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Shia-chung Chen - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the Effects of Injection Molding Processing Parameters on Conductive Polymeric Composites for Electromagnetic Interference Shielding Effectiveness
    Polymer-plastics Technology and Engineering, 2009
    Co-Authors: Wei-seng Cheng, Shia-chung Chen, Chunsheng Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) composites filled with conductive nickel-coated carbon fibers (NCFs) were injection-molded under different injection process conditions. They were then used to investigate the influence of the injection processing parameters of melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE). In order to study the effect of the molding variables using the minimum number of experiments, the Taguchi method was employed. The aim of the Taguchi method was to optimize the injection processing parameters for better EMI shielding of the conductive polycarbonate composites. It is found out that the Packing Pressure and mold temperature affect the EMI shielding efficiency most significantly.

  • optimum injection molding processing condition on emi shielding effectiveness of stainless steel fiber filled polycarbonate composite
    International Communications in Heat and Mass Transfer, 2008
    Co-Authors: Chunsheng Chen, Shia-chung Chen, Weiren Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) polymers mixed with conductive stainless steel fiber (SSF) is injection-molded under various injection process conditions. The composite formed is then tested for its capability to shield off electromagnetic field passing through. The effects of four major injection processing parameters including melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE) of PC filled with conductive SSF have been investigated. Taguchi method is adopted to obtain the optimum set of injection process parameters to acquire the maximum EMI shielding. It is observed that melt temperature and Packing Pressure significantly affect shielding effectiveness performance for injection-molded PC composites with SSF filler.

  • Investigation on the weldline strength of thin-wall injection molded ABS parts☆
    International Communications in Heat and Mass Transfer, 2007
    Co-Authors: Chunsheng Chen, Rean-der Chien, Tsyr-jang Chen, Shia-chung Chen
    Abstract:

    It is well known that the weldline reduces the mechanical performance of the conventional injection molded parts. Yet, systematic researches and reports on weldline strength of thin-wall molded parts are still insufficient. This study investigates the influence of processing conditions on the weldline strength of thin-wall Acrylonitrile Butadiene Styrene Copolymer (ABS) parts. The relevant parameters include melt temperature, mold temperature, injection speed and Packing Pressure. Tensile tests on specimens of different thickness (1.0, 1.2 and 2.5 mm) are conducted. Comparisons on tensile strength for single-gate molded specimens (without weldline) with those of double-gate molded specimens (with weldline) are presented. From the experimental results, it was found that weldline specimens molded at higher melt temperature, higher mold temperature, faster injection speed and lower Packing Pressure would result in better mechanical strengths. Higher melt and mold temperatures not only lower the residual stress but also help the diffusion of molecular chains leading to a higher degree of surface bonding at the weldline interface. On the other hand, high Packing Pressure leads to higher residual stress formation and reduces the molecular bonding rate. In addition, part thickness also exhibits significant effect on weldline strength. A regression analysis combined with fitting model seems to correlate process conditions and weldline strength reduction quite well.

  • Effect of moulding conditions on the tensile strength of cyclic olefin copolymers (COC) injection moulded parts
    Plastics Rubber and Composites, 2005
    Co-Authors: R.-d. Chien, C.-s. Chen, Shia-chung Chen
    Abstract:

    AbstractThe effect of processing conditions including melt temperature, mould temperature, injection speed and Packing Pressure on the tensile strength of cyclic olefin copolymer (COC) parts has been investigated. Tensile test specimen of 2·5 mm (thick-wall) and 1 mm (thin-wall) thick were injection moulded under specified conditions. Both single gate and double gates were used to form parts with and without weldlines. Part tensile strengths were measured experimentally. The influence of part thickness on the tensile strength is also studied. Higher melt temperature and mould temperature as well as faster injection speed increased tensile strength whereas higher Packing Pressure decreased tensile strength. Melt temperature and Packing Pressure are two parameters that affect tensile strength most significantly within the current moulding window. Higher melt and mould temperatures not only lower the residual stress but also help the diffusion of molecular chains leading to a higher tensile strength. On the ...

