1:30 pm – 6:00 pm:
M14-Injection Molding: Materials
(Moderators: Pete Grelle and Gary Smith)-Room S320H

1:30 pm – 2:00 pm:
Microinjection Molding of Polypro/Graphite Composite

Shengtai Zhou, University of Western Ontario
Shengtai Zhou is a PhD student at the University of Western Ontario, under the supervision of Dr. Andrew Hrymak and Dr. Musa Kamal. His research interest is microinjection molding of carbon filled polymer nanocomposites.

2:00 pm – 2:30 pm:
Foaming Uniformity Control of High Weight Reduction Microcellular Injection Molded Thermoplastic Elastomer Using Gas Counter Pressure

Chang Che-wei, Chung Yuan Christian University
The microcellular injection molding process is widely used in the automotive, packaging, sporting goods, and electrical parts industries. The Mucell® process offers many advantages such as material and energy savings, low cycle time, cost effectiveness, and dimensional stability of products. Thermoplastic Polyurethane (TPU) is a common material for molding the outsole of shoes because of its outstanding properties such as hardness, abrasion resistance, and elasticity. Though many shoe manufacturers have begun applying Mucell® processes to TPU midsoles manufacturing, in moving to mass production, problems remain. The main problem is the uniformity of the cell size in the midsole. The cell size is affected by injection process induced pressure drops which lower the cell size uniformity in different regions and reduce the bouncing properties of the material. To address this problem, gas counter pressure technology was used to achieve a uniform cell size distribution midsole in the Mucell® process in this study.

2:30 pm – 3:00 pm:
Mechanical and Rheological Characteristics of PP/PET Blend with Maleic Anhydrite and Jute Fibre

Abul Saifullah, Swinurne University of Technology
This paper presents an investigation of the effect of mixing natural Jute fibre and Maleic Anhydrite compatibilizer with recycled Polypropylene (PP) and Polyethylene terephthalate (PET) blends. Recycled plastic has a significant contribution to reduce the environmental issues and encourage the economic benefit. PP and PET polymers are commonly used in the industrial fields, however, they are immiscible and it is difficult to be blended. Two different PP & PET (65/35 and 78/22 v/v %) samples have been blended with 0.5% wt (2 g) Jute fibre and 5% wt (20 g) Maleic anhydride (PP-g-MAH). The mechanical mixing has been done by using twin-screw extruder to get pellets of PP/PET/jute/Maleic Anhydrite, which were used to make test samples with injection moulding machine. The comparative result shows that blend of PP/PET with and without any addition of Maleic anhydride and Jute fibre has enhanced tensile and flexural properties significantly.

3:00 pm – 3:30 pm:
Mechanical Properties of Polyamide 6/Zeolite Composites

Davoud Jahani, University of Bonab
Many researchers have investigated the effect of Nano- and Micro-scale materials on the mechanical properties of the thermoplastic polymers. Some researchers showed that adding small amount of some mineral material to polymers matrix may enhance their physical and mechanical properties. In this study polyamide 6/zeolite composites having 2.5, 5, and 7.5 phr of the zeolite were prepared using a twin screw extruder and injection molding process, and different mechanical properties of the composites were investigated. Our results show that adding zeolite particles to polyamide, leads to increase of tensile strength by the maximum of 33%. Also having 7.5 phr of zeolite particles in the polyamide matrix results on 61% increase on the strain to rupture, compared to the pure polymer.

3:30 pm – 4:00 pm:
Effects of Processing Parameters on Fiber Length Distribution and Tensile Strength of Long Glass Fiber Reinforced Nylon66 Composites Molded Parts

Hsin-Shu Peng, Feng Chia University
This study investigates the effects of processing parameters on the tensile strength and fiber length distribution of long glass fiber reinforced nylon66 composites. This study carried out the injection experiment at different screw speeds in order to take the fiber breakage and length distribution as the basis for the setting of processing parameters. The effects of processing parameters on tensile strength of long glass fiber reinforced nylon66 composites (LGF-Nylon66) were then studied using a tensile test specimen mold with single /double gate design (part thickness of 1.8 mm and 3.6 mm). The experimental results show that increasing the screw speed leads to fiber breakage, shortens the fiber length, and thus affects the tensile strength of long glass fiber reinforced nylon66 composites molded parts. On the other hand, as the melt temperature and the mold temperature increase, the tensile strength also increases. In addition, SEM observation presents that the effect of fiber length and orientation distributions on the weldline tensile strength of the molded specimen is very obvious. These results also show that the interfacial adhesion is required to achieve a desired composite strength.

