X-Ray Examination of Polychlorotrifluoroethylene<sup>1</sup>

Kaufman, H. S.

doi:10.1021/ja01102a506

Cited by 35 publications

(9 citation statements)

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“…This indicates that the distribution of orientations of the "rods" for the stretched sample is not random but that there is a greater fraction of them aligned perpendicular to the stretching direction. This may also be seen (8) in photomicrographs and is similar to the observation of Clough for the crystallization of oriented polyethylene (14). The c-axis of the crystal is oriented parallel to the stretching direction requiring that this be oriented perpendicular to the rod axis.…”

Section: May Obtainsupporting

confidence: 86%

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Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Adams

Stein

1967

J. Polym. Sci. B Polym. Lett.

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Section: May Obtainsupporting

confidence: 86%

“…This is a copolymer of 96% PCTFE and 4% vinylidene fluoride). This polymer crystallizes in the hexagonal system (8) where n a = nb and f a = f b so that eq. (2) reduces to (9) where is the intrinsic birefringence of the crystal.…”

Section: Orientational Changes In Crystalline Polychlorotrifluoroethymentioning

confidence: 99%

Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Adams

Stein

1967

J. Polym. Sci. B Polym. Lett.

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“…If it is assumed that this quantity is 10 −7 cm or 10A, which corresponds to four monomer units, σ s proves to be 10.8 erg cm −2 . This choice of l 0 = λ 0 is almost certainly within a factor of four of the correct one: the smallest conceivable value would be 2.5A, corresponding to the repeat distance in the chain, while the largest elementary crystallizing unit that need be seriously considered would correspond to the spiral repeat length of 35 to 43A reported for this polymer [30, 31, 32]. Thus, the above estimate of σ s should be within a factor of two of the true value.…”

Section: Application To Poly(chlorotrifluoroethylene)mentioning

confidence: 99%

Experimental and theoretical study of kinetics of bulk crystallization in poly(chlorotrifluoroethylene)

Hoffman¹,

Weeks²,

Murphey³

1959

J. RES. NATL. BUR. STAN. SECT. A.

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The rate of isothe rm al bulk crystalli zation of poly (e hloro trifluoroethylene) , 2'm = 221° C, was measured from 170 0 to 200 0 C. The intrinsic bulk cr ystallization, which acc uraLe ly ~o llow e d a n n= 2 la\,:, was. shown t o be a res ult of the i~lj ect ion of primary nu clei spora di cally III Lime, with on e-dim ensIOnal growth of cen ters den ved from t hese n uclei. The cr ysLalIi tesare exceedingly s ma ll. The one~dimen sional gro wth process was isolaLe d by nuclca Lin g s peCllllens WJ t h seed crystals, a nd Its te mperature-dependence determincd beL ween 191 0 an d 205 0 C. The seed crystal isotherms followed an n= 1 la w. TIle te mperature coC'ffi cien ts o f t he rate of nu cleation a nd the rate of grow th were both stron gly negati ve .A Lheor y of homogeneo us nucleation t hat takes i nto accou nt t he egmental cha racte r of t he polymer c hai ns is d eveloped in some detail . A cylindrical n ucleu is ass umed . In Lhe te mperat ure ra nge ncar t he mel ting point, region A, where t he r adius a nd length of t he n lI clcus a re u nresLricted, the rate of nucleation is shown to be proportional to exp ( -a / T al). 1'2).The nu cleation rate is pl'oportional to exp( -fJ / T21). 2"' ) in region B, which exten ds from so me-\\' hat below t he melt ing point to considera bly lower temperatlll'es; the length of t he nucleus has a constant value / 0 in t his region, but t he rad ius is ume tricted . (In t he a bove express ions, a a nd fJ a rc constan ts). Finally, at suffi cien Lly low tem peratures, region C is en te red . U llder COl' Lain circ ulllstances, the r ate of n ucleatio n in region C will be extre mely rapid, a nd correspond to a "n ucleative collapse" of t he supcrcooledliqu id state. A calculation of Lh c one-dim e nsio na l growt h rate s hows that it is p ropo rt ional to exp( -,,(/ T 2I).'1') where fJ = "(.A careful analysis o f t he expe ri men tal data ob Lain ed between 170 0 an d 200 0 C clearl y showed t hat both t he rate of n ucleation an d t he raLe of growth were p ropor t iona l to cxp( -{3/ T2I).T), and not ex p ( -a/ ' 1.'3I).T2).The p rimary n ucleation event wa th us of ty pe H in Lhis interval. A delailed a na lysis of the data is given, a nd s urface free enerO'ie a nd t he d ime nsio ns of the n uclei quoLed. Quenchin g experimenLs, where t he poly mer ;as crys lallized well below 170 0 C, gave a firm indi cation of t he ex iste nce o f reg ion C.An experi mental sLud y was ma de of t he extremely slow cry lalli zation process t hat prevail ed when Lhe degree of crysLallini ty became hig h. The on set of t his stage of t he crysLalli zation was interp reted as being Lile resul t of a m assive degree of impinge ment. This i r~Lcrpretati o n is jll st i~cd by Lhe caleulaL ions of Laurilzen, who has g iven a t heor y of imPJtl gc me nts t hat pred lC L::; a pse udoequ ill b n um degree of crystaUi n ily.As indi cated a bove t ile growl h p rocess orig inaL in g at ho moge neo us nuclei is not o f a Lh ree-dimensional or spile ruli t ic characLer in Lhe reg ion o...

