Synergistic gelation of solutions of isotactic polypropylene and bis-(3,4-dimethyl benzylidene) sorbitol and its use in gel-processing |
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Authors: | Magnus KristiansenTheo Tervoort Paul Smith |
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Affiliation: | Department of Materials, Eidgenössische Technische Hochschule (ETH), Institute of Polymers, Universitatstrasse 41 UNO C14, Zürich CH-8092, Switzerland |
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Abstract: | We report the synergistic, rapid gelation of solutions of isotactic polypropylene (i-PP) and the nucleating agent 1,3:2,4-bis-(3,4-dimethyl benzylidene) sorbitol (DMDBS) in decalin. Cooling to room temperature of a solution comprising, for instance, 3.0 wt% of a moderately high molecular weight i-PP (Mv=1.3×106 g/mol) and as little as 0.0075 wt% DMDBS (0.25 wt% based on the polymer) resulted in the fast formation of highly ductile gels. In reference experiments without DMDBS, often ‘mud-cracked’, brittle polymer films were obtained, and decaline solutions of DMDBS alone at the above concentration did not form macroscopically coherent gels. In the present work we employed this useful occurrence for gel-processing/drawing of i-PP, yielding material with Young's moduli of 35 GPa, tensile strengths of approximately 1 GPa and melting temperatures measured for constrained samples as high as 228 °C. |
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Keywords: | Isotactic polypropylene Sorbitol derivatives Nucleating agent |
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