ISSN:0032-3888    

DOI:10.1002/pen.760050112

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractExtrapolation from data on low molecular weight n‐alkanes indicates that the surface tension of polyethylene at 150°C is 26 dynes/cm. The total surface energy, γ — Tdγ/dT, is 51 dynes/cm and is much less dependent on chain length. The surface tension of polyethylene extrapolated to 20°C is 34 dynes/cm, consistent with the critical surface tension below which liquids will wet the polymer. The total surface energy is in reasonable accord with the incremental energy of vaporization, 1.029 kcal/mole of CH2groups. The surface entropy is less than that of low molecular substances. This is attributed to a reduction in the opportunities for rotational isomerism at the

ISSN:0032-3888    

DOI:10.1002/pen.760050102

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractMore than seventy materials were examined for their ability to improve the performance of DTDP plasticized PVC wire formulation in a modified 105°C wire oven aging test. Twenty of these were as effective as the widely used Bisphenol A, four of which were effective at a lower concentration

ISSN:0032-3888    

DOI:10.1002/pen.760050103

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractA first order transition was observed in the temperature range of about 210°C by dilatometric studies on both isotactic and atactic polypropylene and for isotactic poly (butene‐1) and poly (pentene‐1). No such transition was observed for polyethylene. It was found that the transition is not due to the measurements per se, to polymer treatment, to catalyst residues, or to polymer degradation. It is suggested that the transition could be due to the disappearance of liquid crys

ISSN:0032-3888    

DOI:10.1002/pen.760050104

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractPolymer crystallization is discussed with attention given to primary nucleation, spherulite growth, and bulk crystallization. Primary nucleation is the area of least knowledge, and the authors discuss the kinetics of nuclei appearance and recent observations concerning the effects of foreign materials and surfaces. Spherulitic growth rates are discussed in general and specifically with respect to data at low degrees of supercooling in conjunction with secondary nucleation theory. The Avrami Theory and its limitations are discussed in the interpretation of bulk crystallization data. The authors propose that n = 4 in all cases and that the Avrami Theory be used for calculating the primary nucleation rate, kn, not for determining n itself.

ISSN:0032-3888    

DOI:10.1002/pen.760050105

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractThis article is a brief review of recent work in the author's laboratory on heat stable polyaromatic heterocycles. New polymers based on 2,7‐disubstituted‐1,3,6,8‐tetraazopyrene structure are described.Some background material on ladder or two‐strand polymer structures will be discussed. This will be followed by a description of recent work aimed at producing polyquinoline types and some properties of such p

ISSN:0032-3888    

DOI:10.1002/pen.760050106

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractThe melt viscosities of three low density polyethylenes of widely varying melt indices were studied as a function of temperature over a broad range of shear rates and shear stresses. Apparent viscosities at constant shear stress could be fitted adequately to a simple Arrhenius equation over the entire temperature range studied. However, pronounced curvature of the log ηa–1/T curves was observed for apparent viscosities at constant shear rate. The apparent activation energies for viscous flow at constant shear stress were found to decrease slowly with increasing shear stress and also to decrease with decreasing molecular weight. A temperature‐shear rate superposition was demonstrated to hold, and the shift factor dependence on temperature was determ

ISSN:0032-3888    

DOI:10.1002/pen.760050107

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractThe method of determining the epoxy equivalent weight of resins derived from Bis Phenol A and epichlorohydrin described by Kagarise and Weinberger has been extended to resins derived from epichlorohydrin and Tetra Brom Bis Phenol A and/or Bis Phenol A. In the infrared spectra of the latter, the characteristic aromatic band at 1610 cm−1is replaced by a strong band at 738 cm−1, the intensity of which increases linearly with the content of Tetra Brom Bis Phenol A. The logarithm of the epoxy equivalent weight is linearly related to the ratio of the absorbance at 915 cm−1to a linear combination of those at 1610 and 738 cm−1, respe

ISSN:0032-3888    

DOI:10.1002/pen.760050108

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractThermal conductivity curves for the 0°C to 170°C temperature region are presented for six irradiated low density polyethylene samples (radiation doses from 0 to 3100 megarads) and one irradiated high density sample (120 megarad dose). In agreement with data in the literature for unirradiated polyethylene, the thermal conductivity values for lightly irradiated polyethylene are found to decrease with increasing temperature in the elevated temperature region where the crystallites begin to melt. Beyond the crystalline melting point, test results for lightly irradiated and crosslinked samples indicate that the thermal conductivity is almost independent of temperature. Although radiation doses of less than 250 megarads produce only small changes in the thermal conductivity, higher radiation doses result in a significant lowering of the conductivity in the room temperature region and an increase of the conductivity at temperatures above the melting point. The decrease in conductivity at low temperatures is considered to be a result of disordering of the crystallites by the radiation, and the increase above the melting point is attributed primarily to radiation induced crosslinkin

ISSN:0032-3888    

DOI:10.1002/pen.760050109

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY

摘要:

AbstractThe interlaminar shear strength of reinforced plastic composites has long been recognized as a critical property in the structural performance of composites. However, its role in structural performance and the many factors that influence it have not been clearly elucidated. Although much attention has been given to the importance of resin‐glass adhesion, little is known regarding the contribution of resin strength and composite quality. In this article it is shown that interlaminar shear strength is a direct function of both resin strength and composite void content. The curves of resin tensile strength vs interlaminar shear strength indicate a limiting value for interlaminar shear above which increases in resin tensile strength do not increase defect

ISSN:0032-3888    

DOI:10.1002/pen.760050110

出版商:Society of Plastics Engineers, Inc.    

年代:1965

数据来源: WILEY