摘要:

AbstractPoly(vinyl chloride) and chlorinated poly(vinyl chloride) films were saturated at 100°C with fluorotrichloromethane (Genetron‐11, a foaming agent) and then allowed to desorb at RT and 65°C. The desorption data for a three month period was fitted into a mathematical relationship which could be used for long term predictions of the G‐11 retention in the films. Using thermoanalytical techniques, plots of glass transition temperature vs G‐11 concentration were made for the polymers under study. These plots were used to demonstrate the effect of stabilizer, polymer type and temperature on the desorption of t

ISSN:0032-3888    

DOI:10.1002/pen.760210402

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractUni‐ and biaxial stretching of poly(ethylene terephthalate) (PET) specimens of appropriate geometry at temperatures near the glass‐rubber transition may lead to non‐uniform deformation unless the draw ratio exceeds a critical value, the natural draw ratio, characteristic of the onset of strain hardening due to stress‐induced crystallization. Experimental results obtained in the present investigation show that natural draw ratios in uni‐ and biaxial stretching decrease with increasing resin molecular weight and with decreasing temperature. Undesirable uneven wall thickness distribution in biaxially stretched cylindrical parisons can only be prevented if draw ratios in both orthogonal principal stretching directions exceed the corresponding natural values. The minimum thickness reduction required for uniform biaxial stretching of a cylindrical parison at 95°C may vary between 12 and 5 depending on the resin's molecular weight or viscosity and this will affect the optimum design of parison geometry. The degree of unbalanced biaxial molecular orientation in the wall of cylindrical parisons stretched up to or beyond the natural draw ratios also depends on the resin molecular weight. Unbalanced biaxial orientation has been investigated by means of wide angle X‐ray diffraction and birefringence measurements as well as its effect on various properties: rigidity, yield stress, creep compliance, and dimension

ISSN:0032-3888    

DOI:10.1002/pen.760210403

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractAn experimental study was carried out to investigate the effects of coupling agents on the rheological properties, processability, and mechanical properties of highly filed polypropylenes (PP). Inorganic fillers used were CaCO3and glass beads, and coupling agents used were two silane coupling agents, N‐octyl triethoxy silane and γ‐aminopropyl triethoxy silane, and one titanate coupling agent, isopropyl triisostearoyl titanate. It was found that the addition of the coupling agents to the PP‐CaCO3(50 wt percent) decreased the melt viscosity and increased the melt elasticity (first normal stress difference). However, the addition of the silane coupling agents to the PP‐glass beads (50 wt percent) affected the rheological properties of the melts quite differently. The N‐octyl triethoxy silane had relatively little effect on either the melt viscosity or the melt elasticity, whereas the γ‐aminopropyl triethoxy silane increased the melt viscosity and decreased the melt elasticity. The CaCO3‐ or glass bead‐filled polypropylenes, with and without coupling agents, were injection‐molded and the mechanical properties of the molded specimens were measured by the use of an Instron testing machine. It was found that the effect on the tensile strength and percent elongation of the filled polypropylenes depended upon the specific coupling agent utilized. A melt‐spinning study was also carried out to investigate the effect of coupling agents on the spinnability (defined as the maximum draw‐down ratio) of the PP‐CaCO3system, and on the mechanical properties of the melt‐spun fibers. It was found that the spinnability of the PP‐CaCO3was enhanced considerably by the addition of the coupling agents, and that the tensile strength of the melt‐spun fibers was also improved by their addition. Scanning electron micrographs were taken of the fracture surface of injection‐molded specimens and an attempt was made, with the aid of photomicrographs, to explain the mechanical properties of molded

ISSN:0032-3888    

DOI:10.1002/pen.760210404

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe impact modification mechanisms of polycarbonate (PC) blended with polyethylene (PE) and blends of polyxylenol ether (PXE)/high impact polystyrene (HIPS), were studied using a volume dilation technique. With two extensometers, measurements of volume change during tensile deformation were made on the plastics. Strain rates of 2 × 10−5s−1to 4 s−1were achieved with a MTS servo‐hydraulic testing machine. Analysis of both systems were supported with scanning and transmission electron microscopy. Results on the PC/PE system indicate that the impact modification mechanism is one of voiding and shear banding. The mechanism appeared to be rate sensitive: the amount of voiding increased with rate. The toughening mechanism in the PXE/HIPS blends is identified as a combination of crazing and shear banding. The amount of shear banding that occurs is proportional to the amount of PXE in the blends. The point of craze initiation was found to be delayed by increasing strain rate. The stress for craze initiation appears to be greater than for shear

