摘要:

AbstractThe thermal decomposition of poly(butene‐1 sulfone), poly(pentene‐1 sulfone), poly(hexene‐1 sulfone), poly(styrene sulfone), and polystyrene was investigated in helium at a heating rate of 20°C/min using an experimental system which consists of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, and a vapor‐phase infrared spectrophotometer. Poly(butene‐1 sulfone), poly(penetene‐1 sulfone), and poly(hexene‐1 sulfone) displayed two‐step decomposition; the primary products of decomposition at both steps were the comonomers (olefin and SO2). For poly(styrene sulfone), in addition to styrene and SO2, products with molecular weights corresponding to dimers of styrene were observed. Decomposition of this polymer was compared with that of polystyrene, which forme

ISSN:0021-8995    

DOI:10.1002/app.1977.070210501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractAn experimental study was carried out with the objective of comparing the critical conditions for the onset of gross extrudate distortion, usually called melt fracture, in capillaries and slits. Narrow and broad molecular weight distribution polystyrenes as well as low‐ and high‐density polyethylenes were used. The onset of melt fracture was observed to take place at higher shear stresses in slits than in capillaries. It is argued that the flow‐average value of the recoverable shear strain should be used as the criterion for the initiation of melt fra

ISSN:0021-8995    

DOI:10.1002/app.1977.070210502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractIn previous papers, interpenetrating polymer networks were shown to display a cellular structure. The phase domain size of polymer II was shown to depend inversely on the crosslink density of polymer I. The present paper presents a semiempirical derivation of equations which show quantitatively the dependence of the phase domain size of polymer II on the crosslinking density of polymer I, and also on the interfacial energy and the overall composition. If polymer II is linear, the dependence on the molecular weight of polymer II is also included. The values of the phase domain sizes so estimated are compared with experimental results. While theory and experiment yield good agreement, the semiempirical nature of the equations must be borne in mind.

ISSN:0021-8995    

DOI:10.1002/app.1977.070210503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe monomersp‐hydroxystyrene (p‐HS) andp‐methoxystyrene (p‐MS) have been synthesized and polymerized using azobisisobutyronitrile as free‐radical initiator. The polymerization behavior ofp‐HS is anomalous, and a mechanism is suggested to account for this phenomenon. Poly(p‐hydroxystyrene) (PHS) and poly(p‐methoxystyrene) (PMS) homopolymers have been subjected to vacuum pyrolysis at temperatures in the range of 300–500°C. The products of degradation have been identified and qualitatively and quantitatively analyzed and the degradation behavior of the two systems compared with polystyrene. PHS shows anomalous behavior resulting from the high reactivity of thep‐HS monomer and the facility for transfer afforded by the proton of the hydroxyl substituent. Mechanisms to account for the degradation behavior of each

ISSN:0021-8995    

DOI:10.1002/app.1977.070210504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractComparative thermal degradation studies have been made in air and nitrogen on polystyrene (PS), poly(p‐methoxystyrene) (PMS), poly(p‐hydroxystyrene) (PHS) andp‐hydroxystyrene/styrene copolymers (p‐HS/S) by thermal analytical methods (TG and DSC). The degradation behavior shown by these polymers in an oxidizing or inert atmosphere is different. PMS and PS, however, degrade in a similar manner in the same test atmosphere, suggesting that similar degradation mechanisms are operative for these systems. Polymers containingp‐HS behave differently to PMS and PS in both atmospheres. Their behavior in air is discussed it terms of the antioxidant effect of the phenolic hydroxyl grouping and the related crosslinking reactions. In nitrogen, the anomalous behavior is discussed in terms of the observed carbonization

ISSN:0021-8995    

DOI:10.1002/app.1977.070210505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractBench‐scale equipment for wet spinning was designed and built. An experimental study of the wet spinning of several polyamides has been carried out. The polymers studied include nylon 6, nylon 66, redissolved Nomex, and redissolved Kevlar. The superstructure of the wet‐spun fibers were studied by optical and scanning electron microscopy as well as small‐ and wide‐angle x‐ray diffraction. Mechanical properties were measured and related to the spinning variables. For nylon 6 and nylon 66, the coagulation bath composition was found to be of major importance in determining fiber superstructure. For the case of the redissolved Kevlar, anisotropic spinning dopes were obtained from redissolved fiber, and the wet‐spun filaments produced from such solutions were investigated. These fibers proved to have relatively high modulus and strength as spun. They had even greater strengths after

ISSN:0021-8995    

DOI:10.1002/app.1977.070210506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe permeation properties of glycol chitosan–chondroitin sulfate C and glycol chitosan–heparin complex membranes have been studied. Discussion is devoted primarily to the desalination properties in reverse osmosis. Salt rejection and flux were dependent both on the composition of the membranes and the pH of the feed solutions. The results indicate that these complexes behave like polyampholytes. Minimum salt rejection occurs around the isoelectric point. Another characteristic of these membranes is a large pressure dependence of the salt rejection. This could be interpreted by assuming the compaction of these highly swollen membranes at high press

ISSN:0021-8995    

DOI:10.1002/app.1977.070210507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractAntiplasticization, defined as an increase in glassy modulus of polymers upon dilution with low molecular weight compounds, was studied for highly crosslinked epoxy resins. A series of oligomers with average molecular weight 500–4000 was incorporated with epoxy resins for elucidating the effect of their molecular weight on antiplasticization. The antiplasticization was found to be dependent on the molecular weight of the oligomers used. It was most evident when the lowest molecular weight oligomer was incorporated, and seems to be suppressed by increasing molecular weight of the oligomers. These results were discussed in correlation with the behavior of dynamic mechanical properties and the changes in specific volume as a function of the epoxy resin and diluent

ISSN:0021-8995    

DOI:10.1002/app.1977.070210508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA method of multipeak resolution and computation of background scatter in x‐ray diffraction from fiber has been applied to jute fibers. While crystallinity as determined by this method in raw and delignified jute fibers remains unchanged, perfection of the crystalline regions improves on delignificatio

ISSN:0021-8995    

DOI:10.1002/app.1977.070210509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractNumerous simple compounds have been shown to be capable of accelerating the photo‐oxidation of polyethylene upon exposure to wavelengths near 300 nanometers. Probable mechanisms of photo‐initiation by the principal classes of degradation‐promoting additives are disc

ISSN:0021-8995    

DOI:10.1002/app.1977.070210510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY