摘要:

AbstractA series of tests have been conducted to measure the effects of fatigue loading on environmental stress crazing in PMMA. Testing in methanol has shown that long crazes are grown prior to fracture in the same manner as previously observed for constant‐load conditions. An analytical model which had been used to describe craze kinetics in terms of environmental flow within the craze for static loads has been amended to account for the variable loads and gives excellent prediction of craze speeds under numerous types of loading. The correlation of theory and experimental data for this second case suggests that environmental crazing is controlled mainly by the way in which the hostile environment is able to flow through the voided structure of the craze. A brief description of the effects of varying the cyclic frequency is also given in an attempt to provide guidelines for future researc

ISSN:0021-8995    

DOI:10.1002/app.1973.070170401

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

年代:1973

数据来源: WILEY

摘要:

AbstractPeel strength values of sodium‐etched poly(tetrafluoroethylene) film bonded to polyurethane substrates have been monitored and found to decrease as a function of exposure to ultraviolet radiation. Attenuated total reflectance (ATR) spectra were monitored on unbonded sodium‐etched poly(tetrafluoroethylene) surfaces for the same environmental aging conditions and were found to vary significantly in the region of 1650 cm−1. Techniques are proposed to retard UV‐initiated etch degradation and thereby prolong bond in

ISSN:0021-8995    

DOI:10.1002/app.1973.070170402

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe adhesion between rubber and short glass or asbestos fibers has been studied using restricted equilibrium swelling measurements. It has been demonstrated that with improved adhesion between short fiber and rubber,\documentclass{article}\pagestyle{empty}\begin{document}$ V_r = \left( {\frac{{V_I - V_F }}{{V_I }}} \right) $\end{document}decreases by more than 0.04 units, whereVIandVFrespectively are the volume fractions of rubber in the dry and swollen samples. Goodrich compression fatigue and tensile measurements have been used to substantiate the adhesion‐promoting role of bonding agents. The preferential role of silica over black as an adhesion promoter has been questioned. The effect of fiber orientation in controlling the anisotropy of restricted swelling has also been demonstrate

ISSN:0021-8995    

DOI:10.1002/app.1973.070170403

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

年代:1973

数据来源: WILEY

摘要:

AbstractIn the previous paper a practical method has been applied for an analysis of non‐isothermal crystallization in terms of data of isothermal crystallization. The fundamental equation was written on the assumption of the isokinetic conditions in the following form:\documentclass{article}\pagestyle{empty}\begin{document}$ X\left( {\rm t} \right) = 1 - \exp \left[ { - \left( {\int_0^t {K\left( T \right)d\tau } } \right)^n } \right] $\end{document}whereX(t) is the degree of phase transformation at timet, andnis the Avrami index determined in the isothermal experiments;K(T) is connected with the crystallization rate constant of the isothermal crystallization,k(T), through the relationK(T) =k(T)1/n. The equation is derived on the basis of the well‐known theory of phase transformation. Experiments of nonisothermal crystallization of high‐density polyethylene were carried out under various cooling conditions. The change in crystallinity during the process was followed by using the above equation in the course of the primary crystallization. A procedure of the analysis of the whole, including both the primary and secondary processes, is suggested as an eminently practical one on a more general assum

ISSN:0021-8995    

DOI:10.1002/app.1973.070170404

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

年代:1973

数据来源: WILEY

摘要:

AbstractReverse osmosis data using different samples of Loeb‐Sourirajan‐type porous cellulose acetate membranes and single‐solute aqueous solution systems involving 16 monohydric alcohols, 4 phenols, 18 polyhydric alcohols, pyrogallol, ethylene glycol monoethyl ether, 6 aldehydes, and 8 carbohydrates (sugars) have been studied. The solute concentrations used were in the range of 0.0005 to 0.003 g mole/l. (∼100 ppm), and operating pressure used was 250 psig in all cases. The results show that correlations of acidity and basicity parameters (obtained from IR spectra) with solute separation data are equivalent, and they have predictive capability. A method is given for estimating Taft numbers (Σσ*) for monohydric and polyhydric alcohols from available data based on the additive nature of σ*. Data on solute transport parameters (DAM/Kδ) for the different solutes were calculated from membrane performance data. For all the alcohols studied, the Σσ*‐versus‐log (DAM/K)δ correlation was found to be a straight line with a slope different for different ranges of Σσ*, but independent of the porous structure of the membrane. Based on this result, it is shown that the parameters of the Taft equation can serve as a basis for expressing solute transport parameter, and this basis offers a means for predicting membrane performance for all alcohol–water systems from a single set of experimental data for a reference solute system. This prediction technique is illustrated using experimental data for 1,3‐butanediol taken as the reference solute. The general applicability of the technique has been tested for predicting the separation of some ald

ISSN:0021-8995    

DOI:10.1002/app.1973.070170405

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

年代:1973

数据来源: WILEY

摘要:

AbstractThis work is a study of some dilute solution properties of polyhexene‐1. Results with the following experimental measurements are reported: osmotic pressure, phase equilibrium, viscosity, light scattering, molecular weight, molecular weight distribution, and degree of chain extension. Three good solvents were used, cyclohexane, tetrahydrofuran, and toluene, and one poor solvent, phenetole, in order to obtain theta conditions. The properties of polyhexene‐1 are compared with those of other α‐olefin polymers reported in the lite

ISSN:0021-8995    

DOI:10.1002/app.1973.070170406

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe influence of imbibed water in cellulose, polypropylene, and polyester on their x‐ray diffraction patterns has been studied. It was found that both hygroscopic and nonhygroscopic polymers behave similarly, in that the resolution of the peaks in their x‐ray diffraction patterns increases. This is because the addition of water enhances the x‐ray absorption coefficient of the polymers which are poor absorbers of x‐rays in their dry state. It is concluded that there is no x‐ray evidence at present which indicates that water has an influence on the cellulos

ISSN:0021-8995    

DOI:10.1002/app.1973.070170407

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe properties of raw polymer and gum vulcanizates of several ethylene–propylene terpolymers with respect to thermal transitions, stress relaxation, and swelling behavior are discussed in relation to the influence of ethylene content and microstructure. It is shown that at high ethylene contents, the presence of associated regions, perhaps microcrystallites, in low concentration produces polymers having thermoplastic behavior. The degree of crystallinity is apparently very low, and polymers of nominally similar ethylene contents can exhibit disparate behavior reflecting differences in heterogeneity of molecular compositio

ISSN:0021-8995    

DOI:10.1002/app.1973.070170408

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

年代:1973

数据来源: WILEY

摘要:

AbstractA new technique of pyrolysis gas chromatography was used for the investigation of pyrolysis of phenol formaldehyde polycondensates and useful information about the nature of the chemical bonds and their relative strengths in these polycondensates were obtained. It was also found that by identifying only one of the pyrograms of a series of homologous compounds produced by the pyrolysis of polycondensates, all the pyrograms of the series were easily characterized and correspondingly the number of components in each series were identified.

ISSN:0021-8995    

DOI:10.1002/app.1973.070170409

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe effect of various inorganic fillers on the storage modulus of four elastomers was determined experimentally. Results are interpreted using the Kerner equation, modified to include a parameter,B, in the volume fraction terms. This factor combines particle size and specific interaction effects, and in theory can be evaluated from energy dissipation measurements.

ISSN:0021-8995    

DOI:10.1002/app.1973.070170410

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

年代:1973

数据来源: WILEY