摘要:

AbstractDielectric α‐relaxation of a bisphenol‐A type epoxide oligomer has been investigated in the vicinity of the glass transition temperature (Tg) by the direct current (DC) transient method. The logarithm of the DC transient current for the oligomer was well approximated by the third order function of the logarithm of time. The complex dielectric constant was calculated through the Fourier transformation of that approximation function according to Simpson's integration rule in a frequency range of 10−5− 1 Hz. At the temperature around theTg(45°C), the dielectric α‐relaxation process of the oligomer was found to be governed by the Havriliak‐Negami equation. The relationship between the DC conductivity (σ) and the dielectric relaxation time (τ), σ·τm= const, is valid near and above theTgof the oligomer. The DC transient current method combined with the DC conduction and the dielectric bridge measurements is considered to be a practical tool for analyzing the dielectric α‐relaxation process of the epoxide oligomer over a wide frequency

ISSN:0032-3888    

DOI:10.1002/pen.760332002

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractSteady shear vxiscosity, dynamic moduli and the appearance of fracture surfaces of model composites, consisting of monodisperse crosslinked polymeric spheres of varied composition in a polymethyl‐methacrylate matrix, depend on the compatibility of filler particle and matrix. After intensive mixing, “compatible” systems form uniform and stable dispersions. Filler particles cluster in incompatible composites producing a highly non‐Newtonian response. At 40 w% filler, yield behavior results, with a yield stress of 3100 Pa for polystyrene particles and 1900 Pa for copolystyrene‐acetoxystyrene particles. The flow properties of compositionally complex particles from seeding are determined by particle surface co

ISSN:0032-3888    

DOI:10.1002/pen.760332003

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractA modified observation system for the leveling process of a coated fluid is proposed, and the observation results are presented and compared with previous results. For the thermosetting waterborne coatings, the theory of Orchard, et al., and ones based on it are not applicable and fail to give even a qualitative description. The theory of Overdiep was found to be reasonable. However, it was insufficient to predict the leveling performances of coatings without experimentation. Qualitatively, the original theory suggests the possibility of the reappearance of surface ripples, in other words, the occurrence of the negative amplitude in the surface ripples during the course of leveling, although little data were presented regarding the phenomenon. It was found here that added co‐solvent plays an important role on the leveling rate and also the occurrence and the control of the negative amplitude of the surface ripples. These are thought to relate closely to the volatility of the co‐solvent and the composition of the solvent residue in the coated film during the leveling proc

ISSN:0032-3888    

DOI:10.1002/pen.760332004

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study, styrene‐(ethylene‐co‐butylene)‐styrene (SEBS) triblock copolymer (Kraton G‐1652) was modified with maleic anhydride (MA). The maleated SEBS was used as compatibilizer for the blends of Nylon 6 (PA6) and SEBS. The morphology and impact strength of the blends were measured as functions of concentration and MA graft ratio of maleated SEBS. The compatibility and fracture mechanism of the blends were evaluated from the SEM micrographs of the xylene‐etched surfaces and of fractured surfaces. Some of the blends exhibited an impact strength up to about 30 fold greater than neat PA6. The fracture involved both both cavitation and shear yielding. The mechanism of compatibilization of maleated SEBS in the ternary components blends w

ISSN:0032-3888    

DOI:10.1002/pen.760332005

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractBlends of γ‐irradiated and unirradiated low density polyethylene with polyamide 6 were made in order to study possible modifications induced by this irradiation. Blends with γ‐irradiated polyethylene show structure and properties significantly different with respect to blends made with the unirradiated polyethylene. In this paper data on mechanical properties (tensile and impact) of these blends are presented. Results are related to the different morphologies in the b

ISSN:0032-3888    

DOI:10.1002/pen.760332006

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper reports on the theoretical and experimental studies of structure formation and strengthening (stiffening) of flexible‐chain polymers. Two techniques of strengthening relying on the melt extrusion, i.e., orientational crystallization (crystallization initiated by melt extension) and drawing (uniaxial stretching of a crystallized polymer) are analysed by theory. The experiments involved preparation and study of melt extruded films and film fibers of linear polyethylene formed by the two techniques mentioned above. The effect of the degree of orientation and other parameters of the formation processes on the mechanical characteristics and the factors limiting the ultimate values of these characteristics are discussed. It is shown that multistage drawing succeeds in achieving a higher tensile strength and elastic modulus (1.2 and 35 GPa, respectively) than the orientational crystallization, which gives 0.8 and 15 GPa. The strengthening by drawing is accompanied by microcrack formation. In contrast, no discontinuities are observed in orientationally crystallized samples up to their ultimate extensio

ISSN:0032-3888    

DOI:10.1002/pen.760332007

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractBlends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition‐dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubbe

ISSN:0032-3888    

DOI:10.1002/pen.760332008

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractAn experimental setup is presented that enables the whole optical characterization of an anisotropic medium to be achieved at the same spot. Based on total internal reflection measurements, the Double Arm Pulfrich Refractometer provides high precision simultaneous refractive index data, which are gathered without moving the sample. This technique is particularly well suited to the case of biaxial materials. Illustration of its potential is given on some preliminary orientation measurements of biaxially stretched polystyrene films.

ISSN:0032-3888    

DOI:10.1002/pen.760332009

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractTransport studies of two organic liquids, toluene and n‐hexane, have been performed in polyurethane and poly (methyl methacrylate‐g‐urethane). A high degree of selectivity in the permeation of these two liquids has been achieved by MMA grafting. A near perfect separation has been realized by grafting of MMA t

ISSN:0032-3888    

DOI:10.1002/pen.760332010

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760332011

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY