scholarly journals Experimental and Numerical Investigation of Flow and Alignment Behavior of Waste Tire-Derived Graphene Nanoplatelets in PA66 Matrix during Melt-Mixing and Injection

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 949
Author(s):  
Kuray Dericiler ◽  
Hadi Mohammadjafari Sadeghi ◽  
Yavuz Emre Yagci ◽  
Hatice S. Sas ◽  
Burcu Saner Okan
Keyword(s):  
Mechanical Performance ◽  
Flow Direction ◽  
Graphene Nanoplatelets ◽  
Injection Molding Process ◽  
Molding Process ◽  
Melt Mixing ◽  
Shear Rates ◽  
Waste Tire ◽  
High Shear Rates ◽  
Reinforcing Agent

Homogeneous dispersion of graphene into thermoplastic polymer matrices during melt-mixing is still challenging due to its agglomeration and weak interfacial interactions with the selected polymer matrix. In this study, an ideal dispersion of graphene within the PA66 matrix was achieved under high shear rates by thermokinetic mixing. The flow direction of graphene was monitored by the developed numerical methodology with a combination of its rheological behaviors. Graphene nanoplatelets (GNP) produced from waste-tire by upcycling and recycling techniques having high oxygen surface functional groups were used to increase the compatibility with PA66 chains. This study revealed that GNP addition increased the crystallization temperature of nanocomposites since it acted as both a nucleating and reinforcing agent. Tensile strength and modulus of PA66 nanocomposites were improved at 30% and 42%, respectively, by the addition of 0.3 wt% GNP. Flexural strength and modulus were reached at 20% and 43%, respectively. In addition, the flow model, which simulates the injection molding process of PA66 resin with different GNP loadings considering the rheological behavior and alignment characteristics of GNP, served as a tool to describe the mechanical performance of these developed GNP based nanocomposites.

Effect of gas counter pressure on shrinkage and residual stress for injection molding process

2017 ◽  
Vol 37 (5) ◽  
pp. 505-520 ◽  
Author(s):  
Wen-Ren Jong ◽  
Shyh-Shin Hwang ◽  
Ming-Chieh Tsai ◽  
Chien-Chou Wu ◽  
Chi-Hung Kao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Injection Molding ◽  
Flow Direction ◽  
Injection Molding Process ◽  
Molding Process ◽  
Daily Lives ◽  
Counter Pressure ◽  
Packing Pressure ◽  
Sink Marks ◽  
Feedback Data

Abstract Plastic products are common in contemporary daily lives. In the plastics industry, the injection molding process is advantageous for features such as mass production and stable quality. The problem, however, is that the melt will be affected by the residual stress and shrinkage generated in the process of filling and cooling; hence, defects such as warping, deformation, and sink marks will occur. In order to reduce product deformation and shrinkage during the process of molding, the screw of the injection molding machine will start the packing stage when filling is completed, which continuously pushes the melt into the cavity, thus making up for product shrinkage and improving their appearance, quality, and strength. If the packing pressure is too high, however, the internal residual stress will increase accordingly. This study set out to apply gas counter pressure (GCP) in the injection molding process. By importing gas through the ends of the cavity, the melt was exposed to a melt front pressure, which, together with the packing pressure from the screw, is supposed to reduce product shrinkage. The aim was to investigate the impacts of GCP on the process parameters via the changes in machine feedback data, such as pressure and the remaining injection resin. This study also used a relatively thin plate-shaped product and measurements, such as the photoelastic effect and luminance meter, to probe into the impacts of GCP on product residual stress, while a relatively thick paper-clip-shaped product was used to see the impacts of GCP on shrinkage in thick parts. According to the experimental results, the addition of GCP resulted in increased filling volume, improvement of product weight and stability, and effective reduction of section shrinkage, which was most obvious at the point closest to the gas entrance. The shrinkage of the sections parallel and vertical to the flow direction was proved to be reduced by 32% and 16%, respectively. Moreover, observations made via the polarizing stress viewer and luminance meter showed that the internal residual stress of a product could be effectively reduced by a proper amount of GCP.

