摘要:

AbstractA method of analysis of continuous‐drawing processes in terms of the basic load/extension/temperature properties of high polymers is given. Experimental work has been largely confined to polyethylene terephthalate (‘Terylene’ multi‐filament yarn), for which material quantitative results are presented. This includes load/extension curves covering the temperature range in which uniform extension takes place, and results on ‘natural’ draw ratios when the extension proceeds by ‘necking’.A brief account of a theory of ‘cold

ISSN:0021-8871    

DOI:10.1002/jctb.5010040401

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe degree of polymerization of a polyamide is determined by the equilibrium between carboxyl, amino, and amide groups, and water molecules. Equations are deduced for the relationship between the equilibrium constantk1, the number‐average chain lengthnand the partial pressure of water. Allowance is made for the presence of a cyclic monomer, whose amount is determined by a second equilibrium constantk2. For monomers capable of forming 8‐membered or larger ringsk2approaches 0, and for those capable of forming 5‐ or 6‐membered ringsk2approaches 1, and no polymer is formed. For 7‐membered ringsk2has such a value that cyclic monomer and polymer can exist together. When the cyclic monomer is not miscible with the polymer, polymer formation is possible from 5‐ and 6‐membered rings, e.g. diketopiperazine (dioxopiperazine), which polymerizes to polyglycine.From data on polymers of<‐caprolactam equations have been deduced giving the relationship betweenk1andk2and the temperatureT, and from these the heat of formation Δk, the entropy ΔS, and the free energy ΔFfor the polyamide bond in polyaminocaproic acid have been calculated. Assuming that the values for nylon 66 (produced from hexamethylenediamine and adipic acid) are not greatly different, equations are obtained for the chain lengthnof nylon 66 in terms of the temperatureTand the partial pressure of water, and also fornas a function ofTin the presence of an aqueous phase.The reaction between carbon dioxide and a diamine is discussed, and it is shown that for the formation of a polymethyleneurea by this reactionk1is probably much smaller than for the polyamides, so that conditions are less favourable to the formation of high polymers.It is shown that the inability of α‐amino‐acids to polymerize directly is due to the large amount of ionic work that has to be done in adding a single amino‐acid to a peptide chain. Tripeptides and higher peptides should be able to polymerize.A comparison is made between polyesters and polyamides. The formation of the amide group is accompanied by a large increase in entropy, 20–30 cal./mole degree, which is probably due mainly to the release of oriented water molecules held by the charged carboxyl and amino groups. Polyesters are formed by interaction between uncharged groups, so that the increase in entropy will be much smaller, and the conditions less favo

ISSN:0021-8871    

DOI:10.1002/jctb.5010040402

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe present position reached in a general study of how fabrication conditions affect the crystalline texture and therefore the properties of crystalline polymers is reviewed. The mechanism by which long‐chain molecules order themselves into some form of crystalline array is postulated to be one involving normal nucleation processes, but modified to take account of the fact that polymers melt over a range of temperatures, and the nucleation act is followed by preferential crystal growth in the direction of the polymer chains. This mechanism, with the additional concept of coiling growth, is not inconsistent with kinetics that fit the crystallization‐rate processes on the one hand and observable structure in crystalline polymers on the other.It is considered that lateral accretion of the polymer molecules to the already formed long helical polymer‐crystal results in haphazard branching growth with the new fibril developing along a path parallel to the parent crystal. This leads to the formation of coiled families of fibrillar crystals and this structure appears to be a suitable model on which to explain the many wide‐angle and low‐angleX‐ray observations that have been made at various stages of the drawing and relaxing of filaments of crystalli

ISSN:0021-8871    

DOI:10.1002/jctb.5010040403

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe differences in physical and chemical properties of 6, 6‐, 6, 10‐ and 6‐polyamides are reflected in the conditions required for the production of the fibres, and in their properties. These factors have been compared.The 6, 6‐polymer has the highest melting‐point and the least thermal stability. On the other hand, 6‐polymer produces a fibre containing sufficient monomer to involve process complications, and its initial modulus is low. The 6, 10‐fibres absorb less moisture t

ISSN:0021-8871    

DOI:10.1002/jctb.5010040404

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe manufacturing details of the production of ‘Saran’ (vinylidene chloride copolymer) monofilaments are given. The changes in molecular structure occurring during each stage of the production are analysed, and the effect of these on the properties of the final monofilament are discussed with a view to obtaining the conditions for producing monofilaments with optimum propert

ISSN:0021-8871    

DOI:10.1002/jctb.5010040405

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractTwo types of denaturing agents, (a) urea, guanidine salts and related compounds and (b) amines, have been investigated with groundnut protein for fibre formation. The considerable rise in the viscosity increment of the protein on denaturation with urea and the hydrochloride and thiocyanate of guanidine, and with bases of dissociation constant higher than 10−4, has been interpreted in terms of increased asymmetry of the protein molecules, and only where such a rise was observed could solutions of the protein with the denaturant be prepared suitable for extrusion into fibr

ISSN:0021-8871    

DOI:10.1002/jctb.5010040406

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010040407

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe interaction between cellulose and heavy water allows absorptions due to stretching of OH groups in crystalline and amorphous regions to be studied independently. Crystalline regions give several absorption bands in the 3600–3000 cm.−1range and it is shown that all the bands are due to stretching of OH groups. Arguments are presented that support the idea that these bands can be interpreted in terms of vibrations of individual groups. It is shown that all the OH groups in crystalline regions of regenerated and bacterial celluloses are hydrogen‐bonded, and that crystal structures suggested by Peirce for these celluloses are incorrect. Suggestions are made about the types of hydrogen bond present in regenerated cellulose.The relationship between infra‐red absorption frequencies and O……O distances in crystals is discussed. It is concluded that no reliable estimate of O……O distances in cellulose can be made from absorption frequencies on the basis of results avail

ISSN:0021-8871    

DOI:10.1002/jctb.5010040408

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractA new series of condensation polymers, the polyaminotriazoles, are described. These are made most simply by condensation of aliphatic dihydrazides in the presence of excess of hydrazine. The polymers are fibre‐forming and can be melt‐spun to give filaments which, after drawing, possess high strength and good affinity for dyestuffs of the acid and S.R.A. types, i.e. disperse types, as used for cellulose acetate ra

ISSN:0021-8871    

DOI:10.1002/jctb.5010040409

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY