ISSN:0730-6679    

DOI:10.1002/adv.1995.060140301

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

年代:1995

数据来源: WILEY

摘要:

AbstractIt is a well‐known fact that weldlines are unavoidable in most injection‐molded products of even moderate complexity. While there are many situations where they are barely perceptible, weldlines represent a potential source of weakness in molded parts. In injection molding weldlines are generated when two separate melt streams join either in multigated molds or as a consequence of flow around obstacles. The development of many interesting materials has been hampered by poor weldline strength. Among such materials are plastics reinforced with fibers or platelets, liquid crystal polymers, and a number of multiphase polymer blends. Weldlines have ever been called the “Achilles' heel” of these multiphase materials. This article is a review of the literature published on weldlines in injected parts. It deals primarily with the aspects related to the mechanical behavior of weldline‐containing parts. It begins with a brief description of the phenomena important for the part formation in the mold, including those leading to weldlines, in addition to the techniques used to characterize weldline‐containing parts. The following three sections consider the structure and properties of weldlines in neat amorphous and semicrystalline polymers, filled and reinforced plastics, and finally in polymer blends and alloys. In the last section methods developed for increasing the weldline strength are discussed. © 1994 John Wil

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140302

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

年代:1995

数据来源: WILEY

摘要:

AbstractGas‐assisted injection molding (GAIM) has proven itself to be a breakthrough in molding technology. However, the process involves additional gas‐related parameters to control the molding process. The interaction between melt and gas makes the gas‐assisted process complicated. To make satisfactory parts, the material, the mold, and process parameters determine the “moldability” of a specific system. The concept of “molding areas” on the critical plane can be extended from thermoplastic injection molding to GAIM. This research is devoted to the development of a proper moldability diagram for GAIM. The first part of this study employs gas‐related parameters to define the molding area. The second part is devoted to identifying the relative importance of process parameters. The results show that melt temperature and short shot are the two factors which most significantly affect the GAIM process. The third part of this study defines the moldability based on critical parameters. The application of the moldability concept is demonstrated in selecting the optimum rib geometry. These moldability studies are intended to give first guidelines for system optimization. © 1995 John

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140303

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

年代:1995

数据来源: WILEY

摘要:

AbstractOn‐line rheological measurements are usually employed to monitor the reactive modification of single polymers during extrusion. This article provides data on the use of an on‐line rheometer to monitor the reactive compatibilization of polyamide/polyolefin blends in a corotating twin‐screw extruder. The type of functionalized compatibilizer and the choice of compounding conditions are among the variables examined. On‐line and off‐line rheological data are correlated with the morphologies of the extrudates and the mechanical properties of injection‐molded samples in attempts to establish general relationships between on‐line rheology, microstructure, and properties of polymer blends. © 1995 John W

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140304

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

年代:1995

数据来源: WILEY

摘要:

AbstractHigh–molecular‐weight esters are frequently used to plasticize commercial polymers. Because the physical properties of the polymer matrix can be significantly modified by the type of the plasticizer that is used, these high–molecular‐weight esters have been extensively investigated during the last decade. Liquid density, for example, has been found to be a useful bulk property of these liquid plasticizers, since density helps define the internal molecular flexibility. Most of the time, however, experimental difficulties prevent the accurate determination of density. Moreover, the existing empirical models are tedious because of many ill‐defined parameters. In this study a simple artificial neural‐network–based model was utilized for the density of these esters as a function of their chemical structure and temperature. The sum of squared error for densities predicted by this proposed model was within 0.0009. In this study, the density of a series of five different esters was investigated. These were DSEs, DDEs, TGEs, TTEs, and PTEs. © 1995 John W

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140305

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

年代:1995

数据来源: WILEY

摘要:

AbstractPolymer blending of reclaimed PET with various types of polyethylene was utilized for the production of materials suitable for the manufacturing of containers using conventional extrusion blow‐molding equipment. Several marketed polymers bearing functional groups that are potentially reactive to PET end groups were used as compatibilizers. A number of blends were produced and found to possess melt properties suitable for the production of extrusion blow‐molded containers having acceptable mechanical characteristics. Containers were tested for compatibility with different chemicals and permeability of commonly used organic solvents. © 1995 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140306

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

年代:1995

数据来源: WILEY

摘要:

AbstractA model dissolution/reprecipitation process is studied for the recycling of high‐density polyethylene (HDPE). The process proposed basically comprises dissolution of the plastic in an appropriate solvent, reprecipitation by using a nonsolvent, thorough washing of the material obtained, and drying. The solvent mixtures involved are separated by distillation for further reuse. Toluene/acetone was tried as a potential solvent/nonsolvent pair and proved to be very satisfactory, similarly to the case of recycling low‐density polyethylene. Further investigation was focused on the effect of sample history through successive recycling cycles. The recycled grades were evaluated in terms of the following properties: melt flow index (MFI), molecular weight, crystallinity, mechanical performance in tensile mode, and grain size analysis. In all cases the recycled polymer exhibited excellent retention of its properties. © 1995 John Wiley&Sons,

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140307

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

年代:1995

数据来源: WILEY

摘要:

AbstractA new physical method of modification of polymers is discussed. The method is developed to improve strength and other properties of molded polymers and to shorten the post‐treatment time. © 1995 John Wiley&Sons, I

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140308

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

年代:1995

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140309

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

年代:1995

数据来源: WILEY

ISSN:0730-6679    

DOI:10.1002/adv.1995.060140310

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

年代:1995

数据来源: WILEY