Rubber modified acrylic materials

Analysis of these effects is difficult and time consuming. Much recent work has utilized two-dimensional, finite-difference computer codes which require as input extensive material properties, e.g., yield and failure criteria, and constitutive laws. These codes solve the equations of motion for boundary conditions corresponding to given impact geometry and velocities. They have been widely and successfully used to predict the response of metals to high rate impact (2), but extension of this technique to polymeric materials has not been totally successful, partly because of the necessity to incorporate rate effects into the material properties. In this work we examined the strain rate and temperature sensitivity of the yield and fracture behavior of a series of rubber-modified acrylic materials. These materials have commercial and military importance for impact protection since as much as a twofold improvement in high rate impact resistance can be achieved with the proper rubber content. The objective of the study was to develop rate-sensitive yield and failure criteria in a form which could be incorporated into the computer codes. Other material properties (such as the influence of a hydrostatic pressure component on yield and failure and the relaxation spectra necessary to define viscoelastic wave propagation) are necssary before the material description is complete, but these areas will be left for later papers. 

Core-shell rubber (CSR) particles are prepared by emulsion polymerization, and typically exhibit two or more alternating rubbery and glassy spherical layers (Lovell 1996 Chapter 8). These core-shell particles are widely used in thermoplastics, especially in acrylic materials (Lovell, 1996), and have also been used to modify thermosets, such as epoxies, cyanates, vinyl ester resins, etc. (Becu et al., 1995). 

Rubber systems do stick to many plastics well, but they are relatively moisture-sensitive. There s always a risk that they may lose their adhesive strength at high humidity levels. At temperatures above about 40°C, they turn very soft and lose their inherent strength. Pure acrylates and modified acrylates are primary materials that provide PSAs with greater moisture resistance and thermal stability. Pure acrylates above all remain sufficiently adhesive up to about 150 or for short periods 200°C. Adhesive tapes of this kind are used for masking purposes in powdercoating techniques. 

Chem. Descrip. Calcium carbonate CAS 471-34-1 EINECS/ELINCS 207439-9 Uses Filler for plastics, PVC, polyolefins, polyesters, BMC/SMC, paint, caulks, sealants, adhesives, paper, foam urethane, modified acrylics, filled thermosets/thermoplastics, and rubber Features Improves impact str., dimensional stability Regulatory NSF approved for potable water materials Properties Wh. powd. 2 avg. particle diam. 99.9% finer than 8 0.15% sol. in water sp.gr. 2.70-2.71 dens. 22.57 Ib/gal bulk dens. 38 Ib/tP (loose) oil absorp. 23 01 cc/100 g brightness (Hunter) 95 ref. index 1.6 pH 9.5 (sat.) hardness (Mohs) 3.0 Toxicobgy Nontoxic Camel-TEX [IMERYS]... 

These materials may be bonded with neoprene or nitrile-phenolic elastomer, epoxy, epoxy-polyamide, epoxy-phenolic, phenolic, polyester, modified acrylic, cyanoacrylates, phenolic-polyvinyl butyral, polyurethane, butyl rubber, polyisobutylene, and PMMA. 

Antioxidant an-te- ak-so-dont, ian- tI- (1926) n. A substance that slows down the oxidation of oils, fats, etc., and thus helps to check deterioration antioxidants are added commercially to foods, soaps, etc. Although the term technically applies to molecules reacting with oxygen, it is often applied to molecules that protect from any free radical molecule with unpaired electrons. Chemistry encyclopedia, www. ChemistryAbout.com. A substance incorporated in a material to inhibit oxidation at normal or elevated temperatures. Antioxidants are used mainly with natural and synthetic rubbers, petroleum-based resins, and other such polymers that oxidize readily due to structural unsaturation. However, some thermoplastics, namely polypropylene, ABS, rubber-modified polystyrene, acrylic and vinyl resins, also require protection by antioxidants for some uses. There are two main classes (1) Those inhibit oxidation by reacting with chain-propagating radicals, such as hindered phenols that intercept free radicals. These are called primary antioxidants or free-radical scavengers. (2) Those decompose peroxide into non-radical and stable products examples are phosphates and various sulfur compounds, e.g., esters of thiodipropionic acid. These are referred... 

There are several ways in which the impact properties of plastics can be improved if the material selected does not have sufficient impact strength. One method is by altering the composition of the material so that it is no longer a glassy plastic at the operating temperature of the product (Chapter 6). In the case of PVC this is done by the addition of an impact modifier which can be a compatible plastic such as an acrylic or a nitrile rubber. The addition of such a material lowers the glass transition temperature and the material becomes a rubbery viscoelastic plastic with much improved impact properties. This is one of the methods in which PVC materials are made to exhibit superior impact properties. 

The same technique can be used to dye a material that is otherwise difficult to dye. An ethylene-propylene copolymer rubber was reacted first with maleic anhydride, then with an aromatic amine dye in an extruder to produce a dyed rubber.81 Dye sites can also be inserted into polyolefins by grafting them with dimethylaminoethyl methacrylate, using azo or peroxide catalysts in an extruder.82 jV-Vinylimidazole has been grafted to polyethylene in an extruder with the help of dicumylperoxide.83 The product was mixed with an acrylic acid-modified polypropylene and used to compatibilize polyethylene and polypropylene. This could be helpful in the recycling of mixed polyolefins from municipal solid waste. Recycling of cross-linked (thermoset) polymers is more of a problem because they cannot be remelted in an extruder. However, they can be if... 

Floor underlayments are utilized to produce a level and smooth surface before placing vinyl tile, asphalt tile, rubber tile, or other resilient flooring materials. Acrylic latex modified underlayments are ideally suitable for leveling floors prior to the installation of these surfacing materials, since these underlayments provide an excellent substrate for bonding purposes, as well as offering good chemical resistance to tile adhesives and solvents which some of them contain. 

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