摘要:

AbstractThe effect of cold rolling on the Izod impact strength of amorphous polycarbonates has been studied. The impact strength is a function of the roll reduction as well as the original sheet thickness. Sheets varying from 0.125 to 0.645 inches in thickness have been studied and roll reductions up to 50 percent have been utilized. It is shown that enhancement in impact strength occurs at very small percent roll reductions. The orientation release stress has been measured as a function of roll reduction and the internal stresses through the thickness of the sheets have been studied by birefringence methods. It is suggested that the residual stresses are responsible for impact enhancement rather than the molecular orientation.

ISSN:0032-3888    

DOI:10.1002/pen.760140402

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractAmorphous polycarbonate sheets up to 1/4 inch in thickness have been crystallized both thermally and by acetone vapor sorption. For thick sheets acetone vapor sorption is the superior technique and a method has been developed for assuring homogeneous crystallized sheets. The crystallized polycarbonate can be cold rolled providing there is a residual acetone content to act as a plasticizer for the sheet. The tensile stress strain characteristics of the as‐crystallized sheets as well as the rolled crystallized sheets have been determined as a function of the residual acetone content. It is shown that a crystallized polycarbonate whose thickness is reduced by 74 percent can achieve a true stress at fracture of 27,180 psi and a strain of 33 percent. These values are significantly greater than the values obtained for rolled amorphous polycarbonate

ISSN:0032-3888    

DOI:10.1002/pen.760140403

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe purpose of this study was two‐fold:To determine the relationship between the composition and curing characteristics of glass‐reinforced diallyl phthalate (DAP) compounds and their molding performance.To develop quality control tests in order to assure their satisfactory processing.DAP compounds were analyzed with regard to composition, flow, curing characteristics, and heat stability. Tests involving “Spiral of Archimedes” and differential scanning calorimetry (DSC) were used to determine the flow and curing characteristics, respectively. A Brabender torque rheometer was employed to measure both flow and curing properties of DAP. The results obtained indicate that curing properties are of major importance in controlling the DAP processing. Good correlation was observed between the Brabender processing time, the onset curing temperature as measured by DSC, and the molding performance. A computer program was developed capable of calculating the kinetic parameters from the dynamic DSC scan of uncured DAP compounds. The curing data obtained from this method agree with those determined by isothermal DSC. A method based on the penetration of a hot metallic cone has been developed to measure rapidly the percent cure of molded DAP parts. The above mentioned techniques are recommended for the quality control of DAP molding co

ISSN:0032-3888    

DOI:10.1002/pen.760140404

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractTwo series of glass‐reinforced diallyl phthalate molding compounds from two different manufacturers were evaluated using a Rheometrics, Inc. Mechanical Spectrometer and a Brabender Torque Rheometer. Comparison of reactivity and minimum viscosity as measured by these two instruments is presented. The Mechanical Spectrometer appears capable of differentiating smaller changes in melt viscosity than does the Brabender Torque Rheomete

ISSN:0032-3888    

DOI:10.1002/pen.760140405

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe polymerization of methyl methacrylate with Ziegler‐Natta catalyst, anionic catalyst and gamma radiation has been shown possible at temperatures below 0°C. A free radical mechanism is suggested in the case of Ziegler‐Natta catalyst which is known for a coordinate anionic polymerization mechanism. In view of this, the Ziegler‐Natta catalysts based on vanadium compounds were investigated for the polymerization of methyl methacrylate. They were found effective for polymerization of methyl methacrylate at, and around, room temperature. The structure of the polymer was stereoblock. This apparently leads to the conclusion that the mechanism of polymerization of methyl methacrylate was not free radical but coordinate anionic. Similarly, the catalyst system of chromium acetyl acetonate and aluminium triethyl polymerized methyl methacrylate at and around room temperature into an highly stereoblock structure containing high isotac

