Mujtahid Kaavessina

Preparation and characterization of poly(lactic acid)/elastomer blends prepared by melt blending technique

Poly(lactic acid) (PLA) and biodegradable elastomer were melt blended and molded in an injection molding machine. The crystallinity, viscoelasticity, thermal and mechanical properties of the molded blend and annealed blend samples were studied. Differential scanning calorimetry was used to evaluate the crystallinity and thermal property of all the samples. It was found that the melting temperature decreased as the amount of elastomer increased. Additionally, the presence of elastomer tended to increase the crystallinity of PLA at 10 and 20 wt%. The injection molding led to the diminishing of neat PLA crystallinity to be 20.79%; however, annealing could recover it to be 29.94%. This result was supported by x-ray diffraction and dynamic mechanical analysis tests. The complex viscosity and storage modulus of PLA melt decreased upon addition of elastomer. The elongation at break increased as the content of elastomer increased. However, the Young’s modulus and tensile strength decreased severely due to the addition of elastomer.

In Vitro Biodegradability of Poly(lactic Acid)/Hydroxyapatite Biocomposites Prepared by Solvent-Blending Technique

Poly (lactic acid) was solvent-blended and formed as thin ribbons with different weight fraction of hydroxyapatite, namely 5, 10 and 20wt%. In-vitro biodegradability of biocomposites was performed in phosphate buffer solution (PBS) at 37°C. The presence of hydroxyapatite tended to increase biodegradability of poly (lactic acid) in its biocomposites. Thermal stability of biocomposites was always higher than that neat poly (lactic acid) either before and after hydrolytic degradation tests. After biodegradation tests, some micro-holes and cracks were appeared in the surface morphology of biocomposites as well as the increasing crystallinity occurred.

Carboxymethyl konjac glucomannan from konjac flour: The effect of media and temperature on carboxymethylation rate

To increase the solubility of porang flour or konjac flour in the water, the konjac flour was modified chemically into carboxymethyl konjac-glucomannan (CM-KGM), so that the utilization of the product may be wider. The aims of this research were to study the effect of ethanol concentration as the solvent media (50% ethanol and 90% ethanol) and temperature (45-50 °C dan 65-70 °C) on the rate of degrees of substitution (DS) formation in carboxymethylation step. CM-KGM was prepared by alkalization of konjac flour using sodium hydroxide for 30 minutes at 30°C. Then, the product of alkalization was carboxymethylated using sodium monochloroacetic (Na-MCA) with ratio 1:1 gram flour/NA-MCA. Based on the experimental results, the higher DS was attained by carboxymethylation using media solvent of 90% ethanol and temperature carboxymethylation 65-70°C. The relationship between temperature and reaction constant (k) follows: k = 0.3082 exp ((−15,277)/(8.314 T)).To increase the solubility of porang flour or konjac flour in the water, the konjac flour was modified chemically into carboxymethyl konjac-glucomannan (CM-KGM), so that the utilization of the product may be wider. The aims of this research were to study the effect of ethanol concentration as the solvent media (50% ethanol and 90% ethanol) and temperature (45-50 °C dan 65-70 °C) on the rate of degrees of substitution (DS) formation in carboxymethylation step. CM-KGM was prepared by alkalization of konjac flour using sodium hydroxide for 30 minutes at 30°C. Then, the product of alkalization was carboxymethylated using sodium monochloroacetic (Na-MCA) with ratio 1:1 gram flour/NA-MCA. Based on the experimental results, the higher DS was attained by carboxymethylation using media solvent of 90% ethanol and temperature carboxymethylation 65-70°C. The relationship between temperature and reaction constant (k) follows: k = 0.3082 exp ((−15,277)/(8.314 T)).

Effect of Date Palm Fiber Loadings on the Mechanical Properties of High Density Polyethylene/Date Palm Fiber Composites

The trend of using natural fibers as green filler in the fabrication of polymer composites is increasing. One of these natural fibers is date palm fiber (DPF). Date palm fiber is considered as agricultural waste in certain areas, such as Middle East countries. Therefore, the utilization of this fiber in the composites fabrication is an interesting topic of research. In the current study, composites were prepared by melt blending DPF with high density polyethylene (HDPE). Five different DPF loadings were studied (i.e. 0, 5, 10, 20, 30 wt%). The effect of the DPF loadings on the mechanical properties and water absorption behavior of the composites were investigated. The tensile test result showed that tensile strengths of all the composites samples were all higher than the neat HDPE with the maximum improvement was achieved at the DPF loading of 5 wt% (i.e. DFC-5), which was about 19.23 MPa (138% higher than the neat HDPE). Whereas, the flexural test result showed that the flexural strength of the composites slightly increased compared to that of the neat HDPE only until 5 wt% DPF loading (i.e. DFC-5). Afterward, the flexural strength of the DFC-10 was equal to that of the neat HDPE, and decreasing with further increase of DPF loadings. Additionally, the water absorption test result showed that the water absorption rate and uptake of water (at equilibrium) increased with the increase of DPF loading.

