摘要:

AbstractHeat capacity data of semicrystalline poly(oxymethylene) samples. Delrin and Celcon, are analysed in order to discuss the glass transition behaviour of this polymer. There are two types of non‐crystalline poly(oxymetheylene). the mobile and rigid amorphous parts. The glass transition of the former occurs in a rather wider range of temperature: it starts at 180 K and could end at 265 K. The latter, under restraint due to the crystallites, remains frozen up to the melting temperatur

ISSN:0007-1641    

DOI:10.1002/pi.4980170101

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980170102

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract1H n.m.r. spectra of the title polymers containing 0%, 57% and 100%cisdouble bonds and having various degrees of head‐tail (HT) bias have been analysed. The olefinic protons give distinct signals for HH, HT and TTtransdyads, also for HT and TTcisdyads, but HHcisdyads are not present in any polymer. The ring protons adjacent to the double bonds also give distinctcisandtranssignals as do the methyl protons. The latter give four lines, assigned tocc, ct, tcandttdouble bond pairs, and their intensities indicate a somewhat blockycis/transdistribution for polymers having a highciscontent. There is no fine structure which can be positively assigned to ring tacticity effect

ISSN:0007-1641    

DOI:10.1002/pi.4980170103

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe Kirkwood equation and a Monte‐Carlo technique which employs Metropolis sampling have been used to calculate diffusion coefficients (D) for low molar mass cyclic poly(dimethylsiloxanes). Correlations between calculated and experimental values ofDshow that the effective segment size is larger for cyclic than for linear PDMS. Thus, free‐draining flow is reduced for the cyclic species consistent with its greater segment density. The cyclic molecules also show enhanced diffusion coefficients at very low molar masses which may be associated with the rigid toroidal shapes of these molecu

ISSN:0007-1641    

DOI:10.1002/pi.4980170104

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractTwo model epoxy resin precursors based on theN‐glycidyl derivatives of 4.4'‐diaminodiphenylene methane (DDM) were prepared:N,Nbis‐(2,3‐epoxypropyl)‐N′,N″‐dimethyl‐4.4'‐diaminodiphenylene methane (G2A);N.N′ bis‐(2,3‐epoxypropyl)‐N,N′‐dimethyl‐4,4'‐diaminodiphenylene methane (G2S). To prepare these, aniline orN‐methyl aniline was reacted with epichlorohydrin, using acetic acid as catalyst. The products were coupled via acid‐catalysed condensations in the presence of formaldehyde or withN,N‐dimethylaminobenzyl alcohol. The coupled chlorohydrins formed were then dehydrochlorinated to form the desired product. All reactions were monitored and purifications of the crude products were effected by high pressure liquid chromatographic techniques. The products were characterised by proton and carbon‐13 nuclear magnetic resonance, infrared and mass spectroscopy, elemental and titrametric analysis. Results were compared with those obtained for tetra‐N‐glycidyl‐4,4'‐diaminodiphenylene methane (TGDDM). All the data confirmed the structures of the model resins. These, together with TGDDM. will be used to prepare epoxy resin networks of co

ISSN:0007-1641    

DOI:10.1002/pi.4980170105

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThree samples of a commercial hydroxyl‐terminated polybutadiene, Arco R45M. were characterised with respect to number‐average and weight‐average molar mass, intrinsic viscosity, number‐average hydroxyl functionality and effective functionality for gelation. Two of the samples were fractionated on the basis of solubility in toluene/methanol mixtures, and the fractions were characterised with respect to number‐average molar mass, intrinsic viscosity and number‐average hydroxyl functionality. For both sets of fractions, the average functionality was practically independent of average molar mass. It is concluded that the functionality distribution is almost identical at all points in the molar mass range o

ISSN:0007-1641    

DOI:10.1002/pi.4980170106

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractComb‐branched copolymers containing ethylene amine side chains of the general structure ‐NH(CH2CH2NH)xH with x=1, 2, 3 and 4, were prepared by the reaction of poly(monoalkyl‐codialkyl itaconate)s, using an excess of the appropriate diamine in the presence of dicyclohexylcarbo‐diimide. Incorporation of ethylene amine units in the itaconate copolymers resulted in an increase in the glass transition temperature (Tg) and in the complex modulus of the modified copolymers aboveTg. Both effects were proportional to the ethylene amine content of the copolymers. Chemical modification also occurred when samples were heated to about 450 K when imide formation was

ISSN:0007-1641    

DOI:10.1002/pi.4980170107

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractX‐ray scattering from continuously rotated samples of directionally crystallised pentadecaethylene glycol di‐n‐heneicosyl ether falls on a pattern of layer lines which is readily interpreted. The unit cell is orthogonal witha=0.938nm.b=9.13nm andc=0.916nm. and with four molecules per unit

ISSN:0007-1641    

DOI:10.1002/pi.4980170108

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractAtactic and isotactic polypropylene (APP and IPP), and ethylene‐propylene copolymers (EP). functionalised by reacting the molten polymer with diethylmaleate (DEM) in the presence of dicumylperoxide (DCP). have been blended with poly(vinylchloride) (PVC) and polystyrene (PS). These mixtures have been investigated by means of infrared spectroscopy at different compositions in the region of carbonyl absorption. The features of this last band in the mixture suggest the occurrence of intermolecular interactions involving mainly the carbonyl groups of the functionalised polymer and the methine hydrogens of PV

ISSN:0007-1641    

DOI:10.1002/pi.4980170109

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractChitin membrane was prepared by casting aN,N‐dimethyl acetamide,N‐methyl 2‐pyrrolidone and lithium chloride (DMA‐NMP‐LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2‐Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2‐propanol and water. The membrane obtained in 2‐propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms

ISSN:0007-1641    

DOI:10.1002/pi.4980170110

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY