02066nas a2200169   4500008004100000022001400041245012000055210006900175260007100244300001400315490000700329520138100336100001601717700001901733700001501752856012901767       2008                        eng d  a0024-929700aRole of solvent molecules as a trigger for the crystal phase transition of syndiotactic polystyrene/solvent complex0 aRole of solvent molecules as a trigger for the crystal phase tra  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC  a9814-98180 v413 a<p>The phase transitions occurring in the syndiotactic polystyrene-norbornadiene complex were investigated by simultaneous measurements of wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). To understand the effect of norbornadiene molecules on the phase-transition behavior, the delta form samples with different contents of norbornadiene were prepared. By heating these samples, we found that the delta-to-gamma transition occurred well below 100 degrees C in a broad temperature range, and the onset of the transition temperature depended on the content of norbornadiene included in the starting sample. The sample without norbornadiene molecules showed the delta-to-gamma transition to be above 100 degrees C. Upon further heating, the gamma form transformed into a mixture of alpha and beta forms in the presence of norbornadiene molecules, whereas the sample without norbornadiene transformed into only the alpha form. In this way, it has been found that the solvent molecules, which are not completely evaporated from the sample but are transiently trapped in the amorphous region because of the slow diffusion, have a significant role in facilitating the phase transitions as well as the transition temperatures in the crystalline region. On the basis of WAXD and DSC results, a phase-transition model has been reasonably constructed.</p>1 aGowd, Bhoje1 aTashiro, Kohji1 aRamesh, C.  uhttps://library.ncl.res.in/content/role-solvent-molecules-trigger-crystal-phase-transition-syndiotactic-polystyrenesolvent-001569nas a2200241   4500008004100000022001400041245006100055210006100116260010600177300001200283490000700295520074200302653002201044653001301066653002101079653001701100653003601117653002901153100001601182700001901198700001501217856009501232       2009                        eng d  a0079-670000aStructural phase transitions of syndiotactic polystyrene0 aStructural phase transitions of syndiotactic polystyrene  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR  a280-3150 v343 a<p>Syndiotactic polystyrene (sPS) exhibits four crystal modifications (alpha, beta, gamma, and delta), along with intermediate forms with different molecular conformations, as well as different chain-packing structures. The extensive literature on the crystal structures exhibited by sPS is reviewed herein, including, the mechanisms of phenomena such as solvent-induced crystallization, thermally induced crystallization and gelation, and the phase transitions among the various crystalline forms. The latter have been studied by static and dynamic wide-angle and small-angle X-ray scattering, infrared and Raman spectra, and neutron scattering, etc., in addition to computer simulations. (C) 2009 Elsevier Ltd. All rights reserved.</p>10acrystal structure10aGelation10aphase transition10apolymorphism10aSolvent-induced crystallization10aSyndiotactic polystyrene1 aGowd, Bhoje1 aTashiro, Kohji1 aRamesh, C.  uhttps://library.ncl.res.in/content/structural-phase-transitions-syndiotactic-polystyrene-0