Acrylic plastics poly

The acrylic plastics use the term acryl such as polymethyl methacrylate (PMMA), polyacrylic acid, polymethacrytic acid, poly-R acrylate, poly-R methacrylate, polymethylacrylate, polyethylmethacrylate, and cyanoacrylate plastics. PMMA is the major and most important homopolymer in the series of acrylics with a sufficient high glass transition temperature to form useful products. Repeat units of the other types are used. Ethylacrylate repeat units form the major component in acrylate rubbers. PMMAs have high optical clarity, excellent weatherability, very broad color range, and hardest surface of any untreated thermoplastic. Chemical, thermal and impact properties are good to fair. Acrylics will fail in a brittle manner, independent of the temperature. They will suffer crazing when loaded at stress about halfway to the failure level. This effect is enhanced by the presence of solvents. 

Poly acrylates. A sub-group of acrylic plastics comprising homopolymers and copolymers of acrylic esters. Solutions and dispersions of polyacrylates are mainly used for manufacturing paints, varnishes, finishes, and adhesives. 

Poly(acrylates) and poly(methacrylates) are commercially important polymers with a myriad of uses, including paper and textile coatings, adhesives, caulks and sealants, plasticizers, paint and ink additives, and optical components for computer displays. Since they are derived from monosubsti-tuted and unsymmetrical 1,1-disubstituted vinyl monomers, poly(acrylate) and poly(methacrylate) products with a spectrum of tacticities and thereby mechanical properties are potentially accessible. To date, however, industrially produced materials are generated using free-radical polymerization technology, which offers limited scope for tacticity control. Therefore, there has been much interest in the development of metal-catalyzed routes to these polymers where the coordination environment of the metal offers the potential to influence tacticity. 

Furthermore, the C=C bonds in the natural rubber structure might induce poor thermal and oxidative resistance in the natural rubber blends. Thus, Thawornwisit and coworkersproposed the preparation of hydrogenated natural rubber, which is one of the chemical modifications available to improve the oxidation and thermal resistance of diene-based natural rubber before blending with poly(methyl methacrylate-co-styrene). The poly(methyl methacrylate-co-styrene) was resistant to the outdoor environment and had excellent optical properties with a high refractive index, but it was extremely brittle and had low impact strength. Hydrogenated natural rubber could, however, be used as an impact modifier, as well as to improve its thermal and oxidative resistance for these acrylic plastics. 

As mentioned in the previous section, it is common practice to plasticize poly(vinyl acetate) intended for surface coatings by such materials as dibutyl phthalate, A limitation of external plasticizers of this kind is that they may eventually be lost by evaporation or by migration into the substrate, leaving an imperfect and brittle film. This limitation may be overcome by the use of copolymers and these are now widely used in surface coatings and other applications. Comonomers which may be employed for this purpose include alkyl (commonly 2-ethylhexyl) acrylates, fumarates and maleates. Typically, the copolymers contain 15—20% by weight of such comonomers. These... 

There are presently about 100 different plasticizers produced worldwide, although only about 50 of these are classified as commercially important. Of these 50 products, just 7 plasticizers comprise more than 80% of the global plasticizer market. Approximately 90% of all plasticizers are used in the production of plasticized or flexible PVC materials. For this reason, the majority of the information discussed in this chapter will focus on PVC plasticizers. Other polymer systems that use small amounts of plasticizers include poly (vinyl butyral) or PVB, acrylic polymers, poly(vinylidene chloride), nylon, polyolefins, polyurethanes, and certain fluoroplastics. The estimated worldwide production of plasticizers in 2014 was about 14 billion pounds [6] with the majority of the plasticizer consumption taking place in Asia Pacific, predominately China. About 75% of this volume is phthalate ester plasticizers. 

Molding and Extrusion Compounds D4802 Poly (Methyl Methacrylate) Acrylic Plastic Sheet... 

Thus, acrylics are used for such diverse products as pressure-sensitive and structural adhesives, coatings, and rigid plastics. Because of their low 7, poly(ethyl acrylate) and poly (butyl acrylate) are used in acrylate-based rubbers. 

Thermoplastics are resins that repeatedly soften when heated and harden when cooled (conditions that refer to fusibility ). Most thermoplastics are soluble in specific solvents and can bum to some degree. Softening temperatures vary with the polymer type and grade. Care must be taken in application conditions not to exceed the heat distortion temperature of the plastic, wherein the plastic begins to soften and potentially warp. Typical thermoplastics utilized in the automotive arena include, poly(olefins)—for example, poly(propylene) (PP) and poly(ethyl-ene)—nylon, acrylic, acetal, poly(styiene), poly(vinyl chloride) (PVC), poly-(sulfone), and the like. Also within this group are highly elastic, flexible resins known as thermoplastic elastomers (TPEs). 

Complex reflectors within new vehicle headlamp assemblies typically must withstand temperatures of up to 400°F. Appropriate thermoplastic materials must be selected not only for the lamp backcan and lens, but also for the electronic/electrical connectors. Variations on filled polyester, poly(imides), bulk molding compound (a sheet molding compound [SMC] analogue), and nylon/poly(phenylene oxide) alloys are typically utilized in these applications. Poly(carbonate) (PC) or impact-modified PC is typically used in the lens applications where high heat is required. Acrylic plastics can and are most typically utilized in lens apphcations that do not require high heat, such as rear stop mount designs. 

Acrylic ESTER POLYMERS Acrylonitrile POLYMERS Cellulose esters). Engineering plastics (qv) such as acetal resins (qv), polyamides (qv), polycarbonate (qv), polyesters (qv), and poly(phenylene sulfide), and advanced materials such as Hquid crystal polymers, polysulfone, and polyetheretherketone are used in high performance appHcations they are processed at higher temperatures than their commodity counterparts (see Polymers containing sulfur). 

Functional derivatives of polyethylene, particularly poly(vinyl alcohol) and poly(acryLic acid) and derivatives, have received attention because of their water-solubility and disposal iato the aqueous environment. Poly(vinyl alcohol) is used ia a wide variety of appHcations, including textiles, paper, plastic films, etc, and poly(acryLic acid) is widely used ia detergents as a builder, a super-absorbent for diapers and feminine hygiene products, for water treatment, ia thickeners, as pigment dispersant, etc (see Vinyl polymers, vinyl alcohol polymers). 

The thermoplastic or thermoset nature of the resin in the colorant—resin matrix is also important. For thermoplastics, the polymerisation reaction is completed, the materials are processed at or close to their melting points, and scrap may be reground and remolded, eg, polyethylene, propjiene, poly(vinyl chloride), acetal resins (qv), acryhcs, ABS, nylons, ceUulosics, and polystyrene (see Olefin polymers Vinyl polymers Acrylic ester polymers Polyamides Cellulose ESTERS Styrene polymers). In the case of thermoset resins, the chemical reaction is only partially complete when the colorants are added and is concluded when the resin is molded. The result is a nonmeltable cross-linked resin that caimot be reworked, eg, epoxy resins (qv), urea—formaldehyde, melamine—formaldehyde, phenoHcs, and thermoset polyesters (qv) (see Amino resins and plastics Phenolic resins). 

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