摘要:

Polymers of urethane diacrylate containing an aliphatic or aromatic backbone chain were prepared in the presence of a number of monofunctional and polyfunctional monomers under UV curing. These monomers have different glass transition temperatures ranging from — 110° to 250°C. Film hardness, gel content, tensile properties, and shape recovery characters of these polymers were determined. A correlation between the glass transition temperatures and these properties was established. The monomerN-vinyl pyrrolidone demonstrated the best performance in the preparation of polymers. Some of these polymer films have achieved a unique character of shape recovery phenomenon.

ISSN:0360-2559    

DOI:10.1080/03602559508012202

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Thiocarbamyl sulfenamide in combination with 2-mercaptoben-zothiazyl disulfide (MBTS) is known to produce useful vulcan-izates. A safe amine-based thiocarbamyl sulfenamide, namely,N-methyl piperazinothiocarbamyl-N'-methyl piperazinosulfena-mide (MPTS), when used in combination with MBTS in the vulcanization of natural rubber (NR) imparts a notable cure syner-gism in the vulcanization process. The performance of the MPTS-MBTS system has been compared directly with that of the conventionalN-oxydiethylene thiocarbamyl-N'-oxydiethyl-ene sulfenamide (OTOS)-MBTS system. Like the OTOS-MBTS system, the MPTS-MBTS system also exhibits maximum torque (Rα), modulus, and tensile value at the molar accelerator ratios of 6:3 and 4.5:4.5. Although the vulcanizates of OTOS-MBTS-accelerated stock exhibit higher torque values than those obtained from the vulcanizates of the MPTS-MBTS system, the modulus and tensile values are higher in the latter system. It is revealed from the study that the systems containing MBTS + thiacarbamyl sulfenamide have good thermal and age resistance properties. The knowledge gathered in the gum vulcanization has been utilized in preparing the filled vulcanizates which demonstrate that a mixture of MBTS and MPTS in suitable proportions can be an effective substitute for the conventional OTOS-MBTS combination.

ISSN:0360-2559    

DOI:10.1080/03602559508012203

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Studies have been carried out on the compatibilization of polypropylene and nylon using maleic anhydride grafted polypropylene (Polybond™ 3002). Solution and FTIR studies on the resin indicated that the compatibilizer reacted with nylon. The usefulness of the compatibilizer has been demonstrated for the recycling of shredded industrial carpet waste containing polypropylene and nylon. The mechanical properties and morphology of the extruded resin from carpet are reported.

ISSN:0360-2559    

DOI:10.1080/03602559508012204

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Tensile impact strength of blends of high-density polyethylene (HDPE) and acrylonitrile-butadiene-rubber (NBR) has been studied with special reference to the effect of blend ratio and com-patibilizer concentration. Even though the tensile impact strength of the blend is inferior to that of virgin plastic, a substantial improvement was observed in the tensile impact strength values of the compatibilized systems. The compatibilizers, phenolic modified polyethylene (PhPE) and maleic anhydride modified polyethylene (MAPE), act by locating at the interface due to their propensity to phase separation. By the addition of compatibilizers the interfacial tension is reduced and better mixing between components becomes possible, which results in finer and uniform morphology. The compatibilizers also improve the interfacial adhesion. The improvement in tensile impact strength has been explained on the basis of the blend morphology, that is, size, shape, and distribution of the rubber phase in the plastic matrix; tensile properties; and interfacial adhesion between the phases.

ISSN:0360-2559    

DOI:10.1080/03602559508012205

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ethylene propylene diene rubber (EPDM) was brominated. The curing behavior and tensile properties of the brominated EPDM (BEPDM) were investigated using a typical sulfur curing formulation. The brominated EPDM was observed to cure with a shorter cure induction time than the unbrominated one. The activation energies (Ea) of curing for EPDM and brominated EPDM were found to be approximately 145 kJ/mol and 58 kJ/mol, respectively. Analysis of curing behavior with individual curatives and stress-strain measurements indicates that these significant improvements could be attributed to the role of bromine as a more efficient crosslinking site, forming C—O—C crosslinks. In addition, the bromine also seems to increase the solubility of sulfur in the rubber, promoting sulfur crosslinks which are apparently not observed with the unbrominated EPDM. Consequently, the BEPDM displayed significantly higher tensile strength than the unbrominated one.

ISSN:0360-2559    

DOI:10.1080/03602559508012206

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Although the area of composites has advanced significantly over the past three decades, there is still a lack of understanding as to the coupling between materials and processing variables, especially as related to the use of resin systems in emerging processes such as resin transfer molding (RTM). As materials are tailored through the use of additives to resin systems, intricate fiber architectures, and the use of specific processing parameters, the need for a thorough understanding of the effect of minor variations in the materials system and the ultimate need for process control techniques increases. The current investigation is aimed at developing an understanding of variation in performance in three similar vinyl ester resin based composite systems as a function of mold release agent concentration, presence of a wetting/dispersion agent, and preform tool temperature. It is seen that the concentration of mold release agent has a significant influence on performance, which can be correlated with results of dynamic mechanical analysis tests. The importance of using statistically based studies to determine optimum settings and overall variation in performance is emphasized. This approach is favored over the use of ann[sgrave]approach, which gives the user a means of controlling quality based on postproduction control rather than through the selection of settings that are insensitive to variation in the quality of incoming material process changes. The achievement of quality through control of material and process variables is important not only for the cost-efficient production of composite parts but also for the fabrication of large parts such as would be needed for civil infrastructure applications (bridge decks, piers, etc.), where postproduction rejection would result in significant losses.

ISSN:0360-2559    

DOI:10.1080/03602559508012207

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effects of vibromilling on particle size, crystalline structure, optical density, and the plasticizer absorption of poly(vinyl chloride) (PVC) were studied through Fourier-transform infrared spectroscopy, scanning electron microscopy and physical property tests. The experimental results show that the intensity of the FTIR absorption band at 635 cm−1of PVC becomes weaker and tends to disappear during vibromilling. The particle size of PVC is decreased, and the surface area and the amount of plasticizer absorption increase with increased vibromilling time. The low molecular weight PVC so prepared has lower crystallinity and glass transition temperature, and higher plasticizer absorption capacity; it should have good processability.

ISSN:0360-2559    

DOI:10.1080/03602559508012208

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Thermoplastic elastomers from blends of natural rubber (NR) and polystyrene (PS) have been prepared by the solution-casting technique. The blend of NR and PS is an incompatible one and can be made compatible by the addition of NR-g-PS. The compatibilizing action of NR-g-PS in NR/PS blends has been studied with special reference to the effect of the nature of the casting solvents and compatibilizer loading. Chloroform and carbon tetrachloride were selected as the casting solvents. The nature of the casting solvent has a profound influence on the compatibilizing action of the graft copolymer. This has been explained based on the preferential interaction of the solvent with one of the components in the mixture. The domain size of the dispersed polystyrene phase was decreased by the addition of a few percent of the compatibilizer, followed by a leveling off at higher concentrations. The leveling off is an indication of interfacial saturation. The mechanical properties of the blends were improved by the addition of the compatibilizer.

ISSN:0360-2559    

DOI:10.1080/03602559508012209

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Abstract

ISSN:0360-2559    

DOI:10.1080/03602559508012210

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor