I. M. Inuwa

Properties of polylactic acid composites reinforced with oil palm biomass microcrystalline cellulose

In this work, polylactic acid (PLA) composites filled with microcrystalline cellulose (MCC) from oil palm biomass were successfully prepared through solution casting. Fourier transform infrared (FT-IR) spectroscopy indicates that there are no significant changes in the peak positions, suggesting that incorporation of MCC in PLA did not result in any significant change in chemical structure of PLA. Thermogravimetric analysis was conducted on the samples. The T50 decomposition temperature improved with addition of MCC, showing increase in thermal stability of the composites. The synthesized composites were characterized in terms of tensile properties. The Youngs modulus increased by about 30%, while the tensile strength and elongation at break for composites decreased with addition of MCC. Scanning electron microscopy (SEM) of the composites fractured surface shows that the MCC remained as aggregates of crystalline cellulose. Atomic force microscopy (AFM) topographic image of the composite surfaces show clustering of MCC with uneven distribution.

Isolation and characterization of cellulose nanowhiskers from oil palm biomass microcrystalline cellulose.

The objective of this study is to compare the effect of two different isolation techniques on the physico-chemical and thermal properties of cellulose nanowhiskers (CNW) from oil palm biomass obtained microcrystalline cellulose (MCC). Fourier transform infrared analysis showed that there are no significant changes in the peak positions, suggesting that the treatments did not affect the chemical structure of the cellulose fragment. Scanning electron microscopy showed that the aggregated structure of MCC is broken down after treatment. Transmission electron microscopy revealed that the produced CNW displayed a nanoscale structure. X-ray diffraction analysis indicated that chemical swelling improves the crystallinity of MCC while maintaining the cellulose I structure. Acid hydrolysis however reduced the crystallinity of MCC and displayed the coexistence of cellulose I and II allomorphs. The produced CNW is shown to have a good thermal stability and hence is suitable for a range of applications such as green biodegradable nanocomposites reinforced with CNW.

Mechanical Properties and Morphological Characterization of PLA/Chitosan/Epoxidized Natural Rubber Composites

Poly (lactic acid) (PLA)/chitosan (CS) natural polymer/epoxidised natural rubber (ENR) composites were successfully prepared through a solution casting method. The morphological characteristics of fabricated composites were investigated by scanning electron microscopy (SEM) and optical microscopy. The microstructure of PLA/ENR was significantly altered with the addition of CS. SEM analysis of composites fractured surfaces revealed smooth and homogeneous texture and good dispersion of CS. However for 15 wt% CS composites, the phase segregation and poor adhesion between the polymers were observed. Fourier transform infrared spectroscopy revealed some levels of attractive interaction between CS, PLA, and ENR in the composites. The mechanical properties of composites in terms of tensile strength and tensile modulus were significantly improved with the addition of CS into the matrix while the percent elongation at break decreased. The tensile strength increased up to 5 wt% CS loading for both PLA/CS and PLA/ENR/CS and thereafter decreased while Young’s modulus increased up to 10 wt%. However, when the CS content was increased to 15 wt%, the tensile strength and tensile modulus were slightly decreased. These improvements were attributed to good dispersion of CS at the optimum filler levels and attractive interaction between the composites components.

Exploring the effect of cellulose nanowhiskers isolated from oil palm biomass on polylactic acid properties

In this work, polylactic acid (PLA) reinforced cellulose nanowhiskers (CNW) were prepared through solution casting technique. The CNW was first isolated from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) by using 64% H2SO4 and was designated as CNW-S. The optical microscopy revealed that the large particle of OPEFB-MCC has been broken down by the hydrolysis treatment. The atomic force microscopy confirmed that the CNW-S obtained is in nanoscale dimension and appeared in individual rod-like character. The produced CNW-S was then incorporated with PLA at 1, 3, and 5 parts per hundred (phr) resins for the PLA-CNW-S nanocomposite production. The synthesized nanocomposites were then characterized by a mean of tensile properties and thermal stability. Interestingly to note that incorporating of 3 phr/CNW-S in PLA improved the tensile strength by 61%. Also, CNW-S loading showed a positive impact on the Youngs modulus of PLA. The elongation at break (Eb) of nanocomposites, however, decreased with the addition of CNW-S. Field emission scanning electron microscopy and transmission electron microscopy revealed that the CNW-S dispersed well in PLA at lower filler loading before it started to agglomerate at higher CNW-S loading (5phr). The DSC analysis of the nanocomposites obtained showed that Tg,Tcc and Tm values of PLA were improved with CNW-S loading. The TGA analysis however, revealed that incopreated CNW-S in PLA effect the thermal stability (T10,T50 and Tmax) of nanocomposite, where it decrease linearly with CNW-S loading.

