Effect of gas counter pressure on the carbon fiber orientation and the associated electrical conductivities in injection molded polymer composites

2015 ◽  
Vol 35 (5) ◽  
pp. 503-510 ◽  
Author(s):  
Shia-Chung Chen ◽  
Min-Yuan Chien ◽  
Su-Hsia Lin ◽  
Rean-Der Chien ◽  
Ming-Chung Lin
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fiber ◽  
Injection Molding ◽  
Layer Thickness ◽  
Fiber Orientation ◽  
Core Layer ◽  
Acrylonitrile Butadiene Styrene ◽  
Skin Layer ◽  
Carbon Fiber Composites ◽  
Counter Pressure

Abstract Polymers filled with conducting fibers to provide electrical conductivity performance have received great attention due to the requirements of many engineering applications. In the present article, injection molding of acrylonitrile butadiene styrene (ABS)/carbon-fiber composites using applied gas counter pressure (GCP) was conducted and the overall fiber orientation and associated through-plane electrical conductivity (TPEC) of each layer (core, shear and skin layers) and various locations (far gate, center and near gate) were characterized. Results show that GCP had significant effects on the fiber orientation and skin layer thickness, resulting in decreases in the fiber orientation level (FOL) value in all locations and TPEC increases with increasing GCP in the core region of the molded composites (improvement of 62% when 100 bar GCP was applied). However, the effect of increased skin layer thickness in reducing TPEC was stronger than the effect of decreased FOL in raising TPEC when GCP was applied. This resulted in the overall TPEC falling slightly with increasing GCP. The results also show that the electrical conductivity followed the sequence of far gate>center>near gate and the FOL followed the order of core layer<shear layer<skin layer. The results obtained in this investigation reveal the potential application of GCP technology associated with mold temperature control in injection molding to manufacture products with enhanced electrical conductivity in the future.

Dual-Scale Modeling and Simulation of Skin Layer Thickness in Injection Molding with Variable Mold Temperatures

2016 ◽  
Vol 13 (10) ◽  
pp. 7125-7136
Author(s):  
Bei Su ◽  
Ying-Guo Zhou ◽  
Lih-Sheng Turng
Keyword(s):  
Injection Molding ◽  
Layer Thickness ◽  
Mold Temperature ◽  
Optical Microscope ◽  
Skin Layer ◽  
Injection Flow ◽  
Scale Modeling ◽  
Molded Parts ◽  
Dual Scale ◽  
Conventional Injection Molding

Compared with the constant mold temperature in conventional injection molding (CIM), injection molded parts with variable mold temperatures undergo a different thermomechanical history. As a result, the microstructure—for example, the skin–core structure found often in CIM—can be changed. However, unlike conventional injection molding, there have been few studies on the microstructure of injection molding with variable mold temperatures (IMVMT), possibly because the experimental control of variable mold temperatures remains difficult. In this paper, the skin layer thickness of CIM and IMVMT under different mold temperatures was carefully investigated by optical microscope. The higher mold temperatures and longer holding times during the injection flow stage caused a thinning of the highly oriented skin layer, and vice-versa. A dual-scale modeling was then proposed based on the prediction of crystal dimensions, and it was further used to predict the thickness of the skin layer. The predicted results were in agreement with the experimental observations under the different mold temperatures during IMVMT processing, and the proposed model proved to be effective.

Mechanical properties and fiber characteristics of glass fiber/carbon fiber reinforced polyethylene terephthalate hybrid composites fabricated by direct fiber feeding injection molding

2018 ◽  
Vol 38 (6) ◽  
pp. 513-523 ◽  
Author(s):  
Wiranphat Thodsaratpreeyakul ◽  
Putinun Uawongsuwan ◽  
Akio Kataoka ◽  
Takanori Negoro ◽  
Hiroyuki Hamada
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Injection Molding ◽  
Glass Fiber ◽  
Polyethylene Terephthalate ◽  
Fiber Orientation ◽  
Mechanical Performance ◽  
Hybrid Composites ◽  
Fiber Distribution ◽  
Volume Fractions

Abstract Improving the applicability of polyethylene terephthalate (PET) by carbon fiber/glass fiber reinforcement is of great interest. Glass fiber (GF)/carbon fiber (CF)/PET hybrid composites were fabricated by direct fiber feeding injection molding (DFFIM) process. The aim of DFFIM is to obtain longer fibers in composites in order to improve their mechanical properties. In this study, the mechanical properties of GF/PET composites fabricated by conventional injection molding and hybrid GF/CF/PET composites fabricated by DFFIM process were investigated. The influence of GF and CF volume fractions on fiber distribution, fiber orientation, and fiber length is discussed. Fiber distribution status was quantitatively measured by the fiber distribution index. Fiber agglomeration problem was observed by scanning electron microscopy. The results indicate that incorporating CF in GF/CF/PET hybrid composites by the DFFIM process greatly enhances mechanical performance even when only a small amount of CF is added. Too high GF content leads to less effective CF hybridization because it causes poor fiber distribution and poor fiber orientation and intensifies fiber attrition. The ideal volume fractions of GF and CF for fabricating GF/CF/PET hybrid composites by using DFFIM are provided.

