摘要:

AbstractIt has been shown that lamellar crystals of amylose V complexes with 71helical configuration can be obtained by using complexing agents larger in cross section thann‐butanol. The electron diffraction studies indicated a new unit cell for the unheated lamellar crystals which are composed of molecules with 71helical configuration and hold water molecules on the exterior of the helix. Furthermore, from a throughly dried specimen at 100°C.in vacuowe obtained a pattern which showed only three Debye rings. Its spacings were explained by a two‐dimensional hexagonal unit cell havinga=b= 14.7 A. proposed by Zaslow. It was also found that when the crystals were dispersed in methanol at room temperature, their electron diffraction pattern was the same as that of the anhydrous amylose V complex ofn‐b

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040201

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe relationship of intrinsic viscosity to the number‐average molecular weight has been obtained for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene in a few solvents. Values of (〈L2〉0/M)1/2have been estimated for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene through the use of the treatment of Stockmayer and Fixman. The values of (〈L〉0/M)1/2have been obtained as 2.18 ± 0.08 and 2.52 ± 0.07 for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene, respectively. The σ value of a series of polystyrene derivatives has been found to increase with the bulk of side groups. This seems to indicate that the σ value is mainly determined by the

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040202

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractGood yields of some crystalline γ‐alkyl esters ofL‐glutamic acid were obtained by carrying out the esterfication with a small (20–50 mole‐%) excess of alcohol in aqueous hydrochloric acid or 60–80% sulfuric acid followed by neutralization with an alkaline solution. This new method made it possible to synthesize various γ‐alkylL‐glutamates, including those higher than ethyl, and consequently, various poly(γ‐alkylL‐glutamates) such as methyl, ethyl,n‐propyl,n‐butyl, isobutyl, and isoamyl. The conformation of these poly‐L‐glutamates in the solid state was determined by the infrared absorption method. The molecular motions of the polymers of γ‐methyl, ‐ethyl, ‐n‐propyl, ‐n‐butyl, and‐isoamylL‐glutamates and poly(γ‐methyl‐D‐glutamate) in the solid state were studied by NMR, and dielectric and mechanical measurements. At temperatures up to 400°K., the NMR spectra of poly(γ‐methylD‐glutamate) can be explained only by rotational motion of the side chain. Also, from NMR results, rotational motion of CO groups in the side chain of poly(γ‐methylD‐glutamate) is expected near room temperature, and such a motion was examined by dielectric measurements. Rotation of CO groups in the side chains of polymers of γ‐methyl, γ‐ethyl, γ‐n‐propyl, γ‐n‐butyl, and γ‐isoamylL‐glutamate was also observed near room temperature by dielectric measurements in the frequency range from 102to 106cps. Activation energies obtained by dielectric and mechanical measurements were similar to those for the side chain motions of the corresponding esters of poly(methacrylic acid). Although it has been noted that the molecular motion of poly(γ‐benzylL‐glutamate) in the solid state at room temperature may be related to the motion of its back bone, the molecular motion in these

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040203

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe preparation of five samples of poly(methyl methacrylate) covering a wide range of tacticity and their electron irradiation to produce series of varying molecular weight are described. The glass transition temperatureTgof each polymer was determined by DTA techniques. Plots ofTgand the reciprocal of the molecular weight are well fitted in every case by a straight line. The data are also fitted to the Gibbs‐DiMarzio theory and the values of the energy and free‐volume parameters obtained are discussed. A method of estimatingTgof pure syndiotactic poly(methyl methacrylate) by extrapolation is presented, the value obtained being 16

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040204

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe principles of a method are outlined whereby one can determine the partial specific volume of a solute, V̄, by means of measurements ofdn/dcusing a suitable pair of equations and a simple graphical interpolation procedure. The method yields V̄ data which compare well with densitometrically obtained V̄ data if the polarizability of both solvent and solute molecules is unaffected by the solution process. It is tested successfully on solutions of polystyrene in various solvents. The method appears to be particularly attractive for measurements of the change of V̄ with temperature and also for conveniently following the time rate of changes in ‐ such as during the coil → helix tra

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040205

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractPolypropylene was oxidized with nitric acid in a manner contrived to remove its amorphous component. Concurrent with the loss in weight there was an increase in crystallinity, a decrease in molecular weight, a drop in melting point, and a change in visible structure. The crystalline component, which survived from polymer which had orginally crystallized isothermally, consisted of separated spherulites. These spherulites could be broken apart into lamellae which gave electron diffraction patterns like those now associated with a variety of solution‐grown single crystals. As opposed to the high molecular weight of the unoxidized parents, the lamellae which survived the acid treatment consisted of short chains whose length depended on the temperature at which the parents had crystallized. If, as diffraction studies indicate, these short molecules are lined up in rank and file, then the length of the molecules and the height of the lamellae should correspond. The heights of the lamellae could not be measured precisely enough to establish an exact correlation, but the variations in average chain length calculated from viscosity data at least approximated the heights of the lamellae which were observed visuall

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040206

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractA preliminary study of the isothermal crystallization of “even‐even” polyamides reveals striking similarities in spherulitic morphology. The observed variations in textural features of spherulites of nylon 210, nylon 66, nylon 610, and nylon 1010 show parallel changes during growth conditions and conform to a definite sequence of behavior. At least four different types of spherulites exist in each polymer. Optical and x‐ray techniques were used to examine some of these spherulites. Crystalline platelets possessing single‐crystal properties have been grown in thin films of these polymers near their respective melti

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040207

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractIntercrystalline links in polyethylene have been revealed by crystallizing from the melt mixtures of fractionated polymer and the linear hydrocarbonn‐C32H66, the latter constituent being removed later by washing at room temperature in an organic solvent. These fibrous links measure up to 15,000 A. in length and are 30–300 A. in thickness. Molecular chains are oriented parallel to the lengths of the links, and apparently nucleate on tie molecules formed by the simultaneous crystallization of different parts of the same molecule on the surfaces of different, and often widely separated, crystals. The maximum length of the links found in a given polymer varies as the square root of molecular weight, and there are indications that molecules in the melt are much more extended than is predicted by conventional configurational statistics. The links are under tension and presumably exert a significant influence on physical propert

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040208

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040209

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY