Thermosetting acrylic polymers

In practice, synthetic polymers are sometimes divided into two classes, thermosetting and thermo-plMtic. Those polymers which in their original condition will fiow and can be moulded by heat and pressime, but which in their finished or cured state cannot be re softened or moulded are known as thermo setting (examples phenol formaldehyde or urea formaldehyde polymer). Thermoplastic polymers can be resoftened and remoulded by heat (examples ethylene polymers and polymers of acrylic esters). 

Table VIII. Comparison of the Properties of Several Thermoset Acrylic Polymers...

U.S. Pat. No. 5,288,775 [22] describes moldable thermoset acrylic polymer composites containing 3-15% of cellulose fibers, fillers, and water the composite is a hard, high molecular crosslinking type that requires a chemical hardener. 

Titanium hydroxide, 129 Wollastonite, 129 Wood flour, 129 Mold and spores, 412,413 Mold growth, 27, 412-416 Mold propagation, 26,412 16 Mold shrinkage, 105, 131 Nucleation, effect of, 131 Plastic crystalllinity, effect of, 131 Moldable thermoset acrylic polymer, 80 Molecular weight distribution (MWD), 63, 636, 649-651... 

Thermoset polymers cannot be solvent cemented or fusion welded. However, they can be adhesive bonded using epoxies, thermosetting acrylics, and urethanes. Prior to bonding, the surfaces must be abraded... 

Uses Monomer for large-volume resins and polymers, organic synthesis comonomer for thermosetting acrylic resins carboxylated comonomer for S/B-nItrlle latex engineering adhesives thickener for hair care prods. paints Ion-exchange membrane processing agent, binder for paper and textiles leather treatment adhesion promoter pharmaceutical ophthalmics... 

Uses Monomer improving adhesion in thermoset acrylic and urethane coatings, fibers, syn. resins, radiation-curable inks ManufJDistrib. Monomer-Polymer Dajac Labs Rhodia... 

Bonding The use of solvents (mostly with a cement made of a viscous solution of the same polymer) is common for easily soluble amorphous polymers like acrylics, polystyrene, cellulose, and PVC. However, this method does not apply to most crystalline polymers. The proper choice of solvent (or mixture of solvents) also takes into account the desired rate of diffusion. In this matter, the concept of solubility parameters may be exploited when there is a similarity between polymer and solvent. Various glues may also be used (contact glue, epoxy) in order to bind plastics to each other, including crystalline polymers or thermosets. 

A large variety of hyperbranched polymers with acrylate, vinyl ether, allyl ether, or epoxy functions were studied as multifunctional cross-linkers in coatings and in thermosets, using thermal as well as UV curing methods Clearly, polyesters are most prominent in the field, with the Perstorp Boltom products leading in technical studies. The commercialized poly(esteramide)s from DSM, sold under the trade name Hybrane polyethylenimines from BASF AG, available under the trade name TupasoF and poly(urethane)s (PUs) and polyesters developed by BASF are examples for hyperbranched polymers suited for coatings and resin products. 

Thermosetting acrylic resins are used widely in surface coatings. Both acrylic and methacrylic esters are utilized and the term is applied to both of them. Often such resins are terpolymers or even tetra polymers where each monomer is chosen for a special function [214]. One is selected for rigidity, surface hardness, and scratch resistance another for the ability to flexibilize the film, and the third one for cross-linking it. In addition, not all comonomers are necessarily acrylic or methacrylic esters or acids. For instance, among the monomers that may be chosen for rigidity may be methyl methacrylate. On the other hand, it may be styrene instead, or vinyl toluene, etc. The same is true of the other components. Table 6.12 illustrates some common components that can be found in thermoset acrylic resins. 

The acrylics can be formulated as thermoplastic resins, thermosetting resins, and as a water emulsion latex. The resins are formed from polymers of acrylate esters, primarily polymethyl methacrylate and polyethyl acrylate. Since the acrylate resins do not contain tertiary hydrogens attached directly to the polymer backbone chain, they are esceptionally stable to oxygen and UV light. The repeating units for the methacrylate and acrylate are as follows ... 

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