等规聚丙烯压力下晶型转变及其熔融过程
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摘要
利用压力-体积-温度测量仪(PVT),使等规聚丙烯在几个不同压力下进行非等温结晶,结合示差扫描量热仪(DSC)、在线小角X射线散射(SAXS)和广角X射线衍射(WAXD)等手段,研究了不同压力下聚丙烯的晶型转变及其熔融过程的晶体变化。结果发现,随压力增加,样品中γ晶型含量逐渐增加,α晶型减少;熔融升温过程中,样品的SAXS散射图谱(I-s)始终显单一峰,推测认为在片晶结构中α晶型与γ晶型是混合形成的。
A series of specimens of the isotactic polypropylene were obtained by non-isothermal crystallization at different pressures using the Pressure-Volume-Temperature(PVT) instrument.Time resolved synchrotron small and wide angle X-ray scattering(SAXS/WAXS) experiments,together with differential scanning calorimetry(DSC) studies were carried out in order to study the crystal transfer during the non-isothermal crystallization process and their melting behavior.The results indicated that the content of γ-form crystallites increased with the pressure.During the melting process,all SAXS data showed a single peak,indicating that the internal structure of the specimens was periodically ordered.It was also found that long period increased with the temperature.Comparing the long period changes in different specimens,it was speculated that the α-form and γ-form crystallites were mixed together in the lamellae structure.
A series of specimens of the isotactic polypropylene were obtained by non-isothermal crystallization at different pressures using the Pressure-Volume-Temperature(PVT) instrument.Time resolved synchrotron small and wide angle X-ray scattering(SAXS/WAXS) experiments,together with differential scanning calorimetry(DSC) studies were carried out in order to study the crystal transfer during the non-isothermal crystallization process and their melting behavior.The results indicated that the content of γ-form crystallites increased with the pressure.During the melting process,all SAXS data showed a single peak,indicating that the internal structure of the specimens was periodically ordered.It was also found that long period increased with the temperature.Comparing the long period changes in different specimens,it was speculated that the α-form and γ-form crystallites were mixed together in the lamellae structure.
引文
[1]王松.聚丙烯及其共聚物分子链结构、凝聚态结构与材料性能研究[D].长春:中国科学院长春应用化学所博士论文,2003.
[2]T.Foresta,S.Piccarolo,G.Goldbeck-Wood.Competition betweenαandγphases in isotactic polypropylene:effects of ethylene content and nucleating agents at different cooling rates[J].Polymer,2001,42(3):1167-1176.
[3]E.Pérez,D.Zucchi,M.C.Sacchi,F.Forlini,A.Bello.Obtaining theγphase in isotactic polypropylene:effect of catalyst system and crystallization conditions[J].Polymer,1999,40(3):675-681.
[4]B.Lotz,J.C.Wittmann,A.J.Lovinger.Structure and morphology of poly(propylenes):a molecular analysis[J].Polymer,1996,37(22):4979-4992.
[5]S.V.Meille,S.Bruckner,W.Porzio.γ-Isotactic polypropylene.A structure with nonparallel chain axes[J].Macromoleeules,1990,23(18):4114-4121.
[6]E.B.Bond,J.E.Spruiell,J.S.Lin.A WAXD/SAXS/DSC study on the melting behavior of Ziegler-Natta and metallocene catalyzed isotactic polypropylene[J].Journal of Polymer Science Part B:Polymer Physics,1999,37(21):3050-3064.
[7]Do.Y.Yoon,P.J.Flory.Chain packing at polymer interfaces[J].Macromolecules,1984,17(4):868-871.
[8]杨剑,孙昭艳,安立佳,等.利用PVT分析仪测定PS的热膨胀系数等温压缩系数和热压系数[J].中国塑料,1999,13(1):90-97.
[9]M.Krasteva,M.L.Cerrada,R.Benavente,E.Pérez.Non-isothermal crystallization of a vinyl alcohol-ethylene copolymer studied by DSC and real time WAXS/SAXS scattering[J].Polymer,2005,46(23):9831-9839.
[10]R.A.Campbell,P.J.Phillips,J.S.Lin.The gamma phase of highmolecular-weight polypropylene:1.Morphological aspects[J].Polymer,1993,34(23):4809-4816.
[11]K.Mezghani,P.J.Phillips.Theγ-phase of high molecular weight isotactic polypropylene:Ⅲ.The equilibrium melting point and the phase diagram[J].Polymer,1998,39(16):3735-3744.
[12]M.Gahleitner,C.Bachner,E.Ratajski,G.Rohaczek,W.Neiβl.Effects of the catalyst system on the crystallization of polypropylene[J].Journalof Applied Polymer science,1999,73(12):2507-2515.
[2]T.Foresta,S.Piccarolo,G.Goldbeck-Wood.Competition betweenαandγphases in isotactic polypropylene:effects of ethylene content and nucleating agents at different cooling rates[J].Polymer,2001,42(3):1167-1176.
[3]E.Pérez,D.Zucchi,M.C.Sacchi,F.Forlini,A.Bello.Obtaining theγphase in isotactic polypropylene:effect of catalyst system and crystallization conditions[J].Polymer,1999,40(3):675-681.
[4]B.Lotz,J.C.Wittmann,A.J.Lovinger.Structure and morphology of poly(propylenes):a molecular analysis[J].Polymer,1996,37(22):4979-4992.
[5]S.V.Meille,S.Bruckner,W.Porzio.γ-Isotactic polypropylene.A structure with nonparallel chain axes[J].Macromoleeules,1990,23(18):4114-4121.
[6]E.B.Bond,J.E.Spruiell,J.S.Lin.A WAXD/SAXS/DSC study on the melting behavior of Ziegler-Natta and metallocene catalyzed isotactic polypropylene[J].Journal of Polymer Science Part B:Polymer Physics,1999,37(21):3050-3064.
[7]Do.Y.Yoon,P.J.Flory.Chain packing at polymer interfaces[J].Macromolecules,1984,17(4):868-871.
[8]杨剑,孙昭艳,安立佳,等.利用PVT分析仪测定PS的热膨胀系数等温压缩系数和热压系数[J].中国塑料,1999,13(1):90-97.
[9]M.Krasteva,M.L.Cerrada,R.Benavente,E.Pérez.Non-isothermal crystallization of a vinyl alcohol-ethylene copolymer studied by DSC and real time WAXS/SAXS scattering[J].Polymer,2005,46(23):9831-9839.
[10]R.A.Campbell,P.J.Phillips,J.S.Lin.The gamma phase of highmolecular-weight polypropylene:1.Morphological aspects[J].Polymer,1993,34(23):4809-4816.
[11]K.Mezghani,P.J.Phillips.Theγ-phase of high molecular weight isotactic polypropylene:Ⅲ.The equilibrium melting point and the phase diagram[J].Polymer,1998,39(16):3735-3744.
[12]M.Gahleitner,C.Bachner,E.Ratajski,G.Rohaczek,W.Neiβl.Effects of the catalyst system on the crystallization of polypropylene[J].Journalof Applied Polymer science,1999,73(12):2507-2515.