Bioactive poly(etheretherketone) composite containing calcium polyphosphate and multi-walled carbon nanotubes for bone repair: Mechanical property and in vitro biocompatibility

2018 ◽  
Vol 33 (5) ◽  
pp. 543-557 ◽  
Author(s):  
Jianfei Cao ◽  
Yue Lu ◽  
Hechun Chen ◽  
Lifang Zhang ◽  
Chengdong Xiong
Keyword(s):  
Mechanical Property ◽  
Carbon Nanotubes ◽  
Bone Repair ◽  
Mechanical Performance ◽  
Injection Molding Process ◽  
Molding Process ◽  
Calcium Polyphosphate ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Poly(etheretherketone) exhibits good biocompatibility, excellent mechanical properties, and bone-like stiffness. However, the natural bio-inertness of pure poly(etheretherketone) hinders its applications in biomedical field, especially when direct bone-implant osteo-integration is desired. For developing an alternative biomaterial for load-bearing orthopedic application, combination of bioactive fillers with poly(etheretherketone) matrix is a feasible approach. In this study, a bioactive multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite was prepared through a compounding and injection-molding process for the first time. Bioactive calcium polyphosphate was added to polymer matrix to enhance the bioactivity of the composite, and incorporation of multi-walled carbon nanotubes to composite was aimed to improve both the mechanical property and biocompatibility. Furthermore, the microstructures, surface hydrophilicity, and mechanical property of multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite, as well as the cellular responses of MC3T3-E1 osteoblast cells to this material were investigated. The mechanical testing revealed that mechanical performance of the resulting ternary composite was significantly enhanced by adding the multi-walled carbon nanotubes and the mechanical values obtained were close to or higher than those of human cortical bone. More importantly, cell culture tests showed that initial cell adhesion, cell viability, and osteogenic differentiation of MC3T3-E1 cells were significantly promoted on the multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite. Accordingly, the multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite may be used as a promising bone repair material in dental and orthopedic applications.

scholarly journals Effects of a Phosphorus Flame Retardant System on the Mechanical and Fire Behavior of Microcellular ABS

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 30 ◽  
Author(s):  
Vera Realinho ◽  
David Arencón ◽  
Marcelo Antunes ◽  
José Velasco
Keyword(s):  
Flame Retardant ◽  
Impact Energy ◽  
Weight Reduction ◽  
Flame Retardants ◽  
Mechanical Performance ◽  
Fire Behavior ◽  
Acrylonitrile Butadiene Styrene ◽  
Injection Molding Process ◽  
Molding Process ◽  
The Impact

The present work deals with the study of phosphorus flame retardant microcellular acrylonitrile–butadiene–styrene (ABS) parts and the effects of weight reduction on the fire and mechanical performance. Phosphorus-based flame retardant additives (PFR), aluminum diethylphosphinate and ammonium polyphosphate, were used as a more environmentally friendly alternative to halogenated flame retardants. A 25 wt % of such PFR system was added to the polymer using a co-rotating twin-screw extruder. Subsequently, microcellular parts with 10, 15, and 20% of nominal weight reduction were prepared using a MuCell® injection-molding process. The results indicate that the presence of PFR particles increased the storage modulus and decreased the impact energy determined by means of dynamic-mechanical-thermal analysis and falling weight impact tests respectively. Nevertheless, the reduction of impact energy was found to be lower in ABS/PFR samples than in neat ABS with increasing weight reduction. This effect was attributed to the lower cell sizes and higher cell densities of the microcellular core of ABS/PFR parts. All ABS/PFR foams showed a self-extinguishing behavior under UL-94 burning vertical tests, independently of the weight reduction. Gradual decreases of the second peak of heat release rate and time of combustion with similar intumescent effect were observed with increasing weight reduction under cone calorimeter tests.

In-Mold Monitoring of Temperature and Cavity Pressure During the Injection Molding Process

2014 ◽  
Author(s):  
Catalin Fetecau ◽  
Felicia Stan ◽  
Laurentiu I. Sandu
Keyword(s):  
Injection Molding ◽  
Pressure Sensors ◽  
Temperature Sensors ◽  
Injection Molding Process ◽  
Cavity Pressure ◽  
Molding Process ◽  
Shear Rates ◽  
Wide Range ◽  
Simulation Results ◽  
Two Temperature

This paper focuses on the in-mold monitoring of temperature and cavity pressure. The melt contact temperature and the cavity pressure along the flow path were directly measured using two pressure sensors and two temperature sensors fitted into the cavity of a spiral mold. Three melt temperatures and dies of different heights (1.0, 1.5 and 2 mm) were used to achieve a wide range of practically relevant shear rates. In order to analyze the extent to which the numerical simulation can predict the behavior of the molten polymer during the injection molding process, molding experiments were simulated using the Moldflow software and the simulation results were compared with the experimental data under the same injection molding conditions.

scholarly journals Effect of Pyrolysis Temperature on Biochar Microstructural Evolution, Physicochemical Characteristics, and Its Influence on Biochar/Polypropylene Composites

2019 ◽  
Vol 9 (6) ◽  
pp. 1149 ◽  
Author(s):  
Ahmed Y. Elnour ◽  
Abdulaziz A. Alghyamah ◽  
Hamid M. Shaikh ◽  
Anesh M. Poulose ◽  
Saeed M. Al-Zahrani ◽  
...  
Keyword(s):  
Microstructural Evolution ◽  
Pyrolysis Temperature ◽  
Physicochemical Characteristics ◽  
Thermomechanical Properties ◽  
Injection Molding Process ◽  
Chemical Compositions ◽  
Molding Process ◽  
Melt Mixing ◽  
Factors Affecting ◽  
Polypropylene Composites

Environmental management through effective utilization of biowastes has been a topic of intensive research in recent years. This study examines the effect of pyrolysis temperature on the physical and morphological characteristic of biochar (BC) derived from lignocellulosic wastes. The biochar was prepared by pyrolysing date palm biomass at various temperatures, i.e., 300, 400, 500, 600, and 700 °C. These pyrolysed biochars were then characterized for their carbon content, mineral compositions, chemical functionalities, and morphological structures, for understanding their physicochemical characteristics and microstructural evolution. It was revealed that the pyrolytic condition plays a key role in the formation of biochar microstructure. These biochar samples were then utilized without any further treatments/purifications for their practical application as reinforcement materials for polymer composites. They were blended with a polypropylene matrix by a melt mixing technique followed by injection molding process. The type of biochar was found to significantly affect the composites properties. Differences in microstructure, surface chemistry, and chemical compositions of BCs were observed to be determining factors affecting the compatibility and thermomechanical properties of resulted composites.

scholarly journals High-Performance of a Thick-Walled Polyamide Composite Produced by Microcellular Injection Molding

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4199
Author(s):  
Dariusz Sykutera ◽  
Piotr Czyżewski ◽  
Piotr Szewczykowski
Keyword(s):  
Injection Molding ◽  
High Performance ◽  
Flow Direction ◽  
Cell Diameter ◽  
Injection Molding Process ◽  
Polyamide 66 ◽  
Molding Process ◽  
Sem Images ◽  
Microcellular Injection Molding ◽  
Sink Mark

Lightweight moldings obtained by microcellular injection molding (MIM) are of great significance for saving materials and reducing energy consumption. For thick-walled parts, the standard injection molding process brings some defects, including a sink mark, warpage, and high shrinkage. Polyamide 66 (PA66)/glass fiber (GF) thick-walled moldings were prepared by MuCell® technology. The influences of moldings thickness (6 and 8.4 mm) and applied nitrogen pressure (16 and 20 MPa) on the morphology and mechanical properties were studied. Finally, the microcellular structure with a small cell diameter of about 30 μm was confirmed. Despite a significant time reduction of the holding phase (to 0.3 s), high-performance PA66 GF30 foamed moldings without sink marks and warpage were obtained. The excellent strength properties and favorable impact resistance while reducing the weight of thick-walled moldings were achieved. The main reason for the good results of polyamide composite was the orientation of the fibers in the flow direction and the large number of small nitrogen cells in the core and transition zone. The structure gradient was analysed and confirmed with scanning electron microscopy (SEM) images, X-ray micro computed tomography (micro CT) and finite element method (FEM) simulation.