  • Effects of processing conditions on birefringence development in injection molded parts. II. Experimental measurement
    Polymer International, 1996
    Co-Authors: Yung Cheng Chen, Chao-hsun Chen, Shia-chung Chen
    Abstract:

    The birefringence of injection molded parts was measured using a digital photoelasticity system, which combines a digital image analysis technique and the half-fringe photoelasticity (HFP) method The effects of processing conditions, including melt temperature, mold temperature, filling time and Packing Pressure, on the birefringence development in the molded parts were investigated. It was found that temperature and Pressure are the two dominant factors that determine the birefringence development in the parts during the molding process. Frozen-in birefringence of the molded parts decreases with increasing melt temperature, mold temperature and injection speed. Birefringence of the parts also increases with increased Packing Pressure, especially around the gate area. Numerical simulations using the Leonov viscoelastic fluid model predict similar dependence of birefringence of parts on processing conditions. Simulated results are also consistent with measured values.

Rean-der Chien - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the Effects of Injection Molding Processing Parameters on Conductive Polymeric Composites for Electromagnetic Interference Shielding Effectiveness
    Polymer-plastics Technology and Engineering, 2009
    Co-Authors: Wei-seng Cheng, Shia-chung Chen, Chunsheng Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) composites filled with conductive nickel-coated carbon fibers (NCFs) were injection-molded under different injection process conditions. They were then used to investigate the influence of the injection processing parameters of melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE). In order to study the effect of the molding variables using the minimum number of experiments, the Taguchi method was employed. The aim of the Taguchi method was to optimize the injection processing parameters for better EMI shielding of the conductive polycarbonate composites. It is found out that the Packing Pressure and mold temperature affect the EMI shielding efficiency most significantly.

  • optimum injection molding processing condition on emi shielding effectiveness of stainless steel fiber filled polycarbonate composite
    International Communications in Heat and Mass Transfer, 2008
    Co-Authors: Chunsheng Chen, Shia-chung Chen, Weiren Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) polymers mixed with conductive stainless steel fiber (SSF) is injection-molded under various injection process conditions. The composite formed is then tested for its capability to shield off electromagnetic field passing through. The effects of four major injection processing parameters including melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE) of PC filled with conductive SSF have been investigated. Taguchi method is adopted to obtain the optimum set of injection process parameters to acquire the maximum EMI shielding. It is observed that melt temperature and Packing Pressure significantly affect shielding effectiveness performance for injection-molded PC composites with SSF filler.

  • Investigation on the weldline strength of thin-wall injection molded ABS parts☆
    International Communications in Heat and Mass Transfer, 2007
    Co-Authors: Chunsheng Chen, Rean-der Chien, Tsyr-jang Chen, Shia-chung Chen
    Abstract:

    It is well known that the weldline reduces the mechanical performance of the conventional injection molded parts. Yet, systematic researches and reports on weldline strength of thin-wall molded parts are still insufficient. This study investigates the influence of processing conditions on the weldline strength of thin-wall Acrylonitrile Butadiene Styrene Copolymer (ABS) parts. The relevant parameters include melt temperature, mold temperature, injection speed and Packing Pressure. Tensile tests on specimens of different thickness (1.0, 1.2 and 2.5 mm) are conducted. Comparisons on tensile strength for single-gate molded specimens (without weldline) with those of double-gate molded specimens (with weldline) are presented. From the experimental results, it was found that weldline specimens molded at higher melt temperature, higher mold temperature, faster injection speed and lower Packing Pressure would result in better mechanical strengths. Higher melt and mold temperatures not only lower the residual stress but also help the diffusion of molecular chains leading to a higher degree of surface bonding at the weldline interface. On the other hand, high Packing Pressure leads to higher residual stress formation and reduces the molecular bonding rate. In addition, part thickness also exhibits significant effect on weldline strength. A regression analysis combined with fitting model seems to correlate process conditions and weldline strength reduction quite well.

Chunsheng Chen - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the Effects of Injection Molding Processing Parameters on Conductive Polymeric Composites for Electromagnetic Interference Shielding Effectiveness
    Polymer-plastics Technology and Engineering, 2009
    Co-Authors: Wei-seng Cheng, Shia-chung Chen, Chunsheng Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) composites filled with conductive nickel-coated carbon fibers (NCFs) were injection-molded under different injection process conditions. They were then used to investigate the influence of the injection processing parameters of melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE). In order to study the effect of the molding variables using the minimum number of experiments, the Taguchi method was employed. The aim of the Taguchi method was to optimize the injection processing parameters for better EMI shielding of the conductive polycarbonate composites. It is found out that the Packing Pressure and mold temperature affect the EMI shielding efficiency most significantly.

  • optimum injection molding processing condition on emi shielding effectiveness of stainless steel fiber filled polycarbonate composite
    International Communications in Heat and Mass Transfer, 2008
    Co-Authors: Chunsheng Chen, Shia-chung Chen, Weiren Chen, Rean-der Chien
    Abstract:

    Polycarbonate (PC) polymers mixed with conductive stainless steel fiber (SSF) is injection-molded under various injection process conditions. The composite formed is then tested for its capability to shield off electromagnetic field passing through. The effects of four major injection processing parameters including melt temperature, mold temperature, injection velocity and Packing Pressure on the electromagnetic interference (EMI) shielding effectiveness (SE) of PC filled with conductive SSF have been investigated. Taguchi method is adopted to obtain the optimum set of injection process parameters to acquire the maximum EMI shielding. It is observed that melt temperature and Packing Pressure significantly affect shielding effectiveness performance for injection-molded PC composites with SSF filler.

  • Investigation on the weldline strength of thin-wall injection molded ABS parts☆
    International Communications in Heat and Mass Transfer, 2007
    Co-Authors: Chunsheng Chen, Rean-der Chien, Tsyr-jang Chen, Shia-chung Chen
    Abstract:

    It is well known that the weldline reduces the mechanical performance of the conventional injection molded parts. Yet, systematic researches and reports on weldline strength of thin-wall molded parts are still insufficient. This study investigates the influence of processing conditions on the weldline strength of thin-wall Acrylonitrile Butadiene Styrene Copolymer (ABS) parts. The relevant parameters include melt temperature, mold temperature, injection speed and Packing Pressure. Tensile tests on specimens of different thickness (1.0, 1.2 and 2.5 mm) are conducted. Comparisons on tensile strength for single-gate molded specimens (without weldline) with those of double-gate molded specimens (with weldline) are presented. From the experimental results, it was found that weldline specimens molded at higher melt temperature, higher mold temperature, faster injection speed and lower Packing Pressure would result in better mechanical strengths. Higher melt and mold temperatures not only lower the residual stress but also help the diffusion of molecular chains leading to a higher degree of surface bonding at the weldline interface. On the other hand, high Packing Pressure leads to higher residual stress formation and reduces the molecular bonding rate. In addition, part thickness also exhibits significant effect on weldline strength. A regression analysis combined with fitting model seems to correlate process conditions and weldline strength reduction quite well.

Vijay K. Stokes - One of the best experts on this subject based on the ideXlab platform.

  • Solidification of thermoviscoelastic melts. Part 3: Effects of mold surface temperature differences on warpage and residual stresses
    Polymer Engineering and Science, 1996
    Co-Authors: Wit C. Bushko, Vijay K. Stokes
    Abstract:

    The solidification of a molten layer of amorphous thermoplastic between cooled parallel plates is used to model the mechanics of part warpage in the injection-molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The model allows material to be added to fill the space created by the Pressure applied during solidification so that this model can be used to assess Packing-Pressure effects in injection molding. Parametric results are presented on the effects of the mold temperatures and the Packing Pressure-the Pressure applied during solidification to counteract the effects of volumetric shrinkage of the thermoplastic-on the in-plane and through-thickness shrinkages, on warpage, and on residual stresses in plaque-like geometries. The Packing Pressure is shown to have a significant effect on part warpage. While the results are presented in terms of normalized variables based on the properties of bisphenol-A polycarbonate, they can be interpreted for other amorphous thermoplastics, such as modified polyphenylene oxide, polyetherimide, and acrylonitrile-butadiene-styrene.

  • Solidification of thermoviscoelastic melts. Part 4: Effects of boundary conditions on shrinkage and residual stresses
    Polymer Engineering and Science, 1995
    Co-Authors: Wit C. Bushko, Vijay K. Stokes
    Abstract:

    The solidification of a molten layer of thermoplastic between cooled parallel plates is used to model the mechanics of part shrinkage and the buildup of residual stresses in the injection-molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The model allows material to be added to fill the space created by the Pressure applied during solidification, so that this model can be used to assess Packing-Pressure effects in injection molding. Parametric results are presented on the effects of the mold and melt temperatures, the part thickness, and the Packing Pressure—the Pressure applied during solidification to counteract the effects of volumetric shrinkage of the thermoplastic—on the in-plane and through-thickness shrinkages, and on residual stresses in plaque-like geometries. The Packing Pressure is shown to have a significant effect on part shrinkage, but a smaller effect on residual stresses. Packing Pressure applied later in the solidification cycle has a larger effect. Mold and melt temperatures are shown to have a much smaller effect. The processing parameters appear to affect the through-thickness shrinkage more than the in-plane shrinkage. While the results are presented in terms of normalized variables based on the properties of bisphenol-A polycarbonate, they can be interpreted for other amorphous thermoplastics such as modified polyphenylene oxide, polyetherimide, and acrylonitrile-butadiene-styrene.

