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| 1 | CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅰ.POLY(P-PHENYLENE TEREPHTHALATE)显示文摘The morphology and crystal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin film melt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electron microscopy, electron diffraction and molecular modeling. The unit cell is monoclinic (P21/a space group) with parameters a =7.89, b = 5.49, c =12.65 A α= γ= 90°,β= 100.33°, density = 1.48 g/cm3, the a, b andβ values differing slightly from those reported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted [001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence was found for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220°C (up to 370°C) and CTFSP crystals polymerized at 300°C consisted of lamellae 100-200 A thick. | J.Yang J.Wang G.Sidoti J.Liu F.Rybnikar M.Kaszonyiova P.H.Geil | 2003 | Chinese Journal of Polymer Science2003，21，2： | 2 |
| 2 | MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE——Ⅰ.HIGH MOLECULAR WEIGHT SINGLE-AND MULTI-MOLECULE FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES显示文摘The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weight polytetrafluoroethylene (PTFE) on a substrate as a function of 'melt' time and temperature is described. Folded chain single crystals parallel to the substrate and as ribbons on-edge (with double striations), as well as bands, are produced for longer sintering times; particle merger and diffusion of individual molecules, crystallizing as folded chain, single (or few) molecule,single crystals when 'trapped' on the substrate by cooling occur for shorter sintering times. It is suggested the observed structures develop with sintering time, in a mesomorphic melt. The structure of the nascent particles is also discussed. | J.Yang K.L.Petersen R.A.Williams P.H.Geil T.C.Long P.Xu | 2005 | Chinese Journal of Polymer Science2005，23，2： | 2 |
| 3 | CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅱ. POLY(p-PHENYLENE 2,6-NAPHTHALATE)显示文摘Confined thin film melt polymerization (CTFMP) of naphthalene chloride/hydroquinone (NC/HQ, 1/1, molar)mixtures at polymerization temperatures (Tp) below ca. 300℃ resulted in relatively thick, elongated crystals. Polymerization of NC/HQ above 300℃ between glass yielded well-formed lamellar crystals ca. 100 A thick. Phase Ⅰ and Ⅱ [001] ED patterns were obtained for all Tp, the relative amount of phase Ⅰ increasing with Tp. Polymerization of naphthalene dicarboxylic acid/hydroquinione diacetate 1/1 mixtures at high Tp also yielded lamellar crystals that 'curled up' off of the substrate. When the high temperature CTFMP polymerization was conducted between mica, aggregates of lamellae on-edge developed but epitaxial growth did not occur. Epitaxial growth of lamellae between mica could be obtained, however, by confined thin film solution polymerization, with both of the latter samples yielding apparently related ED patterns from a different unit cell than phase Ⅰ or Ⅱ. Fiber patterns, obtained from sheared samples, indicated considerably greater crystal disorder than in the nascent crystals. Refinement of the phase Ⅰ unit cell parameters, based on the [001] and [011] ED patterns, with modeling based on Cerius2, suggests a monoclinic phase Ⅰ unit cell with a = 7.76, b = 5.71, c = 14.99 A, α = γ= 90°, β= 99.7°, p = 1.47 g/cm3, space group P121/al. | J.Yang J.Wang G.Sidoti J.Liu F.Rybnikar M.Kaszonyiova P.H.Geil | 2003 | Chinese Journal of Polymer Science2003，21，2： | 0 |
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