ISSN:0032-3888    

DOI:10.1002/pen.760210405

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractSimple quantitative mixing experiments in well‐defined deformations clearly demonstrate the validity of previously derived equations relating deformation and mixing. A simple mixture of black and white polyethylene is studied by direct measure of striation thickness. The well‐known linear relationship in simple shear is demonstrated. By using a simple method for uniform reorientation, the second power relationship in shear once interrupted, the third power relationship in shear twice interrupted and the fourth power relationship in shear interrupted three times are demonstrated. In uniaxial elongational mixing of a silicone fluid, exponential dependence of mixing on strain is demonstra

ISSN:0032-3888    

DOI:10.1002/pen.760210406

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe dependence of crack propagation energyRof an acrylonitrile‐butadiene‐styrene (ABS) resin on crack velocity was characterized in air and in several organic liquids. In the liquids an abrupt transition inRfrom a level like that in air down to a level characteristic of the liquid occurred with decreasing crack velocity. The velocity at the transition varied strongly with liquid viscosity. A simple model of each craze at the crack tip as a set of pipes through which liquid flows, driven by capillary force and retarded by viscous drag, serves to predict the transition veloc

ISSN:0032-3888    

DOI:10.1002/pen.760210407

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractFollowing the reported pronounced effects of metal halides incorporated into nylon‐6 on its glass transition temperature, melting temperature, melt viscosity, crystallization rate and final crystallinity, the tensile mechanical properties and crystallinity of nylon‐6 as affected by the absorption of metal halides were studied. At low salt content, some of the mechanical properties are substantially altered and at higher salt concentrations the ductile polymer becomes brittle. There is no marked difference between the salts studied (CuCl2, CuBr2, FeCl3) regarding their effects on the polymer mechanical properties. In the concentration range studied, absorbed Cu salts do not significantly change the polymer's degree of crystallinity, whereas absorbed FeCl3results in a pronounced reduction, indicating its effect also on the crystalline ph

ISSN:0032-3888    

DOI:10.1002/pen.760210408

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractWhile biaxial stretching plays a central role in several polymer processes, there has been no technique suitable for laboratory study of controlled biaxial stretching of molten thermoplastics at typical melt processing temperatures. The sheet inflation technique, which has been used previously to study rubbers and very high viscosity melts, has been adapted for use with molten thermoplastics by the use of oil as an inflation medium. Problems encountered in the use of the first prototype were eliminated in a second model, which is thought to produce reliable results. Stress growth data are presented for a low density polyethylene and for a polystyrene. A basic limitation of the technique is that the maximum achievable strain is in the range of 1.3 to 1.7, and this is often insufficient to bring out the nonlinear viscoelastic behavior of the melt.

ISSN:0032-3888    

DOI:10.1002/pen.760210409

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractRheological tests are reported for two types of polyorganophosphazenes, one being a fluorinated alkoxy terpolymer (PNFT) and the other an aryloxy copolymer (PAP). Non‐Newtonian viscosity η(\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \gamma } $\end{document}) and complex viscosity components η′(ω) and η″(ω) were measured as functions of shear rate\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \gamma } $\end{document}and oscillatory frequency ω, using a Weissenberg rheogoniometer, and a limited amount of normal stress data was also obtained. Solutions of both polymers in tetrahydrofuran were tested, over a concentration range 0‐22 percent for PNFT and 0‐35 percent for PAP. Melts of PNFT were examined for temperatures 50‐178°C, and melts of PAP at 210°C even though they were not truly fluid at this temperature. Solution and melt data are shown to obey conventional superposition principles to give master curves. For solutions, superposition is achieved by using the Bueche relaxation time as a concentration reducing factor with no adjustable parameters, and the Spriggs model also proves useful in predicting normal stress and shear stress results. For PNFT melts, master curves are fitted by the new WS2H2model which incorporates detailed molecular weight distribution (MWD) information and extracts the entanglement lengthMefrom the data. Temperature shift factorsaTshow Arrhenius behavior and the corresponding activation energiesEreare reported. Results for PNFT melts were complicated by lack of agreement between two samples of nominally the same composition; η′(ω) shapes and levels andErevalues differed widely. This is interpreted in terms of detailed MWD information and the possibility of mesomorphic phase transitions occurring in these nomina

ISSN:0032-3888    

DOI:10.1002/pen.760210410

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760210411

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY