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Physical aging and thermal aging resistance of polycarbonate/poly(styrene‐ b ‐(ethylene‐ co ‐butylene)‐ b ‐styrene) blends
Author(s) -
Suzuki Shuta,
Nishitsuji Shotaro,
Inoue Takashi
Publication year - 2012
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.23137
Subject(s) - izod impact strength test , materials science , differential scanning calorimetry , composite material , polycarbonate , endothermic process , impact resistance , ultimate tensile strength , annealing (glass) , styrene , copolymer , brittleness , embrittlement , polymer , organic chemistry , chemistry , physics , adsorption , thermodynamics
The effect of thermal annealing on the mechanical properties of polycarbonate (PC) was investigated by tensile testing, Izod impact testing, and differential scanning calorimetry (DSC). An endothermic peak appeared in the DSC curve by annealing at various temperatures below T g . The peak area, as a measure of the degree of physical aging, increased with annealing time. The Izod impact strength decreased suddenly just before an endothermic peak became detectable. The results imply that at the very early stage of physical aging, a trigger for the ductile‐to‐brittle transition may be initiated. By blending hydrogenated styrene‐butadiene‐styrene block copolymer (SEBS), the embrittlement by annealing was prevented. That is, in the PC/SEBS blends, the physical aging of PC matrix proceeded in the same way as in neat PC; however, the Izod impact strength did not decrease. This thermal aging resistance seems to originate from the negative pressure effect of SEBS particles that provides dilational stress fields for PC matrix to enhance the local segment motions. POLYM. ENG. SCI., 52:1958–1963, 2012. © 2012 Society of Plastics Engineers