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“…If the quenched films had not been exposed to 325 K or higher temperatures, the x-ray (CnKα) diffraction patterns of these highly amorphous samples all showed an intense halo centered around a 26 value of 15.5° or around a spacing of 5.7 Å plus two fainter broad halos at around 32° and 39° or around 2.8 and 2.3 Å, similar to that found in commercial PCTFE films [ 12 , 13 ]. A faint halo at 8° or about 11 Å was always observed.…”

Section: Experimental Detailmentioning

confidence: 56%

Heat capacity and thermodynamic properties of poly(chlorotrifluoroethylene) from 2.5 to 620 K

Chang

Weeks

1992

J. RES. NATL. INST. STAN.

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Heat capacities and thermodynamic properties of a number of poly(chlorotrifluoToethylene) samples subjected to various thermal treatments, to achieve crystallinities ranging from approximately 10 to 90%, have been studied from 2.5 to 370 K by automated adiabatic calorimetiy and from 250 to 620 K by differential scanning calorimetry. Small heat capacity discontinuities in the temperature range from 320 to 350 K were observed in all samples with crystallinities greater than 40%. Spontaneous adiabatic temperature drifts associated with these anomalies were prasitive (exothermic) for quenched samples and negative (endothermic) for annealed samples. Therefore these anomalies were believed to be associated with a relaxation phenomenon similar to that of a glass transition. For highly quenched low crystallinity films, a much larger heat capacity discontinuity of greater than 15% was observed, amidst a crystallization exotherm. In addition to the above phenomena, annealing of the sample at any temperature between 240 to 400 K would produce a shift in the population distribution of crystallites from reorganization or melting and recrystallization. As a result, the apparent heat capacity became somewhat lowered at the annealing temperature and somewhat raised at about 20 K above the annealing temperature.

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X-Ray Examination of Polychlorotrifluoroethylene¹

Cited by 35 publications

References 0 publications

Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Experimental and theoretical study of kinetics of bulk crystallization in poly(chlorotrifluoroethylene)

Heat capacity and thermodynamic properties of poly(chlorotrifluoroethylene) from 2.5 to 620 K

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X-Ray Examination of Polychlorotrifluoroethylene1

Cited by 35 publications

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Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Orientational changes in crystalline polychlorotrifluoroethylene copolymer films

Experimental and theoretical study of kinetics of bulk crystallization in poly(chlorotrifluoroethylene)

Heat capacity and thermodynamic properties of poly(chlorotrifluoroethylene) from 2.5 to 620 K

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Product

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X-Ray Examination of Polychlorotrifluoroethylene¹