摘要:

AbstractA singular class of polymer reactions can be caused by mechanical stress. Sufficient storage of mechanical energy to break chemical bonds in the main chain is generally possible only on deformation of polymers of high molecular weight. The corresponding appropriate conditions of high stress may occur in both polymer processing and use. This review summarizes reports of such polymer stress reactions published principally after 1980. The survey is organized by polymer type and by analysis technique.

ISSN:0032-3888    

DOI:10.1002/pen.760250302

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractDynamic mechanical properties have been investigated for interpenetrating‐network systems based on polyol‐cured polyurethanes (PU) and 2 to 1 n‐butyl acrylate‐n‐butyl methacrylate (Ac) networks. The systems were formed simultaneously (SIN) from all of the precursors and reactants for both networks in the same vessel, and sequentially (SIPN) by swelling a precured PU with the reactants that will form the Ac network. If the Ac network is formed after gelation of the PU, the IPNs are transparent and appear to have singleT(tan δmax) between those of the homonetworks; visible‐phase separation occurs if the Ac is intentionally polymerized prior to PU gelation. Damping curves were lower and broader and theT(tan δmax) and rubber moduli were higher for the SIN than for the SIPN systems. Up to 65 percent Ac, theT(tan δmax) data for both SIN and SIPN fit the Gordon‐Taylor equation if aT(tan δmax) for the Ac homonetwork 7°C higher than observed is used, suggesting a higher crosslink density for the Ac network under these conditions. The differences in properties of the SIN and SIPN are assumed to be dependent on sample homogeneity and upon the presence of a tin catalyst in the SIN preparation. This can result in limited Ac‐network formation and consequent phase separation before PU gelation has occurred, and the catalyst may also increase the extent of interaction, such as grafting or hydrogen‐bond formatio

ISSN:0032-3888    

DOI:10.1002/pen.760250303

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractIntegral sorption/desorption measurements were carried out for the sulfur dioxide‐glassy polyarylate polymer system at 25°C, 40°C, 55°C, and 63°C. The transport of sulfur dioxide in the glassy polyarylate polymer was governed by Fickian diffusion. The effective diffusion coefficient of sulfur dioxide increased with increasing penetrant concentration. The concentration dependence of the effective diffusion coefficient is explained on the basis of the partial‐immobilization model developed by Paul and Koros. The mobility of the molecules sorbed in the Langmuir mode is shown to be significantly lower than the mobility of the molecules in Henry's law dissolution mode. The predictions of permeability values as a function of upstream gas pressure are presented. The equilibrium sorption isotherms for this system are well represented by the dualmode sorption model. The eltergetics and the temperature dependence of the dual‐mode parameters are also

ISSN:0032-3888    

DOI:10.1002/pen.760250304

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe fatigue behavior of pure poly (vinylchloride) (PVC) and a PVC pipe compound has been investigated. Unnotched S‐N lifetime, fatigue‐crack growth, and craze/crack‐initiation data are presented. The data trends, coupled with direct‐microscopic observation, suggest that the unnotched‐specimen lifetime in fatigue is dominated by the craze/crack‐initiation process. This differs from the observed consistency of crack propagation and specimen‐lifetime trends in several other polymers, whose failure can be traced to the initiation and growth to instability of a single dominan

ISSN:0032-3888    

DOI:10.1002/pen.760250305

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractBlends of polyarylate (PA)‐a copolyester of bisphenol A with a mixture of terephthalic/isophthalic acids at 50/50 proportion–and polycarbonate of bisphenol A (PC) were melt mixed into films with a Brabender Plasticorder. The processing produced transreacted mixtures that exhibited a modulus and yield stress with a maximum that is above the linear (very similar to that observed for compatible polymer blends). The elongation at yield did not show any maximum but it is also above linear

ISSN:0032-3888    

DOI:10.1002/pen.760250306

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractSingle Kevlar‐29 fibers have been subjected to creep loading over a temperature range of 23 to 400°C for which the applied load was 50 percent that of tensile strength at each temperature considered and also subjected to a range of loads at 23°C. It has been shown that strain expressed as a logarithmic function of time describes the experimental results obtained. Up to 70 percent of breaking load, a primary creep mechanism dominates and at higher loads a secondary creep process becomes increasingly import

ISSN:0032-3888    

DOI:10.1002/pen.760250307

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractRheological and processing parameters have been measured for a commercial polystyrene at temperatures from 155°C to 210°C resulting in no clear evidence for the existence of liquidliquid transition. Zero shear viscosities obtained from dynamic measurements and ends corrections and extrudate swell from capillary rheometry are analyzed, with the conclusion that the mechanism of flow is the same throughout the range of temperatures considere

ISSN:0032-3888    

DOI:10.1002/pen.760250308

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760250301

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY