Impact polystyrene properties

BiaxiaHy oriented films have excellent tensile strength properties and good tear and impact properties. They are especially well regarded for their brilliance and clarity. Essentially all poly(ethylene terephthalate) film is biaxiaHy oriented, and more than 80% of polypropylene film is biaxiaHy oriented. Polystyrene film is oriented, and a lesser amount of polyethylene, polyamide, poly(vinyl chloride), and other polymers are so processed. Some of the specialty films, like polyimides (qv), are also oriented. 

The use of stabilisers (antioxidants) may, however, have adverse effects in that they inhibit cross-linking of the rubber. The influence of phenolic antioxidants on polystyrene-SBR alloys blended in an internal mixer at 180°C has been studied. It was found that alloys containing 1% of certain phenolic antioxidants were gel-deficient in the rubber phase.The gel-deficient blends were blotchy in appearance, and had lower flow rates compared with the normal materials, and mouldings were somewhat brittle. Substantial improvements in the impact properties were achieved when the antioxidant was added later in the mixing cycle after the rubber had reached a moderate degree of cross-linking. 

This section deals with atactic polystyrene homopolymer, and high-impact polystyrene. The properties of SMA are included in Table 4.36 and are not otherwise detailed. 

In the most general sense, all plastics are engineering materials, in that they offer specific properties which we judge quantitatively in the design of end-use applications. Among die large-volume established thermoplastics, we should certainly pay tribute to the engineering performance of the polyolefins, polystyrene, impact styrene, ABS, vinyls, acrylic, and cellulosic plastics. 

Typical physical properties for an injection-molded transparent acrylic polyblend resin are given in Table II. The injection molding conditions used are given in Table III. Tensile, flexural, and impact properties are within the range reported for typical ABS and high impact polystyrene resins. Optical properties approach those of the acrylics [i.e., poly (methyl methacrylate)]. The strength properties are on the low side of those reported in the first paper for the transparent diene... 

As block copolymers are still rather expensive materials, it may be advantageous to use them as additives to important industrial polymers. In this domain, possibilities are extremely numerous and diverse. They include an improvement of chemical properties such as resistence to degradation agents, or rheological properties such as adhesion of vinylic paints, high impact properties of conventional thermoplastics, or a compatibilization of polyolefins, polystyrene and poly(vinyl chloride) allowing the reuse of polymeric waste products. The above examples illustrate the great intrinsic potential of block copolymers in the quest of new materials with specific properties. 

In our studies we found that phosphonic acids (16), phosphinic acids (25), and phosphine oxides (17) are additives capable of imparting fire retardant properties to thermoplastic polymers. Tables I and II present data for some of these compounds when added to polyethylene or to poly (methyl methacrylate). The concentration reported is not necessarily the lowest effective concentration for the additive in the polymer. These additives also were effective in other thermoplastic polymers such as polystyrene, impact polystyrene, polypropylene and ABS. The compounds were completely compatible with the polymers. 

The addition of an elastomer (typically a high butadiene content SBS) to SBC will serve to enhance further the elastomeric properties of the SBC. One key feature mentioned previously was improvement in hinge life properties. SBS copolymers can also be added to thermoformed sheet in blends of SBC and crystal polystyrene. The SBS does cause some loss of clarity, but gives more impact resistance to the sheet. Selection of the proper SBS can result in minimal loss of clarity, typically at 3-10% loadings. Styrene-isoprene copolymers (SIS) have also been tested with SBC and can give similar results in impact property improvement. 

K-Resin SB Copolymer/Crystal Polystyrene Sheet Property Modification with High Impact Polystyrene, Plastics Technical Center Report 409, Chevron Phillips Chemical Co., Bartlesville, OK. 

Studies on the morphology and on the melt rheological, tensile, and impact properties were carried out on ternary blend of iPP with two of the following polymers low and high density polyethylene, styrene-b-ethylene butylene-b-styrene triblock copolymer, polystyrene, and acrylonitrile-butadiene-styrene terpolymer (30-33). The results are interpreted for the effect of each individual component by comparing the ternary blends with the respective iPP-based binary blends as the reference systems. 

Compared to unmodified crystal polystyrene, impact polystyrene consisting of copolymers of styrene and butadiene are more sensitive to oxidation. This sensitivity is a consequence of the double bonds in polybutadiene component and manifests itself in yellowing and the loss of mechanical properties of the polymer. In impact polystyrene, the following antioxidants or their mixture are used in total concentrations of 0.1%-0.25% BHT, octadecyl-3-(3,5-di-fert-butyl-4-hydroxyphenyl)-propionate, l,l,3-tris-(5-tert-butyl-4-hydroxy-2-methylphenyl)-butane, and dilauryl thiodipropionate. 

In the same manner, blends containing (100% to 90%) polystyrene and (0% to 10%) styrene-butadiene rubber (SBR) exhibited improved impact properties after gamma irradiation at a dose of 100 kGy. FTIR provided evidence that irradiation produced a radical in the benzene ring of PS that could react with the double bond of polybutadiene producing a metasubstituted benzene (Figure 9.5). Hence, this chemical link between the two polymers gave rise to the increase in Izod impact strength parhcularly for 100 kGy y-irradiated 90/10 PS-SBR blend. 

In polystyrene (PS), talc is used in combination with an elastomer to overcome reduction in impact properties (note the improvement in Table 12.6 from Ref [5]). 

Polystyrene is extensively used in a range of applications, such as car headlamp lenses, where its mechanical properties are important. Polystyrene has a Tg value of 100 °C and can withstand a reasonable impact. However, improvement of its impact properties is commercially desirable and requires incorporation of a... 

The characteristie properties of an IPN depend upon many factors such as blend ratio, morphology, crosslink density and nature of the component polymers. For instanee, Mathew and coworkers followed the above mentioned procedure and studied the impact behaviour of semi- and full IPNs based on NR and polystyrene (PS). Their results showed that the impact properties are immensely improved by the addition of NR to pure PS and they also found that impact resistance increases with crosslinking level of an IPN. However, increase in crosslinking beyond a certain limit was found to be undesirable and... 

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