Physical and mechanical performance of bentonite and barite loaded low density polyethylene composites: Influence of surface silanization of minerals

2020 ◽  
Vol 54 (28) ◽  
pp. 4359-4368 ◽  
Author(s):  
Hesham Elkawash ◽  
Seha Tirkes ◽  
Firat Hacioglu ◽  
Umit Tayfun
Keyword(s):  
Mechanical Performance ◽  
Water Repellency ◽  
Surface Characteristics ◽  
Melt Flow Index ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Injection Molding Process ◽  
Low Density ◽  
Melt Flow ◽  
Molding Process

In this study, two kinds of mineral fillers, bentonite (BNT) and barite (BRT), were incorporated into low density polyethylene (LDPE) by extrusion process. Silane treatment was applied to BRT and BNT surfaces in order to increase their compatibility with LDPE matrix. Surface characteristics of fillers were examined by Fourier transformed infrared spectroscopy (FTIR). LDPE-based composites were prepared at a constant concentration of 10%wt for each additives. Test samples were shaped by injection molding process. Mechanical, thermo-mechanical, water repellency, melt-flow and morphological characterizations of LDPE and its composites were performed by tensile and impact tests, dynamic mechanical analysis (DMA), water absorption test, melt flow index (MFI) measurements and scanning electron microscopy (SEM) technique, respectively. Test results showed that surface treatments led to increase for final properties of composites since they promoted to stronger adhesion between minerals and LDPE matrix compared to untreated ones. Tensile and impact strength values, storage modulus and glass transition temperature of LDPE were improved by inclusion of silane treated minerals. BRT and BNT additions caused no remarkable changes with regard to MFI of LDPE. Additionally, silane modified mineral filled composites exhibited remarkable water resistance behavior. According to SEM analysis of composites, silane treated BNT and BRT containing samples displayed homogeneous dispersions into LDPE phase whereas debondings were observed for untreated BNT and BRT filled composites due to their weak adhesion to polymer matrix.

Experimental study of penetration interfaces in the overflow fluid-assisted co-injection molding process

2016 ◽  
Vol 36 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Tangqing Kuang ◽  
Chuncong Yu ◽  
Baiping Xu ◽  
Lih-Sheng Turng
Keyword(s):  
Experimental Study ◽  
Injection Molding ◽  
Cross Section ◽  
High Density Polyethylene ◽  
Flow Direction ◽  
Injection Molding Process ◽  
Molding Process ◽  
The Difference ◽  
The Stability ◽  
Plastic Products

Abstract The fluid-assisted co-injection molding (FACIM) process can be used to produce hollow plastic products with outer and inner layers. It can be divided into two categories: water-assisted co-injection molding (WACIM) and gas-assisted co-injection molding (GACIM). An experimental study of penetration interfaces in overflow FACIM was carried out based on a lab-developed FACIM system. High-density polyethylene and polypropylene were used as the outer layer and inner layer plastics, respectively, in the experiments and the injection sequence was reversible. Six cross-section cavities were investigated in the experiments. The penetration behaviors of water and gas in different sequences and cavities were compared and analyzed. The penetration interfaces were characterized by the residual wall thickness (RWT). The experimental results showed that the RWT of the inner layer in WACIM fluctuated along the flow direction, while that in GACIM was more even. The difference of viscosity between the outer and inner layer melts affected the stability of the interface between them. The penetration sections of the inner layer and the gas were closer to the cavity sections in GACIM, while the penetration sections of the inner layer and the water were closer to the circular forms in WACIM.

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