ISSN:0730-6679    

DOI:10.1002/adv.1993.060120101

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe use of neural networks in the modeling of the inflation stage of the blow molding process is discussed. The simulation is enacted in the reverse process direction, predicting initial membrane dimension requirements from final part thickness distributions. This situation has practical implications because tooling costs and machine down times can be minimized with the information obtained. The optimal network topology entails simultaneous pre‐ and postprocessing of the data. An adaptive window is employed for modeling of the effects of adjacent segments. The optimal window length is 16 for both the input and output layers in the network topology. Simulations are run for bottles blown using various constant and pulsed die gaps. © 1993 John Wiley&Sons, I

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120102

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

年代:1993

数据来源: WILEY

摘要:

AbstractDue to the ever growing and more complex demands on the properties of polymer materials, raw material producers and plastic processing industries are more and more interested in the continuous synthesis and modification of polymers. In this article the production of polystyrene and styrene–isoprene copolymers by anionic s‐butylithium initiated bulk polymerization in a co‐rotating close intermeshing twin screw extruder is described. In spite of high reaction temperatures of above 200°C the polystyrene stays “living,” which makes it possible to modify it in the melt by adding more monomers. The following processing methods were developed and analyzed: (1) homopolymerization of styrene; (2) copolymerization of styrene–isoprene monomer mixtures; (3) sequential polymerization of styrene and isoprene. The polymerized material resulting from the above‐mentioned processes differed considerably in structural features and final properties depending on the process parameters. As for homopolymerization of styrene, the influence of the process parameters screw rotation speed and screw geometry on the range of molecular weight distribution was investigated. Products made according to the two copolymerization methods were analyzed with regard to their structure and mechanical properties. The tests revealed that for sequential copolymerization the temperature in the polymerization zone has a decisive influence on the product quality. The influence of the screw rotation speed is less important. © 1993 John

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120103

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

年代:1993

数据来源: WILEY

摘要:

AbstractTo establish the parameters for converting sheet molding compounds (SMCs) to useful products, various technical approaches, viz., solvent extraction, hydrolysis, and pyrolysis, have been explored. Thermogravimetric analysis of an SMC sample indicated that it contains about 25% by weight organics and 75% inorganics, mainly glass fibers and CaCO3as filler. Solvent extraction of ground SMC with acetone, methylene chloride, chloroform, or chloroform : benzene (1 : 1 vol) yielded low quantities of a gummy, viscous extract. Hydrolysis of the extracted SMC sample under strong alkaline conditions was also studied. A unit structure was postulated for the hydrolysate based upon elemental and molecular weight analysis. Pyrolysis of both extracted and unextracted SMCs in nitrogen at 500°C and in air at 400°C yielded organic oils. These oils were characterized for their calorific values. The products of pyrolysis consisted of mainly aromatics along with some oligomers. The extract and the oil from pyrolysis appear to be compatible with epoxy systems. Their use as an extender for epoxy systems, while that of the inorganic residue (glass fibers and CaCO3) as a filler for epoxy system, have been explored. © 1993 John Wiley&Sons, I

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120104

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe aim of this work is to study the influence of different types of compatibilizing agents, different processing conditions, and the molecular weight of the two components on the properties of immiscible blends of polypropylene and nylon 6. Increasing the content of the functional group of the modified polypropylene and the content of nylon in the blend, the effectiveness of the compatibilization improves. The same effect is observed by decreasing the molecular weight of the two components, in particular, that of the polyamide. The influence of the processing conditions is slight provided no degradation takes place during processing. © 1993 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120105

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn this article, a new encapsulation injection molding method for electronic devices such as integrated circuits (ICs) is described as a superior technology to the conventional transfer molding process widely used in the electronics industries. The quantitative analysis has been carried out utilizing a computer simulation program covering cavity‐filling behavior to analyze the relationship between the deformation of gold wires that are bonded with mounted IC chips and mold geometries, operational conditions, and physical properties of a thermoplastic encapsulant, i.e., polyphenylene sulfide. As a result, a new technology to encapsulate ICs has been established, preventing no practical gold wire deformation or break‐up damage. © 1993 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120106

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

年代:1993

数据来源: WILEY

摘要:

AbstractCrystallization of polymers plays an important role in polymer processing because the structure developed during crystallization influences the mechanical and physical properties of the polymer product. The crystallization of polymers takes place under nonisothermal crystallization is essential for optimizing the processing conditions to obtain a product with desired properties. A simple approach based upon analysis of the nonisothermal crystallization behavior of a polymer to characterize the inherent crystallizability of the polymer and its sensitivity to processing conditions is reported. The polymers used in the present investigation include various grades of polyethylenes and polypropylenes. It is shown that a simple graphical analysis of the nonisothermal crystallization parameters can be used to quantify the inherent crystallizability of polymers and sensitivity of its structure development to changes in the cooling rates. © 1993 John Wiley&Sons, Inc

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120107

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

年代:1993

数据来源: WILEY

摘要:

AbstractAn investigation was undertaken on the application of the three‐dimensional solubility parameter method to predict miscibility of polyblends. The three‐dimensional method attempts to account for the combined effects of dispersion, polar, and hydrogen bonding interactions between molecules. This study focused mainly on the miscibility of blends of poly(vinyl chloride) (PVC) with homopolymers as well as with copolymers. The three components of solubility parameters were calculated from the group contributions of the structural units of the polymers. By comparing the parameters of different PVC blends in two categories, PVC/homopolymer and PVC/copolymer blends, the miscibility trend of PVC blends was revealed. The three‐dimensional solubility parameter approach successfully predicted the miscibility of several homopolymers. For copolymers, the chance of miscibility was increased because of the ability to adjust the solubility parameter through composition. This was reflected in a smaller distance between the solubility parameter of copolymer and that of PVC. Experimental results reported in the literature confirmed this conclusion. © 1993 John Wiley&Son

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120108

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

年代:1993

数据来源: WILEY

摘要:

AbstractSome new aspects of mechanochemical treatment are reported. The method is developed to bond such specific materials as polytetrafluoroethylene, polyethylene, polypropylene, and others that are known as hard‐to‐bond materials. The new method possesses such advantages as low cost, simplicity, high strength of adhesive joints and stability of properties. © 1993 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120109

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

年代:1993

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1993.060120110

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

年代:1993

数据来源: WILEY