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Title: The effects of hemp fibres on the mechanical and physical properties of E-glass fibres reinforced polypropylene (Twintex) composites
Author: Al-Kahtani, Salah Msfir
ISNI:       0000 0004 2699 1885
Awarding Body: University of Portsmouth
Current Institution: University of Portsmouth
Date of Award: 2005
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The main aim of this research is to investigate the mechanical and environmental properties of E-glass/polypropylene (Twintex) composite with and without natural fibres (Hemp) reinforcementA. serieso f lab testsw ere done to explain the impact damage characteristics of the composites were evaluated. The impact of mass applied started with 3.6 Kg and was incremented 3 Kg at a time to a maximum mass of 18.6 Kg. The effect of the impact damage and velocity was found to be significant- within the range of the velocities used. The absorbed impact energy significantly affected the impact performance of the Twintex panels. On the other hand, Twintex panels showed an ability to confine the damage zone and hence, to increase the damage tolerance of the panels. The results of impact were analysed using C-Scan. They significantly show that with the increase of mass the area of damage increases accordingly. The flexural properties of composite samples were evaluated by 3-point bending test methods. In contrast, the loads for sample's deformation in three-point bending test proved to be less when high-impact loaded samples were used. For the samples without hemp, the highest flexural stress was 317.616 MPa and the lowest was 116.552 MPa. The highest flexural modulus was 9937.63 MPa and the lowest was 4439.898 MPa. The effect of the flexural percentage of the load decreases with the increase of mass. The load decrease from sample 1 to sample 7, which indicated a loss in flexural strength by 63.03% and a loss in flexural modulus by 55.32%. With hemp reinforcement the highest flexural stress was found 189.092 MPa and the lowest was 101.763 MPa. The highest flexural modulus was found 10299.37 MPa and the lowest was 2437.73 MPa. The effect of the flexural percentage of the load decreases with the increase of mass. Twintex plus hemp retained 85.81 % of the original flexural strength it means that adding of hemp into the Twintex reduces the strength of the sample by 2.01 %. IV Abstract Tensile test results show the tangent modulus for the Twintex has reach to 1967.79 MPa, however adding hemp into the Twintex decrease the tangent modulus by 1.465% times. This is meant that the Twintex plus hemp makes the material weaker and softer. The Twintex plus hemp will be weaker by 30.765%. The SEM evaluation also shows that by increasing the impact load the state of the damage becomes more severe. There arc more instances of brittle and catastrophic fibre damages with high impact load. The Twintex plus hemp samples gained in weight, as expected, by an average of 2.64%. This 2.64% increase, assuming that the hemp absorbs all the water and not the polypropylene, means that the fibres increased weight by approximately 8.2%. Along with this increase in weight, the fibres also expanded due to the water absorption. After the water bath the samples lost only 2.5% of their flexural strength and an insignificant loss in flexural modulus. The addition of hemp caused a 35.4% reduction in the flexural modulus of the samples. This means that the samples with hemp became more elastic, deforming more than samples without the hemp layers. The effect of water absorption seemed to have little effect on any of the samples, with the largest effect being a 5.4% reduction in water boiled Twintex and hemp samples. Twintex obtains its highest flexural modulus properties from the glass fibres in the matrix. A reduction (35.4%) suggests that the reinforcement properties of the glass fibres are being reduced due to the incorporation of the hemp. This could be due to the hemp fibres taking away matrix material from the glass fibres in the centre of the sample. Creep and Stress relaxation properties of the sandwich panels with and without natural reinforcements were investigated and compared under different temperatures such as 30 °C, 40 °C, 50 °C, 60 °C. Melting point of both materials was determined. These qualitative and quantitative conclusions can be drawn regarding the use of hemp as reinforcement in Twintex sandwich panel.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available