Effects of dynamic mold temperature control on melt pressure, cellular structure, and mechanical properties of microcellular injection-molded parts: An experimental study

2019 ◽  
Vol 38 (5-6) ◽  
pp. 111-130
Author(s):  
Guiwei Dong ◽  
Guoqun Zhao ◽  
Junji Hou ◽  
Guilong Wang ◽  
Yue Mu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Temperature Control ◽  
Cellular Structure ◽  
Weld Line ◽  
Mold Temperature ◽  
Cell Diameter ◽  
Cooling Stage ◽  
Molded Parts

In this work, the effects of dynamic mold temperature control (DMTC) on melt pressure, cellular structure, and mechanical properties of microcellular injection molding (MIM)-molded parts are investigated experimentally. It is found that with the increase of the mold temperature, the duration of foaming pressure in the cooling stage increases. Meanwhile, the average cell diameter and cell diameter dispersion increases as well as the cell density decreases in MIM molded parts. The turning point of mold temperature after which the foaming pressure in the cooling stage and the cellular structure in MIM molded parts generate a significant change is around the glass transition temperature of the used plastic material. Under DMTC conditions, with the increase of mold temperature, the tensile strength, flexural strength, and impact strength of MIM molded specimens of single gate without weld line change a little, while the tensile strength, flexural strength of MIM molded specimens of double gates with weld line increase obviously. When the mold temperature increases to 120°C and over, the tensile strength, flexural strength of MIM molded specimens of double gates with weld line reach an equivalent level of specimens of single gate without weld line.

Effect of Weld Line Formation on Morphology and Mechanical Properties for 3D-MID Technology

2015 ◽  
Vol 659 ◽  
pp. 659-665
Author(s):  
Supakit Chuaping ◽  
Thomas Mann ◽  
Rapeephun Dangtungee ◽  
Suchart Siengchin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Injection Molding ◽  
Filler Content ◽  
Research Work ◽  
Weld Line ◽  
Processing Conditions ◽  
High Reduction ◽  
Flexural Tests

The topic of this research work was to demonstrate the feasibility of a 3D-MID concept using injection molding technique and investigate the effects of two weld line types on the structure and mechanical properties such as tensile, flexural strength and morphology. In order to obtain more understanding of the bonds between polymer and metals, two different polymer bases of polyphthalamide (PPA) with the same type and amount of filler content were produced by injection molding at the different processing conditions. A mold was designed in such a way that weld and meld line can be produced with different angles by changing as insert inside of the mold. The mechanical properties such as stiffness, tensile strength and flexural strength were determined in tensile and flexural tests, respectively. The results showed in line with the expectation of high reduction on mechanical properties in area where weld/meld lines occurred. The result of tensile test was clearly seen that weld and meld line showed a considerable influence on mechanical properties. The reduction in tensile strength was approximately 58% according to weld line types, whereas in flexural strength was approximately 62%. On the other hand, the effect of the injection times and mold temperatures on the tensile strength were marginal.

A method to improve dimensional accuracy and mechanical properties of injection molded polypropylene parts

2017 ◽  
Vol 37 (4) ◽  
pp. 323-334 ◽  
Author(s):  
Shuai Li ◽  
Guoqun Zhao ◽  
Jiachang Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Injection Molding ◽  
Weld Line ◽  
Dimensional Accuracy ◽  
Holding Time ◽  
Dimensional Shrinkage ◽  
Injection Molded ◽  
The Impact

Abstract Gas counter pressure (GCP) technology can impose a reverse pressure to melt and thereby effectively increase the pressure acting on the melt at flow front. Theoretically, it has a potential to solve some defects often occurring in conventional injection molding (CIM) process. This paper designed and manufactured a GCP injection mold. GCP injection molding experiments were conducted. Effects of GCP process on melt flow and density, dimensional accuracy, and mechanical properties of molded samples were investigated. The results showed that GCP process can effectively inhibit the “fountain effect” in melt filling process, decrease the dimensional shrinkage of molded samples, increase dimensional accuracy of samples, and effectively improve impact property of samples. For the samples without weld line, tensile strength and flexural strength of GCP injection molded samples are slightly increased in comparison with those of CIM samples, but for the samples with weld line, GCP process can greatly improve the tensile strength and flexural strength of molded samples. When GCP is 9 MPa and GCP holding time is 10 s, the dimensional accuracy of molded samples without weld line, the tensile strength and flexural strength of the molded samples with weld line all increase up to maximum values. In comparison with CIM samples, the dimensional shrinkage of samples without weld line decreases by 17.2%, the tensile strength and flexural strength of samples with weld line increase by 30.51% and 23.69%, respectively. The impact value of the samples molded by process parameter combination of GCP 9 MPa and GCP holding time 20 s is the highest, and the impact value increases by 18.65%.

Preparation and Properties of Wood Flour/HDPE Microcellular Foamed Composites

2015 ◽  
Vol 1094 ◽  
pp. 105-108
Author(s):  
Hong Li Jiang ◽  
Jing Lun Zhou ◽  
Jian Dong ◽  
Yu Min Wang ◽  
Jiu Yong Ruan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Flexural Strength ◽  
Wood Flour ◽  
Cell Diameter

The wood flour/HDPE microcellular foamed composites were prepared by means of torque rheometer. The effect of different wood flour content on mechanical properties and foamed behavior were studied. Results showed that the tensile strength and flexural strength of microcellular foamed composites first increased then decreased and the notched impact strength decreased with addition of wood flour, this was consistent with non-foamed composites. The density of composites increased and the density of foamed composites was less than non-foamed composites. With increasing wood flour content, the cell diameter of foamed composites first decreased then increased. When the content of wood flour was 40%, the cell diameter of the composites obtained the minimal value.

scholarly journals External Gas-Assisted Mold Temperature Control Improves Weld Line Quality in the Injection Molding Process

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2855 ◽  
Author(s):  
Tran Minh The Uyen ◽  
Nguyen Truong Giang ◽  
Thanh Trung Do ◽  
Tran Anh Son ◽  
Pham Son Minh
Keyword(s):  
Tensile Strength ◽  
Temperature Control ◽  
Weld Line ◽  
Flow Simulation ◽  
Mold Temperature ◽  
Cavity Surface ◽  
Injection Molding Process ◽  
Molding Process ◽  
Packing Pressure ◽  
The Impact

Simulations and experiments were conducted with gas temperatures of 200–400 °C to investigate the impact of external gas-assisted mold temperature control (Ex-GMTC) on the quality of weld line of molding products. In the heating step, the heating rate was 19.6 °C/s from 30 to 128.5 °C in the first 5 s in a 400 °C gas environment. When applied to heating the weld line area of an injection mold, Ex-GMTC improved the appearance of the weld line when the cavity temperature was preheated to 150 °C. For the tensile strength test, a melt flow simulation comparing the packing pressure of different mesh thicknesses revealed that Ex-GMTC helped maintain a high pressure in the weld line area in different packing periods. This was verified by an experiment where Ex-GMTC was applied with 400 °C gas to change the mesh area temperature. The result indicated that an increase in the weld line area temperature from 60 to 180 °C improves the tensile strength of all mesh thicknesses, which was more pronounced with thinner parts, especially at 0.4 mm. The simulations revealed that high temperature is concentrated in the weld line area of the cavity surface, thus reducing the energy wasted during heating.

Mechanical Property Improvement of Poly(Butylene Succinate) by Reinforcing with Modified Fumed Silica

2014 ◽  
Vol 1025-1026 ◽  
pp. 215-220 ◽  
Author(s):  
Sasirada Weerasunthorn ◽  
Pranut Potiyaraj
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Flexural Strength ◽  
Fumed Silica ◽  
Tensile Modulus ◽  
Silica Particles ◽  
Melt Mixing ◽  
Butylene Succinate ◽  
Ir Spectrophotometry

Fumed silica particles (SiO2) were directly added into poly (butylene succinate) (PBS) by melt mixing process. The effects of amount of fumed silica particles on mechanical properties of PBS/fumed silica composites, those are tensile strength, tensile modulus, impact strength as well as flexural strength, were investigated. It was found that the mechanical properties decreased with increasing fumed silica loading (0-3 wt%). In order to increase polymer-filler interaction, fumed silica was treated with 3-glycidyloxypropyl trimethoxysilane (GPMS), and its structure was analyzed by FT-IR spectrophotometry. The PBS/modified was found to possess better tensile strength, tensile modulus, impact strength and flexural strength that those of PBS/fumed silica composites.

scholarly journals Performance Evaluation of Cellulose Nanofiber with Residual Hemicellulose as a Nanofiller in Polypropylene-Based Nanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1064
Author(s):  
Mohd Nor Faiz Norrrahim ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Mohd Ali Hassan ◽  
Nor Azowa Ibrahim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Weight Loss ◽  
Tensile Strength ◽  
Performance Evaluation ◽  
Flexural Strength ◽  
Decomposition Temperature ◽  
Cellulose Nanofiber ◽  
Hemicellulose Removal ◽  
Reinforcement Material

