Transparent HIPS

HIPS with a SB-block copolymer having small transparent HIPS Asahi Chemical Industry, 1982... 

Whilst SBS and related block copolymers have been widely used as interfacial agents (9), they are also used in large amounts as a major constituent of a binary blend. Thus "transparent HIPS", in which SBS lamellae modify polystyrene, has been described (10) and the morphology and other properties of various styrene-butadiene block copolymers in admixture with polystyrene are also known (11). In these cases although some modest... 

Other products having properties similar to those of the transparent ABS, transparent HIPS, transparent MBS, etc., can be included. Since such similar products have the properties and qualities similar to those of the transparent ABS, the names used may be the same, but the manufacturing methods and compositions differ somewhat. 

As can be seen from Table 6.12, the transparent ABS uses polybutadiene rubber, whereas transparent HIPS or transparent MBS uses poly(stjn-ene-butadiene) copolymer. Although such a difference in the rubber used does not bave a great influence on properties, it creates a difference in the refractive index, which in turn creates a difference in the composition of the shell. The refractive index of poly(stjn-ene-butadiene)... 

Transparent HIPS Bulk, bulk suspension 1.53-1.56 Styrene-butadiene... 

I ew Rubber-Modified Styrene Copolymers. Rubber modification of styrene copolymers other than HIPS and ABS has been useful for specialty purposes. Transparency has been achieved with the use of methyl methacrylate as a comonomer styrene—methyl methacrylate copolymers have been successfully modified with mbber. Improved weatherability is achieved by modifying SAN copolymers with saturated, aging-resistant elastomers (88). 

Because of such desirable characteristics as low cost, good mouldability, excellent colour range, transparency, rigidity and low water absorption, polystyrene became rapidly developed. For many purposes, however, it was considered to be unacceptably brittle and this led to the development of the rubber-modified high-impact polystyrene (HIPS) and to the complex ABS, AMBS and... 

The major weaknesses of polystyrene are brittleness, and softening in hot water. Brittleness is remedied by dissolving 2-10 percent of rubber in styrene monomer before polymerization, producing high-impact styrene (HIPS), in which 10- xm rubber particles improve impact strength by an order of magnitude, with some sacrifice of other mechanical properties and transparency this accounts for more than half of the total polystyrene market. 

This class of additives covers a broad range from butadiene to acrylic polymers. Since these additives are polymeric in nature, diffuse reflection will occur at the polymer-modifier interfaces similar to polymer blends. Again, this will result in colors that appear lighter and duller. Table 23.5 contains three examples of impact-modified colors again in polyester compared to the neat resin without modifier. As expected, the impact-modified colors are lighter and have lower chroma. In practice, acrylonitrile butadiene styrene (ABS) or HIPS would have a more restricted color gamut compared to their transparent SAN and polystyrene (PS) base polymers. 

The first patent on HIPS, a blend of synthetic rubber and transparent polystyrene, was granted in Great Britain as early as 1912. The first graft copolymerization of styrene in the presence of rubber was carried out by Ostromislensky [5]. The decline in the demand for styrene monomer and styrene-butadiene rubber and the simultaneous availability of natural rubber on the world market in the late 1940s drove the development of styrene copolymer processes. 

For non-transparent specimens, as shown by Bucknall and Stevens useful information relative to the deformation mode can be obtained by recording hysteresis loops as a function of cycles. Figure 6 shows hysteresis loops obtained at 0.2 Hz at various N values for PS tested at a stress amplitude of 24.1 MPa and Fig. 7 for HIPS tested at 17.2 MPa. For PS, with Nf = 1,451 cycles, there is no detectable change in loop area at this stress amplitude up to the final cycle. This illustrates the highly localized nature of the fatigue-induced damage zone in PS and indicates that, for this polymer, hysteresis loop observations are not an effective method for detecting craze... 

Styrene CH2=CH 6 Polystyrene (PS) —(-CH,—CH 6" Transparent and brittle used for cheap molded objects, e.g., Styron, Carlnex, Hostyren, Lustrex. Modified with rubber to improve toughness, e.g.. High impact Polystyrene (HIPS) and acrylonitriie-butadiene-styrene copolymer (ABS). Expanded by volatilization of a blended blowing agent (e.g., pentane) to make polystyrene foam, e.g., Styrocell, Styrofoam. 

Several other common industrial polymers are also used in biomedical applications [51]. Because of its low cost and easy processibility, polyethylene is frequently used in the production of catheters. High-density polyethylene is used to produce hip prostheses, where durability of the polymer is critical. Polypropylene, which has a low density and high chemical resistance, is frequently employed in syringe bodies, external prostheses, and other non-implanted medical applications. Polystyrene is used routinely in the production of tissue culture dishes, where dimensional stability and transparency are important. Styrene-butadiene copolymers or acrylonitrile-butadiene-styrene copolymers are used to produce opaque, molded items for perfusion, dialysis, syringe connections, and catheters. 

It has exceptionally good optical properties its transparency has made it a popular substitute for glass in apphcations where breakage must be avoided (plexiglass). It has a variety of industrial uses including automotive parts and glazings. PMMA was the first implanted synthetic polymeric biomaterial it was used as a hip prosthesis in 1947 (see USP XVIII, The Pharmacopia of the USA, (18th Revision), US Pharmacopoeia Convention, Inc., Rockville, MD, 1 September 1980). PMMA is currently used in orthopedic applications, as bone cement, and in intraocular lenses. 

Other Impact-Modified Commercial Grafting-Based Polymers Typical HIPS and ABS polymers are opaque materials however, MABS (methyl methacrylate-acrylonitrile-butadiene-styrene) polymers, which are produced by processes similar to those used in the production of ABS, are transparent materials. This property is obtained by the addition of methyl methacrylate (MMA) to the recipe in order to impart transparency to the polymer by equalizing the refracting index of the rubber particles to that of the matrix. These materials find applications... 

Polystyrene is one of the largest volume thermoplastics. It is a versatile polymer whose principal characteristics include transparency, ease of coloring and processing, and low cost. It is usually available in general-purpose or crystal (GP-PS), high impact (HIPS), and expanded grades. Some members of this family of styrene polymers are copolymers of styrene with other vinyl monomers. 

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