Effects of compatibilizers on mechanical properties of PET/PP blend

Polyethylene terephthalate (PET) and polypropylene (PP) are incompatible thermoplastics due to differences in chemical structure and polarity hence their blends posses inferior mechanical properties. Compatibilization with a suitable block/graft copolymer is one way to improve the mechanical properties especially impact strength of such a blend. In this work, the effects of two compatibilizers, maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH), were investigated for compatibilization of PET/PP blends and the results were compared. PET, PP, and compatibilizers were melt blended in a single step using a counter-rotating twin screw extruder with compatibilizer concentrations 0, 2, 4, 6, 8, and 10 phr, respectively. Standard test samples were prepared by injection molding process. The resulting compatibilized blends were characterized by tensile, flexural, and impact tests. The results showed improvements in mechanical properties of the blends due to the in situ polymerization reaction between the ester groups of PET and the maleic anhydride (MAH) during melt extrusión. The incorporation of 4 phr PP-g-MAH in the blends resulted in the highest tensile and flexural strength, while no significant improvements in Young’s modulus were observed for both compatibilized blends. The máximum impact strength of the blends was obtained at 8 phr of SEBS-g-MAH. Improvement of impact strength of the blends may be attributed to the elastomeric nature of the SEBS-g-MAH while greater improvement recorded for tensile and flexural strength is likely to be due to the affinity between PP-g-MAH with PP of the blend. Scanning electron microscopy shows the addition of PP-g-MAH and SEBS-g-MAH compatibilizers into the blends promote a better dispersión of PP into PET matrix.

Enhanced mechanical and thermal properties of hybrid graphene nanoplatelets/multiwall carbon nanotubes reinforced polyethylene terephthalate nanocomposites

The effects of graphene nanoplatelets (GNP) and multiwall carbon nanotube (MWCNT) hybrid nanofillers on the mechanical and thermal properties of reinforced polyethylene terephthalate (PET) have been investigated. The nanocomposites were melt blended using the counter rotating twin screw extruder followed by injection molding. Their morphology, mechanical and thermal properties were characterized. Combination of the two nanofillers in composites formulation supplemented each other which resulted in the overall improvement in adhesion between fillers and matrix. The mechanical properties and thermal stability of the hybrid nanocomposites (PET/GNP1.5/MWCNT1.5) were significantly improved compared to PET/GNP3 and PET/MWCNT3 single filer nanocomposites. However, it was observed that GNP was better in improving the mechanical properties but MWCNT resulted in higher thermal stability of Nanocomposite. The transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) revealed uniform dispersion of the hybrid fillers in PET/GNP1.5/MWCNT1.5 nanocomposites while agglomeration was observed at higher filler content. The MWCNT prevented the phenomenal stacking of the GNPs by forming a bridge between adjacent GNP planes resulting in higher dispersion of fillers. This complimentary geometrical structure is responsible for the significant improvement in the thermal stability and mechanical properties of the hybrid nanocomposites.

Feasibility Study of Pulse Detonation Engine Fueled by Biogas

The hottest issue toward the environment today is the Clean Development Mechanism (CDM) and Green House Gases (GHG) which influenced climate change. At the same time, the world is facing the crisis of limited reserves of petroleum-based fuel resource which is being continuously depleted. Therefore, these three issues can possibly be overcome by using alternative fuels such as biogas, biodiesel, biomass, biofuel, alcohol, vegetable oils etc. The use of biogas as fuel for Pulse Detonation Engine (PDE) possibly promise great advantages on power production with less emission. This is because PDE operates with higher thermodynamic efficiency by operating on constant volume pressure. Biogas usage will somewhat contributed to the CDM and and lessen the GHG issues. Here through detailed literature review, the challenges such as lower flame speed (compared to hydrocarbon fuel) and biogas impurities are discussed. Combustion characteristics of biogas in detonation mode are also investigated. Strategy is presented here for looking at the possibility of PDE operation using biogas.

