摘要:

AbstractThe, Theological properties of suspensions of relatively small amounts of titanate fibers in polystyrene solution have been measured by means of a Weissenberg rheogoniometer. The titanate fibers employed have diameters smaller than 0.5 micron and aspect ratios higher than 40. It has been found that the rheological properties of the suspensions are markedly time dependent; the steady‐flow shearing stress increases with increasing time when the rate of shear is changed abruptly from an initial high value to a considerably lower final value. This behavior can be attributed to the re‐formation of a structure formed by the dispersed fibers and broken at higher shear rates. The dynamic storage modulusG′ also depends strongly upon the re‐formation of the structure. Although the structure reformation process under shear appears too complicated to be analyzed satisfactorily, an attempt has been made to generalize the experimental data with a simple e

ISSN:0032-3888    

DOI:10.1002/pen.760170102

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe frictional coefficients of three glassy polymers (polystyrene, polycarbonate, and polymethylmethacrylate) and three crystalline polymers (high density polyethylene, low density polyethylene and polypropylene) on a highly polished steel surface were measured at high temperatures, high pressures, and high speeds, all comparable to actual processing conditions. The frictional behavior of these polymers was found to depend on temperature, pressure‐and speed in a very complicated manner. There appears to exist inter‐relationships among the temperature, pressure and speed dependences of the frictional coefficients. The frictional coefficients of ductile, crystalline polymers as a function of temperature appear to undergo two distinct transitions: one associated with yielding and the other associated with melting. The frictional coefficients of glassy polymers go through only one transition, associated with the glass transition. The friction‐generated heat at high pressures and high speeds can increase the sliding interface temperature of a polymer to values much greater than the metal surface temperature, and thus the polymer can start to melt (or plasticate) at metal surface temperatures appreciably below its thermodynamic melting (or glass transition) temper

ISSN:0032-3888    

DOI:10.1002/pen.760170103

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractPowders of ultra‐high molecular weight polyethylene from three suppliers were characterized for density, crystallinity, particle size, particle size distribution and particle morphology. The powders had molecular weights in the range 2‐5 million. Bulk powder behavior, compressibility, green strength and springback were evaluated and explained in terms of particle characteristics. The green densities of the powders were found to reach a plateau at pressures of about 100 MPa. These plateau density levels were found to depend upon powder, characteristics and to lie between 80 and 90 percent relative density. Green strength is shown to be a unique function of a densification parame

ISSN:0032-3888    

DOI:10.1002/pen.760170104

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractResults of dynamic mechanical spectroscopy, infrared spectroscopy, and tensile stress‐strain data show that the non‐ionic surfactant Igepal CO‐630, often used as a stress cracking agent, and water are absorbed by high density polyethylene to cause an internal stress relaxation of the intercrystalline tie molecules. The resulting molecular rearrangements produce changes in both the crystalline and amorphous regions. Thus, a molecular mechanism is proposed for the long‐term aging process based on the results of accelerated aging in the presence of an environmental stress crackin

ISSN:0032-3888    

DOI:10.1002/pen.760170105

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA forced torsional oscillator (FTO) for measuring dynamic properties from 0.01 to 30 Hz and −190 to +250°C is described. It uses a digital transfer function analyzer to determineG′ andG″ directly. Errors such as clamping corrections, phase angle resolution, and instrument phase shift are evaluated. FTO measurements vs temperature on polymethylmethacrylate (PMMA) and polycarbonate compare well with free torsion pendulum data. Measurements on a silicone liquid vs frequency compare well to eccentric rotating disks data. The frequency sensitivity of the dynamic mechanical response of PMMA and polycarbonate is evaluated at 0.1, 1 and 10 Hz. The frequency dependence of the transitions is fit to an Arrhenius relation and activation energies calculated. A dimensionless transition temperature shift, ΔT*, giving the shift for a one decade frequency change divided by the temperature, is found to be approximately 0.01 for the glass transition and 0.07 for several secondary transitions in glassy p

