摘要:

AbstractThe electrical properties of poly(α‐chloroacrylonitrile) (PCIAN) carbon black compositions were determined. These materials were prepared by polymerizing α‐chloroacrylonitrile in the presence of carbon black (GC resistors). Resistivities measurement of GC resistors shows a semiconductor‐like behavior. Moreover, the resistance change of GC resistors with electrical field strength is very large. It is concluded that the conduction of GC resistors is controlled by the thin polymer layer present at the surface of the carbon black particles. Heat degradation of such compositions was also investigated: A significant weight loss above 150°C is observed in all cases which can be attributed to thermal dehydrochlorination of PCIAN. After heat treatment at 300°C, during 1 h, the resistivities decrease of about 1 order of magnitude because of the formation of a semiconducting polyconjugated polymer by dehydrochlorination

ISSN:0021-8995    

DOI:10.1002/app.1988.070350111

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

年代:1988

数据来源: WILEY

摘要:

AbstractA study of the immobilization of trypsin and other enzymes onto hydrolyzed poly(2‐hydroxyethyl methacrylate)‐g‐co‐polyethylene using hydroxyl and carboxyl activating agents has been undertaken. Some emphasis was placed on the immobilized trypsin system which involved examination of the variation of (i) the extent of hydrolysis of the graft copolymer, (ii) the concentration of activating agent, and (iii) the temperature of coupling. With the trypsin system, an increase in carbodi‐imide concentration gave an increase in the amount of protein immobilized but a marked decrease in the retention of enzymic activity. Comparison of the behavior of the free with the immobilized enzyme showed that satisfactory yields were obtained and the immobilized system has an extended pH profile and good stability and thus would have broad applicability. The kinetic factors were examined further, and the role of the graft copolymer chains in the immobilized system is

ISSN:0021-8995    

DOI:10.1002/app.1988.070350112

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

年代:1988

数据来源: WILEY

摘要:

AbstractSorption and permeation of CO2were investigated by using synthetic polymer membranes having pyridine moiety or pyridine–Cu(II) complex group as a fixed carrier. The solubility data for CO2were interpreted by the dual sorption model, Henry's law plus Langmuir‐type adsorption. The permeation results of CO2through the present membranes containing pyridine moiety were analyzed in terms of the partial immobilization model, while the solubilities and permeablities of O2and N2obeyed Henry's law. Permselectivity of the present membrane for CO2was achieved. These results were explained by the acid‐base interaction between CO2molecules and fixed carrier in the present mem

ISSN:0021-8995    

DOI:10.1002/app.1988.070350113

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

年代:1988

数据来源: WILEY

摘要:

AbstractDynamic viscoelastic properties of the rigid polyurethane foam, which is used in Japan as a thermal insulator for refrigerators were studied during the curing process using the RDS‐7700 Dynamic Spectrometer. The curing process, in which large volume expansion and heat evolution occurred, was easily analyzed by this method. The apparent storage modulus (G′app), the apparent loss modulus (G″app), and the apparent loss tangent (tan δapp) were measured as a function of cure time. The effects of the curing temperature and the amine catalyst on the curing process were investigated. It was found that the curing process proceeded through three stages: logarithm ofG″app(logG″app) increased with increasing cure time in the first stage, logG″appincreased with increasing logarithm of cure time in the second, and the change ofG″appcannot be expressed simply in the final. Curing behavior can be estimated from changes of rheological parameters during the curing. The fluidity of reaction mixture can be also predicted from the peak ti

ISSN:0021-8995    

DOI:10.1002/app.1988.070350114

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

年代:1988

数据来源: WILEY

摘要:

AbstractLiterature data for the dynamic viscoelastic properties of binary blends of nearly monodisperse polybutadienes, polystyrenes, and poly(methyl methacrylate)s was analyzed usinglogarithmicplots of dynamic storage modulusG′ versus loss modulusG″, based on a recent theoretical study by Han and John.28It has been found that for binary blends of monodisperse polymers with molecular weightsMmuch greater than the entanglement molecular weightMe, the value ofG′ in logG′ − logG″ plots becomes independent of molecular weight, increases sharply as small amounts of a high‐molecular‐weight component are added to a low‐molecular‐weight component, and passes through a maximumG′maxat a critical blend composition (ϕ2)max, and thatG′maxbecomes larger and (ϕ2)maxbecomes smaller as the ratio of component molecular weights increases. However, as the molecular weight distribution of the constituent components becomes broader, the effect of blend composition onG′ in logG′ − logG″ plots becomes less pronounced. This observation has enabled us to explain why logG′ − logG″ plots of binary blends of commercial polymers, namely, blends of two low‐density polyethylenes, blends of poly(ϵ‐caprolactone) and poly(styrene‐co‐acrylonitrile), and blends of poly(methyl methacrylate) and poly(vinylidene fluoride), all having broad molecular weight distributions, give rise to values ofG′ between those of the constituent components. When one of the constituent components has molecular weight smaller thanMe, while the other has molecular weight larger, and as small amounts of the high‐molecular‐weight component are added to the low‐molecular‐weight component, logG′ − logG″ plots of binary blends give rise to values ofG′ larger than those of the constituent components at low values ofG″, but approaches the value ofG′ for the low‐molecular‐weight component as the value ofG″ is increased. However as the amount of the high‐molecular‐weight component is increased above a certain critical composition, binary blends give rise to values ofG′ close to that of the high‐molecular‐weight component at all values ofG″. The experimentally observed dependence ofG′ on blend composition in logG′ − logG″ plots is favorably c

