摘要:

Wood-plastic composites (WPC) were prepared with two monomers, methylmethacrylate (MMA) and butylmethacrylate (BMA), using ionizing radiation and two low-grade woods (simul and mango). Moisture adsorption characteristics of both wood and WPC were investigated. The equilibrium moisture contents of WPC were lower than the untreated wood in the entire water activity range. The experimental sorption data were fitted to the Henderson, Chung-Pfost, Smith, and Oswin models. Henderson's model gave the best prediction of the adsorption of wood and WPC.

ISSN:0360-2559    

DOI:10.1080/03602559108019211

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A comparison has been made between the pressure drops arising during injection molding as predicted by a simulation software package named SIMPOL® and as measured during molding trials conducted to study the effects of molding variables. The theory used to design the software has been reviewed and the operation described. The comparison was made using amorphous thermoplastic polyesters, PET and PCTG. The molding conditions used for the simulated trials were the same as those used in practical molding trials. The molding trials were conducted using a mold fitted with a cavity transducer and a machine fitted with a hydraulic pressure sensor. The simulation shows qualitative agreement to the observations made in practice. The difference in pressure drop values are attributed to the software's dependence on crystalline PET physical properties for calculations and an overestimation of the frozen layer thickness by the simulation model. Overall the simulation has been shown to be a pragmatic tool for the production engineer working in the thermoplastic injection molding industry.

ISSN:0360-2559    

DOI:10.1080/03602559108019212

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Diffusion and sorption of a variety of organic liquids into six engineering polymers have been investigated over the interval of 25°–60°C by the use of a conventional weight-gain experiment. While the method is laborious and time consuming, it yields reliable diffusion data. The transport mechanism depends, to a great extent, on the type of the solvent molecule and the barrier material. In all the polymer-solvent systems, the activated diffusion mechanism is operative and that the Arrhenius parameters of diffusion prove the conventional wisdom that smaller diffusion coefficients and higher activation energies are observed for the bigger solvent molecules. The diffusion mechanism has been classified to be anomalous. Sorption equilibrium data have been used to estimate the polymer-solvent interaction parameter in addition to molar mass between crosslinks and other thermodynamic quantities such as enthalpy and entropy of sorption. A first-order kinetic model appears to explain satisfactorily the transport of solvent molecules into polymer networks. Furthermore, attempts have been made to generalize, at least in qualitative terms, the polymer-solvent interactions.

ISSN:0360-2559    

DOI:10.1080/03602559108019213

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Current annual demand for natural rubber in the United States is around 900,000 metric tons, all of which must be imported from countries with tropical rain forest climates. Since natural rubber is a strategic material, it is vital for the US to develop both a domestic source and the technology to extract and utilize the rubber and coproducts efficiently (Bragg and Lamb, 1980).

ISSN:0360-2559    

DOI:10.1080/03602559108019214

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The year 1989 marked the 30th anniversary of the establishment of the Division of Polymers and Composite Materials within the framework of the Institute of Chemical Physics of the USSR Academy of Sciences. The conference to commemorate this event was held October 19–21, 1989. The results obtained by the division for the last 30 years were discussed. The division was created in 1959 on the initiative of Academician N. N. Semyenov, later the director of the institute. First, Prof. A. M. Markevich was appointed the head of the division. From the early 1970s to the late 1980s the division was headed by Academician N. S. Enikolopov; in 1988 Prof. A. A. Berlin was elected in charge of the division. About 700 people, including 50 doctors of sciences and 250 candidates for doctor of science degrees are engaged in the work of the division at the present time.

ISSN:0360-2559    

DOI:10.1080/03602559108019215

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The XV All-European Colloquium “Chemical Technology of Polymers” was held March 14–16, 1990, in Aachen (Germany). The colloquia are organized by the Institute of Polymer Processing (Aachen) and the German Chemical Society (Frankfurt am Main) and are sponsored by many chemical companies of the areas. Prof. W. Michaeli, director of the Institute of Polymer Processing (Aachen) is the chairman of the organizing committee.

ISSN:0360-2559    

DOI:10.1080/03602559108019216

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In Tambov from May 22 to May 24, 1990, the regular All-Union Scientific and Technical Conference on Chemical Admixtures for Polymer Materials was held. The conference was organized by the Ministry of Chemical and Petroleum Refinery Industry, the Tambov Regional Board of the All-Union D. I. Mendeleev Chemical Society, the Scientific and Research Institute of Chemicals for Polymer Materials (NIIkhimpolymer, Tambov), and the subsidiary of NIITEKhIM (Cherkassy).

ISSN:0360-2559    

DOI:10.1080/03602559108019217

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In the period from July 8 to July 13, 1990, in Montreal, the 33rd IUPAC International Symposium on Macromolecules was held. More than 2000 participants from 45 countries took part in the conference. Honorary chairman of this symposium was Professor Herman F. Mark (Brooklyn Polytechnic University, New York) and president of the Organizing Committee was Prof. Robert E. Prud'homme (Universite Laval, Quebec City, Canada). The symposium included 7 plenary lectures, 4 divisions, and an exhibition.

ISSN:0360-2559    

DOI:10.1080/03602559108019218

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Diffusion coefficients of 1,2-dichloroethane, 1,1,2-trichloroethylene, 1,1,2,2-tetrachloroethane, and carbon tetrachloride into neoprene, SBR, EPDM, NBR, and natural rubber have been obtained from sorption experiments in the temperature interval of 25° to 60°C. Diffusion was found to be dependent on the type and nature of the barrier material in addition to the diffusant size. The mechanism of diffusion appears to follow the anomalous diffusion. Activation energies for diffusion have been estimated and used in the discussion of transport data. Equilibrium sorption data were used to calculate the enthalpy and entropy of sorption for polymer-solvent pairs.

ISSN:0360-2559    

DOI:10.1080/03602559108019219

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Kinetics and rheological studies were carried out on polyurethane reactions involving a new polyol and TDL Conversion of isocyanate by uncatalyzed polymerization under isothermal conditions was monitored by IR spectrometry and titration. Viscosity changes of the reaction mixture were followed by a digital cone-and-plate viscometer under identical conditions. Conversion and viscosity were found to follow a power relationship. A relationship involving the order of the reactionnthat connects the viscosity with time was derived. This provides a new viscometric method to find the order of the reaction. The order of the reaction determined by this method was very close to the values obtained by a fractional-life method already reported.

ISSN:0360-2559    

DOI:10.1080/03602559108019220

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor