000			01512nam a2200169Ia 4500
008			220216s9999 xx 000 0 und d
100			_aSchloman W W
245		0	_aEffects of environment and composition on degradation of Guayule rubber
260			_bJournal of Applied Polymer Science _c1996
300			_a1015-1023
520			_aBales of antioxidant-stabilized guayule rubber underwent significant losses in bulk viscosity when stored under ambinent comditions at an Arizona processing facility. Previous work implicated the unsaturated fatty acid esters present in entrained resin as promoters of such degradation. Ageing studies as functions of storage temperature and unsaturated acid ester content were carried out on both bulk rubber and rubber-resin solution (miscella) for cultivar AZ-101. The rate of thermo-oxidative degradation, determined as a function of Mooney viscosity, was increased by the addition of unsaturated ester. Anaerobic degradation was not affected in this way. The activation energy of chain thermolysis was found to be 116 +_ 6kJ/mol (28 +_ 1kcal/mol). At temperatures above 60 C, chain recombination successfully competed with chain scission in lower viscosity rubber. The rate of thermo-oxidative degradation was substantially higher in a typical process miscella. A hindered amine antioxidant significantly reduces chain scission under these conditions.
650			_aGuayule rubber
700			_aBeinor R T
700			_aHilton A S
700			_aMcIntyre D
942			_cJS
999			_c58325 _d58325