is as follows equ1 where t thickness in mils and a absorbance standard specific gravity ssg of the molding powder is measured by water displacement of a standard molded test specimen in accordance with astm d1457 69 the standard molded part is formed by preforming 12 0 g of the molding powder in a 2 86 cm diameter die at a pressure of 34 48 and 6 90 mpa 352 and 70 4 kg cm 2 followed by the sintering cycle of the preform of heating from 300 u00b0 to 380 u00b0 c at 2 u00b0 c min holding at 380 u00b0 c for 30 minutes cooling to 295 u00b0 c at 1 u00b0 c min and holding at this temperature for 25 minutes after which the specimen is cooled to room temperature and tested for specific gravity ssa was measured by a 34 quantasorb 34 surface area analyzer the measurement was made on raw polymer obtained directly from the polykettle vessel after washing and drying melt viscosity is calculated by measuring the tensile creep of a sintered piece held at 380 u00b0 c specifically 12 g of molding powder is placed in a 7 6 cm diameter mold between 0 152 cm rubber cauls and paper spacers pressure is then slowly applied on the mold until a value of 40 5 kg cm 2 is obtained this pressure is held for 5 minutes and then released slowly after the sample disc is removed from the mold and separated from the cauls and paper spacers it is sintered at 380 u00b0 c for 30 minutes the oven is then cooled to 290 u00b0 c at a rate of about 1 u00b0 c minute and the sample is removed a.