  • Solidification of thermoviscoelastic melts. Part I: Formulation of model problem
    Polymer Engineering and Science, 1995
    Co-Authors: Wit C. Bushko, Vijay K. Stokes
    Abstract:

    The solidification of a molten layer of amorphous thermoplastic between cooled parallel plates is used to model the mechanics of part shrinkage and warpage and the buildup of residual stresses in the injection molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The equilibrium thermomechanical properties of the material and the shift function can be temperature- and Pressure-dependent. The model allows material to be added to fill the space created by the Packing Pressure applied during solidification; therefore, this model can be used to assess Packing-Pressure effects in injection molding. The model also accounts for freeze-off effects in which the cavity Pressure is controlled by the solidification process and must therefore be determined as a part of the solution.

G Titomanlio - One of the best experts on this subject based on the ideXlab platform.

  • Rapid control of mold temperature during injection molding process: Effect of Packing Pressure
    2015
    Co-Authors: Sara Liparoti, Andrea Sorrentino, G Titomanlio
    Abstract:

    A thorough analysis of the effect of operative conditions of injection molding process on the morphology distribution inside the obtained molded is performed, with particular reference to semi- crystalline polymers. In particular, fully characterized injection molding tests are presented using an isotactic polypropylene, previously carefully characterized as far as most of properties of interest. The effects of mold temperature and Packing conditions are analyzed. The mold temperature was controlled by a thin heating device, composed by polyimide as insulating layer and polyimide loaded carbon black as electrical conductive layer, that is able to increase temperature on mold surface in few seconds (70°C/s) by joule effect and cool down soon after. The shear layer thickness in the molded is reduced in the samples produced at high mold temperatures, that means high electrical power and long heating time, and this reduction is more significant at lower Packing Pressures, indeed, at 360bar as Packing Pressure...

  • morphology evolution during injection molding effect of Packing Pressure
    Polymer, 2007
    Co-Authors: Roberto Pantani, I Coccorullo, Vito Speranza, G Titomanlio
    Abstract:

    Injection molding is one of the most widely employed methods for manufacturing polymeric products. The final properties and then the quality of an injection molded part are to a great extent affected by morphology. Thus, the prediction of microstructure formation is of technological importance, also for optimizing processing variables. In this work, some injection molding tests were performed with the aim of studying the effects of Packing Pressure on morphology distribution. The resulting morphology of the moldings was characterized and it was compared with previous results gathered on samples obtained by applying a lower holding Pressure. Furthermore, the molding tests were simulated by means of a code developed at University of Salerno. The results obtained show that on increasing holding Pressure the molecular orientation inside the samples increases, and simulations show that this is due mainly to the increase of relaxation time caused by the higher Pressures. On discussing the simulation results, some considerations are made on the effects of Pressure on crystallization kinetics and on rheology.

  • morphology evolution during injection molding effect of Packing Pressure
    10TH ESAFORM CONFERENCE ON MATERIAL FORMING, 2007
    Co-Authors: Roberto Pantani, I Coccorullo, Vito Speranza, G Titomanlio
    Abstract:

    Injection molding is one of the most widely employed methods for manufacturing polymeric products. The final properties and the quality of an injection molded part are to a great extent affected by morphology. Thus, the prediction of microstructure formation is of technological importance, also for optimizing processing variables, in order to cut down on the expensive costs of tooling and the trial‐and‐error procedures. In this work, some injection molding tests were performed with the aim of studying the effects of Packing Pressure on morphology distribution. The resulting morphology of the moldings was in fact characterized by adopting different experimental techniques and, in order to underline the effects of holding Pressure, it was compared with previous results gathered on samples obtained applying a lower holding Pressure. Furthermore, the molding tests were simulated by means of a code developed at University of Salerno, which implements procedures able to model molecular orientation, crystallizat...