Flexural characteristics

Flexural characteristics are of paramount importance in applications involving movement or vibration of parts. Valve diaphragms are an example of a part in which the membrane experiences repetitive movement. Flexural or flex life is defined as the number of cycles that a part can endure before catastrophic fatigue occurs the higher the molecular weight the higher the flex life. Increased crystallinity has a detrimental effect on the flex life the higher the crystallinity the lower... 

Reis, J.M.L. (2006) Fracture and flexural characteristics of natural fiber reinforced polymer concrete. Constr. 

Torsion box wrap. Fiber-reinforced composites that use glass, aramid, or carbon fibers. A variety of weaves and weights of reinforcement are possible that are utilized to tune the flexural characteristics of the ski. 

K. Kobayashi and R. Cho, Flexural characteristics of steel fibre and polyethylene fibre hybrid - reinforced concrete , Composites. 13,1982,164-168. 

Use active controls for temperature or to correct for thermally induced distortion. Elastic materials with repeatable flexure characteristics are desirable. Provisions in the blank for good ventilation may be necessary. 

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. 

Polyarylate (PAR)-b-PSt and PAR-b-PMMA for compatibiiizers are described 135,39,40). The addition of PAR-b-PSt (1-10 parts) to 100 parts of a blend of PAR-PSt (7w-3w) resulted in improvement of the tensile and flexural modulus (Fig. 4), and PSt dispersed particles were diminished from 1-5 microns to an order that is undetectable by SEM, indicating the excellent, compatibilizing effect of the block copolymer. The alloy thus formed exert the characteristic of PAR, an engineering plastic, as well as easy processability of PSt. Addition of PAR-b-PMMA (3 or 8 parts) to 100 parts of a blend of PAR-polyvinylidenefluoride (PVDF) (7w-3w) resulted in improved microdispersed state of PVDF due to compatibility of PMMA with PVDF, while segregation of PVDF onto the surface was controlled. 

The majority of tests to evaluate the characteristics of plastics are performed in tension or flexure hence, the compressive stress-strain behavior of many plastics is not well described. Generally, the behavior in compression is different from that in tension, but the stress-strain response in compression is usually close enough to that of tension so that possible differences can be neglected (Fig. 2-19). The compression modulus is not always reported, since defining a stress at... 

ISO 844 2001 Rigid cellular plastics - Determination of compression properties ISO 3386-1 1986 Polymeric materials, cellular flexible - Determination of stress-strain characteristics in compression - Part 1 Low-density materials ISO 3386-2 1997 Flexible cellular polymeric materials - Determination of stress-strain characteristics in compression - Part 2 High-density materials ISO 5893 2002 Rubber and plastics test equipment - Tensile, flexural and compression types (constant rate of traverse) - Specification ISO 7743 2004 Rubber, vulcanized or thermoplastic - Determination of compression stress-strain properties... 

Figure 6.8 plots the reinforcement ratios for short glass fibre reinforced polyamide (PA-GF) versus neat polyamide for six important characteristics calculated versus density and material cost. These characteristics are tensile strength, tensile and flexural modulus, impact strength, HDT A and B. 

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