4:00 pm – 4:30 pm:
Evaluating the Through-Plane Conductivity of Molded Parts via Magnetic Field in the Injection Molding Process

Chiu Min-Chi, Chung Yuan Christian University
As industries transition, the application of composite materials has expanded. Composite materials manufacturing processes and technologies have become a focus of technology research and development. For fiber composite materials, since the fibers affect product properties, controlling them is a key to improving product performance. In this study, conductive paths were formed by adding nickel-coated carbon fiber to give the products electrical conductivity. In combination with a permanent magnet mold, experiments were conducted to verify whether the external magnetic field had an effect on the fiber orientation during filling. In the experimental part, the external magnetic field was ineffective due to cooling. Therefore, injection molding parameters such as temperature (melt temperature, mold temperature) as discussed herein. To understand whether there is an external magnetic field for the fiber orientation tensor, the influence of different parameters on the fiber orientation tensor and the through-plane conductivity under the condition of external magnetic field are explored.

4:30 pm – 5:00 pm:
Improved Processability of Ultra-high Molecular Weight Polyethylene via Supercritical Nitrogen and Carbon Dioxide in Injection Molding

Galip Yilmaz, Wisconsin Institute for Discovery at University of Wisconsin–Madison
The processability of injection molding ultra-high molecular weight polyethylene (UHMWPE) was improved by introducing supercritical nitrogen (scN2) or supercritical carbon dioxide (scCO2) into the polymer melt, which decreased its viscosity and injection pressure while reducing the risk of degradation. When using the special full-shot option of microcellular injection molding (MIM), it was found that the required injection pressure decreased by up to 30% and 35% when scCO2 and scN2 were used, respectively. The mechanical properties in terms of tensile strength, Young’s modulus, and elongation-at-break of the supercritical fluid (SCF)-loaded samples were examined. The rheological properties of regular and SCF-loaded samples were analyzed using parallel-plate rheometry. The results showed that the use of scN2 and scCO2 with UHMWPE and MIM retained the high molecular weight, and thus the mechanical properties of the polymer, while regular injection molding led to signs of degradation.

5:00 pm – 5:30 pm:
Effect of Stress Relaxation on Shrinkage and Warpage of Injection Molded Parts

Zhiliang Fan, Moldflow R&D Center, Autodesk
The residual stresses in the injection molding process are built up due to the restriction of thermal contraction during the process, coupled with the frozen layer growth with varying pressure history. The stress relaxation behavior of plastic materials complicates the stress field. A three-dimensional linear anisotropic thermo-viscoelastic residual stress model is developed for predicting the effect of stress relaxation on shrinkage and warpage of injection molded parts. Thermo-rheological simplicity is assumed for the material, and the viscoelastic master curve is fitted with a generalized Maxwell model. A time-temperature shift factor table over the range of temperatures which occur during the injection molding process is preferred over the WLF equation and Arrhenius equation due to its general applicability. Two numerical examples are given, and the simulation result comparison between the thermo-viscoelastic model and thermo-viscous-elastic model shows that stress relaxation reduces the molded-in residual stresses slightly, and has a modest impact on shrinkage and warpage. The validation cases also confirm that the simple thermo-viscous-elastic residual stress model is generally able to give a good qualitative and reasonable quantitative prediction of the final shrinkage, warpage and molded-in residual stresses.

5:30 pm – 6:00 pm:
Studying of Viscoelasticity on Warpage Validation

RuJing Jhang, CoreTech System (Moldex3D) Co., Ltd.
Warpage is an important indicator when evaluating the quality of an injection molding product. How to control the warp within tolerance is a critical issue concerned by designer and molder. Accurate computer aided engineering (CAE) warpage prediction helps designer to find the best design from different prototypes quickly at the beginning of development, decreasing the cost. However, the warpage is the final result affected by several factors during injection molding, for instance material, injection machine, part and mold design. Hence, an accurate warpage prediction must take these factors into consideration comprehensively. The real machine response is compared with filling pressure to verify whether the flow simulation is accurate enough as input parameter of following warpage prediction. Unlike linear warpage calculation simply based on material PVT property, Moldex3D solver considers material viscoelasticity to simulate the significant modulus change when polymer transits from rubbery phase to glassy phase. Together with in-mold constraint and free deformation after ejection in warpage calculation, the warpage prediction shows high agreement with real box product on three different materials, PS, PC and PP.