Thermoplastic and thermoset acrylic

Acrylic homopolymers [(—CH2CH(COOR)—) ] and copolymers are synthesized from acrylates and methacrylates. Through copolymerization, the polymer properties are widely varied from soft, flexible elastomers to hard, stiff thermoplastics and thermosets. Acrylic polymers are produced in many different forms including sheet, rod, tube, pellets, beads, film, solutions, lattices, and reactive syrups. 

In September 1964 the Du Pont company announced materials that had characteristics of both thermoplastics and thermosetting materials. These materials, known as ionomers, are prepared by copolymerising ethylene with a small amount (1-10 % in the basic patent) of an unsaturated carboxylic acid such as acrylic acid using the high-pressure process. Such copolymers are then treated... 

Acrylics. Acrylic resins are the most widely used polymers in the paint and coating industry. The two principal forms of acrylic used in surface coatings are thermoplastic and thermoset. Thermoplastics form a film by the evaporation of the solvent present in the coating formation. Thermosets are cured at ambient or elevated temperatures by reacting them with other polymers. The following monomers are generally used in the synthesis of acrylic polymers (Table 7.6) [10]. 

Synthetic polymers in general can be classified (1) by thermal behavior, i.e., thermoplastic and thermosetting (2) by chemical nature, i.e., amino, alkyd, acrylic, vinyl, phenolic, cellulosic, epoxy, urethane, siloxane, etc. and (3) by molecular structure, i.e., atactic, stereospecific, linear, cross-linked, block, graft, ladder, etc. Copolymers are products made by combining two or more polymers in one reaction (styrene-butadiene). See cross-linking block polymer epitaxy homopolymer plastics. 

Chem. Descrip. 2-Flydroxy-4-n-octyloxybenzophenone CAS 1843-05-6 EINECS/ELINCS 217-421-2 Uses Lt. stabilizer, UV absorber for polymers incl. acetals, acrylics, ABS, alkyds, cellulosics, epoxies, PC, thermoplastic and thermoset polyester, polyethylene, PP, PS, SAN, and surface coatings UV absorber for PVC flexible and semirigid applies, such as automotive body side molding, automotive surface coatings costabilizer for polyethylene film in agric. or greenhouse applies. 

CICH2CH20)2P00CH2CH20P0(0CH2CH2CI)2 Properties M.w. 472.02 Uses Flame retardant additive for flexible PU foams for the transportation, bedding, and furniture industries, and in thermoplastic and thermoset resins such as acrylates, polyolefins, PAN, styrene, ABS, polyesters, epoxies, and PET... 

A large mrmber of polymeric materials are involved in a web coating. These include poly-virtylchloride, polyurethanes (thermoplastic and thermoset solvent-based and water-based), natural, nitrile, chloroprene, and ethylene-propylene rabbers, silicones, polyethylene (chlorinated and chlorositifonated), polyamide, polyester, acrylic resins, polyvinylal-cohol, polytetrafluroethylene, and ethylene-vinyl acetate copolymer as the main matrix polymers of coating compositions. Most of these polymers are not plasticized or seldom... 

Commercial acrylic resins comprise a broad array of polymers and copolymers derived from esters of acrylic acid and methacrylic acid. They range from the homopolymer of methyl methacrylate to a variety of copolymers including both the thermoplastic and thermoset type and ranging from hard and stiff types to soft and elastomeric types. The most common of the thermoplastic acrylic resins are the poly(methyl methacrylate) homopolymer (PMMA) and the copolymers containing predominantly methyl methacrylate but with small amounts of methyl or ethyl acrylate, acrylonitrile, or styrene comonomers added for improved toughness. 

Acrylics Solutions and aqueous emulsions Both thermoplastic and thermoset formulations available Very wide adhesion range Excellent resistance to discolouration, hght, and oxidation Curing types are available that have wash and dry-cleaning resistance Pressure-sensitive adhesives Laminating adhesives... 

Stops static and removes electrostatic charges and related dust and dirt attraction on all types of hard surfaced plastics such as acrylics, polystyrenes, PVC, styrenes, vinyl, thermoplastics, and thermosets. Stops static on films and paper. Assists solar heat-transfer. 

As mentioned above, both thermoplastic and thermosetting type acrylic resins are commercially available for coatings, elastomers, sealants and adhesive applications. These resins are supplied in many different delivery forms such as powders or pellets, solutions in organic solvents and aqueous dispersions. These resin types are briefly described below. 

The term solution acrylics refers to acrylic resins prepared by chain-growth polymerization using a solutionbased polymerization process. Here, acrylic monomers and initiators are slowly added to an organic solvent and polymerization is carried out at a predetermined temperature and inert atmosphere with efficient stirring. Both monomers and the polymer formed are miscible in the selected solvent. With the progress of polymerization, the solution viscosity will Increase and heat transfer becomes difficult, limiting the solid content of the final solution. Both thermoplastic and thermosetting solution acrylics can be prepared by this technique. 

Commercial latexes are supplied both as thermoplastic and thermosetting types. Thermoplastic acrylic (and vinyl) latexes are very commonly used as binders for architectural paints and some specialty coatings. Such coatings are required to dry under ambient conditions without any chemical cross-linking and hence are designed to precise T and minimum film formation temperature. 

All plastics can be classified into two categories thermoplastics and thermosets. Thermoplastics are not cross-linked, and the polymeric molecules making up the thermoplastic can easily slip by one another. This slip or flow can be caused by thermal energy, by solvents or other chemicals, and by the application of continuous stress. Thermoplastics can be repeatedly softened by heating and hardened on cooling. Hence, they can be welded by the application of heat. Thermoplastics can also be dissolved in solvents, so it is also possible to join thermoplastic parts by solvent cementing. Typical thermoplastics are polyetb-ylene, polyvinyl chloride, polystyrene, polypropylene, nylon, and acrylic. 

Many alternatives exist and the choice between thermoplastic and thermosetting resins depends on the expected lifetime and maximum operating temperature. Styrene-butadiene block copolymers and acrylic resins can be used to produce low-end adhesives with an acceptable stability up to 100°C, whereas epoxy and silicone thermosets are preferred for their robustness at 150-200°C. In the most severe environments, poly(imide-siloxanes) and polyimides can sustain medium-term exposures to 250 and 300°C, respectively. Various conductive fillers are cited in the literature, including noble metals such as gold or silver, and low-cost metals such as copper, nickel, chromium, and soft solders. 

Maleate esters such as dimethyl maleate, diethyl maleate and dibutyl maleate are extensively used in the production of latex emulsion polymers, thermoplastic and thermosetting plastics. Dimethyl maleate has found use in applications where improvement in hardness and toughness of polymer films are desired. This includes, in particular, the improvement of anti-blocking properties of copolymers of vinyl acetate with dimethyl maleate. It is also used as an internal modifier to increase the glass transition temperature of styrene or vinyl chloride polymer. The intermediate in esterification of maleic acid with methanol, monomethyl maleate provides plastsizing effect, as well as promotion of improved polymer adhesion due to the carboxylic group. It can be copolymerized with a variety of vinyl and acrylic monomers to provide coatings with improved stiffness and adhesion and reduced tackiness or tendency to block. Monoesters of maleates are used to provide carboxylic acid functionality in emulsions and water-soluble polymers. 

Several acrylic copolymers have been mentioned in the preceding sections, but generally the products described contain a preponderance of one monomer with minor amounts of other monomer(s). There also exists a large number of acrylic copolymers in which one monomer does not predominate to any great extent. Such copolymers find widespread use in surface coatings. Two distinct types of copolymers are used in surface coatings, namely thermoplastic acrylics and thermosetting acrylics and it is these materials which are the subject of this section. 

Water reducible acrylic resins are available to the coatings formulator as both thermoplastic, and thermosetting types. The thermoplastic acrylics film form by simple solvent evaporation and, therefore, cosolvent and amine selection are important. One of the cosolvents used must be a true solvent for the system and be less volatile. It must evaporate more slowly than water. This is to minimise the potential for blushing or flocculation that could be caused by having water as the last solvent to leave the film. The amine should also be volatile at ambient temperatures to minimise the retained water solubility, or sensitivity of the film after drying. This is particularly important since there is no curing reaction with thermoplastics. 

A family of plastics technically known as polyacrylates. Derived from acrylic (or methacrylic) acid, the family includes a variety of materials, including thermoplastic and thermoset resins, textile fibers, paints, and adhesives. Polymethyl methacrylate (PMMA) is one of the most important. Another interesting member of this family is cyanoacrylate, better known as super glue. 

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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