ISSN:0032-3888    

DOI:10.1002/pen.760140406

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractTensile yield, flow, and fracture mechanisms in styrene A (SA), a styrene‐acrylonitrile copolymer rubber‐modified styrene A (RMSA) have been studied and characterized into two basic types: tensile crazing and shear banding. Each can be represented by a master curve and equation over ranges of temperature and deformation rates. Each exhibits distinctive activation energy and volume values. Tensile crazing predominates in unoriented SA below 70°C, and in RMSA. Shear yielding predominates in oriente

ISSN:0032-3888    

DOI:10.1002/pen.760140407

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractResults are presented of friction and thermal tests of molded polyimide and pyrrone polymers. The coefficient of sliding friction up to surface velocities of 2 m/sec (394 ft/min) and the coefficient of thermal expansion from 300 to 500°K (80 to 440°F) were measured. An apparatus was constructed to measure simultaneously the coefficient of sliding friction and the friction‐generated temperature. Measurements were made at a nominal pressure‐velocity product of 0.25 MN/msec (7100 lb/in.2× ft/min) and at temperatures between 300 and 500°K (80 and

ISSN:0032-3888    

DOI:10.1002/pen.760140408

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractA simple method has been developed for interpreting rheological data from virtually any of the common rheometers. The method involves the use of an overlapping scale to provide a direct readout of apparent viscosity. The procedure can accommodate data from either rotational or capillary instruments and for the conditions of either shear rate or shear stress control. The method is fully described along with several examples of its application.

ISSN:0032-3888    

DOI:10.1002/pen.760140409

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe procedures developed in this paper enable the die designer to estimate the dimensions of the die at the exit and to define a flow channel within the body of the die appropriate to the required dimensions and output rate of the extruded product. Design procedures are given for predicting die swell (and hence die exit dimensions) from a knowledge of product dimensions, output rate and the basic shear, elasticity, and viscosity data. Within the body of the die the length and included angle of a convergent tapered section should be such that the critical tensile deformation rate is not exceeded. At the die entry the taper angle is related to the tensile and shear viscosities. Analytical expressions based on flow data are given for predicting pressure drops resulting from flow through circular and slot dies of constant cross‐section and through conical and wedge‐shaped dies. A numerical example shows how the theory may be applied to the design of a die for a thin‐walled tube. For the resultant die design, the likely effects are predicted to changes in output rate and melt temperature for the chosen material, of changes in grade of the same type of polymer, and of changes in polymer

ISSN:0032-3888    

DOI:10.1002/pen.760140410

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractCommercial, suspension‐type PVC resin, poly (vinyl chloride), molecular weightMw× 10−4= 8.6 ± 0.9, polydispersityMw/Mn= 2.26, was mixed with plasticizer di(2‐ethyl hexyl)phthalate (DOP) and organo‐tin stabilizer in four different proportions. The mixtures were milled and pressed into sheets for testing. The polymer content in these samples was 97, 80, 60, and 40 wt percent. The viscoelastic properties of the materials were investigated using a Weissenberg rheogoniometer in a cone‐and‐plate, steady‐state shearing mode. The viscosities and primary normal stress difference coefficients were measured at shear rates of 10−2≤\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document}(sec−1) ≤ 102and at temperatures from 151 to 246°C. The zero shear viscosities, plotted as log η0vs 1/T(Tis the absolute temperature) did not follow either a straight line dependence, reported for PVC melts at low shear rates at 170–190°C, nor was any discontinuity found near 195°C as by others; the data follows a continuous concave curve. The apparent activation energy of flow increases steeply with decreasing temperature. The data can be represented by a WLF type of equation, but the magnitudes of the parameters of this relation differ from expected values. A crossplot of log η0(T= const.) vs logw(wherewis the polymer content) also demonstrates a faster increase of η0withwthan expected from the straight line dependence. The primary normal stress difference coefficient was found to increase withwand decrease withT, paralleling

ISSN:0032-3888    

DOI:10.1002/pen.760140411

出版商:Society of Plastics Engineers, Inc.    

年代:1974

数据来源: WILEY