Tensile and Creep Behavior

Second, the ductility normally evident in HiPS was shown by Biglione et al. (1969) to be essentially completely suppressed by the application of 

in HiPS, the density is known to decrease by about 8% on straining (Merz et al., 1956) and Poisson s ratio to decrease from 0.33 to 0.15 (Nielsen, 1965). On the other hand, the density of PVC and rubber-modified PVC is a complex function of strain (Petrich, 1972) in the former case, density first increases and then levels off, while in the latter density tends to decrease after an initial rise. Again, the diversity of density effects presumably reflects the various balances achieved between crazing and shear effects in different polymers under different loading conditions. 

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Grzywinski and Woodford [118.119] report on the use of stress relaxation tests for the determination of design data for polycarbonates, in trying to determine long-term tensile and creep behavior from a 24 hour relaxation test, w hilc Tsou et al. [120] examine the stress relaxation of several types of plastic film in bending and tension. 

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