DILUTE SOLUTION PROPERTIES OF HIGH-MOLECULAR-WEIGHT POLY(ISOBUTYL METHACRYLATE). VII. EFFECT OF CENTRIFUGING ON VARIOUS PARAMETERS.
PICATINNY ARSENAL DOVER N J PLASTICS AND PACKAGING LAB
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Three samples of high-molecular-weight polyisobuyl methacrylate, designated 937,SW630082 and SW620298, were all found to be shear dependent. Sample SW620298, which has the highest molecular weight, readily dissolved in acetone and methyl ethyl ketone. Both its weight average molecular weight and its intrinsic viscosity decreased as the centrifuging time increased. The number average molecular weight, determined by light scattering, seemed to remain constant. Sample SW630082, with the next highest molecular weight, did not readily dissolve in acetone and methyl ethyl ketone. but again, the weight average molecular weight and the intrinsic viscosity decreased with centrifuging time, while the number average molecular weight remained constant. Sample 937 behaved somewhat differently. First, the intrinsic viscosity decreased slightly as the centrifuging time increased, but levelled off at three hours. The weight average molecular weight stayed constant for three hours, but dropped slightly after four hours. The number average molecular weight remained constant. From light scattering measurements, the molecular weight, chain dimensions, and degree of polymerization for the weight, number, and Z averages were calculated. The number average molecular weight was determined by osmometry. Author
- Atomic and Molecular Physics and Spectroscopy