摘要:

AbstractBy means of compounding, we have developed a rigid poly(vinyl chloride) (PVC) formulation with improved overall combustion properties. Newly developed analytical methods indicate a considerable reduction in the level of gases released during combustion, in addition to excellent flammability characteristics and low visible smoke emission levels. The analytical methods discussed are expected to aid in the selection of a feasible protocol for biological testing and in the interpretation of results obtained from such testing. The under‐lying compounding technology is currently restricted to normal impact rigid PVC cube compounds but expected to be expanded into high impact PVC, flexible PVC, PVC powder compounds and cellular PV

ISSN:0032-3888    

DOI:10.1002/pen.760180702

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe line‐source method, previously used for measuring thermal conductivity of plastics, was increased in sensitivity so that automatic recording of data and data reduction by computer could be used, The correspondence between the underlying mathematics and the experiment is examined. The apparatus is described. The effect of experimental variables such as heating rate is determined‐ Measured values of thermal conductivity are reported for several commercial plastics, from room temperature, or lower, to processing temperatures. The precision of the results is excell

ISSN:0032-3888    

DOI:10.1002/pen.760180703

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe periodic diameter variations in melt spinning known as draw resonance have been extensively studied, both theoretically and experimentally. The theory has evolved from analyses for isothermal, Newtonian spinning in which the critical draw ratio was found to be 20.21. Compared with this, recent theories have shown that elasticity and cooling are stabilizing (with certain qualifications on the range of variables) and that non‐linear rheological response is destabilizing. The present work presents systematic data on two polymers, one that is always amorphous (polystyrene) and one that solidifies into a semi‐crystalline state (polypropylene). Isothermal and non‐isothermal data are available for the former; non‐isothermal data, for the latter. The melt temperature, the cooling environment, the die length, the spinning length, the mass flow rate and the draw ratio were varied. Certain observations cannot be explained within the existing theoretical framework, specifically the destabilizing effect of certain cooling histories in the case of polystyrene and the destabilizing effect of short dies, presumably a die swell effect, in the case of polypropylene. Very highly oriented polystyrene can be produced under certain conditions when the fiber temperature is held

ISSN:0032-3888    

DOI:10.1002/pen.760180704

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA discussion of the effect of deformation on mixing leads to reorientation of fluid interfaces as a proposed mechanism for special “mixing sections” in single screw extruders. Based on the kinematics of mixing it is shown how a mixing section can greatly decrease the amount of work necessary to accomplish extensive mixing through orienting the fluid more favorably for mixing by subsequent shear. Mathematical development quantitatively describes favored configurations of mixing sections. An upper bound for the mixing performance of a simple model of an extruder with special sections is shown to be similar to turbulent mixing. Based on this theory the key actions of the special sections are identif

ISSN:0032-3888    

DOI:10.1002/pen.760180705

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA graphical method based on dimensional analysis is presented for estimating the injection pressure and clamp force required for injection molding amorphous polymers to form disk‐shaped parts with a constant wall thickness. A procedure is suggested for estimating clamp force when the projected area of the mold cavity is smaller than the surface area of one side of the molded part. The results reported here are based on a numerical simulation of a power‐law fluid filling a cold mold at a constant injection rate. The dimensionless bulk temperature and the ratios of the nonisothermal injection pressure (clamp force) to the isothermal injection pressure (clamp force) are given as functions of the dimensionless cooling time τ, the Brinkman numberBrwhich characterizes viscous heating, the power‐law exponentn, and a dimensionless temperature β which includes the inlet melt and mold wall temperatures and the temperature coefficient for vi

ISSN:0032-3888    

DOI:10.1002/pen.760180706

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA major objective in polymer rheology is to predict a fluid's response to a general deformation from molecular information. A method has been developed which allows one to predict the viscoelastic properties of polymer melts from a limited amount of rheological and molecular data for the polymer. The input parameters are: (a) zero‐shear viscosity; (b) molecular weight distribution; (c) temperature and density; and (d) constants relating Graessley's relaxation time to the Rouse relaxation time. The technique then “simulates” a discrete relaxation spectrum using G′ and G″ data from the Rouse theory and finally requires that a continuum model of polymer viscoelasticity be fit to shear viscosity data predicted by Graessley's theory. Examples of the utility of the procedure are given to illustrate the role of molecular weight and weight distribution in determining rheological

ISSN:0032-3888    

DOI:10.1002/pen.760180707

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe electrodic polymerization on graphite fibers of a variety of monomers having different types of functional groups has been investigated. In addition to vinyl polymerization, some novel polymerizations of cyclic functional groups have been conducted under appropriate polymerization conditions. In many instances, the grafting of the surface polymer to the fiber has been confirmed. The stereochemical configuration of poly(methyl methacrylate) resulting from electropolymerization was measured, but conclusive evidence could not be obtained for the occurrence of stereo‐regulation in electrochemical polymerization on graphite fiber surface; Composite specimens were prepared by the incorporation of the coated fibers in an epoxy matrix. It was demonstrated that the effect of electropolymerization on the interfacial properties of the resulting composite was manifested in variations of the measured interlaminar shear and impact strengths of the composite specimens. The increase or decrease in interlaminar shear was accompanied by the usually observed reverse change in impact strength. In exception to this general trend, it was also indicated that the shear and impact strengths could simultaneously be increased. Implicit in these findings is the contribution of the electrochemically formed interlayer to one or more of the toughening mechanisms that are available to fiber reinforced composites. The potential value of interphase modification by electrochemical polymerization is thus clearly indicate

ISSN:0032-3888    

DOI:10.1002/pen.760180708

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractTwo models are used to describe vinyl chloride monomer (VCM) diffusion from poly(vinyl chloride) (PVC) packages to food simulating solvents. It was found that when the initial solid concentration in a PVC package is 0,35 ppm: (a) For poor solvents such as water and oils, VCM concentration in the solvent,Cl, theoretically will not exceed 20 ppb. (b) For strong solvents, the volume ratio of package solid/solvent should not exceed 0.1 in order to keep (Cl)maxbelow 20 ppb. (c) It was demonstrated that thickness can be adjusted to give aCl= 20 ppb at the time equal to the shelf‐life of the package. The method can also be used to calculate the initial concentration of VCM in a package which will give a proposed level of maximumClwhen the solvent and package geometry are fixed. VCM diffusion from PVC pressure pipe to pipe fluids was similarly analyze

ISSN:0032-3888    

DOI:10.1002/pen.760180709

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe purpose of this work was to determine if capillary extrusion rheometer and mechanical spectrometer data can be used to predict the molding performance of a commercially available diallyl phthalate (DAP) compound. In addition, differential scanning calorimetry (DSC) curves of “good” and “bad” batches were statistically analyzed in order to determine if the DSC peak shape is related to the molding performance. It was found that the data obtained from all three techniques correlate very well with the molding behavior of the DAP material studied. Capillary rheometer and mechanical spectrometer results show that lower melt viscosities and lower curing rates are desirable for obtaining satisfactory molding performance. The mathematical moments analysis of DSC curves indicates that DAP batches which molded well give peaks of fairly high symmetry, while all peaks of “bad” batches are skewed to the left. The center of gravity of the former is at a higher temperature and the variance is smaller than the corresponding values of “b

ISSN:0032-3888    

DOI:10.1002/pen.760180710

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760180701

出版商:Society of Plastics Engineers, Inc.    

年代:1978

数据来源: WILEY