Mesophase features in isotactic poly(propylene‐co‐1‐heptene) copolymers |
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| Authors: | Alberto García‐Peñas José M Gómez‐Elvira María U de la Orden María L Cerrada Ernesto Pérez |
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| Affiliation: | 1. Instituto de Ciencia y Tecnología de Polímeros (ICTP‐CSIC), Madrid, Spain;2. Departamento de Química Orgánica I, Facultad de óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain;3. Research Group ‘Polímeros: Caracterización y Aplicaciones’ (U.A. of ICTP‐CSIC), E.T.S.I. Industriales, Universidad Politécnica de Madrid, Madrid, Spain |
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| Abstract: | The influence of crystallization rate on the interesting polymorphism of random isotactic poly(propylene‐co‐1‐heptene) copolymers was studied, with particular attention to the conditions for obtaining the mesomorphic phase. Owing to the important decrease of cooling rate involved as the 1‐heptene content increases, the mesophase can be clearly observed by DSC for co‐unit contents above about 5 mol%. Furthermore, only the mesophase (or the amorphous phase) was found for the copolymer with 13.9 mol% 1‐heptene at common cooling rates of the calorimeter. Additionally, the copolymer with 21.4 mol% co‐units was found to be completely amorphous under any thermal treatment analyzed. Variable‐temperature diffraction experiments were carried out to ascertain unambiguously the nature of the phases involved. Finally, a remarkable transparency was attained (above 80% transmittance in the visible light region) at intermediate and high 1‐heptene contents, using easily accessible cooling rates. © 2016 Society of Chemical Industry |
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| Keywords: | propylene‐co‐1‐heptene copolymers polymorphism mesophase formation DSC study variable‐temperature diffraction experiments transparency |
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