ISSN:0032-3888    

DOI:10.1002/pen.760170106

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractLow density polyethylene sheet was subjected to treatment by corona discharge in oxygen, nitrogen, helium and argon; in addition some sheets were treated with ozone gas. The bond strength between two similarly treated sheets was then measured using a commercial flexographic ink as an adhesive. The results showed that although surface oxidation improved both the ink adhesion and the wetting properties of polyethylene it is not a necessary prerequisite for good bonding. When the sheet was subjected to electrical discharge in nitrogen, argon or helium, considerable enhancement of ink adhesion was obtained without any detectable change in the surface chemistry of the polymer. The results indicate that ink adhesion after treatment in various gases follows closely the trends established previously in corona‐induced autohesion of polyethylene. This suggests that the mechanism of bonding is similar in the two case

ISSN:0032-3888    

DOI:10.1002/pen.760170107

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA new class of pharmaceutical dosage forms—therapeutic systems—has been developed. Unlike conventional dosage forms (i.e., pills, capsules, or sustained release preparations), which are specified only by the amount of drug they contain, therapeutic systems are described both by the rate and duration of drug delivery. The first products to embody this technology are: (1) an ocular therapeutic system that delivers the anti‐glaucoma drug, pilocarpine, to the eye for one week; (2) an intrauterine contraceptive system that delivers the fertility controlling hormone, progesterone, to the uterus for one year; and (3) an oral osmotic delivery system for administration of drug to the gastrointestinal tract. Specific furictiQns of polymers as constructional elements of therapeutic systems are discussed and consideration is given to properties critical to the intended performance, test procedures, and parameters for prediction of mechanical and physico‐chemical functionality, stability, and

ISSN:0032-3888    

DOI:10.1002/pen.760170108

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThis new coupling agent shows promise for use in reinforcing hydrocarbon type polymers, such as polyolefins and polystyrene, with glass fibers and inexpensive mineral fillers. Sulfonyl azide derivatives readily form durable bonds to many thermoplastics at normal extrusion and molding temperatures, without the use of peroxide or sulfur‐type curing agents. Alkoxy silanes, attached to the sulfonyl azide, hydrolyze in the known manner forming bonds to inorganic fillers. Using commercial compounding and injection molding procedures, 40 wt percent of mineral fillers containing 1 percentofan azidosilane coupling agent were incorporated in polypropylene. Very substantial improvements in tensile, flexural and heat distortion properties were obtained with little loss in impact strength. An initial evaluation in a filled polystyrene showed significant, but less dramatic, improvement

ISSN:0032-3888    

DOI:10.1002/pen.760170109

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe processing characteristics of various glass fiberreinforced thermoplastics (FRTP) and the basic approaches for their production are discussed. Experimental work on twostage production‐scale continuous kneaders was conducted to define the most important process variables in compounding FRTP materials. Results demonstrate how processing conditions and screw design influence the temperature profile in the kneader and the glass‐fiber length in finished products. Feed steek appearance (i.e., pellet shape and size), melt viscosity, and volume percentage of fibers are basic material variables. High quality products can be achieved through a careful, layout of the continuous kneader in order to minimize thermal degradation of the base polymer and to effect adequate dispersion of the glass fibers in the mat

ISSN:0032-3888    

DOI:10.1002/pen.760170110

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA significant advance in ion exchange resin and adsorbent technology has been the development of the macroreticular pore structure. Synthetic rotes have been developed for preparing both ion exchange resins and polymeric adsorbents of high surface area and pore volume. Syntheses have been developed to the degree that the surface area and pore.parameters can be widely varied. Several of these macroreticular polymers based upon the crosslinked styrene and acrylate systems are now available commercially. These polymeric adsorbents are hard, durable, insoluble spheres of high surface area and porosity. They are available in a variety of polarities. The nonpolar adsorbents are particularly effective for adsorbing nonpolar solutes from polar solvents. Conversely, the polar adsorbents are very effective for adsorbing polar solutes from nonpolar solvents. Of particular interest is the use of these polymeric adsorbents for the treatment of effluent wastes. In some cases it has been demonstrated that one can recover significant quantities of re‐usable chemicals that more than pay for the waste, treatment. The use of the polymeric adsorbents for the treatment of phenolicwastes is an example. Other related applications include the removal of chlorinated pesticides, TNT residues, and other noxious compounds from waste effluents and water supplie

ISSN:0032-3888    

DOI:10.1002/pen.760170111

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY