Acetal plastics properties

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). 

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. 

Some results, which were considered supporting the lubricity theory, were also found Verhoek, who measured vapor pressures of plasticizers in polymers, found that plasticizers reduce solvent retention, which was considered to support these theories (plasticizers fill voids and so they exclude solvents). Rententivity and permeability of cellulose acetate plasticized with different sulfonamides, phthalates and phosphates, were measured by Kirkpatrick who concluded that these properties depended on the attractive forces resulting between the plasticizer and the polymer. Houwink measured swelling of some butadiene-acrylonitrile copolymers with different acrylonitrile content when these were mixed with solvents of different polarities, and proved the importance of the polarity of the plasticizer and the polymer. Moreover, Houwink measured the brittle point of ethyl... 

Diethyl phthalate used as a plasticizer in cellulose acetate films was found to be completely degraded in 4 weeks of composting degradatioa Citrate esters used as a plasticizer in cellulose acetate improved properties and processing characteristics but also dramatically increased its biodegradability. These two examples show that plasticizers can also be effectively used in biodegradable materials. 

The exact choice of monomers is determined primarily by the properties required in the final coating. Acrylic polymers tend to give high-quality coatings, whereas formulations based on vinyl acetate plasticized with butyl acrylate have good... 

Uses Intermediate for surfactants and wetting agents in copolymerization of PVC and vinyl acetates plasticizer for vinyl resins internal plasticizer in copolymer films also in latex paints, paper and textile coatings, adhesives Properties Colorless cl. oily liq. sp.gr. 0.938-0.942 b.p. 209 C acid no. < 0.25 flash pt. 360 F 100% cone. 

Tetraethylene glycol may be used direcdy as a plasticizer or modified by esterification with fatty acids to produce plasticizers (qv). Tetraethylene glycol is used directly to plasticize separation membranes, such as siHcone mbber, poly(vinyl acetate), and ceUulose triacetate. Ceramic materials utilize tetraethylene glycol as plasticizing agents in resistant refractory plastics and molded ceramics. It is also employed to improve the physical properties of cyanoacrylate and polyacrylonitrile adhesives, and is chemically modified to form polyisocyanate, polymethacrylate, and to contain siHcone compounds used for adhesives. 

Plasticizers. Monomeric (mol wt 250—450) plasticizers (qv) are predominantiy phthalate, adipate, sebacate, phosphate, or trimeUitate esters. Organic phthalate esters like dioctyl phthalate (DOP) are by far the most common plasticizers in flexible PVC. Phthalates are good general-purpose plasticizers which impart good physical and low temperature properties but lack permanence in hot or extractive service conditions and are therefore sometimes called migratory plasticizers. Polymeric plasticizers (mol wt up to 5000 or more) offer an improvement in nonmigratory permanence at a sacrifice in cost, low temperature properties, and processibiHty examples are ethylene vinyl acetate or nitrile polymers. 

Properties of plastic LDPE LLDP E HDPE PP PVC (flexible ) PS ABS Polyacryhc (glazing) Polycarbonat e (glazing) Epoxy (minera 1 fihed) Acetal homopolym er... 

The cellulose esters with the largest commercial consumption are cellulose acetate, including cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate. Cellulose acetate is used in textile fibers, plastics, film, sheeting, and lacquers. The cellulose acetate used for photographic film base is almost exclusively triacetate some triacetate is also used for textile fibers because of its crystalline and heat-setting characteristics. The critical properties of cellulose acetate as related to appHcation are given in Table 10. 

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