by the old fashioned name for the monomer from which the plastic is derived i.e the name is source-based. Because of this practice we get names such as polystyrene and polyethylene for homopolymers. When the plastics material has more than one word in the name, parentheses, or brackets, may be put around the words so that we get poly (vinyl chloride). However this practice is not universal and so we also meet the same term without the brackets i.e. polyvinyl chloride. Source-based nomenclature is not however, universally used and so names such as acetals and cellulosics are also encountered. Other, more logical systems of nomenclature have been proposed but as yet, they have not been adopted,... 

These thermoplastics have properties which are superior to those of commodity plastics (namely, olefinics and styrenics). They go into a number of engineering applications and are termed engineering thermoplastics. Besides polyamides (nylons) and polyesters, some of the other homopolymers which fall into this category of engineering thermoplastics are the acrylics, acetals and polycarbonates. 

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