ISSN:0021-8995    

DOI:10.1002/app.1988.070350115

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

年代:1988

数据来源: WILEY

摘要:

AbstractCopolyamides of nylon 6,6 withbis(2‐carboxyethyl)methylphosphine oxide (CEMPO) were prepared by melt polycondensation of nylon 6,6 salt with CEMPO and hexamethylene diamine. The effect of CEMPO upon melting point, moisture regain, boiling water shrinkage, water wicking, tensile properties, thermal stability, static dissipation, and flammability of nylon 6,6 fibers and fabrics was determined. The fiber properties were greatly affected by the high water absorption and solubility characteristics of the phosphine oxide linkage. However, crystallinity and orientation were not greatly disturbed by up to 30–40M% CEMPO substitution in nylon 6,6. The copolyamides were of improved flame resistance compared to nylon 6,6 and were also found to give improved flame resistance in blends of the copolymer with various commercial plastics. In addition, CEMPO and the corresponding diamine,bis(3‐aminopropyl)methylphosphine oxide were used to prepare a series of cycloaliphatic and aromatic ring‐containing polyamides, but problems were encountered with moisture sensitivity and low melting points with some of these p

ISSN:0021-8995    

DOI:10.1002/app.1988.070350116

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

年代:1988

数据来源: WILEY

摘要:

AbstractThermal analyses, including differential scanning calorimetry (DSC), thermogravimetry (TG), and differential thermogravimetry (DTG), were performed on a series of derivatives of cyclic ureas under nitrogen. Such compounds are used extensively for durable press finishing of cotton textiles. Three common features were discovered in 15 compounds analyzed. Two features related to the presence of an oxygen‐containing substituent on the ring carbons or the ring nitrogens. The former substitution was expressed as an exothermic response between 200 and 300°C and the latter as an endotherm between 300 and 400°C. Specific substituent modifications that changed these responses are described. A final feature was identified. The presence ofN‐methylol groups was recognized. This represented the first evidence that compounds capable of releasing formaldehyde have a thermoanalytical marker. The amount of residue produced in TG analyses was related to structure and indicated that thermally induced polycondensations were occu

ISSN:0021-8995    

DOI:10.1002/app.1988.070350117

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

年代:1988

数据来源: WILEY

摘要:

AbstractAn investigation was conducted to establish the viability of blending Kraft lignin (L), a naturally occuring, readily available polymer resource, with polyurethane‐(PU) based sealants. The sealants were tested in a detailed program where lignin‐sealant blends, having blend ratios varying between 0 and 20 pbw L, were prepared on substrates of aluminum, mortar, and wood, and subjected to laboratory control (C), artificial weathering (AW), and natural weathering (NW) conditions. Results of tension testing showed that generally, lignin acts as a reinforcing agent which adds rigidity to the polymeric matrix, as indicated by the increase in toughness and modulus of blended sealants with the addition of lignin. In addition, the curing mode of PU, as determined by sequence hardness testing, was modified with the addition of lig

ISSN:0021-8995    

DOI:10.1002/app.1988.070350118

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

年代:1988

数据来源: WILEY

摘要:

AbstractMixtures of methyl glycol chitosan and glycol chitosan were reacted with poly(vinyl sulfate) to form many different water‐insoluble polyelectrolyte complexes (PEC) in aqueous solution at various hydrogen ion concentrations. It was revealed from elemental analyses, infrared (IR) spectroscopy, and solubilities of PEC that molecular structures of each PEC are dependent on [H+]. PEC membranes were made from casting solutions of all kinds of PEC, and transport phenomena through the membrane of PEC prepared in a pH 13.0 solution were investigated under various conditions. The transport ratio of Na+and the electric potential difference between the left‐ and right‐hand sides of the membrane were measured, and it is suggested that the driving force for active transport depends on the membrane potential, Donnan potential and diffusion potential. Moreover, permeability of K+was higher than that of Na+in selective tran

ISSN:0021-8995    

DOI:10.1002/app.1988.070350119

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

年代:1988

数据来源: WILEY

ISSN:0021-8995    

DOI:10.1002/app.1988.070350120

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

年代:1988

数据来源: WILEY