Evaluation of the interfacial state in high impact polystyrene through dynamic mechanical analysis as a function of the synthesis conditions

Authors

  • R. Díaz de León,

    1. Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna No. 140, (25253), Saltillo Coahuila, México
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  • G. Morales

    Corresponding author
    1. Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna No. 140, (25253), Saltillo Coahuila, México
    • Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna No. 140, (25253), Saltillo Coahuila, México
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  • Presented at the National Congress of the Sociedad Polimérica Mexicana, Saltillo, Coahuila, México, 2006.

Abstract

High impact polystyrene was synthesized using two series of styrene/butadiene (SB) tapered block copolymers with a polystyrene (PS)/polybutadiene (PB) composition of 30/70 and 10/90 wt%. During the synthesis, concentration of initiator, SB and transfer agent were varied. From dynamic mechanical analysis, the corresponding α relaxation of the rubber phase was detected at low temperature (near −100°C) and that of the glassy PS phase at high temperature (near 100°C). Also, another relaxation at temperature near 40°C was identified, which was associated to the β relaxation of the glassy PS phase. The variations found in the α relaxation of the rubber phase, were attributed to changes in the morphological structure as a consequence of variation in initiator, SB or transfer agent concentrations and in SB composition. β relaxation showed a strong dependency with the interfacial state between the rubber and the glassy phase, where an increase in the amount of graft PS at the interface, which promotes the interfacial adhesion between phases, causes an increase in the magnitude of β relaxation of the PS phase. The results were attributed to variations in the interfacial area as a result of the change in the particle size and to the contribution of molecular chains of each phase in participating in the relaxation process. POLYM. ENG. SCI., 47:1827–1838, 2007. © 2007 Society of Plastics Engineers

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