Physio-thermo-mechanical and morphological properties ofhybrid polypropylene / kenaf /rice husk / calcium carbonate composite / Mohd Muizz Fahimi Mohamed

• Main Author: Mohamed, Mohd Muizz Fahimi
• Format: Thesis
• Language: English
• Published: 2018
• Online Access: https://ir.uitm.edu.my/id/eprint/86919/1/86919.pdf; https://ir.uitm.edu.my/id/eprint/86919/

The abundance of lignocellulosic filler in the nature has driven researchers to develop new products from the material. This research has used plant sourced lignocellulosic material that is turned into composite filler due to its wide range of properties and flexibility. Lignocellulosic filler is widely researched because it is environmental friendly, readily degraded in natural environment, non-toxic and non-abrasive. This material is sourced from plant waste such as rice husk and sustainably grown kenaf thus making it cheap and green and thus added into polymeric material to conform into hybrid composite. The major material of the hybrid composite is polypropylene (PP) which has been reinforced with the addition of kenaf fiber and rice husk. Calcium carbonate (CaCO3) was added to increase the impact strength of the hybrid composite for end consumer application. CaCO3 is a cheap source of mineral filler and has been proven to escalate the hybrid composite by previous researchers. The hybrid composite pellets were then hot compressed into one piece and portioned into different sizes for characterisation purposes. The samples were then characterized for physical, mechanical, thermal and morphological properties. Formulations of the hybrid composite were done by keeping the PP and CaCO3 ratios fixed while changing the percentages of kenaf fiber and rice husk particulate. The weight percentages of PP and CaCO3 were kept constant by 40wt.% and 20wt.%, respectively. The remaining 40wt.% of composite elements were varied from 0wt.% to 35wt.% for kenaf fibers and vice versa for rice husk particulate. The formulations were made into seven hybrid formulations with systematic percentage variation. During compounding of hybrid composite, the Twin Screw Extrusion was set to temperature of 190°C at 50 rpm. Density and water absorption tests were done for physical properties. Tensile and flexural tests were performed to characterise its mechanical properties. In addition, thermal properties were exemplified by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Sequentially, morphological characteristics of the hybrid composite were distinguished by Field Emission Scanning Electron Microscope (FeSEM). Density test shows that formulation P1 has the highest value due to the highest ratio of rice husk particulate to kenaf fiber. Formulation P6 shows the lowest density value due to the lowest ratio of rice husk particulate to kenaf fiber. Water absorption test shows that water intake of the hybrid composite increases when the ratio of kenaf fiber increases and vice versa to rice husk particulate. Mechanical properties are portrayed by tensile, flexural and impact tests. Maximum tensile strength is shown by formulation P1 with 10.54 MPa and minimum tensile strength is shown by P6 with 7.38 MPa. Formulation P1 shows maximum flexural strength value which is 28.58 MPa while P6 shows 23.73 MPa. Formulation P1 shows highest impact strength and P6 has the lowest strength with value of 2.20 KJm-2 and 1.52 KJm-2, respectively. DSC and TGA tests shows that the increase of the two lignocellulosic fillers increased the hybrid composite thermal stability. FeSEM micrograph of fracture impact shows occurrence of either bonding or de-bonding of fibers’ matrices. This research conveys that the naturally sourced lignocellulosic filler helps to increase mechanical and thermal strength with 10wt.% of kenaf and 30wt.% of rice husk particulate, while its ability to absorb water decreases with the decrease of kenaf fibers. Hence, it is concluded that formulation P1 is the optimum blend of hybrid for industrial purposes with matched applications.