Residual hemicellulose could enhance cellulose nanofiber (CNF) processing as it impedes the agglomeration of the nanocellulose fibrils and contributes to complete nanofibrillation within a shorter period of time. Its effect on CNF performance as a reinforcement material is unclear, and hence this study seeks to evaluate the performance of CNF in the presence of amorphous hemicellulose as a reinforcement material in a polypropylene (PP) nanocomposite. Two types of CNF were prepared: SHS-CNF, which contained about 11% hemicellulose, and KOH-CNF, with complete hemicellulose removal. Mechanical properties of the PP/SHS-CNF and PP/KOH-CNF showed an almost similar increment in tensile strength (31% and 32%) and flexural strength (28% and 29%) when 3 wt.% of CNF was incorporated in PP, indicating that hemicellulose in SHS-CNF did not affect the mechanical properties of the PP nanocomposite. The crystallinity of both PP/SHS-CNF and PP/KOH-CNF nanocomposites showed an almost similar value at 55–56%. A slight decrement in thermal stability was seen, whereby the decomposition temperature at 10% weight loss (Td10%) of PP/SHS-CNF was 6 °C lower at 381 °C compared to 387 °C for PP/KOH-CNF, which can be explained by the degradation of thermally unstable hemicellulose. The results from this study showed that the presence of some portion of hemicellulose in CNF did not affect the CNF properties, suggesting that complete hemicellulose removal may not be necessary for the preparation of CNF to be used as a reinforcement material in nanocomposites. This will lead to less harsh pretreatment for CNF preparation and, hence, a more sustainable nanocomposite can be produced.

scholarly journals Preparation and properties of silicone rubber materials with foam/solid alternating multilayered structures

2021 ◽  
Author(s):  
Wenhuan Zhang ◽  
Zhaoping Deng ◽  
Hongwei Yuan ◽  
Shikai Luo ◽  
Huayin Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silicone Rubber ◽  
Cellular Structure ◽  
Cellular Structures ◽  
Compressive Property ◽  
Solid Layer ◽  
Multilayered Structures ◽  
Element Analysis ◽  
Morphology And Mechanical Properties

AbstractIn this paper, silicone rubber materials with foam/solid alternating multilayered structures were successfully constructed by combining the two methods of multilayered hot-pressing and supercritical carbon dioxide (SCCO2) foaming. The cellular morphology and mechanical properties of the foam/solid alternating multilayered silicone rubber materials were systematically studied. The results show that the growth of the cell was restrained by the solid layer, resulting in a decrease in the cell size. In addition, the introduction of the solid layer effectively improved the mechanical properties of the microcellular silicone rubber foam. The tensile strength and compressive strength of the foam/solid alternating multilayered silicone rubber materials reached 5.39 and 1.08 MPa, which are 46.1% and 237.5% of the pure silicone rubber foam, respectively. Finite element analysis (FEA) was applied and the results indicate that the strength and proportion of the solid layer played important roles in the tensile strength of the foam/solid alternating multilayered silicone rubber materials. Moreover, the small cellular structures in silicone rubber foam can provided a high supporting counterforce during compression, meaning that the microcellular structure of silicone rubber foam improved the compressive property compared to that for the large cellular structure of silicone rubber foam.

Influence of the Composition of Cement Mortars Modified by Lime or Polymers on the Mechanical Properties and Microstructure of Mortars

2013 ◽  
Vol 592-593 ◽  
pp. 647-650 ◽  
Author(s):  
Małgorzata Lenart
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Polymer Composites ◽  
Adhesion Strength ◽  
Hardened Cement ◽  
Cement Mortars ◽  
Styrene Butadiene

Cement – polymer composites are nowadays widely used in repair systems not only in case of concrete or reinforced concrete constructions but also in masonry. Polymers addition for example already at 5% m.c. modifies the structure of the cement – polymer composite in a way that many of the mechanical properties such as flexural strength, tensile strength or adhesion to substrates are improved. The paper presents the results of tests such as flexural, compressive or adhesion strength to ceramic substrate of hardened cement mortars with different composition, as well as selected cement mortars modified by two polymers: polyvinyl alcohol and styrene – butadiene polymer dosed at 5 % m.c. Four types of cement mortars modified by lime (component used in historical constructions as well as in contemporary masonry mortars) are also examined for comparison.

