ISSN:0032-3888    

DOI:10.1002/pen.760170402

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractSI surpasses previous metric systems in coherence, simplicity, distinction between force and mass, choice of units, and uniformity of usage. Coherence eliminates conversion factors, other than powers of ten, within the system. Through simplification, only seven base units, two supplementary units, seventeen named derived units, and sixteen prefixes are needed to describe the entire system. Promotion of the newton as a unit of force and retention of the kilogram for mass clarifies the difference between the two quantities. New units are: pascal for pressure, siemens for electric conductance, and mole for amount of a substance. International agreement minimizes proliferation of specialized units or usage. Adopted conventions include spelling, abbreviations, style, and usage, as well as definitions for the units. Toleranceg, rounding of numbers, and elimination of the comma in multidigit numbers assume new significance. Conversion to SI offers a unique opportunity to reduce the number of sizes of many products. Several schemes for metric modularism have been developed for this purpose. In changing from conventional tip SI units, the key idea is “think metric” rather than use dual dimension

ISSN:0032-3888    

DOI:10.1002/pen.760170403

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe stress‐strain properties of oriented polymers are measured parallel and perpendicular to the direction of hot stretching. The polymers include styrene‐acrylonitrile copolymers, vinyl alcohol copolymers, acrylic acid copolymers, polyelecf trolytes, and a high density polyethylene. Polarity and hydrogen bonding tend to increase the strength, especially in the direction perpendicular to the direction of hot stretching. Strong electrostatic bonding in polyelectrolytes and too much polar bonding in styrene‐acrylonitrile&polymers decrease the strength by reducing the molecular mobility, which is required to prevent brittl

ISSN:0032-3888    

DOI:10.1002/pen.760170404

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractOriented short fiberglass mats prepared by the ERDE converging flow technique of fiber/glycerine dispersions were studied. Fiber orientation distribution in mats, prepregs and molded sheets were investigated by optical and X‐ray techniques. Longitudinal and transverse fracture surfaces of short fiberglass/epoxy molded sheets were analyzed. The effect of fiber length on tensile properties was also studied. The experimental results obtained on longitudinal, transverse, and off‐axis tensile modulus and ultimate strength were compared with classical elastic equations for continuous reinforcem

ISSN:0032-3888    

DOI:10.1002/pen.760170405

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractFlexural fatigue data about a non‐zero mean stress are presented for unidirectional fiberglass‐reinforced polyester composites. The data are useful for the design of structural components and extend our knowledge regarding the mechanical performance of composite materials. In particular, the dependence of modulus, strength, and fatigue strength on glass content, both dry and wet, is described. Also, the extent to which design allowable stresses are influenced by minor impacts and by machining is discus

ISSN:0032-3888    

DOI:10.1002/pen.760170406

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractFatigue tests in reversed tension‐compression have been carried out on samples of polyethylene and polystyrene of widely varying molecular weights, extending up to 2, 000, 000. All tests on polystyrene specimens were made at 1600 rpm. For polyethylene, tests speeds had to be reduced to 100 rpm in order to avoid serious temperature effects. For both materials, increasing molecular weight leads to improved resistance to alternating loading. For polystyrene, this improvement in ultimate properties even continued well beyond molecular weight values whereTg, becomes effectively independent of molecular weight. For polyethylene, samples of high molecular weight did not fail even after 107cycles of alternating loading at a stress level of 3000 ps

ISSN:0032-3888    

DOI:10.1002/pen.760170407

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe physical and mechanical properties of interpenetrating polymer networks (IPN's) based on castor oil‐urethane and polystyrene are detailed in this paper. Dynamic mechanical spectroscopy showed extensive but incomplete molecular mixing of the two polymers. The glass transition temperatures of the IPN's gradually merged from two distinct transitions into one broad transition at an intermediate temperature as the crosslink level of the castor oil component was increased. At low polystyrene contents, the IPN's yielded stress‐strain behavior similar to reinforced elastomers, but at high polystyrene contents, they exhibited increased elongation. For example, the latter materials showed well developed yield points. Stress whitening and necking were also observed, suggesting a possible failure mechanism by crazing. Cold drawing was exhibited by the materials under tension. The tensile strength and Young's modules were enhanced as the polymer II (polystyrene) content was increased at constant crosslink level of polymer I (castor oil‐urethane). A similar effect was also observed by maintaining the polystyrene content constant but increasing the crosslink level of polymer I. The impact strength of the materials ranged from 32.1 to 53.4 N · m/m, which is approximately two to three times that of homopolymer polystyrene. The best materials were those with compositions in the range of 40‐46 percent castor oil‐urethane. The materials prepared by using tolylene diisocyanate as crosslinker for the castor oil phase had the best impact properties, especially at an NCO/OH rat

ISSN:0032-3888    

DOI:10.1002/pen.760170408

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe phenomenon of wall slip during the capillary flow of polymer melt is investigated for low and high density polyethylene. It is found that wall slip occurs in both cases, and that the effect is related to melt fracture. In addition, it is shown that a silicone fluid exhibits wall slip. The performance of the metering zone of a 38 mm diameter single‐screw extruder is discussed in relation to wall slip. It is suggested that the power consumption of the extruder is reduced as a result of slip at the polymer/metal interface. Results based on experiments with the silicone fluid tend to support this hypothesis. A theoretical analysis of the effects of wall slip upon throughput rate and power consumption for a one‐dimensional isothermal Newtonian case is inclu

ISSN:0032-3888    

DOI:10.1002/pen.760170409

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA method for determining the melt viscosity and molecular weight of ultra high molecular weight polyethylene (UHMWPE) is described. The method, based on squeeze flow, was used to characterize seventeen UHM W‐PE samples varying in molecular weight from 0.6 × 106to 5.1 × 106and in viscosity from 2.9 × 106to 3.4 × 109poise. A correlation between melt viscosity and molecular weight was demonstrated, but the reliability of a molecular weight determination decreased somewhat as molecular weight increased. As a predictor of melt processability, the method provides the speed and simplicity heretofore lacking in UHMW‐PE characterization by solution viscosity while retaining high reproduc

ISSN:0032-3888    

DOI:10.1002/pen.760170410

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe rate of vapor‐development of poly(olefin sulfones) subjected to electron beam irradiation is markedly, dependent upon the olefin structure. At room temperature, poly(butene‐1sulfone) and poly(cyclopentene sulfone) vapor‐develop at rates several orders of magnitude lower than, for example, poly(2‐methyl pentene‐1 sulfone). Differences in vapor development rate for the various sulfones are shown to be related to differing rates of depolymerization which, in turn, are related to differences in ceiling temperatures for polymer formation. Kinetic analysis indicates that the mechanism involves random scission followed by depropagation and bimolecular te

ISSN:0032-3888    

DOI:10.1002/pen.760170411

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY