Compounding, injection moulding and characterisation of mangrove particle/high density polyethylene Composites / Ganiyat Olusola Adebayo

Ganiyat Olusola , Adebayo (2019) Compounding, injection moulding and characterisation of mangrove particle/high density polyethylene Composites / Ganiyat Olusola Adebayo. PhD thesis, University of Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (175Kb)
	PDF (Thesis PhD) Restricted to Repository staff only until 31 December 2021. Download (5Mb)

Abstract

This study elucidates the processing and characterisation of mangrove particle (MP) reinforced high density polyethylene (HDPE) composites, this is borne out of the keen interest by researchers in developing materials of renewable origin, by substituting a fraction of polymeric, synthetic, finite materials with eco-friendly types, e.g. MP. However, the poor surface interactions between these hydrophilic natural fibres and hydrophobic polymer matrices, pose a significant threat to this interesting area of research. Thus, MP size between 500-1000 microns was heat-treated at 120oC, 140oC, 160oc and 180oC in an anoxic condition by using nitrogen gas at a flow rate of 100 ml/min for 1 h in order to improve the surface adhesion between MP and HDPE matrix. The untreated (at 0oC) and the treated MPs were characterised in order to obtain the optimum treatment temperature. The results obtained for the chemical composition of treated MP showed an increase in cellulose content from 46% to 56% at 120oC, which decreased at further heating. Surface morphology by FESEM revealed that heat treatment exposed the inner fibrillar feature of MP, thereby increasing the roughness of the MP surface. TGA further indicated that heat- treated MPs are more stable than the untreated. The untreated and the treated MPs (at 120oC) were compounded with HDPE at 10, 20 and 30 wt% in a twin- screw extruder and injection moulded into dumb-bell and rectangular bar shapes for tensile/flexural and impact tests, respectively, including thermal analysis (differential scanning calorimetry, DSC and thermogravimetric analysis, TGA). The results of the mechanical properties indicated the improvement of the heat-treated MP/HDPE composites as the particle loading increased. The SEM images showed that the interfacial interaction between the HDPE and untreated MP is weaker than the heat-treated MP. The DSC results showed a decreasing trend in the degree of crystallinity (Xc) of both untreated and treated composites, while TGA indicated an increase in the maximum degradation temperature of the treated composites. Samples were also compression-moulded for rheological characterisation. Higher rheological properties were also observed in the treated composites as the MP loading increased with the storage and loss moduli were found to increase. Furthermore, the effects of adhesion promoter (maleic anhydride grafted polyethylene, MA-g-PE) at 0, 4, 8 and 12 parts per hundred (phr) loadings were evaluated. The mechanical properties and thermal stabilities of the untreated composites that contain MA-g-PE showed more enhancements than the treated composites that contain MA-g-PE. Furthermore, two other different particle sizes (250-500 microns and 125- 250 microns) of 20 wt% of untreated and treated MPs were compounded and injection moulded with 80 wt% HDPE. Composites with smaller particle sizes exhibited optimum values of mechanical and thermal properties. The effects of water absorption at room temperature for 1440 hand outdoor weathering at 720 h, 1440 h and 2160 h were also studied. Generally, water absorption led to the reduction of mechanical and thermal properties of composites, with the untreated/MA-g-PE composites showing the optimum values. The untreated composites containing MA- g- PE exhibited the best properties during outdoor weathering, as confirmed by colour spectroscopy, FESEM and the mechanical and thermal characterisations of the exposed surfaces.

Actions (For repository staff only : Login required)