摘要:

The technique described here combines elastomeric materials and thermosetting resins, specifically natural rubber and cardanol-formaldehyde (CF) resins, to improve mechanical properties (such as toughness) and thermal properties (such as high-temperature resistance). The natural product cashew nut shell liquid was used to obtain the cardanol required, which was then used to prepare cardanol-formaldehyde resole and novolak resins. This was done using a condensation polymerization with formaldehyde in the presence of base and acid catalysts. The resins were found to be compatible with natural rubber in various formulations. The cure behavior of natural rubber blended with either the CF resole or novolak was investigated. The blended materials showed improved mechanical properties and good thermal stability, with an increase in the resin-hardener ratio leading to increases in tensile strength and thermal stability. Aging studies showed that these modified elastomers also had improved oxidative stability.

ISSN:0360-2559    

DOI:10.1080/03602559909351571

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The antioxidants, 3, 5-di-tertiary-butyl-4-hydroxy toluene (BHT) and α-tocopherol were incorporated into multilayer coextrusions consisting of a heat-seal layer, a core layer of high-density polyethylene (HDPE) impregnated with antioxidant (either BHT or α-tocopherol), and an outer HDPE layer. The rates of loss of the antioxidants from the respective films were determined as a function of time and temperature, using ultraviolet spectrophotometric and high-pressure liquid chromatographic procedures.

ISSN:0360-2559    

DOI:10.1080/03602559909351572

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A spectroscopic system based on vapor-phase absorption of infrared radiation produced by a diode laser is shown to be useful for measuring water vapor diffusion rates through materials in sheet form. Measurements of water vapor diffusion through four polymer membranes and membrane laminates show an excellent correlation with an existing water vapor transport apparatus that uses hygroscopic polymer-film capacitance sensors. The diode laser spectroscope eliminates sorption hysteresis artifacts present in the capacitance sensors.

ISSN:0360-2559    

DOI:10.1080/03602559909351573

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The multicomponent injection-molding process is a sequential molding process in which one plastic material (overmold) is molded onto a previously filled and solidified plastic part (substrate). This innovative manufacturing process is gaining popularity among plastic manufacturers because of its flexibility and potential to produce multifunctional plastic parts. In contrast with increasing popularity, an integrated computer simulation software for this process is currently unavailable, partially because of the difficulty in mapping the boundary between the substrate and the overmold. As a matter of fact, multicomponent molders are still using the trial-and-error approach while the computer-aided engineering prevails in the conventional injection-molding practice. When the flow pattern of the overmold is of interest, it may be justifiable to use the conventional mold-filling simulation to predict the pattern. It is postulated that the influence of the interface boundary on the flow pattern of the overmold is insignificant due to the high filling rates normally encountered in the multicomponent injection-molding process. In this article, the flow patterns of the overmold of the handle of Gillette's shaving razor for ladies are predicted based on an approach where an integrated filling-packing-cooling simulation is first run for the substrate; upon completion of the substrate cooling, the substrate surface temperature is used as the initial boundary condition for the overmold in the second-stage analysis. Boundary interface techniques are applied to map the boundary condition from the substrate to the over-mold. The predicted flow pattern is found to be in reasonably good agreement with that obtained using the conventional injection-molding simulation as well as with the experimental results.

ISSN:0360-2559    

DOI:10.1080/03602559909351574

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The article presents some Theological results obtained on a large domain of shear rates for semidilute solutions of ultrahigh-molecular-weight poly(methyl methacrylate) at different concentrations. The observed unusual behavior was explained as being due to the flow instabilities of long-chain polymers in an entangled state.

ISSN:0360-2559    

DOI:10.1080/03602559909351575

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effect of coagulants on the preparation of dipped film with good physical properties was studied. In order to optimize various parameters like coagulant concentration, latex concentration, and former dipping time in latex and coagulant, the effect of coagulant on the physical properties of radiation vulcanized natural rubber latex film was evaluated. Calcium nitrate, calcium chloride, and ammonium nitrate were used as the coagulant by dissolving either in water or ethanol. Calcium nitrate solution was found to be the best one among the coagulants used.

ISSN:0360-2559    

DOI:10.1080/03602559909351576

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Vinyltoluene and divinylbenzene were copolymerized in suspension to obtain copolymers with different cross-linking degrees. The copolymer beads were characterized by specific density measurements and their equilibrium swelling in various solvents was investigated. The average molecular weights between cross-links were calculated based on swelling and glass transition temperature data.

ISSN:0360-2559    

DOI:10.1080/03602559909351577

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this article, we develop a predictive controller for ram velocity of an injection-molding machine. First, we select a state model with process disturbances to design the predictive controller. Second, by making use of a steady-state Kalman filter suggested by Kwon et al., an observer is presented to predict the process states. Next, we discuss the closed-loop characteristics of the proposed controller. Finally, simulations results reveal that the proposed control has a good setpoint tracking performance and disturbance rejection.

ISSN:0360-2559    

DOI:10.1080/03602559909351578

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Butyl rubber (BR) is blended with polypropylene (PP) in ratios of 92: 8, 84: 16, 68: 32, 50: 50, 32: 68, 16: 84, and 8 : 92 (w/w) for the study of dynamic vulcanization. It is observed that the cure torque increases with the decrease in BR content up to the ratio of 50: 50. No cure torque is observed in the ratios of 16: 84 and 8: 92 of BR: PP blends as the PP content becomes very high. On comparison of cure rate of the blends, the BR (100%) shows the highest cure rate because of the fast saturation of double bonds present in BR, whereas maximum cure torque, work energy, and totalized torque are observed in the 32: 68 BR: PP blend. It is the result of the formation of an interpenetrating network.

ISSN:0360-2559    

DOI:10.1080/03602559909351579

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Six different ratios of blends from nylon-12 and acrylonitrile-butadi-ene-styrene (ABS) were prepared by the melt mixing technique. Thermal analysis of these blends were carried out by differential scanning calorimetry and thermogravimetric analysis. It has been observed that the blend ratios such as 70/30 and 60/40 of nylon-12/ABS were more compatible in comparison with other blend ratios. It is evident from the values of glass transition temperature and activation energy. Thermogravimetric analysis shows a decreasing trend of pyrolysis temperature of these blends with the increase in ABS concentration. The melt-flow index and density data are found to indicate better physical and flow characteristics in the blend compared to pure nylon-12.

ISSN:0360-2559    

DOI:10.1080/03602559909351580

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor