Acrylic plastics acrylate IPNs

Another area of recent interest is covulcanization in block copolymers, thermoplastic rubbers, and elasto-plastic blends by developing an interpenetrating network (IPN). A classical example for IPN formation is in polyurethane elastomer blended acrylic copolymers [7]. 

The latexes themselves are basically semi-I IPNs or IPNs, prepared in a two-stage process. An acrylic, crosslinked seed latex serves as the core, while a plastic monomer mix II containing methacrylic or styrene monomers and monomers with reactive sites (epoxy, carboxy, hydroxy) is polymerized to form the shell of the latex. The graded composition is brought about by beginning to add the monomer II mix before the first monomer mix is completely polymerized. 

Around 1945, acrylic-type plastics were introduced as restorative materials.These materials, prepared as a two-component package, were semi-II IPNs based on linear poly(methyl methacrylate) as polymer I, and MMA monomer plus crosslinking agents as network II. 

Methacrylic/acrylic latex IPNs, Section 5.4.1, yield convenient semicompatible compositions. Tables 8.15 and 8.16 ° delineate several experimental and commercial compositions. Poly(vinyl acetate) copolymers, appropriately plasticized and filled, are the most important group of the latter materials. 

Ryan and Crochowski teach the use of acrylic latex IPNs dispersed in PVC copolymers to produce transparent, impact-resistant vinyls (see Table 8.1). A three-stage polymerization of the latex particles is required. A crosslinked rubbery latex such as poly(butyl acrylate) makes up the seed latex. A crosslinked vinyl aromatic, such as polystyrene, makes up network II. A linear poly(alkyl methacrylate), such as PMMA, forms polymer III. The finished latex is coagulated and blended with PVC to produce a tough, transparent plastic. Transparency is achieved by a close match of refractive indices. 

Spilner, in Example 7, prepared a two-stage latex IPN, based on butyl acrylate copolymers. The latex is dispersed in an MMA monomer mix (Example 13) to produce tough acrylic plastics after polymerization. Materials of this nature also exhibit a high degree of clarity. 

O. B. Johnson and S. S. Labana, Thermoset Molding Powders from Hydroxy-Functional Graded Elastomer Particles and Monoblocked Diisocyanate and Molded Article, U.S. Pat. 3,659,003 (1972). Acrylic/methacrylic IPNs. Latex-based, rubber-toughened plastics. 

B. Vollmert. Impact-Resistant Plastic Compositions Comprising Styrene Polymer and a Cross-Linked Acrylic Acid Ester Polymer, and Process for Preparing Same, U.S. Pat. 3,055,859 (1962). Numerous multipolymer grafts and IPNs. Impact-resistant plastics. 

A. J. Yu and R. E. Gallagher, Acrylate-Styrene-Acrylonitrile Composition and Method of Making the Same, U.S. Pat. 3,944, 631 (1976). Latex IPN of acrylate elastomer/styrene-acrylonitrile. Latex IPN embedded in linear styrene-acrylonitrile. Rubber-toughened, impact-resistant 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. 

Hutchinson and coworkers examined a wide range of IPNs, SINs and semi-IPNs that were useful as reinforced elastomers. PU/PMMA semi-IPNs prepared by bulk polymerization are used in shaping polymer articles. Epoxy/PU semi-IPNs are used as adhesives. Ion exchange resins are prepared from chloromethyl PS/sulfonate PS IPNs. PS/PS IPNs are used to prepare optically smooth plastic surfaces. Poly(ethyhnethacrylate)/poly(ra-butyl acrylate) prepared by Sperling et find the applications as noise damping coatings. 

Blends and IPNs of Natural Rubber with Acrylic Plastics... 

Thus, these acrylate polymers are hard and brittle plastics that can have a direct effect on the mechanical properties in both the natural rubber blends and IPNs. They show an increase in modulus, tensile strength, tear strength, hardness and impact energy, but a decrease in elongation at break. 

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