Lamellar Thickness Dependence of Crystal Modification Selection in the Syndiotactic Polystyrene gamma-to-alpha/beta Phase Transition Process

doi:10.1021/acs.macromol.7b01943

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	Lamellar Thickness Dependence of Crystal Modification Selection in the Syndiotactic Polystyrene gamma-to-alpha/beta Phase Transition Process
	Wang, Hai; Wu, Chunji; Cui, Dongmei; Men, Yongfeng
刊名	MACROMOLECULES
	2018-01-23
卷号	51 期号:2 页码:497-503
ISSN号	0024-9297
DOI	10.1021/acs.macromol.7b01943
英文摘要	The syndiotactic polystyrene (sPS) gamma-to-alpha/beta phase transition was investigated using temperature-dependent synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) measurement. The sPS gamma form samples, which were obtained from acetone solvent induced crystallization followed by annealing at various temperatures (Ta), exhibited a regular manner on the selection of the a or crystal modification during the phase transition process. As the T-a was increased from 25 to 150 degrees C, the weight fraction of form in bulk sPS decreased from 55% to 0%, but that of the a form increased from 45% to 100%. In other words, the a form became the dominating crystalline modification at higher T-a. The lamellar thickness (dc) of the gamma form at the initial state (before heating) ranged from 4.4 to 5.8 nm, and the weight crystallinity (X-c) was between 0.52 and 0.64. However, the d(c) values of the gamma form at the final state (before gamma-to-alpha/beta phase transition) were very close for the samples pretreated at different Tas, which were in the range 7.07.4 nm. Therefore, the most plausible interpretation for the crystal modification selection during the gamma-to-alpha/beta phase transition was that the nucleation of beta form was suppressed totally in the gamma form with higher initial dc value (>5.8 nm). With the elevated Ta and increase of initial dc, the promoted nucleation of a form in the gamma form resulted in the enhanced growth of the a crystalline phase during the ?-to-a/ phase transition. As a result, after the phase transition the crystalline phase in bulk sPS had a gradually increased weight fraction of the a form and turned out to be pure a form when Ta was increased from 25 to 150 degrees C.
语种	英语
出版者	AMER CHEMICAL SOC
WOS记录号	WOS:000423418100023
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/45517]
专题	中国科学院化学研究所
通讯作者	Men, Yongfeng
作者单位	Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Jilin, Peoples R China
推荐引用方式 GB/T 7714	Wang, Hai,Wu, Chunji,Cui, Dongmei,et al. Lamellar Thickness Dependence of Crystal Modification Selection in the Syndiotactic Polystyrene gamma-to-alpha/beta Phase Transition Process[J]. MACROMOLECULES,2018,51(2):497-503.
APA	Wang, Hai,Wu, Chunji,Cui, Dongmei,&Men, Yongfeng.(2018).Lamellar Thickness Dependence of Crystal Modification Selection in the Syndiotactic Polystyrene gamma-to-alpha/beta Phase Transition Process.MACROMOLECULES,51(2),497-503.
MLA	Wang, Hai,et al."Lamellar Thickness Dependence of Crystal Modification Selection in the Syndiotactic Polystyrene gamma-to-alpha/beta Phase Transition Process".MACROMOLECULES 51.2(2018):497-503.