ISSN:0021-8979    

DOI:10.1063/1.1712844

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1712846

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1712845

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1712847

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

A method is described for obtaining a quantitative measure of crystalline hydrocarbon present in stretched rubber samples by comparing the intensities of the diffraction spots and the amorphous halo appearing in the x‐ray diagrams. This method has been applied in studying the crystallinity of stretched vulcanized rubber as it is affected by different vulcanization accelerators, and variations in extension, temperature and cure. To illustrate a connection between the physical performance of a rubber vulcanizate and its degree of crystallization, measurements were made on the relation of crystallinity to creep when the rubber was stretched to different initial elongations under constant loads. The creep as a function of the elongation has a maximum value at the same intermediate elongation for which crystallization becomes appreciable. At higher elongations, the increased crystallinity results in a diminution of the creep. The ultimate strength and extensibility generally associated with stretched vulcanized rubber is the result of the combined effect of the primary valence cross‐linkages formed by vulcanization and the formation of crystallites caused by stretching. Crystallization is an important factor in maintaining the relatively high strengths of vulcanizates having a greater range of extensibilities. In general, the physical properties and performance of vulcanized rubber is related to the amount of crystalline material formed upon stretching, which of course depends upon the structural characteristics of the vulcanizate.

ISSN:0021-8979    

DOI:10.1063/1.1712848

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

The transmission spectra of thin films of the following materials have been measured between 2.2&mgr; and 14.8&mgr;: crude rubber, soft and hard vulcanized rubber, thermoprene, polyvinylchloride, Neoprene and Pliofilm. The spectrum of rubber resembles that of the long chain paraffins more closely than do those of the polymers, polyvinylchloride, Neoprene and Pliofilm, all of which contain chlorine and have distinctive spectra. Vulcanization of rubber with 2.3 percent sulfur gives rise to no new bands in the region 2.2&mgr; to 12.5&mgr; characteristic of molecular cross bonding. Some of the bands in these materials are identified with valence vibrations.

ISSN:0021-8979    

DOI:10.1063/1.1712849

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1712850

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

A summary of the nature and special applications of the more important types of synthetic rubbers is given. Two series of rubber and synthetic rubber stocks, compounded on the basis of comparable pigmentation, were selected for study. In addition to the conventional physical properties (tensile strength and elongation at rupture, modulus, aging, etc.), a number of other mechanical properties such as dynamic rigidity, hysteresis loss, ``blowout resistance,'' ``running temperature,'' and tensile strength at elevated temperature were measured. Swelling tests in various solvents were also made. Results are plotted in the form of correlation charts in an effort to select proper methods of measurement. Some observations on comparative service tests in tires in the case of three synthetic rubbers indicate them to be satisfactory, on a quality basis, for use in time of emergency. The importance of care in selecting the proper physical tests and methods of analysis is emphasized in the light of the results given. It is concluded that rubber testing techniques and interpretation must be modified in certain instances in evaluating synthetic rubber stocks.

ISSN:0021-8979    

DOI:10.1063/1.1712851

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1712852

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

This article gives a series method for the calculation of the fields in certain circularly symmetric resonators. By the use of some new functions, partial tables of which are included, the necessary series are made to converge rapidly enough so that the method becomes useful for numerical calculations of resonance conditions and wall currents.

ISSN:0021-8979    

DOI:10.1063/1.1712853

出版商:AIP    

年代:1941

数据来源: AIP