Siti Norasmah Surip

Essential Work of Fracture and Acoustic Emission Study on TPNR Composites Reinforced by Kenaf Fiber

Kenaf fiber (KF) based thermoplastic natural rubber (TPNR) composite was produced by melt blending with polypropylene (PP). Kenaf fiber (15% by volume) and TPNR were mixed in as Haake 600p internal mixer. The fracture behavior of the TPNR matrix and of TPNR—kenaf (with and without maleic anhydride grafted polypropylene, MAPP) composites was evaluated using the essential work of fracture (EWF) method and double edge notched tensile (DENT) specimens. Various ligament lengths were employed ranging from 4 to 12 mm. The strain rate was fixed at 2 mm/min. The specific work of fracture (we) and plastic work (βwp) showed the highest energy for TPNR that corresponds to its ductility and allows the application of the EWF approach. It was found that the presence of kenaf fibers and MAPP reduced the toughness of TPNR and changed the ductile fracture to brittle behavior. SEM observation revealed that energy absorption mechanisms include matrix deformation, fiber pullout, and fiber breakage. Acoustic emission (AE) was employed to analyze the failure processes further. The signals emitted by composites were substantially higher than that of the TPNR matrix, reflecting that also the failure mechanisms were affected by the fibers incorporated.

Mechanical and Fracture Toughness Behavior of TPNR Nanocomposites

Thermoplastic natural rubber (TPNR) nanocomposites containing organophilic layered silicates were prepared by melt blending method at 180°C using internal mixer (Haake 600P). The aim of this study is to determine the influence of the organoclay filler on the mechanical and fracture properties. In this study, two mixing methods were employed to incorporate filler into matrix, namely the direct (DM) and indirect (IDM) method. The mechanical properties of TPNR nanocomposites were studied using tensile, flexural, and impact tests. The tensile and flexural tests revealed that the optimum loading of organoclay was at 4 wt% using the indirect method of mixing. Plane stress fracture toughness of thermoplastic natural rubber (TPNR) nanocomposite was determined by the essential work of fracture (EWF) concept using tensile-loaded deeply double-edge notched (DDEN-T) specimens. The EWF measurements indicated that the specific essential work of fracture (we) decreased in the presence of nanoclay. Nevertheless, these TPNR nanocomposites met the basic requirement of the EWF concept of full ligament yielding, which was marked by a load drop in the force—displacement curves of the DDEN-T specimens.

Microscopy Observation on Nanocellulose from Kenaf Fibre

Conventional fibre size has large surface area for binding site while nanocellulose posses higher surface area thus making more available binding site for fibre-matrix interaction. Kenaf has poor surface properties before treated. Treatment was applied to overcome this problem with alkali followed by acidic treatment. The nanocellulose has been produced from kenaf core (hibiscus cannabinus) by chemi-mechanical method. The fibre was treated with alkali followed by acidic treatment (HCl). Treated fibres were mechanically process by using pulverisette & cryocrushing to reduce the fibre size. The nanocellulose fibres were observed under Scanning Electron Microscope (SEM). The result convinced that chemi-mechanical method is a new technique for producing high yield kenaf nanocellulose.

Mechanical Properties and Environmental Stress Cracking Resistance of Rubber Toughened Polyester/Clay Composite

Crosslinked polyester clay nanocomposites were prepared by dispersing originically modified montmorillonite in prepromoted polyester resin and subsequently crosslinked using methyl ethyl ketone peroxide catalyst at different clay concentration. Cure process and the mechanical properties of rubber toughened polyester clay composite have been studied. Rubber toughened thermoset polyester composite were prepared by adding 3 per hundred rubber (phr) of liquid natural rubber (LNR) was used in the mixing of producing this composite. Modification of polyester matrix was done due to the brittle problem of polyester composite. Addition of LNR will increase the toughness of composite and produce ductile polyester. Two types of composites were produced which is clay-lnr polyester composite and clay polyester composite. Addition of liquid natural rubber significantly increased the impact strength and flexural properties. Result shows that addition of 6% of clay-lnr composite give good properties on impact, strength and flexural. From the ESCR test, both composites showed good resistance to environmental.

Mechanical and Thermal Properties of Rubber Toughened Carbon Black-Filled Polyester Composite

The influences of Carbon Black (CB) as filler for rubber toughened polyester composite on thermal properties were investigated, in consideration for applications such as automotive parts and integrated circuits (IC) encapsulations. The usage of CB as filler is one of the efforts in increasing and varying the use of rubber and unsaturated polyester thermoset in composite materials. Unsaturated polyester was mixed with 3% liquid natural rubber (LNR) as toughening agent and CB, which were varied from 0, 2, 4, 6, 8, and 10% using mechanical stirrer and moulded by using the open mould technique. Impact testing was conducted for mechanical property and it was found that the addition of CB increased the impact strength by 87%. Thermal properties of the composites were evaluated using a thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The TGA curves of the composites were quite similar, but there were slight increment in thermal stability for several CB filled composites compared to the neat polyester matrix. DSC analysis showed that all the composites were fully cured, and CB filled composites had a slower heat flow rate compared to the neat rubber toughened composite.

Physical and Mechanical Properties of Thermoplastic Natural Rubber (TPNR) Nanocomposites

Thermoplastic natural rubber (TPNR) nanocomposites were prepared by melt blending method with the optimum mixing parameters (140oC, 100 rpm, 12 min) using internal mixer (Haake 600 P). The aim of this work is to study the effects of organo-montmorillonite (OMMT) on the physical and mechanical properties of TPNR with and without coupling agent (maleic anhydride grafted polyethylene, MA-PE). Significant improvement in tensile strength and modulus of TPNR nanocomposites were obtained with the presence of MA-PE.

Permeability properties of thermoplastic natural rubber (TPNR) nanocomposites

Linear low-density polyethylene (LLDPE)/natural rubber (NR)/liquid natural rubber (LNR) with organomontmorillonite (OMMT) were prepared using melt blending method and denoted as TPNR nanocomposites. The melt blending of LLDPE/NR/LNR with a composition of 70:20:10 formed blends. For better dispersion of nanoclay in the TPNR blend, maleic anhydride grafted polyethylene (MA-PE) was used as a coupling agent. The nanoclay dispersion was investigated by X-ray diffraction (XRD), and a novel method using permeability measurements data in a permeability model. The measured d-spacing data proved a good dispersion of nanoclay at low clay contents. The permeability model for flake-filled polymer was used to estimate the aspect ratio of nanoclay platelets in the blend nanocomposites. The oxygen barrier property of the TPNR blend improved about two-fold by adding only 2 wt% of organoclay. Differential scanning calorimetry showed an increase in cystallinity up to 20% suggesting an increase in spherulite growth, by the increased in melting temperature. The increase in the barrier property of the blend with the induction in crystallinity indicates the dominant role of organoclay platelets in barrier improvement. The transmission electron micrograph, showed an intensive intercalation structure and exfoliation structure with the presence of MA-PE.

ZnO nanoparticles for anti-corrosion nanocoating of carbon steel

Nanostructured coatings offer great potential for various applications due to their superior characteristics that are not typically found in conventional coatings. This research aimed at developing a new and improved coating that employs zinc oxide nanopowder as the agent to achieve corrosion resistant properties for a coating. The research project discusses on its corrosion behaviour of epoxy-zinc oxide in different media by measuring its corrosion rate. Mild carbon steel was used as the substrate for the epoxy-zinc oxide coating. The corrosion behavior mechanism of mild steel was investigated in different media, namely fresh water, NaCl solution, HCl solution and NaOH solution. Immersion test was conducted and studied for a period of 60 days, with daily and weekly weighing and immersing. The corrosion rate was calculated and mild steel corrodes in the different environment and degrades in the following trend; HCl → NaCl → NaOH → H2O.

Thermal properties and crystallisation behaviour of thermoplastic natural rubber (TPNR) nanocomposites

The effect of preparation technique on the crystallisation behavior and thermal properties of TPNR filled nanoclay nanocomposites was investigated. The nanocomposites were prepared via melt blending method using internal mixer (Haake 600P). Two types of nanocomposites preparation technique were employed which is method A and B. In method A, the nanoclay was pre-mixed with liquid natural rubber (LNR) before it was charged into the other materials. For method B, the nanoclay was directly charged into the molten TPNR matrix. The result shows, preparation methods were significantly affect the crystallinity and thermal properties of TPNR nanocomposites. DSC thermogram revealed that nanocomposites crystallinity was increased when prepared by method A but decreased with method B. An increment in polypropylene crystallinity was attributed by the nanoclay which is believed to be as a nucleating agent. DMA thermogram suggested that the preparation method has affected the storage modulus and tan δ but not the glass transition temperature (tg).

Flexural Strength of PLA/Kenaf Green Composite

PLA toughened by kenaf green composite were produced involving chemi-mechanical method. The effect of chemical treatment on the surface morphology and flexural properties of PLA/kenaf green composite was investigated. The effect of kenaf fiber loading which is varying for 2%, 4% and 6% on the flexural properties was also investigated. The sample was test for flexural properties according to ASTM D790 and the surface morphology was observed using scanning electron microscope (SEM). The results show that PLA composite toughened with 6% of kenaf gave higher value for MOE which is 944.46 MPa compared to 2% and 4% kenaf loading. This is due to a stiffer material was introduced into PLA matrix. The MOR value for neat PLA is 38.78Mpa. However, the value for MOR was decreased by increasing fiber loading which are 33.43, 28.93 and 29.69 Mpa for 2%, 4% and 6% respectively.