Numerical Simulation of Fiber Orientation of Short Fiber Reinforced Polypropylene in Injection Molding

2011 ◽  
Vol 418-420 ◽  
pp. 1194-1201
Author(s):  
He Sheng Liu ◽  
Ai Hua Xiong ◽  
Xing Yuan Huang ◽  
Jia Mei Lai
Keyword(s):  
Numerical Simulation ◽  
Injection Molding ◽  
Fiber Orientation ◽  
Subsurface Layer ◽  
Core Layer ◽  
Injection Molding Process ◽  
Main Process ◽  
Fiber Reinforced ◽  
Molding Process ◽  
Melt Temperature

Based on generalized non-Newtonian fluid with seven parameters Cross-WLF viscosity model and modified 2-double Tait model, the numerical simulation was carried out for the short glass fiber reinforced PP injection molding process of rectangular part. The influence of main process parameters on fiber orientation is investigated. The results show that fiber orientation can be generally divided into three-regional layers in injection molding, that is outer-surface, subsurface and core layer. The degree of fiber orientation in subsurface layer is the highest and that in core layer is the lowest. The influence of fibers interaction coefficient (Ci) and fibers aspect ratio (re) on fiber orientation is significant. There is obvious difference between simulation results and practical results without consideration of Ci. The effect of melt temperature, mold temperature and cooling tubes number on fiber orientation isn’t obvious.

scholarly journals Preparation and Evaluation of the Tensile Characteristics of Carbon Fiber Rod Reinforced 3D Printed Thermoplastic Composites

2020 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Arivazhagan Selvam ◽  
Suresh Mayilswamy ◽  
Ruban Whenish ◽  
Rajkumar Velu ◽  
Bharath Subramanian
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Layer Thickness ◽  
Shell Thickness ◽  
Fused Deposition Modeling ◽  
Acrylonitrile Butadiene Styrene ◽  
Thermoplastic Composites ◽  
Critical Parameters ◽  
Fused Deposition ◽  
Deposition Modeling

The most common method to fabricate both simple and complex structures in the additive manufacturing process is fused deposition modeling (FDM). Many researchers have studied the strengthening of FDM components by adding short carbon fibers (CF) or by reinforcing solid carbon fiber rods. In the current research, we sought to enhance the mechanical properties of FDM components by adding bioinspired solid CF rods during the fabrication process. An effective bonding interface of bioinspired CF rods and polylactic acid (PLA) was achieved by triangular interlocking sutures and by employing synthetic glue as the binding agent. In particular, the tensile strength of solid CF rod reinforced PLA samples was studied. Critical parameters such as layer thickness, extruder temperature, extruder speed, and shell thickness were considered for optimization. Significant process parameters were identified through leverage plots using the response surface methodology (RSM). The optimum parameters were found to be layer thickness of 0.04 mm, extruder temperature of 215 °C, extruder speed of 60 mm/s, and shell thickness of 1.2 mm. The results revealed that the bioinspired solid CF rod reinforced PLA (CFRPLA) composite exhibited a tensile strength of 82.06 MPa, which was approximately three times higher than the pure PLA (28 MPa, 66% lower than CFRPLA), acrylonitrile butadiene styrene (ABS) (28 MPa, 66% lower than CFRPLA), polyethylene terephthalate glycol (PETG) (34 MPa, 60% lower than CFRPLA), and nylon (34 MPa, 60% lower than CFRPLA) samples.

Numerical Simulation of Co-Injection Molding

2000 ◽  
Author(s):  
James T. Wang
Keyword(s):  
Injection Molding ◽  
Process Design ◽  
Core Layer ◽  
Skin Layer ◽  
Injection Molding Process ◽  
Molding Process ◽  
Part Quality ◽  
Polymer Properties ◽  
Polymer Distribution ◽  
The Cost

Abstract In the co-injection molding process, two (or more) different polymers are injected into the cavity simultaneously or sequentially. Different properties of these two polymers and their distribution in the cavity greatly affect the applications of this molding process. The skin layer can use special polymers to provide good appearance and texture, strength, chemical resistance, EMI shielding and other functions. The core layer can use recycled or inexpensive materials. Together these can improve part quality and lower the cost. However, due to the dynamic interaction of two polymers in the manufacturing process and their difference in properties, process control becomes more complicated and process design becomes a challenge. The rules used for the traditional injection molding process design may not always be useful for co-injection molding any more. An integrated CAE software has been developed to simulate the co-injection molding process. In this study, the capability and usefulness of the CAE tool will be shown. The control of polymer distribution will be discussed. The effects of polymer properties and their distribution on part quality will also be studied.

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