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Weld Line (weld + line)

Distribution by Scientific Domains
Polymers and Materials Science66%

Selected Abstracts

Influence of processing conditions on the weld line in doubly injection-molded glassy polycarbonate and polystyrene: Microindentation hardness study

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2005
M. Boyanova
Abstract The microhardness (H) technique has been used to characterize the quality of the weld line in injection-molded tensile bars from a two-component machine in which both melt streams from the same material can be independently controlled. More specific, the influence of melt temperature and indentation location (closer or further from the sample edge parallel to the injection direction and across the weld line) has been followed on polycarbonate (PC) and polystyrene (PS) glassy samples. For both polymers at lower melt temperatures, a strong H decrease (between 15 and 50%) followed by a sharp increase in a narrow distance (around 0.10 mm), is observed. When the melt temperature increases up to 300°C (for PC) and 270°C (for PS), a much smaller H decrease is observed in the central part of the samples. However, closer to the tensile bar edges (2 mm) the weld line remains undetectable by microhardness measurements. The present results reveal that the processing temperature affects the broadening of the weld line through the conditions for effective mutual interdiffusion of chains from the two fronts coming from opposite sides. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24:14,20, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20028 [source]

Weld line characteristics of PC/ABS blend.

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008

Abstract The effects of reactive compatibilizer and processing temperature on the morphology and the mechanical properties at the weld line of 60/40 (wt/wt) poly- carbonate (PC) and acrylonitrile-butadiene-styrene (ABS) copolymer blends were investigated. Amine functionalized styrene/n -phenyl maleimide/maleic anhydride terpolymer (amine-SPMIMA) was used as the in-situ reactive compatibilizer for PC/ABS blend. Weld tensile strength increased as the content of amine-SPMIMA was increased. Weld impact strength showed maximum value for the blend containing about 3% amine-SPMIMA. The variation in the mechanical property at the weld line was correlated with the change in the morphology of the blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Impact properties and microhardness of double-gated glass-reinforced polypropylene injection moldings

POLYMER ENGINEERING & SCIENCE, Issue 9 2009
Matias Martinez Gamba
Injection moldings with weld lines were produced in glass reinforced polypropylene grades differing in filler content using a two-gated hot runner injection mold. The skin-core microstructure developed during injection molding was qualitatively analyzed by means of optical and scanning electronic microscopy techniques. The load bearing capacity of the moldings was assessed by uniaxial tensile-impact and biaxial instrumented falling dart impact tests. Microhardness was also used to ascertain the possibility of using it as a simple nondestructive technique for characterizing glass fiber-reinforced injection moldings. The properties were monitored at various points to evaluate their variation at the bulk and the knit region. The biaxial impact test highlights the 10-fold reduction of the impact strength caused by the weld line. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

Rotational molding cycle time reduction through surface enhanced molds: Part A,Theoretical study

POLYMER ENGINEERING & SCIENCE, Issue 9 2007
M.Z. Abdullah
Rotational molding has been regarded as a plastic molding method with great potential. The process offers virtually stress-free products having no weld lines or material wastage, and utilizes relatively inexpensive molds. Yet its widespread growth is hindered due to long production cycle times, which are limited by the time required to heat up and cool down the mold and the product. To address this issue, efforts have been made to enhance heat transfer to and from molds, ultimately reducing cycle times. The application of extended and rough surfaces to molds is investigated here. The aim of this study is to predict reductions in cycle time due to the enhancement of mold surfaces (i.e. roughness-enhanced and pin-enhanced molds). By utilizing a combination of heat transfer correlations, numerical analysis, and an existing rotational molding process simulation, cycle time predictions were made. The average predicted cycle time reductions were ,21 and 32% for the roughness-enhanced and pin-enhanced molds considered, under a variety of conditions. POLYM. ENG. SCI., 47:1406,1419, 2007. © 2007 Society of Plastics Engineers [source]