Crystallization behavior and toughening of syndiotactic polystyrene/ poly(2,6-dimethyl-1,4-phenylene oxide) blends = 신디오탁틱 폴리스티렌과 폴리페닐렌 옥사이드 블랜드계의 결정화거동 및 강인화에 관한 연구

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Crystallization behavior, crystal growth and toughening of syndiotactic polystyrene (SPS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blends were investigated. Isothermal and non-isothermal crystallization experiment on the blend sample revealed that (1) melt crystallization temperature ($T_c$) decreased from 239℃ to 212℃, (2) half-time of crystallization($τ_(1/2)$) increased from 20sec to 90sec, (3) Avrami index increased from 1.7 to 3.1, (4) melting temperature($T_m$) decreased from 272℃ to 270℃, and (5) nucleation density are decreased. As the crystallization temperature increases, $T_m$ increased from 270.5℃ to 272℃ while Avrami index decreased from 2.9 to 1.7. Multiple melting behaviors were notable in melting of SPS and SPS/PPO blend system. Different multiple melting behaviors were observed for different compositions, showing optimum annealing temperature. The optimum annealing temperature for the pure SPS was found to be 265℃. The optimum annealing temperature for the 70/30, 80/20, and 90/10 blends of SPS/PPO were found to be 258.5, 261.0, and 263.5℃, respectively. When annealed below the optimum annealing temperature, the ordering took place, the crystallinity increased and lamellae were thickened. Lower temperature peak in DSC thermograms shifted to higher temperature region by annealing by the result of growth of large crystals. On the other hand, annealing at the higher temperature did not promote the crystal growth. In order to analyze such multiple melting phenomena in relation to crystal structure, the combined morphology was observed using polarizing optical microscopy (POM), wide angle x-ray diffraction (WAXD), small angle x-ray scattering (SAXS). The analysis lead to conclusion that in low temperature (at 220℃) crystallization PPO prohibited crystallization of SPS while it was promoted in high temperature crystallization (at 240℃). The thermal behavior of the pure SPS and SPSIPPO (70/30) blend taken from the isothermally crystallized spec...
Advisors
Cho, I-Whan조의환
Description
한국과학기술원 : 신소재공학과고분자전공,
Publisher
한국과학기술원
Issue Date
1999
Identifier
156295/325007 / 000949003
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 신소재공학과고분자전공, 1999.2, [ xx, 202 p. ]

Keywords

Toughening; Poly(2,6-dimethyl-1,4-diphenylene oxide); Syndiotacticpolystyrene; Crystallization; 결정화; 강인화; 폴리페닐렌옥사이드; 신디오탁틱 폴리스티렌

URI
http://hdl.handle.net/10203/49769
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=156295&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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