Investigation on Microstructural Evolution of Mesomorphic Propylene/Ethylene Copolymer upon Thermal Treatment

	Investigation on Microstructural Evolution of Mesomorphic Propylene/Ethylene Copolymer upon Thermal Treatment
	Jiang, Qian-hong 1,2; Zhao, Ying 1; Wang, Du-jin 1,2
刊名	ACTA POLYMERICA SINICA
	2017-09-20
期号	9 页码:1538-1548
关键词	Polypropylene Random Copolymer Mesophase Infrared Spectroscopy
英文摘要	Mesomorphic propylene/ethylene copolymer (PPR) was obtained by quenching quiescent melt. Its microstructural evolution during continuous heating process was studied by in situ Fourier transform infrared spectroscopy (FTIR), in situ wide/small angle X-ray diffraction (WAXD/SAXS), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). No structural change was detected by WAXD in temperature range of 30 - 50 degrees C, while IR results showed the molecular segments experienced conformational changes in this temperature range. Considering the presence of large amount of rigid amorphous fraction (RAF) in the mesomorphic sample, the IR results, in combination with DMA and DSC results of annealed mesomorphic samples, implied that this conformational changes may originate from the helical sequences destruction of partial segments in RAF. The helical conformation regularity bands showed different variation trends during heating. The relative intensity of the conformation bands associated with the long helical sequences (n > 13, the number of monomers in helices) showed no evident change in the temperature range of 30 - 50 degrees C, while the relative intensity of the conformation bands assigned to the helical sequences with medium length (n <= 13) gradually decrease in this temperature range. Therefore, the presence of the helical sequences with n <= 13 was deduced in RAF. Variation of fractions of mesophase, alpha crystal and amorphous phase during the continuous heating process was evaluated by in situ WAXD. The long periods of the sample at different temperatures during heating were derived from SAXS result. The results of IR and XRD indicated that, during the continuous heating process, the tranformation of mesomorphic PPR mainly experienced four stages: helical conformation destruction of partial segments in RAF, transformation of mesophase to alpha crystal, perfection of imperfect alpha crystal and melting of alpha crystal. IR results of isothermal crystallization process showed the transformation from mesophase to alpha crystal was a nucleation-growth process via heterogeneous nucleation. The activation energy of meso-alpha transformation in isothermal crystallization process was determined to Delta E = 67.94 kJ/mol.
语种	英语
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/39143]
专题	化学研究所_工程塑料实验室
作者单位	1.Chinese Acad Sci, Key Lab Engn Plast, Res Educ Ctr Excellence Mol Sci, Inst Chem, Beijing 100190, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Jiang, Qian-hong,Zhao, Ying,Wang, Du-jin. Investigation on Microstructural Evolution of Mesomorphic Propylene/Ethylene Copolymer upon Thermal Treatment[J]. ACTA POLYMERICA SINICA,2017(9):1538-1548.
APA	Jiang, Qian-hong,Zhao, Ying,&Wang, Du-jin.(2017).Investigation on Microstructural Evolution of Mesomorphic Propylene/Ethylene Copolymer upon Thermal Treatment.ACTA POLYMERICA SINICA(9),1538-1548.
MLA	Jiang, Qian-hong,et al."Investigation on Microstructural Evolution of Mesomorphic Propylene/Ethylene Copolymer upon Thermal Treatment".ACTA POLYMERICA SINICA .9(2017):1538-1548.