scholarly journals Space charges formed in the hot compression molding process of low density polyethylene

2007 ◽  
Vol 56 (9) ◽  
pp. 5502
Author(s):  
An Zhen-Lian ◽  
Yang Qiang ◽  
Zheng Fei-Hu ◽  
Zhang Ye-Wen
Keyword(s):  
Compression Molding ◽  
Hot Compression ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Molding Process ◽  
Space Charges

Research on DC dielectric properties of polyaniline nanofibers/LDPE composites

2016 ◽  
Vol 30 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Changming Li ◽  
Sixu Duan ◽  
Chengcheng Zhang ◽  
Jian Zhang ◽  
Baozhong Han
Keyword(s):  
Space Charge ◽  
Breakdown Strength ◽  
Dc Conductivity ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Polyaniline Nanofibers ◽  
Pani Nanofibers ◽  
Space Charges ◽  
Space Charge Distribution ◽  
Ldpe Composites

In this article, polyaniline (PANI) nanofibers were prepared and added to low-density polyethylene (LDPE) to produce PANI nanofibers/LDPE composites. LDPE and the composites were tested for direct current (DC) conductivity, breakdown strength, and space charge characteristics. The results suggested that DC breakdown strength of PANI nanofibers/LDPE composites significantly declined once PANI was added, and the decline was more evident with the increase of PANI nanofibers. Meanwhile, the addition of PANI nanofibers contributed to a decrease in the conductivity of LDPE. As the content of PANI nanofibers increased, the conductivity of the composites declined first and then raised. DC conductivity properties of LDPE could be improved by adding an appropriate amount of PANI nanofibers. Compared with LDPE, the space charge distribution was changed in LDPE due to the addition of PANI nanofibers. With the increase of content of PANI nanofibers, the amount of space charges close to the electrodes decreased gradually.

Compression Molding and Nickel Molds for Directional Gecko-Inspired Adhesives

2021 ◽  
Author(s):  
Capella F Kerst ◽  
Mark R. Cutkosky
Keyword(s):  
Ambient Temperature ◽  
Compression Molding ◽  
Hot Compression ◽  
Molding Process ◽  
Surface Features ◽  
Cycle Times ◽  
The Common ◽  
Temperature And Pressure ◽  
Microscopic Surface ◽  
Adhesive Performance

Abstract In the fabrication of directional gecko-inspired adhesives, a new capability made possible by the availability of metal molds is hot compression molding. This molding process allows the use of elastomers with much higher toughness than those cast at ambient temperature and pressure, as has been the common case in fabricating adhesives. In addition, it permits fast cycle times (minutes instead of hours), which is useful for volume manufacturing. We present the results of hot compression molding of elastomers in metal molds created with overhanging and tapered microscopic surface features, which give rise to anisotropic adhesion. We show that the adhesive performance so obtained is equivalent to that obtained earlier with PDMS.

Curing of Glass Fiber/Epoxy Resin Composites Using Multiwalled Carbon Nanotubes Buckypaper as a Resistive Element

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
J. A. Rojas ◽  
B. Ribeiro ◽  
M. C. Rezende
Keyword(s):  
Glass Fiber ◽  
Epoxy Resin ◽  
Compression Molding ◽  
Hot Compression ◽  
Resin Composites ◽  
Curing Process ◽  
Molding Process ◽  
Multiwalled Carbon ◽  
Resistive Element ◽  
Epoxy Resin Composites

Abstract Glass fiber/epoxy resin composites (GF/EP) were prepared using one and three multiwalled carbon nanotube buckypapers (BPs) as a resistive element. Compared to the conventional hot compression molding process that demanded 4200 W to fabricate the GF/EP laminate, the proposed curing process consumed only 63 W, representing a saving power of 98.5%. The thermal distribution of the BP and their composites were recorded using an infrared thermometer. Differential scanning calorimetry (DSC) curves have not shown a residual cure, suggesting the curing process using the BP as a resistive element was effective. The cross section views of the laminates were analyzed by scanning electron microscopy (SEM), and the mechanical characterizations were performed by impulse excitation technique (IET), compression shear test (CST), and interlaminar shear strength (ILSS). The results demonstrated that the BP composites showed a good consolidation between the prepregs layers, and presented no significant variations in the mechanical tests compared to the traditional hot compression molding process. Nevertheless, dynamic mechanical analyses (DMA) showed a slight decrease in the BP composites’ storage moduli compared to GF/EP laminate.

Experimental investigation of linear low density polyethylene composites based on coir for rotational molding process

2020 ◽  
pp. 096739112095324
Author(s):  
Nikita Gupta ◽  
PL. Ramkumar
Keyword(s):  
Thermal Analysis ◽  
Weight Ratio ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Coir Fiber ◽  
Linear Low Density Polyethylene ◽  
Rotational Molding ◽  
Molding Process ◽  
Weight Percentage ◽  
Heat Parameter

Rotational Molding is a plastic manufacturing process mainly implemented to produce stress free hollow products. Linear Low Density Polyethylene (LLDPE) is widely preferred as base resin for molding roto molded product, but it displays moderate value in some critical applications where strength is the major criteria. Additives can fill the gap in sustaining the necessary strength needed. In the present work, an attempt has been made to analyze the optimum percentage of coir reinforced with LLDPE for rotational molding technique to provide requisite processability for rotational molding process. Coir in its powder form is mixed at concentrations varying in the range of 3% to 20% with respect to LLDPE. In order to justify the prerequisite of processability for rotational molding, various experiments namely FTIR, MFI, rheology and thermal analysis were conducted. FTIR suggested the range of 5% to 15% wherein the significance of LLDPE and coir peaks can be observed. MFI test supported FTIR result which ended in considering 3% to 12% by weight ratio suitable in terms of flow ability. Rheological and thermal analysis subjecting to shear and heat parameter respectively, confirmed the range of 10 weight percentage of coir or below is suitable in terms of material processability. From the experimental results, it is concluded that 10% or less concentration of coir fiber in LLDPE as an optimum range of blend yielding better processability for rotational molding process.

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.

Date Seeds Fiber Reinforced Low-Density Polyethylene: Effect of Stearic Acid on its Mechanical and Morphological Characteristics

2021 ◽  
Vol 1021 ◽  
pp. 290-298
Author(s):  
Abduati Elnaid ◽  
N.Z. Noriman
Keyword(s):  
Tensile Strength ◽  
Morphological Characteristics ◽  
Fiber Surface ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Molding Process ◽  
Elongation At Break ◽  
Impact Properties ◽  
Different Content

The effect of different content of steric acid (3, 6 and 9 wt.%) on the mechanical properies (tensile, flexural and impact properties) and morphology of linear low-density polyethylene / date seeds (LLDPE/DS) composites were evaulated in this research. The composites were produced by using extrusion followed by injuction molding process. Results presented that the addition of steric acid at 3 wt.% to the composite has shown highest tensile strength and elongation at break as compared to other treated samples. This is due to the improvement on the fiber surface in presence of SA. However, the tensile strength and elongation at break decreased thereafter treatment with 6% and 9% of SA. Furthermore, the flexural and impact properties have shown the same trend of the tensile properties, this was consistent with the results shown on SEM micrographs.

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