摘要:

AbstractThe sorption isotherms of annealed films of nylons 66 and 610 at 23°C. are well described by the Flory‐Huggins equation at all humidities. The partial specific volume of water varies from 0.46 cc./g. at 0% R.H. to more than 1.0 cc./g. at 100% R.H. The experimental partial molar heats of sorption are in good agreement with values calculated from the theory, provided allowance is made for the changes in volume on mixi

ISSN:0021-8995    

DOI:10.1002/app.1959.070020501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractDegradation studies on poly‐α‐methylstyrene at 25°C. under vacuum and in hydrogen and oxygen were carried out with the use of a Co60gamma source. The degradation results are explained as a random breaking of skeletal chain bonds accompanied by a depropagation of the resulting fragments. The termination step for depropagation is considered as a chain transfer of the degrading radical to the produced monomer cloud, the monomer radical thus formed repolymerizing to some extent prior to termination. The necessary relationships are derived which permit the evaluation of theG‐value for bond scission, the kinetic chain length for depropagation from the resultingMnandMwvalues, and the unsaturation produced. The determinedG‐values for chain scission are 0.25 in vacuum and hydrogen, 0.16 in air, and 0.08 in oxygen, the gases being at a pressure of one atmosphere. The number of monomer units split off per break was found to be 100 in vacuum, 50 in hydrogen, and essentially zero in the presence of oxygen. It is believed that hydrogen and oxygen terminate the depropagating radical, reducing the kinetic chain length. The reduction in theG‐value for chain scission in the presence of oxygen may be due to either recombination of the terminal peroxide groups formed or deactivation of the chain prior to cleavage. TheG‐values for volatile products at room temperature are listed, the important ones beingG(H2) = 0.035 andG

ISSN:0021-8995    

DOI:10.1002/app.1959.070020502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractIn the investigation of the rheological properties of viscoelastic material, a variety of instruments may be employed. The investigation may be concerned either with mechanical properties under “steady‐state” or dynamic conditions or with optical properties such as are determined by flow birefringence techniques. This paper describes representative instrumentation (available at the Franklin Institute Laboratories) suitable for making the above types of determinations. The types of instruments are: (1) a coni‐cylindrical rotational viscometer, (2) a high‐pressure capillary tube viscometer; (3) the Weissenberg rheogoniometer, (4) a jet extrusion instrument, (5) a vibration tester, (6) a torsion crystal instrument, and (7) a flow birefringence instrument. The fundamental principles underlying the instruments which have not been described previously, are

ISSN:0021-8995    

DOI:10.1002/app.1959.070020503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractDiisocyanates condense readily with hydrazine or hydrazine hydrate to give polyureylenes with the structure:\documentclass{article}\pagestyle{empty}\begin{document}$$ \left[ \hbox{---} {\rm R} \hbox{---} {\rm NHCONHNH} \hbox{---} {\rm CONH} \hbox{---} \right]_x $$\end{document}Similarly, dihydrazides (NH2NHCOR′CONHNH2) condense with diisocyanates to give polymers with the structure:\documentclass{article}\pagestyle{empty}\begin{document}$$ \left[ \hbox{---} {\rm R} \hbox{---} {\rm NHCONHNH} \hbox{---} {\rm COR'} \hbox{---} {\rm CONHNHCONH} \hbox{---} \right]_x $$\end{document}Tough films and fibers can be prepared from these polymers by conventional techniques. Solutions of some of these polymers are relatively unstable at elevated temperatures, the polymer apparently reverting to starting materials. Attempts to stabilize the solutions were unsuccess

ISSN:0021-8995    

DOI:10.1002/app.1959.070020504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractSupporting evidence for the electron bombardment mechanism for the degradation of dielectric materials by corona discharge has been obtained by correlating the maximum radius of oxidized product, oxalic acid, produced by corona discharge from a spherical electrode upon polyethylene, with the theoretical range of electrons produced. Rationalizations concerning the formation of oxalic acid in the process are offered.

ISSN:0021-8995    

DOI:10.1002/app.1959.070020505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractMeasurements of the density of a large number of experimental isotactic polypropylenes have shown that the specific volume is linearly related to per cent crystallinity as determined from x‐ray data. The density is also linearly related to the absorbance of certain absorption bands in the infrared spectrum of isotactic polypropylene. The infrared data allow a determination of the density of the amorphous polymer which is in good agreement with literature values and with a value determined from the x‐ray data by extrapolation to zero crystallinity. It is found that there is a rough, approximately linear correlation between crystallinity (by density) of unextracted polypropylene and the per cent insoluble residue remaining after extraction with boilingn‐heptane or after successive extraction with other solvents and heptane. In all instances, the amount of residue exceeds the crystalline content. The crystallinity‐insolubility relationship is influenced by molecular weight (as judged by intrinsic viscosity). An increase in crystallinity at constant [η] corresponds to an increase in insolubility; at constant crystallinity, a larger [η]corresponds to greater insolubility. In terms of density, the unextracted polymer may not be regarded as simply a mixture of two well‐defined components, since the density of insoluble residue increases with the density of the wh

ISSN:0021-8995    

DOI:10.1002/app.1959.070020506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractA geometrical analysis is given of the tread motions occurring in the contact length of a rolling tire. Both the case of a free rolling wheel and that of a wheel under torque are discussed. We have derived expressions and curves for the relative slip and compressions which occur at the contact length for the two conditions. It is found that two important structural features control the nature of tread motions. These are the torsional rigidity of the sidewall and the compressibility of the tread. In addition, the implication of the analysis in tire design and performance are discussed.

ISSN:0021-8995    

DOI:10.1002/app.1959.070020507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractDifferential spectra have been obtained of a number of irradiated polyamides and monomeric amides. These spectra indicate that both free radical and molecular products are produced as primary products. The transient colored products (which are believed to be free radicals) and molecular products appear to be in the amine portion of the molecvle for the most part. The approximateGyield for radical production in nylon 66 is 5.8, and the approximate molar extinction coefficient of the free radical at 355 mμ is 690

ISSN:0021-8995    

DOI:10.1002/app.1959.070020508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractIntermittent and continuous stress relaxation measurements have been utilized to follow the oxidative degradation of vulcanizates of natural rubber, and of synthetically prepared polybutadienes. Vulcanizates were prepared by exposing samples to high‐energy electrons. For natural rubber, only oxidative scission reactions were detected. Emulsion polymerized polybutadiene and allcis1,4‐polybutadiene exhibited both oxidative scission and oxidative crosslinking. With sulfur vulcanizates of these elastomers, there is superposed on the oxidation reactions a continued vulcanization caused by remaining curing ag

ISSN:0021-8995    

DOI:10.1002/app.1959.070020509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY

摘要:

AbstractUse is made of the basic concepts of a two‐phase model structure for keratin fibers, consisting of a water impenetrable phase embedded in a water penetrable matrix phase. The mechanism of water sorption of a dry fiber in liquid water or in a high humidity atmosphere is discussed. It is assumed that during moisture uptake the matrix goes into a sol‐state. Once moisture uptake is complete the matrix goes through a sol‐gel transformation. Both the torsional rigidity and longitudinal stress at low strain vary during the sorption process, and subsequently, in a manner compatible with this

ISSN:0021-8995    

DOI:10.1002/app.1959.070020510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1959

数据来源: WILEY