Mohd Firdaus Omar

Measurement on Strain Rate Sensitivity and Dynamic Mechanical Properties of Various Polymeric Materials

Strain rate sensitivity and dynamic mechanical properties of polymeric materials are affected to a certain extent especially by the rate of loading. However, there is limited number of works reported on that particular issue. Therefore, the paper presents on static and dynamic mechanical properties of various polymeric materials across strain rate from 10-2 to 10-3 s-1. The specimen were tested using universal testing machine (UTM) for static loading and a conventional split Hopkinson pressure bar (SHPB) apparatus for dynamic loading. From the results, the compression modulus and compressive strength of all tested specimen increased significantly with increasing strain rates. In addition, positive increment in terms of strain rate sensitivity was recorded for all tested polymers over a wide range of strain rate investigated. Meanwhile, the thermal activation volume has decreased as increasing strain rate. Of the three polymers, polypropylene shows the highest strain rate sensitivity at static region. On the other hand, at dynamic region, polycarbonate shows the highest strain rate sensitivity than that of polypropylene and polyethylene.

Thermal properties of polypropylene/muscovite layered silicate composites: effects of organic modifications and compatibilisers

Polymer-layered silicate nanocomposites containing polypropylene, compatibilisers, muscovite, and organomuscovite were prepared through the hot compression technique. Muscovite particles were initially treated with lithium nitrate, followed by cetyltrimethylammonium bromide, to obtain the organomuscovite through an ion-exchange treatment. Maleic anhydride and polyhedral oligomeric silsesquioxane were used as compatibilisers to modify the polypropylene/organomuscovite nanocomposite systems. The effectiveness of the ion-exchange treatment and the implementations of both compatibilisers were successfully proven using the Fourier transforms infrared, X-ray diffraction, as well as the transmission electron microscopy. The overall thermal properties of the polypropylene/muscovite layered silicate composites were investigated by applying both differential scanning calorimetry and thermogravimetric analysis. It was found that the polypropylene reinforced with organomuscovite recorded higher thermal properties in terms of crystallisation temperature and thermal stability than its counterpart; whereas, the melting temperature and the degree of crystallinity displayed an opposite trend. For the effect of the compatibiliser, it was found that compatibilised polypropylene/organomuscovite nanocomposites recorded higher values of decomposition and crystallisation temperatures than that of non-compatibilised polypropylene/organomuscovite nanocomposites. However, the melting temperature and the degree of crystallinity of compatibilised polypropylene/organomuscovite nanocomposites were slightly lower, as compared to non-compatibilised polypropylene/organomuscovite nanocomposites.

Thermal degradation behavior of a flame retardant melamine derivative hyperbranched polyimide with different terminal groups

Melamine derivative hyperbranched polyimide (HPI) polymers with different terminal groups were synthesized by emulsion polymerization reactions, followed by stepwise thermal imidization. The non-isothermal behavior of the synthesized HPI polymers was studied by thermogravimetric analysis under a nitrogen atmosphere and the results were compared with the corresponding terminal groups. In this study, we attempted to clarify the effects of different terminal groups on the non-isothermal degradation kinetics. The derived apparent activation energies using Flynn–Wall–Ozawa and Kissinger methods fit well with each other (showing the same trend). Meanwhile, the type of solid state mechanism was determined using the Coats–Redfern and Criado methods proposed for D1 types such as amine–amine terminals, amine–anhydride terminals and anhydride–anhydride terminals, which are one-dimensional diffusions that follow the unimolecular decay law of first order reactions. The Ea showed significant differences at α > 0.7, which indicates the role of different terminal groups towards degradation behavior. From the calculations, the lifetime prediction at 5% mass loss decreases in the following order: anhydride terminated > amine terminated > anhydride–amine terminated which is related to the dissociation energy between the anhydride functional groups and amine functional groups. Hence, the presence of different terminal groups reveals their contributions towards thermal degradation and stability.

The effect of rice straw particulate loading and polyethylene glycol as plasticizer on the properties of polylactic acid/polyhydroxybutyrate-valerate blends

In this study, polylactic acid (PLA) was blended with polyhydroxybutyrate-valerate (PHBV) with different ratios of rice straw (RS) particulate content and polyethylene glycol (PEG) which acted as a plasticizer. The tensile, thermal and water absorption properties were investigated. The tensile strength and elongation at break, Eb, decreased with increasing RS particulate. The poor adhesion between RS particulate and PLA/PHBV blends was proven through scanning electron microscopy. Besides, the reaction scheme between RS particulate also has been proposed. Increased RS particulate loading and PEG presence also reduced the crystallinity of the blends. Thermal stability of the composites also decreased with the addition of RS particulate and PEG into the blends. The presence of RS particulate increased the water absorption, whereas the addition of PEG reduced water uptake due to its amphiphilic behavior. The mechanism of the effect of water absorption on PLA/PHBV blends and RS particulate was also proposed.

Polarization Study of Sn-0.7Cu Solder Alloy in 1M Hydrochloric Solution

Corrosion properties of Sn-0.7Cu solder were investigated in 1 M HCl. The scanning rates used were 0.5, 1.0, 1.5 and 2.0 mVs-1 to study the aggressiveness level of HCl electrolyte in various environment. The morphological, elemental and structural of the samples were compared before and after the corrosion. Scan rate 1.0 mVs-1 was chosen as the most optimum scan rate during corrosion analysis. The morphological analysis observed two types of corrosion product which is compacted and loosely-compacted corrosion product after the samples was polarized in 1 M HCl.

Low Cost Synthesis Method of Two-Dimensional Titanium Carbide MXene

A layered MAX phase of Ti3AlC2 was synthesized through pressureless sintering (PLS) the initial powder of TiH2/Al/C without preliminary dehydrogenation under argon atmosphere at 1350°C. An elegant exfoliations approach was used to prepare a two-dimensional (2D) metal carbide Ti3C2 from layered MAX phase by removing A layer by chemical etching. The use of PLS method instead of any pressure assistance method such as hot isostatic press (HIP) and hot press (HP) lowered the cost of synthesis. Recently, some unique potential of Ti3C2 has been discovered leads to the proposal of potential application, mostly on electronic devices. Morphology and structural analysis was used to confirm the successful of this research.

Effect of Surface Modification on Rice Husk (RH)/Linear Low Density Polyethylene (LLDPE) Composites under Various Loading Rates

The surface modification of RH filler was carried out using silane coupling agents in order to improve the adhesion between LLDPE and RH. RH was treated using silane coupling agent at four different concentrations (1, 3, 5 and 7 %) at room temperature. In this study, both untreated and treated RH/LLDPE composites were tested under static (0.001 s-1, 0.01 s-1 and 0.1 s-1) and dynamic loading rates (650 s-1, 900 s-1 and 1100 s-1) using universal testing machine and split Hopkinson pressure bar apparatus, respectively. Results show that the 5% treated LLDPE/RH composite shows the higher ultimate compressive strength (UCS) and rigidity as compared to untreated LLDPE/RH composites under various loading rates. Overall, it is proved that the surface treatment of RH gives significant contribution towards the UCS and rigidity of LLDPE/RH composites under both static and dynamic loading rates.

Morphology, Thermal and Chemical Properties of Nanocrystalline Cellulose (NCC) Hydrolyzed from Banana Stem

Banana stem (BS) was used as the natural cellulose source. It must undergo an alkali treatment and bleaching process before continuing with an acid hydrolysis. Then, the Nanocrystalline cellulose (NCC) was synthesized via acid hydrolysis with four different concentrations of sulfuric acid (H2SO4) at 50 %, 52 %, 54 % and 56 % respectively at 50 0C for 1 hour. The influence of acid concentration of morphology, thermal and chemical properties of the NCC was studied in this project. The morphology dimension of the NCC was determined by using field emission scanning electron microscope (FESEM) and thermal stability of the NCC was determined by using thermal gravimetric analysis (TGA). Chemical composition and structural analysis were measured by using Fourier transform infrared (FT-IR) and X-ray diffraction (XRD).

Characterization of Linear Low Density Polyethylene/Rambutan Peels Flour Blends: Effect of Loading Content

The effect of rambutan peels flour (RPF) content on the tensile properties of linear low density polyethylene filled with rambutan peel flour was studied. RPF was melt blended with linear low–density polyethylene (LLDPE). LLDPE/RPF blends were prepared by using twin screw extruder at 150°C with the flour content ranged from 0 to 25 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The highest tensile strength was pure LLDPE meanwhile the tensile strength LLDPE/RPF decreased gradually with the addition of rambutan peels flour. Young’s modulus of rambutan peels flour filled LLDPE increased with increasing fiber loading. The crystallinity of the blends was significantly reduced with increasing RPF content. Instead, the water absorption increased with the addition of RPF content.

Characterization and properties of low-linear-density polyethylene/Typha latifolia composites

ABSTRACT The characterization of the effects of different sizes and loadings of Typha latifolia on the tensile, thermal, and morphological properties of linear-low-density polyethylene (LLDPE)/T. latifolia composites were evaluated using tensile test, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy analyses. Results indicated the tensile strength and elongation at break decreased as T. latifolia loading increased. However, T. latifolia fine size (fs) exhibited better tensile properties than coarse size at the same loading in the composite. T. latifolia (15%, fs) recorded higher thermal stability than LLDPE control and other T. latifolia loadings and sizes due to the strong interaction of T. latifolia (15%, fs) in LLDPE matrix as shown in morphology.