Polystyrene flexural strength

The work of Sterman and Marsden and Plueddeman was carried out with glasscloth polymer laminates (10, II, 14,15). In this way the effect of the silane could be optimized as to time and temperature of the molding cycle. Additionally, the glass was being used in its maximum strength form in that it was continuous. An additional factor is the absence of any shear forces. As an example, for a polystyrene laminate, the use of an epoxyfunctional silane increased the flexural strength 90% over the bare... 

The product studied was produced in THF with a diphenylphos-phine-lithium catalyst it had a molecular weight of 8300. After shear modulus plotting over temperature, a glass stage of 81 °C, a modulus of elasticity of 32,000 kg/cm2 (poly styrene 30,000), and a flexural strength of 661 kg/cm2 (polystyrene 1000) were found. The glass temperature was 20 °C lower than that of polystyrene, but the polymer is more resistant to swelling by aromatics. 

Figure 8. Flexural strength vs. cell size of polystyrene foam (10).

Mechanical Properties. The roost notable differences from polystyrene in mechanical properties are the lower tensile, flexural modulus, and hardness values and the hl er elongation and flexural strength for the BDS resin. All of these differences are due to the presence of butadiene in the resin. 

Figure 17. Flexural strength of glass cloth reinforced polystyrene with polymeric silane-treated glass the sUane to styrene ratio was varied so that the molecular weight of the polystyrene between two silane molecules become from 500 to 10,000 as shown as average molecular weight.

Testing of mechanical properties such as tensile strength (ASTM-D-638), flexural strength (ASTM-D-790), and impact strength (ASTM-D-256) was done following standard methods. The water absorption of both untreated and treated composites was determined as per ASTM-D-570. The variation in tensile, impact, and flexural properties of thermoplastic composites, viz. sisal-polypropylene and sisal polystyrene, is explained here, and the change in fiber volume also given here. 

The modulus of OPF-polystyrene composites increased with fiber loading up to 30%, however the maximum strain and flexural strength decreased [7]. The drop in strain was suspected due to irregular shape of the fibers, which caused inabflity of transferring stress from the matrix. The flexural properties viz., maximum stress, maximum strain, modulus of elasticity and Yoxmg s modulus of OPF-polystyrene composites at 10% fiber content (300-500pm size fibers) were reported as 46.43 MPa, 0.027 mm, 1665.35 MPa and 2685.84 MPa, respectively. The flexural properties were not affected by fiber size when the size was below 300 pm. The flexural properties of polystyrene composites improved upon benzoylation due to better interfacial adhesion and hydro-phobicity of the fibers. 

UncompatibUized blends of PP with 3-30 wt.% of either polystyrene (PS) or high-impact-PS (HIPS) were developed in 1971 for soda-straw tubes with pearly luster. Later, for improved mechanical performance, these blends were compatibilized by addition of either a tri-block styrene-butadiene-styrene copol)uner (SBS), a multiblock (SB) copol)uner. Addition of hydrogenated-SBS, i.e. styrene-ethylene/butylene-styrene block copolymer (SEBS) was found to improve impact and flexural strength, whereas incorporation of a linear three-block copolymer S1-D-S2 (where SI s S2 are PS-blocks and D = polydiene block) gave PP alloys with good crack and impact stress resistance [4]. 

Figure 1 Cost-related (specific) flexural strength of major thermoplastics, versus cost-related (specific) thermal tolerance. The unit cost is the market price in US cents (1992) of 1 cm plastics. The thermal tolerance is the temperature difference (AT) over room temperature (AT — T - room T), by which temperature (7 ) the flexural modulus is equal to 1 GPa. Designations, abbreviations WFRP-S, wood fiber reinforced PP (S type) of AECL, Canada (See Table 1) PMMA, polymethylmethacrylate PVC, pol)winyl chloride PS, polystyrene PP, polypropylene UP, unsaturated polyesters PA-GF, glass fiber (35%) reinforced polyamide PHR, phenolic resin EP, epoxy resin ABS, acrylonitrile/butadiene/styrene copolymer UF, urea/formaldehyde LDPE, low density polyethylene PC, polycarbonate POM, polyoxymethylene CAB, cellulose acetate butyrate LCP, liquid crystal polymers PEEK, polyether-etherketone PTFE, polytetrafluorethylene.

Intensive irradiation of polystyrene by 1 MV electrons will cause total embrittlement [730]. Reductions in flexural strength from 106 to 78 N/mm and in tensile strength from 56 to 28 N/mm were detected following irradiation of polystyrene with 1 MV electrons at a dose of 10 MGy [725],... 

Generally, WPC products have strength and stififiiess properties that are somewhere between both materials (1,2). They are stiffer than neat plastics. Nevertheless, composites based on commodity plastics [e.g., polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinylchloride (PVC)] and wood-fibers do not offer mechanical performance similar to that of solid wood (1). For example, the flexural strength of WPCs made with commodity plastics are about two to three times lower than that of natural pine (softwood) or oak (hardwood). While, flexural modulus of WPC products is about one-half that of natural pine or oak (1). This lowered stiffness implies that, for the same load, a deck constructed with WPC products will bend more than a similar wood deck. 

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... 

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