Poly flexural strength

Heat resistance is an important characteristic of the bond. The strength of typical abrasive stmctures is tested at RT and at 300°C. Flexural strengths are between 24.1 and 34.4 MPa (3500—5000 psi). An unmodified phenoHc resin bond loses about one-third of its room temperature strength at 298°C. Novolak phenoHc resins are used almost exclusively because these offer heat resistance and because the moisture given off during the cure of resole resins results in undesirable porosity. Some novolaks modified with epoxy or poly(vinyl butyral) resin are used for softer grinding action. 

Fig. 10. Radiation effects on the flexural strength on pure and glass-fabric filled poly-imides irradiated at 4.9 K. (O) Spaulrad ( ) Norplex (A) Vespel...

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 10. Dependence of flexural strength on amount of PMMA Incorporated In poly(E6DM) networks. Reproduced with permission from Ref. 39 Copyright 1983, Chapman Hall, Ltd.

To a glass flask equipped with a mechanical stirrer, reflux condenser, and thermometer is added 75 ml of acetone and 0.1 ml of a 10% by weight sodium dispersion in toluene. When acetone/sodium precipitates as a white compound, then 25.0 gm (0.41 mole) ethylene sulfide is added. The exothermic polymerization starts immediately and the polymer precipitates as a fine powder while the temperature rises to cause refluxing of acetone. In 10 min the polymerization is complete and 200 ml of 10% HCl is added followed by a 15 min agitation period. The polymer is filtered, washed with water, and dried under reduced pressure at 50°C to give 24.8 gm (99%) of poly(ethylene sulfide) as a colorless powder, m.p. 211°C. The specific viscosity of a 0.5% DMSO solution at 175°C is 1.30 corresponding to a reduced viscosity of 60 ml/gm. The flexural strengths of test specimens of the polymer are 9,00()-l 97,000 Ib/in. ... 

Ohamal ll l studied the effect of monomer ratio in EVA, SBR, and poly (styrene-butyl acrylate, SAE) latexes on the strengths of latex-modified mortars (Fig. 4.10). The monomer ratio affects the strengths of the latex-modified mortars to the same extent as the polymer-cement ratio. The maximum strengths of EVA- and poly(styrene-butyl acrylate)-modified mortars are obtained at a bound ethylene content of 13% and a bound styrene content of 55% respectively. The strengths of SBR-modified mortar increase with a rise in the bound styrene content. These results are similar to those obtained by Cherkinskii, et al.f i The tensile strength of the dry films made from SBR latexes increases sharply when the bound styrene content is raised, and there is a positive correlation between the strength of the films and the flexural strength of SBR-modified mortars with polymer-cement ratios above 10% as shown in Fig. 4.11.li l... 

Fig. 22. Adhesion rating based on flexural strengths of laminates of poly(styrene) with glass treated with various silane coupling agents vs. solubility parameter of the organo-fiinctional group of the coupling agent. From ref. [117], by permission.

Although poly(2,5-dichlorostyrene) has good impact flexural strength, it has not achieved significance, because of the price of the monomer. As one would expect, poly(o-methyl styrene) keeps its shape well, while the p- and m-methyl compounds show no advantages over poly(styrene) in this context. 

Sis et al. prepared composites based on poly (lactic acid) (PLA)/poly (butylene adi-pate-co-terephthalate) (PBAT)/kenaf fiber using a melt blending method [39]. A PLA/ PBAT blend with the ratio of 90 10 wt%, and the same blend ratio reinforced with various amounts of kenaf fiber were prepared and characterized. The addition of kenaf fiber reduced the mechanical properties sharply due to the poor interaction between the fiber and polymer matrix. Modification of the composite by (3-aminopropyl)tri-methoxysilane (APTMS) showed improvements in mechanical properties, increasing up to 42.5, 62.7 and 22.0% for tensile strength, flexural strength and impact strength, respectively. The composite treated with 2% APTMS successfully exhibited optimum... 

Nylon MXD/6 (poly-m-xylyleneadipamide) n. A type of nylon with lower elongation at break than nylon-6 or 6/6, but capable of attaining their properties by reinforcement with glass fibers. The resin has low melt viscosity, good flexural strength and modulus, and resists alkalies and hydrolytic degradation. 

Yasinskaya et al. (2011) studied flexural strength and thermal conductivity of poly ester/acrylic and polyester/wool insulating tiles as a function of polyester proportion in the mixture and volume density. The analysis of regression equations enabled the optimum combination of factors to be found which provides the required thermal insulation and mechanical properties of the tiles. Karthik and Murugan (2013) optimized the spinning parameters of DREF-3 system. Akyol et al. (2013) considered an industrial textile drying process. 

A mixture of PHBV with PLA had a positive effect on the elasticity modulus, elongation at break and flexural strength for different blends. However, tensile strength did not improve in any of them. In the same way, Zhang et al (1996) reported improved mechanical properties for blends of PHB/PLA compared with the common PHB. In addition, PVA (polyvinylacetate) grafted on PIP (poly-cis-l,4-isoprene) and mixed with PHB had... 

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