Effects of Natural Sand on the Mechanical Properties of High Density Polyethylene and Polypropylene
Composite materials were manufactured from two semi-crystalline thermoplastic polymers namely, high density polyethylene and polypropylene using Malaysian natural sand as filler. The chemical content and structure of the filler were studied using XRF and XRD respectively. Two different types of natu...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2009
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| Online Access: | http://utpedia.utp.edu.my/3022/1/TESFA_-_THESIS.pdf http://utpedia.utp.edu.my/3022/ |
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| Summary: | Composite materials were manufactured from two semi-crystalline thermoplastic polymers namely, high density polyethylene and polypropylene using Malaysian natural sand as filler. The chemical content and structure of the filler were studied using XRF and XRD respectively. Two different types of natural sand, Silica Sand (SS) and Beach Sand (BS) were used for comparison purpose. Test results from composite containing 10% by weight of each filler show that SS composite is much better than the BS composite. The effects of the natural SS content on the mechanical properties of the composite were investigated too. For the study, the composite was prepared in four different filler concentrations by weight of the polymer matrix, 0%, 5%, 10% and 15% using melt mixing process. A decrease in tensile strength of 10.3% and 9.3%, maximum elongation of 19.18% and 26.41% and a substantial increase in stiffness of around 42.9% and 5.8% were observed for the untreated HDPE/SS and PP/SS composites at 15wt% filler content respectively. Flexural test results for the polymer composites show a maximum modulus at 15wt% of 8.0% and an increasing trend of flexural strength for untreated HDPE/SS composite. On the other hand, for untreated PP/SS composite, a decrease in maximum deflection of 1.5% and an increment in flexural modulus of 19.7% and flexural strength of 3.5% have been observed at 15wt% filler content.
The interfacial interaction between filler and matrix was studied by applying chemical treatment on the SS filler using silane coupling agent (SCA). The two types of SCA, γ-methacryloxypropyltrimethoxysilane (MTS) and vinyltriethoxysilane (VTES) were used for treatment. Samples prepared in the same manner as the untreated samples were tested. The HDPE/SS composites showed a tremendous increment in tensile strength and tensile modulus but a reduction in maximum elongation. Analysis of the treated PP composite showed a slight decrease in tensile strength and maximum deflection but a substantial increase in modulus of elasticity was observed as the percentage of filler was increased. Improvements in the flexural strength and flexural modulus were also recorded. A comparison of mechanical properties between 10wt% HDPE composites produced from MTS and VTES revealed that MTS is better than VTES.
Morphology of the fractured surface from tensile test was analyzed by using Scanning Electron Microscopy (SEM). The microstructure revealed that there is weak interaction between the untreated filler and the matrix. On the other hand, a clear interfacial interaction was observed between the filler and polymer matrix in the case of treated sample.
Thermal properties, mixing torque and rheology of the composite were also studied. It was found that the melting and crystalline temperatures show a slight increment of about 1.14% and 1.40% for 15wt% treated HDPE/SS composite. On the other hand, a decrease in melting and crystalline temperature of 0.74% and 0.04% for treated PP/SS composite respectively. The maximum torque required for mixing and rheological properties such as viscosity and shear rate were also increased with the filler content for the untreated composite sample. In the case of treated composite samples, the viscosity show a decrement compared to the untreated composite with maximum decrement of 35.6% was achieved at 15 wt%.
Since this study is in a laboratory level, the maximum amount of filler is limited 15wt%. Applying a filler content of more than 15wt% can cause severe wear of the machine parts during mixing process.
Key words: Natural sand, |
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