Effect of using magnetic water on the mechanical properties of concrete exposed to elevated temperature

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wasim Barham ◽  
Ammar AL-Maabreh ◽  
Omar Latayfeh
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Flexural Strength ◽  
Tap Water ◽  
Splitting Tensile Strength ◽  
Content Type ◽  
Normal Water ◽  
Magnetic Water

PurposeThe influence of using magnetic water instead of tap water in the mechanical properties of the concrete exposed to elevated temperatures was investigated. Two concrete mixes were used and cast with the same ingredients. Tap water was used in the first mix and magnetic water was used in the second mix. A total of 48 specimens were cast and divided as follows: 16 cylinders for the concrete compressive strength test (8 samples for each mix), 16 cylinders for the splitting tensile strength (8 specimens for each mix) and 16 beams to test the influences of magnetized water on the flexural strength of concrete (8 specimens for each mixture). Specimens were exposed to temperatures of (25 °C, 200 °C, 400 °C and 600 °C). The experimental results showed that magnetic water highly affected the mechanical properties of concrete. Specimens cast and curried out with magnetic water show higher compressive strength, splitting tensile strength and flexural strength compared to normal water specimens at all temperatures. The relative strength range between the two types of water used was 110–123% for compressive strength and 110–133% for splitting strength. For the center point loading test, the relative flexural strength range was 118–140%. The use of magnetic water in mixing concrete contribute to a more complete hydration process.Design/methodology/approachExperimental study was carried out on two concrete mixes to investigate the effect of magnetic water. Mix#1 used normal water as the mixing water, and Mix#2 used magnetic water instead of normal water. After 28 days, all the samples were taken out of the tank and left to dry for seven days, then they were divided into different groups. Each group was exposed to a different temperature where it was placed in a large oven for two hours. Three different tests were carried out on the samples, these tests were concrete compressive strength, flexural strength and splitting tensile strength.FindingsExposure of concrete to high temperatures had a significant influence on concrete mechanical properties. Specimens prepared using magnetic water showed higher compressive strength at all temperature levels. The use of magnetic water in casting and curing concrete can increase the compressive strength by 23%. Specimens prepared using magnetic water show higher splitting tensile strength at all temperatures up to 33%. The use of magnetic water in casting and curing can strengthen and increase concrete resistance to high temperatures, a significant enhancement in flexural strength at all temperatures was found with a value up to 40%.Originality/valuePrevious research proved the advantages of using magnetic water for improving the mechanical properties of concrete under normal conditions. The potential of using magnetic water in the concrete industry in the future requires conducting extensive research to study the behavior of magnetized concrete under severe conditions to which concrete structures may be subjected to. These days, there are attempts to obtain stronger concrete with high resistance to harsh environmental conditions without adding new costly ingredients to its main mixture. No research has been carried out to investigate the effect of magnetic water on the mechanical properties of concrete exposed to elevated temperature. The main objective of this study is to evaluate the effect of using magnetic water on the mechanical properties of hardened concrete subjected to elevated temperature.

scholarly journals The Mechanical Properties of Steel-Polypropylene Fibre Composites Concrete (HyFRCC)

2015 ◽  
Vol 773-774 ◽  
pp. 949-953 ◽  
Author(s):  
Izni Syahrizal Ibrahim ◽  
Wan Amizah Wan Jusoh ◽  
Abdul Rahman Mohd Sam ◽  
Nur Ain Mustapa ◽  
Sk Muiz Sk Abdul Razak
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Concrete Strength ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Polypropylene Fibre ◽  
Experimental Results

This paper discusses the experimental results on the mechanical properties of hybrid fibre reinforced composite concrete (HyFRCC) containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The mechanical properties include compressive strength, tensile strength, and flexural strength. SF is known to enhance the flexural and tensile strengths, and at the same time is able to resist the formation of macro cracking. Meanwhile, PPF contributes to the tensile strain capacity and compressive strength, and also delay the formation of micro cracks. Hooked-end deformed type SF fibre with 60 mm length and fibrillated virgin type PPF fibre with 19 mm length are used in this study. Meanwhile, the concrete strength is maintained for grade C30. The percentage proportion of SF-PPF fibres are varied in the range of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% of which the total fibre volume fraction (Vf) is fixed at 0.5%. The experimental results reveal that the percentage proportion of SF-PPF fibres with 75-25% produced the maximum performance of flexural strength, tensile strength and flexural toughness. Meanwhile, the percentage proportion of SF-PPF fibres with 100-0% contributes to the improvement of the compressive strength compared to that of plain concrete.

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