ISSN:0032-3888    

DOI:10.1002/pen.760200802

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractRapid and efficient sulfonation of ethylene‐propylene terpolymer elastomer (EPDM) was achieved in a continuous melt mixing process. A mixture of sulfuric acid and acetic anhydride was used as the sulfonating agent. The reaction of EPDM polymer and the sulfonating agent was carried out in an extruder. It was shown that the continuous melt sulfonation of EPDM polymer may be used as an alternative to the batch solution methods previously reported for the preparation of sulfonated EPDM polymer. The extruder‐reactor method offers advantages of shorter process time, elimination of solvent handling hazards, and abatement of solvent removal and recovery probl

ISSN:0032-3888    

DOI:10.1002/pen.760200803

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractIn this paper we describe the operation of a rheometer that is capable of measuring the viscoelastic response of a polymer melt in a biaxial or planar extensional flow field under circumstances wherein the deformation history can be varied in an arbitrary manner. The principal feature of this rheometer is the use of a closed loop feedback system to control the inflation of a flat, molten polymer sheet clamped around its periphery. The feedback system is especially designed so that either stress or strain can be used as the reference point, thus permitting the deformation history to be varied arbitrarily. Illustrative data are presented on the viscoelastic response of a molten acrylonitrile‐butadiene‐styrene copolymer subjected to a planar extensional flow for the following deformation histories: constant stress, constant strain, constant strain rate, oscillatory stress and oscillatory str

ISSN:0032-3888    

DOI:10.1002/pen.760200804

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractTubular and non‐circular section components have been produced by solid‐phase hydrostatic extrusion of linear polyethylene. Although the extrusion pressures were found to increase with the degree of complexity of the product sections, the module of the products were greatly enhanced and increased linearly with deformation ratio in the manner reported previously for circular section extrusions. Factors influencing the mechanics and stability of the process are discus

ISSN:0032-3888    

DOI:10.1002/pen.760200805

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractFour common 177°C‐curing organic resin formulations were studied dielectrically. Results and discussion are presented on the variation of resin electronic properties during cure. In particular, capacitance and dissipation curves are discussed as a function of time in the cure cycle. Variations in frequency are shown to affect the other electronic properties and a frequency “shift” in dissipation sensitivity is

ISSN:0032-3888    

DOI:10.1002/pen.760200806

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractWhen a polymer melt flows around the cross head or past the fins of a torpedo in a pipe die, a weld line is produced where the separated melt streams rejoin. This weld line may result in an area of weakness in the extruded pipe, although in the case of unfilled materials the effect can be reduced by using a compression section in the die. However, With fiber reinforced polymers it is unlikely that fibers will cross the weld line, and a reduction in strength is inevitable. It is shown theoretically that by rotating the core of the extrusion die the weld line can be modified to form a spiral around the pipe wall, with a large‐surface area for improved strength. Experimental investigations, which employ photographs of thin sections of pipe containing carbon black particles, support these conclusion

ISSN:0032-3888    

DOI:10.1002/pen.760200807

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe techniques of solid state coextrusion and powder extrusion have been employed for the deformation of ultra high molecular weight polyethylene. Chain folded and chain extended morphologies obtained under different crystallization conditions were coextruded within a nylon 11 casing acting as a processing aid at an extrusion draw ratio (EDR) of 5 at ≤ 120°C and 0.20 GPa. The powder was compacted and extruded at ≤ 128°C and 0.23 GPa up to an EDR of 24. The physical and mechanical properties of the extrudates were evaluated and found to be dependent on intial morphology. An extrudate from the chain‐folded morphology gave a low modulus of 0.71 GPa, the chain‐extended morphology a modulus of 6.7 GPa, and the compacted powder a modulus

ISSN:0032-3888    

DOI:10.1002/pen.760200808

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractMelting performance experiments involving three different thermoplastics and three different screw designs have been carried out on a well‐instrumented single screw extruder equipped for cold screw extractions. In the case of the particular polystyrene used it was possible to deduce, from measurements made on the extracted screw, the velocity, and hence acceleration, of the solid bed of compacted polymer at points along the screw channel. The experimental results are successfully compared with the performance predicted by a previously established model, the most important feature of which is the ability to allow the solid bed to deform freely and hence to accelerate. The results show that the bed does indeed suffer significant and non‐uniform acceleration and that the model can predict both this acceleration and the resulting bed break‐up which leads to su

ISSN:0032-3888    

DOI:10.1002/pen.760200809

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractCharpy and tensile impact tests have been conducted on two materials poly(methyl methaerylate) (PMMA) and polycarbonate. It is shown that by adopting a fracture mechanics approach, it is possible to measure meaningful values of material toughness, and that the results obtained in bending are consistent with those in tension. A discussion of the assessment of “kinetic energy” errors is also presen

ISSN:0032-3888    

DOI:10.1002/pen.760200810

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractDumb‐bell shaped specimens of three polyethylenes were subjected to constant uniaxial tensile loads at test temperatures from 298 to 353 K. For the high density polyethylenes, a marked transition appeared in the neck/fracture behavior. At a certain stress level, the instantaneous fracture of the neck formed at high loads was replaced by the formation of a neck that resisted fracture for a considerable time. This transition was more gradual for the medium density polyethylene. Furthermore, at all test temperatures the transition shifts towards higher nominal stresses with increasing molecular weight. Mainly on the basis of measurements of the local strain rate in the neck forming region, a hypothesis is proposed which explains the appearance of the marked transition. The draw ratios and the densities of the fractured neck fibers were also measured and are in accordance with current molecular deformation theorie

ISSN:0032-3888    

DOI:10.1002/pen.760200811

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY