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WATER UPTAKE AND VOLUMETRIC CHANGES IN POLY(METHYLMETHACRYLATE).
No full textWater uptake in amorphous glassy, poly(methylmethacrylate) (PMMA) occurs through a dual mechanism, i. e. part of the penetrant is inserted into the polymer network and causes the swelling of the structure, and part is accommodated into pre-existing microvoids. In this communication we advance the suggestion that the equilibrium sorption isotherm of water in PMMA can be described by the dual sorption model, which can be applied in the gas sorption in glassy polymers. The theoretical expectations of density variation with the weight% of sorbed water agree well with experimental results from literature
EFFECT OF HOT DRAWING ON THE PROPERTIES OF SHORT FIBER REINFORCED EXTRUDED SHEETS
No full textThe hot drawing of extruded composite sheets can be used to control the orientation of both matrix and reinforcing fibers. A study was made of the effect of draw ratio on the properties of an extruded polystyrene sheet containing 0 to 1 percent of short glass fibers. An increase in draw ratio resulted in an increase in fiber orientation. A model of a rigid fiber rotating in an elongational flow field was used to describe the effect of draw ratio on the final orientation distribution. An increase in draw ratio also caused an increase in the amount of fiber breakage. A shear-lag analysis was used to estimate the extent of damage as a function of draw ratio. It was also found that the mechanical properties were dependent upon both the draw ratio and fiber concentration
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