Influence of Packing Phase Parameters in the Optimization of Mechanical, Weight Reduction and Dimensional Properties of Microcellular Foaming Injection Molding of Polypropilene

2012 ◽  
Vol 445 ◽  
pp. 319-324 ◽  
Author(s):  
Angel Fernandez ◽  
Manuel Muniesa
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Weight Reduction ◽  
Mechanical Performance ◽  
Process Window ◽  
Foam Density ◽  
Microcellular Foam ◽  
Molded Part ◽  
Microcellular Foaming ◽  
Conventional Injection Molding

Microcellular foaming of injected plastics offers the possibility to manufacture parts with reductions in costs and weight if compared with conventional injection molding. For this reason there is an increasing interest in challenging applications such as HEV (hybrid and electrical vehicles) and lightweight material applications in general. Complexity of microcellular injection molding is very high because the final properties of the material obtained depend largely on the processing conditions and these in turn unalterable factors such as mold design and manufacturing. The shrinkage of the molded part must be applied as an oversize of the mold cavity in the design phase. Shrinkage of a microcellular foam depends on the reduction of foam density. Moreover, the piece is designed to get a mechanical performance and meet the dimensional tolerances. Knowing that the reduction of foam density implies a reduction of the mechanical properties and influences the final piece dimensions the conclusion is that the microcellular injection process has a very small process window to fit all these factors. This research focuses on two objectives. First is the variation of post-molding shrinkage in terms of reduction of weight to determine the process window. Second is the determination of mechanical properties which do not show a proportional reduction but exponentially with weight reduction components. The results obtained with a 750 Tons. injection moulding machine equipped with a MuCell plastication unit and a large spiral mold have shown small variations in the dimensions for a predetermined process window and smaller reduction of mechanical properties with weight reductions for 20% talc filled polypropylene. The goal of this applied research is that all experiments have been developed with scaled-industry tools (large injection molding machine, Mucell unit and mold and test parts) comparing with conventional injection molding.

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.

Advances in Microcellular Foam Processing of PLA

2016 ◽  
Vol 717 ◽  
pp. 68-72 ◽  
Author(s):  
Zhi Zhong Han ◽  
You Cheng Zhang ◽  
Wei Min Yang ◽  
Peng Cheng Xie
Keyword(s):  
Mechanical Properties ◽  
Cell Density ◽  
Cell Morphology ◽  
Expansion Ratio ◽  
Chain Extender ◽  
Microcellular Foam ◽  
Foaming Process ◽  
Microcellular Foaming ◽  
Alternative Materials ◽  
A Chain

PLA is a bio-based biodegradable plastic, which has excellent biocompatibility and biodegradability. Because the mechanical properties of microcellular foaming material is similar to petroleum-based plastics (PS), PLA foams have been considered as ideal alternative materials. However, PLA has several inherent drawbacks such as low melt strength and slow crystallization kinetics, which severely inhibit the PLA foaming process to produce high-density forms and uniform cell morphology. By adding a chain extender or nanoparticles, and blending with other biological materials, these ways could effectively enhance the expansion ratio and the cell density of PLA and improve the mechanical properties of PLA foams. The most current investigations on microcellular foaming of PLA were reviewed in the article, and outlook of PLA foams was raised.

scholarly journals Effects of Three Different Injection-Molding Methods on the Mechanical Properties and Electrical Conductivity of Carbon Nanotube/Polyethylene/Polyamide 6 Nanocomposite

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1779
Author(s):  
Dashan Mi ◽  
Zhongguo Zhao ◽  
Wenli Zhu
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Shear Stress ◽  
Injection Molding ◽  
Oscillatory Shear ◽  
High Shear ◽  
Shear Forces ◽  
Oscillatory Shear Stress ◽  
Molding Methods ◽  
Conventional Injection Molding

Morphological evolution under shear, during different injection processes, is an important issue in the phase morphology control, electrical conductivity, and physical properties of immiscible polymer blends. In the current work, conductive nanocomposites were produced through three different injection-molding methods, namely, conventional injection molding, multi-flow vibration injection molding (MFVIM), and pressure vibration injection molding (PVIM). Carbon nanotubes in the polyamide (PA) phase and the morphology of the PA phase were controlled by various injection methods. For MFVIM, multi-flows provided consistently stable shear forces, and mechanical properties were considerably improved after the application of high shear stress. Shear forces improved electrical property along the flow direction by forming an oriented conductive path. However, shear does not always promote the formation of conductive paths. Oscillatory shear stress from a vibration system of PVIM can tear a conductive path, thereby reducing electrical conductivity by six orders of magnitude. Although unstable high shear forces can greatly improve mechanical properties compared with the conventional injection molding (CIM) sample, oscillatory shear stress increases the dispersion of the PA phase. These interesting results provide insights into the production of nanocomposites with high mechanical properties and suitable electrical conductivity by efficient injection molding.

Applications of Core Retraction in Manufacturing Low-Density Polypropylene Foams with Microcellular Injection Molding

2018 ◽  
Vol 37 (1) ◽  
pp. 1-20
Author(s):  
Hrishikesh Kharbas ◽  
Thomas Ellingham ◽  
Lih-Sheng Turng
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Tensile Properties ◽  
Weight Reduction ◽  
Low Density ◽  
Cavity Volume ◽  
The Core ◽  
Process Use ◽  
Incomplete Filling ◽  
Microcellular Injection Molding

Without modifying existing part and mold designs, the conventional microcellular injection molding (MIM) process can typically save about 5–10% material without encountering problems such as incomplete filling, excessive shrinkage, or deteriorating microstructure and mechanical properties. In this study core retraction was used in combination with the MIM process to produce thick polypropylene (PP) parts (up to 7.6 mm thick) with high density reductions of 30% and 55%. The cavity volume was modified by changing the retraction distance, which enabled control of density reductions. The lowest densities were achieved with this core retraction-aided microcellular injection molding (CR-MIM) process, the results of which could not have been achieved by the conventional MIM process alone. The effects of delay time in core retraction and weight reduction on the microstructure of the core and skin layers were investigated. It was shown that the CR-MIM process yielded better microstructure and tensile properties than the conventional MIM process. Use of core retraction also yielded more consistent densities and tensile properties throughout the length of the foamed parts.

Injection molding of short fiber thermoplastic bio-composites: Prediction of the fiber orientation

2020 ◽  
Vol 54 (30) ◽  
pp. 4787-4797
Author(s):  
Fatima-Zahra Semlali AouraghHassani ◽  
Mounir El Achaby ◽  
Mohammed-Ouadi Bensalah ◽  
Denis Rodrigue ◽  
Rachid Bouhfid ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Injection Molding ◽  
Fiber Orientation ◽  
Orientation Angle ◽  
Short Fiber ◽  
Thermoplastic Polymer ◽  
Molded Part ◽  
Practical Tool ◽  
Orientation Pattern

Injection molding of short fiber reinforced thermoplastic polymer results in a preferential fiber orientation in the part, which leads to an anisotropy in the material mechanical properties. To anticipate the molded part performances, it is necessary to predict the fiber orientation pattern. Our goal is to have a practical tool that accurately predicts fiber orientation patterns, and to use that information to estimate the final product properties. Consequently, an efficient way to determine the flow induced fiber orientation for different flow cases under real injection molding conditions is presented. The proposed approach allows the average orientation angle prediction in a section by considering the close interaction between the fibers and the flow rheology, the fibers aspect ratio and the mold geometry. Finally, to validate the model, experimental data were taken with different matrices, fibers and mold geometries, where good agreements (R2 ≥ 0.8) were obtained for the fiber orientations measurements.

Morphology and Mechanical Properties of Pc/Lcp in Situ Composites With Compatibilizer

1996 ◽  
Vol 425 ◽  
Author(s):  
Y. Leng ◽  
W. G. Zheng
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Mechanical Performance ◽  
Crystalline Polymer ◽  
Morphology And Mechanical Properties

AbstractA bisphenol A epoxy resin is used to modify compatibility between PC and LCP (Vectra B950, a wholly aromatic liquid crystalline polymer) during injection molding. LCP can effectively reinforce PC, since it forms in situ micro-fibrils in the thermoplastic PC matrix during melt flow. However, the immiscibility of PC and LCP affects the mechanical performance of the LCP in situ composite. Preliminary results of this work indicate that epoxy might improve the interfacial bonding between PC and LCP fibrils, and also modify the tensile properties of the PC/LCP system.

scholarly journals Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2543
Author(s):  
Paweł Muszyński ◽  
Przemysław Poszwa ◽  
Andrzej Gessner ◽  
Krzysztof Mrozek
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Induction Heating ◽  
Polymer Melt ◽  
Mold Temperature ◽  
Polymer Processing ◽  
Mechanical Tests ◽  
Engineering Industry ◽  
Shear Rates ◽  
Molded Part

Injection molding is a polymer processing technology used for manufacturing parts with elastic hinges. Elastic hinges are widely used in FMCG (Fast Moving Consumer Goods) packaging (e.g., bottle closures of shampoos, sauces) and in the electrical engineering industry. Elastic hinge is a thin film that connect two regions of the injection molded part, where significant shear rates are present, which can lead to the degradation of polymers and the decrease in mechanical properties. Selective induction heating is the method that improves the flow of the polymer melt through thin regions by the local increase in mold temperature. In this study, selective induction heating was used to improve mechanical properties of elastic hinges by the reduction of material degradation due to high shear rates. To verify the change of shear rates, selective induction heating simulation and injection molding simulations were performed. The linear relation between mold temperature and maximum shear rate in the cross-section was identified and the mechanical tests showed significant differences in hinge stiffness, tensile strength and elongation at break.

Sign in / Sign up

Export Citation Format

Share Document