Acrylic plastics properties

Certain polymers have come to be considered standard building blocks of the polyblends. For example, impact strength may be improved by using polycarbonate, ABS and polyurethanes. Heat resistance is improved by using polyphenylene oxide, polysulphone, PVC, polyester (PET and PBT) and acrylic. Barrier properties are improved by using plastics such as ethylene vinyl alchol (EVA). Some modem plastic alloys and their main characteristics are given in Table 1.2. 

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. 

Electrode Assembly. This device consists of a specially machined Teflon electrode holder, two disc electrodes (only one is energized), and a clamp machined from acrylic plastic (Figure 3). The electrode discs are of low-temperature isotropic carbon alloyed with SiC (Carbo-metics, Austin, TX). They were originally developed for use in artificial heart valves (14), and are approximately 1.6 cm in diameter and 1.25 mm thick, and have the surface properties of glassy carbon. Treatment of the discs requires only polishing to a high lustre with diamond grinding compounds of 14,000 and 50,000 mesh. 

Features Improves adhesion esp. for difficult substrates compat. with most plasticizers, acrylics, nitrocellulose Properties Off-wh. solid sol. in alcohols, esters, ketones, aromatic soivs. insol. in aliphatic hydrocarbons soften, pt. (B R) 68-76 C 100% solids... 

Uses Epoxy-acrylic tor overprint varnishes, inks, coatings tor paper, paperboard, wood, chipboard, and rigid plastics Properties Gardner 1 color m.w. 525 vise. 7500 cps acid no. 1 tens, str. 27,400 psi tens, elong. 4%... 

Uses Acrylic for mfg. of elastic top coats for crack-bridging paints, syn. resin plasters, coatings on aerated concrete and primers, and for washproof finishing, coating, and lamination of textiles and non-wovens Features Free from film-forming aids, soivs., and plasticizers Properties Whitish liq. ammonia odor dilutable in water dens. 1.05-... 

Chem. Descrip. Dioctyl maleate CAS 2915-53-9 EINECS/ELINCS 220-835-6 Uses Comonomer used in polymerization with vinyl acetate, vinyl chloride, styrene and derivs. of acrylic and methacrylic acids used in latex paints, textiles as specialty plasticizer Properties APHA50 max. liq. m.w. 340 sp.gr. 0.939-0.944 vise. 9.1-9.5 cs (100 F) pour pt. -75 F acid no. 0.10 max. flash pt. (COC) 370 F ref. index 1.452-1.454 94% act. 

Table A.3 Properties of Several Types of Acrylic Plastics...

Volume 1 of this book is comprised of 25 chapters, and discusses the different types of natural rubber based blends and IPNs. The first seven chapters discuss the general aspects of natural rubber blends like their miscibility, manufacturing methods, production and morphology development. The next ten chapters describe exclusively the properties of natural rubber blends with different polymers like thermoplastic, acrylic plastic, block or graft copolymers, etc. Chapter 18 deals entirely with clay reinforcement in natural rubber blends. Chapters 19 to 23 explain the major techniques used for characterizing various natural rubber based blends. The final two chapters give a brief explanation of life cycle analysis and the application of natural rubber based blends and IPNs. 

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. 

Example 2 Bending of bars (see Fig. 3-60). To illustrate the design procedure, assume the bar in this figure is made of an acrylic plastic whose modulus-time properties are those shown in Figure 3-59. Assume that the maximum permissible deflection of the middle of the bar during one year s service is 0.15 in. and that the problem is to find the maximum permissible value of bending moment M or load W. 

Acrylic Polymers. Although considerable information on the plasticization of acryUc resins is scattered throughout journal and patent hterature, the subject is compHcated by the fact that acryUc resins constitute a large family of polymers rather than a single polymeric species. An infinite variation in physical properties may be obtained through copolymerization of two or more acryUc monomers selected from the available esters of acryUc and methacryhc acid (30) (see Acrylic esterpolya rs Methacrylic acid and derivatives). 

Low Temperature Properties. Medium hardness compounds of average methyl acrylate, ie, VAMAC G, without a plasticizer typically survive 180° flex tests at —40° C. Such performance is good for a heat-resistant polymer. Low temperature properties can be greatly enhanced by the use of ester plasticizers (10). Careful selection of the plasticizer is necessary to preserve the heat resistance performance of the polymer. Plasticized high methyl acrylate grades lose only a few °C in flexibiUty, compared to grades with average methyl acrylate levels. 

Today a very wide range of acrylic materials is available with a broad property spectrum. The word acrylic, often used as a noun as well as an adjective in everyday use, can mean quite different things to different people. In the plastics industry it is commonly taken to mean poly(methyl methacrylate) plastics, but the word has different meanings, to the fibre chemist and to those working in the paint and adhesives industries. Unless care is taken this may be a source of some confusion. 

Among the different pressure sensitive adhesives, acrylates are unique because they are one of the few materials that can be synthesized to be inherently tacky. Indeed, polyvinylethers, some amorphous polyolefins, and some ethylene-vinyl acetate copolymers are the only other polymers that share this unique property. Because of the access to a wide range of commercial monomers, their relatively low cost, and their ease of polymerization, acrylates have become the dominant single component pressure sensitive adhesive materials used in the industry. Other PSAs, such as those based on natural rubber or synthetic block copolymers with rubbery midblock require compounding of the elastomer with low molecular weight additives such as tackifiers, oils, and/or plasticizers. The absence of these low molecular weight additives can have some desirable advantages, such as ... 

The increased polarity of the acrylic polymers puts more stringent requirements on the properties of the tackifiers or plasticizers that can be used. The very low polarity additives commonly found in rubber based PSAs are not useful in most acrylic PSA formulations. For example, materials like paraffin waxes, mineral oils, and synthetic hydrocarbon tackifiers have little or no value in most acrylic PSAs. 

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