摘要:

AbstractCornstarch, a canary dextrin, and a maltodextrin were compared in films blown from carbohydrates compounded with poly(ethylene‐co‐acrylic acid) (EAA), low‐density polyethylene (LDPE), and aqueous ammonium hydroxide plasticizer. Dextrins or maltodextrins having dextrose equivalent values of one and greater caused dark‐colored films with caramel odors, probably due to Maillard reactions. Blown films with hydrophobic skins and water sensitive cores were produced with the dextrinized carbohydrates, but not from natural cornstarch. Water sensitivity of films containing the dextrinized carbohydrate was reduced by recycling the films through the blown film die. A mechanism for development of the skins is proposed, as is a method for preparing thin semipermeable membranes. © 1993 John Wiley&Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of

ISSN:0021-8995    

DOI:10.1002/app.1993.070491001

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe copolymerization of ethylene with highly active TiCl4/MgCl2‐supported catalysts in solution reactors at 185°C and 400 Psig pressure is presented. The performance of these supported catalysts at these conditions is characterized by a high initial rate that decays rapidly within the 10 min polymerization period. In the presence of hydrogen and a comonomer, catalyst yields up to about 300 kg/g (Ti) are achieved. The kinetic data indicate rate enhancement when hydrogen is added in moderate concentrations. However, a high concentration of hydrogen results in a decreasing rate of ethylene consumption. Increasing the H2/C2molar ratio in the range 0–10.66 ċ 10−3leads to a reduction in theMnvalues from 31,600 to 17,400. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070491002

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe copolymerization of ethylene with highly active TiCl4/MgCl2‐supported catalysts in solution reactors at 185°C and 400 Psig pressure is presented. The performance of these highly active supported catalysts at high reaction temperature is characterized by a high initial rate that decays rapidly within the 10 min polymerization time period. In the presence of hydrogen and a comonomer, catalyst yields up to about 300 kg/g (Ti) are achieved. Kinetic data obtained on the influence of a comonomer, e.g., 1‐octene or 1‐hexene, indicate rate enhancement when used in moderate concentrations. Higher concentrations of comonomer result in a decreasing rate of ethylene consumption. Comonomer/ethylene molar ratios in the range 0–0.827 resulted in comonomer incorporation up to about 2.6 mol % and a small reduction in the polymer molecular weight. © 1993 John Wiley&

ISSN:0021-8995    

DOI:10.1002/app.1993.070491003

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

年代:1993

数据来源: WILEY

摘要:

AbstractA sample of poly(vinyl chloride) (PVC) and a polar plasticizer consisting of dioctyl phthalate (DOP) and dibutyl phthalate (DBP) was prepared and found to possess inconvenient electrical properties (permittivity, dielectric loss, and conductivity). Different samples of PVC compositions were formulated from the PVC–DOP–DBP system and also variable proportions of a copolymer of 1‐octadecene‐maleic anhydride or its hexadecylester. Lead stearate as a heat stabilizer and kaolin as a filler were added. The effect of copolymer structure on the electrical properties of the PVC–DOP–DBP system was studied to obtain a plasticized PVC of good electrical insulation character. © 1993 John Wil

ISSN:0021-8995    

DOI:10.1002/app.1993.070491004

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of pH, temperature, dye concentration, and additives on the adsorption of the dyes FD&C (Food, Drugs&Cosmetics) Blue 1 and Blue 2 upon the polyamides nylon 4–7,9, and 10–12 was studied and a correlation between these parameters and the dye uptake was found. The adsorption kinetics of the dyes on the polyamides were studied and a mechanism based on the interaction of the acid groups of the dyes and the positively charged groups of the polyamides was suggested. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070491005

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe curing behavior of epoxy resins prepared by reacting epichlorohydrin with 4,4′‐diaminodiphenyl methane (DADPM)/4,4′‐diaminodiphenyl ether (DADPE) or 4,4′‐diaminodiphenyl sulfone (DDS) was investigated using DDS andtris‐(m‐aminophenyl)phosphine oxide (TAP) as curing agents. A broad exothermic transition with two maxima were observed in the temperature range of 100–315°C when TAP was used as the curing agent. The effect of varying DDS concentration on curing behavior of epoxy resin was also investigated. Peak exotherm temperature (Texo) decreased with increasing concentration of DDS, whereas heat of curing (ΔH) increased with an increase in amine concentration up to an optimum value and then decreased. Thermal stability of the resins, cured isothermally at 200°C for 3 h, was investigated using thermogravimetric analysis in a nitrogen atmosphere. Glass fiber‐reinforced multifunctional epoxy resin laminates were fabricated and the mechanical properties were evaluated. © 19

ISSN:0021-8995    

DOI:10.1002/app.1993.070491006

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis article deals with numerical simulations of draw resonance of polymer fluids by employing direct difference methods to solving the governing equations in melt spinning. The stability of each difference method was studied by a comparison of the results obtained from simulations with the theoretical solutions or values. The numerical simulation confirms that the critical draw ratio of draw resonance in an isothermal and uniform tension spinning of a Newtonian fluid is between 20 and 21. The cross‐sectional area of a spinline in draw resonance was found to decrease monotonically from a spinneret toward a take‐up bobbin, although the taken‐up filament shows periodical variation. This study has also illustrated the mechanism of draw resonance previously proposed by the author. © 1993 John Wiley&Son

ISSN:0021-8995    

DOI:10.1002/app.1993.070491007

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

年代:1993

数据来源: WILEY

摘要:

AbstractEffects of copolymer composition on morphology and electrooptical properties of polymer/liquid crystal (LC) (40/60 w/w) composite films were studied with styrene‐co‐acrylonitrile (SAN) of varying acrylonitrile (AN) content (6.3–35 wt %) and a cyanobiphenyl‐type liquid crystal (E8). The dimension of the LC domain in the composite film decreased with increase of AN content of SAN up to 30 and increased at 35 wt %. The contact angle of the film with an LC drop showed a similar trend; however, its minimum was obtained at 24% AN. Threshold voltage (Vth) and rise time (τR) increased, and decay time (τD) decreased with AN content up to 30%, and the tendency is reversed at 35%. The results were interpreted in terms of, possibly, a solubility parameter matching between SAN and LC. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070491008

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe properties of carbon black‐filled thermoplastic elastomers were studied. We compared the extrudate swell behavior and the rheological properties of carbon black‐filled polymers with those of raw polymers. The shear viscosity increases with increasing amount of carbon black. The extrudate swell becomes smaller with increasing carbon black amount, indicated by the decreased elasticity of the material when adding carbon black. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070491009

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

年代:1993

数据来源: WILEY

摘要:

AbstractTo investigate the correlation of viscosity–morphology–compatibility of polymer blends, polystyrene, polybutadiene, and styrene/butadiene triblock copolymer were selected as our materials. A capillary rheometer was used to measure the viscosity. All samples were blended by a two‐roll mill, a Brabender, or by the solution casting method. The morphologies of extruded samples from the capillary were observed by SEM. The relation between the viscosity and the composition of the blend changes with shear rate. It was found that the better the compatability between the two phases of the blend the smaller is the disperse phase domain. The viscosity of polyblends is related to the compatability and composition of the two phase in this blend. In the present study, the rheological behavior of polyblends is explained from the viewpoints of morphology and compatability. © 1993 John Wiley&Son

ISSN:0021-8995    

DOI:10.1002/app.1993.070491010

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

年代:1993

数据来源: WILEY