摘要:

AbstractThe history of PPO®, polymers of 2,6‐dimethylphenol, and Noryl® resins is described from the initial discovery through commercialization. The scope of oxidative polymerization as applied principally to phenols and acetylenes is outlined as well as the chemical reactions which can be performed on the resulting polym

ISSN:0032-3888    

DOI:10.1002/pen.760160102

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractGel permeation chromatography and liquid Chromatography are used for analyzing various epoxy resins. The chromatograms are compared with related information available from each. Because the separation is based on different principles, each method gives unique and different information about the same sample. For a complete analysis of epoxy resins, both techniques seem to be required.

ISSN:0032-3888    

DOI:10.1002/pen.760160103

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractArticles with increased rigidity can be obtained by compression molding at high pressures as shown by experiments with five types of linear polyethylene. The materials, with weight average molecular weight ranging up to 1,000,000 were molded at pressures as high as 80,000 psi. The material temperature was 149–204°C, and the tooling was at 38°C. The duration of load was typically 3 mins, and the thickness of the molded disks was 12.7 mm. The results show that at high molding pressure the tensile modulus of the material is nearly twice that of materials molded conventionally at low pressures. This increase in modulus occurs for all the materials studied and even for a duration of load of only one min. The causes for this large increase in modulus were investigated with the help of density and melting point measurements and optical and electron microscopy. It was observed that the spherulites showed a distinctive and systematic change with the forming pressure. A hypothesis is proposed to explain the high modulus phenomenon on the basis of the kinetics of spherulite format

ISSN:0032-3888    

DOI:10.1002/pen.760160104

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractA number of investigators have reported on the high degree of piezoelectricity manifested by oriented films of poly(vinylidene fluoride) (PVF2). To develop applications for this piezoelectric effect, our laboratory is involved in a systematic investigation of the factors responsible for this remarkable behavior of PVF2. In a unique high‐speed process, commercial PVF2 film was uniaxially stretched to a series of draw ratios ranging up to 7/1. The resulting films were characterized by techniques involving infrared spectroscopy, density, birefringence, sonic modulus, X‐ray diffraction, and dynamic mechanical response. The films were then poled at various electric field strengths, temperatures, and times. Correlations have been made between draw ratio, physical properties, poling conditions, and piezoelectric activity of the films. It was found that the piezoelectric activity increased to limiting values with draw ratio, poling voltage, poling temperature, and poling time. It was evident that for PVF2film a significant amount of oriented phase I crystalline material is required for high degrees of piezoelectric activity. The Appendix gives the apparent rate dependence observed for the piezoelectric effect when signal is measured with a voltage sensor of relatively low input impeda

ISSN:0032-3888    

DOI:10.1002/pen.760160105

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effects of shock cooling and swelling with carbon tetrachloride on the dynamic mechanical spectrum of high density polyethylene have been studied with a torsional pendulum. The resulting spectra have a well‐defined loss peak at −65°C which is associated with the glass transition of high density polyethylene. Similar experiments on polypropylene and low density polyethylene demonstrate the similar effects of these treatments on their glass transit

ISSN:0032-3888    

DOI:10.1002/pen.760160106

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe length‐temperature behavior of elongated elastomeric networks of cis‐1,4 polybutadiene was observed following abrupt, nearly step‐function changes in the temperature of the specimen environment. The thermal expansion behavior is reversible, and the transient length changes are in the direction anticipated from rubber elasticity theory, i.e., dL(t)/dTis negative. The observed long‐time values of the thermal expansion coefficient are in good agreement with equilibrium length‐temperature coefficients reported for other elastomers. Results indicate that both thermal diffusion and retarded creep deformation contribute to the transient phenomenon, with the latter mechanism d

ISSN:0032-3888    

DOI:10.1002/pen.760160107

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThis article describes the use of the Rheovibron Model DDV‐III‐B with a parallel plate modification of the sample holders to obtain oscillatory data in the shear mode for several high density polyethylene melts. A detailed analysis of the Rheovibron to obtain the dynamic shear: moduli of polymer melts using the new sample holders is given, as well as a procedure for determining the instrument compliance and inertia parameters which must be considered in analysis of the data. Using the principle of time‐temperature superposition, the data are extended to an equivalent frequency range of 1500 rad/sec. These data are compared with those obtained using the Weis‐senberg Rheogoniometer Model R‐17 for the same polymers. It is concluded that reliable measurements for dynamic shear moduli for polymer melts using the Rheovibron Model DDV‐III‐B with the modified sample holders can be made for melts with indices of about 5 or less (i.e., zero shear viscosities of 6.0 × 104poi

ISSN:0032-3888    

DOI:10.1002/pen.760160108

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractPolyethylene and reactive, high molecular weight polydimethylsiloxanes have been blended under conditions of shear and elevated temperature in order to form uniform, thermoplastic blends. The materials can be extruded, coated on wire, injection molded, or compression molded. Despite the thermoplastic nature, a high gel fraction is present. A structure is proposed consisting of microgelled and grafted particles of silicone dispersed in polyethylene. When compared to pure polyethylene, the blends show lowered modulus over a temperature range of −150 to +65°C increased gas permeability, and lowered mixing energies. Electrical properties include corona resistance superior to polyethylene and a resistance to degradation under conditions simulating those experienced by buried cables superior to typical silicone rubber. Other electrical properties are intermediate between the values observed in the component polyme

ISSN:0032-3888    

DOI:10.1002/pen.760160109

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe migration of phthalate plasticizers from poly (vinyl chloride) into edible oils has been analyzed. The principal method used involved14C‐labeled dibutyl and dioctyl phthalates with detection by liquid scintillation spectrophotometry. In most cases, the migration of the main plasticizer was accompanied by the migration of the secondary plasticizer, when present, and by diffusion of the oil into the polymer. Comparison of the scintillation results with those obtained by weight loss measurements can give quantitative information on the amount of the liquid medium that diffuses during the migration process. The effect of the following factors on the migration process was examined; (a) the nature and acidity of the edible oil, (b) the composition and amount of phthalate plasticizer, (c) the amount of epoxy plasticizer, and (d) the temperature and time of contac

ISSN:0032-3888    

DOI:10.1002/pen.760160110

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760160101

出版商:Society of Plastics Engineers, Inc.    

年代:1976

数据来源: WILEY