Flame retardancy, Thermal and mechanical properties of Kenaf fiber reinforced Unsaturated polyester/Phenolic composite

Unsaturated polyester (UP) resin has been blended with phenolic resin (PF) resole type at various ratios to obtain a homogeneous blend with improved flame resistance compared to its parent polymers. The polymer blend was reinforced with 20 wt% kenaf using hand lay out technique. Fourier transform infrared spectroscopy (FT-IR) was used to characterize changes in the chemical structure of the synthesized composites. The thermal properties of the composites were investigated using thermogravimetric analysis (TGA). The thermal stability of UP/PF kenaf composites co-varies with the PF content, as shown by the degradation temperature at 50 % weight loss. The char yield of the composites increases linearly with PF content as shown by the TGA results. The flammability properties of the composites were determined using the limiting oxygen index (LOI) and UL-94 fire tests. The LOI increased with the PF content while the composites exhibit improved flame retardancy as demonstrated by UL-94 test. The mechanical and morphological properties of the composites were determined by tensile test and scanning electron microscopy (SEM), respectively. The tensile strength and the Young’s modulus of the blend/composites slightly decreased with increasing PF content albeit higher than PF/kenaf fiber composites.

Pyrolysis of low density polyethylene waste in subcritical water optimized by response surface methodology

Pyrolysis of low density polyethylene (LDPE) waste from local waste separation company in subcritical water was conducted to investigate the effect of reaction time, temperature, as well as the mass ratio of water to polymer on the liquid yield. The data obtained from the study were used to optimize the liquid yield using response surface methodology. The range of reaction temperature used was 162–338°C, while the reaction time ranged from 37 min to 143 min, and the ratio of water to polymer ranged from 1.9 to 7.1. It was found that pyrolysis of LDPE waste in subcritical water produced hydrogen, methane, carbon monoxide and carbon dioxide, while the liquid product contained alkanes and alkenes with 10–50 carbons atoms, as well as heptadecanone, dichloroacetic acid and heptadecyl ester. The optimized conditions were 152.3°C, reaction time of 1.2 min and ratio of water solution to polymer of 32.7, with the optimum liquid yield of 13.6 wt% and gases yield of 2.6 wt%.

Mechanical and Thermal Properties of Hybrid Graphene/Halloysite Nanotubes Reinforced Polyethylene Terepthalate Nanocomposites

In this work, the effects of graphene nanoplatelets (GNP) and halloysite nanotubes (HNT) constant ratio content and processing methods on the mechanical and thermal properties of polyethylene terepthalate (PET) nanocomposites were investigated. The GNP/HNT filled PET nanocomposites were prepared by melt process using single screw extruder and counter rotating twin screw extruder followed by injection molding to produce test samples. The mechanical properties of the nanocomposites was investigated by comparing the effect of extruder types on tensile, flexural and impact test. The results show that the nanocomposites with the ratio of 2 wt% GNP and 1 wt% HNT hybrids have the highest tensile strength, flexural strength and impact strength. By comparing the two processing methods, PET nanocomposites prepared by single screw extruder exhibits higher tensile strength than those prepared using twins screw extruder. Furthermore, the results of differential scanning calorimetry (DSC) shows that the melting temperature of PET is not essentially affected by the presence of the hybrid nanofillers. However, the degree of crystallinity (Xc) and cold crystallization temperature (Tcc) were lower than pure PET with GNP2/HNT1 having the lowest Xc and Tcc. Overall the results show that the maximum improvement in mechanical and thermal properties were achieved by the combination of GNP and HNT in the nanocomposites with 2 wt% and 1 wt% respectively using the single screw extruder.