Date Palm Fiber Reinforced High Density Polyethylene Composites: Effect of Fiber Loadings on the Melt Rheological Behavior

In the recent years, the trend of using renewable source (green) fillers in the composites fabrication is increasing. One of these green fillers is natural fibers, which referred to the plant fibers, such as date palm fiber (DPF). In the present work, high-density polyethylene (HDPE)/DPF composites have been prepared. Four different DPF loadings were used (i.e. 0, 5, 10, 20 wt%) to prepare the composites. The effect of DPF loadings on the melt rheological behavior of the HDPE/DPF composites were studied. The melt rheological test results showed that both of storage modulus (Gʹ) and loss modulus (Gʺ) increased with the increase of DPF loadings. Additionally, the Han plot showed an upward shift from neat HDPE (i.e. DFC-0) to DFC-20, which indicated that the melt rheological properties changed with the increase of DPF loadings. The complex viscosity |h*| of the composites samples also increased with the increase of DPF loadings. The increased was more significant at higher DPF loadings (i.e. DFC-20). Meanwhile, the Carreau-Yasuda model was found to be well fitted with the experimental data.

Poly(Vinyl Alcohol) Fiber Reinforced High Density Poly(Ethylene) Composites: Dynamic Mechanical Thermal Analysis

In the present work, high density polyethylene (HDPE)/poly (vinyl alcohol) (PVA) fiber composites with four different PVA fiber loadings (i.e. 0, 5, 10, 20 wt%) have been prepared via melt compounding method using a twin-screw extruder. The composites were characterized for their morphology by using a scanning electron microscopy (SEM). Whereas, the dynamic mechanical thermal analysis (DMTA) was carried out by using an oscillatory rheometer. The DMTA test was carried out under torsion mode using temperature sweep test on rectangular composites samples. The DMTA results showed that the storage modulus (G¢) of the composites were higher than that of the neat HDPE and increased with increasing PVA fiber loadings. This indicated that there was a considerable stiffness enhancement of the composites. For example, at temperature of 60°C, the increases of stiffness (i.e. storage modulus) of the composites were approximately 3, 31, and 54% for PVAC-5, 10, and 20, respectively. Whereas, at higher temperature (i.e. 120°C), the increases were about 4, 50, and 98% for PVAC-5, 10, and 20, respectively. These results indicated that even at higher temperatures, the enhancement of storage modulus of the composites was still high.

Poly(Vinyl Alcohol) Fiber Reinforced High Density Poly(Ethylene) Composites: Melting and Crystallization Behavior

In the present study, high density poly(ethylene) (HDPE)/poly(vinyl alcohol) (PVA) fiber composites were prepared via melt blending technique using a co-rotating twin screw extruder (TSE). The effect of four different PVA fiber concentrations (i.e. 0, 5, 10, 20 wt%) on the melt and crystallization behavior of the HDPE/PVA fiber composites were investigated. The surface morphology of the composites was analyzed by a scanning electron microscopy (SEM). Whereas, the melt and crystallization behavior of the composites were analyzed by a differential scanning calorimetry (DSC). The SEM analysis on the cryo-fractured surface of the HDPE/PVA fiber composites exhibited that the PVA fibers were well blended/distributed in the HDPE matrix. Additionally, the DSC test results showed that the addition of PVA fiber in the HDPE matrix did not significantly change the melting peak temperature (Tm) of the composites. Furthermore, a slight decrease of the crystallization peak temperature (Tc) can be observed when the PVA fiber was incorporated in the HDPE matrix, which indicated a weak nucleation ability of the PVA fibers in the HDPE crystallization process. The same trend was also observed for the crystallinity index (Xc). The crystallinity index of the composites decreased with increasing PVA fiber loadings.

Non-Isothermal Crystallization and Viscoelastic Behavior of Polypropylene/Nanoclay Composites Fabricated from Masterbatch by Using a Mini Extruder

Polypropylene(PP)/nanoclay composites samples have been fabricated by melt compounding the PP pellets with nanoclay masterbatch (i.e. 50 wt% of nanoclay) using a mini extruder. The effect of three loadings of nanoclay (i.e. 5, 10, and 15 wt%) on the morphology, non-isothermal crystallization, and viscoelastic behavior of the PP/nanoclay composites were investigated. All the nanocomposites samples were characterized by using Scanning Electron Microscope (SEM), Differential Scanning Calorimetry (DSC), and an oscillatory rheometer. The SEM results showed that the distribution of nanoclay in the PP was relatively good at all level of loadings. The DSC analysis results showed that the nanoclay has dramatically enhanced the crystallization temperature, from 117°C (for neat PP) to 127-129°C (for nanocomposites). Additionally, the frequency sweep test results exhibited that the presence of nanoclay increased the viscoelastic behavior of the PP matrix.

Blends of low molecular weight of poly lactic acid (PLA) with gondorukem (gum rosin)

The utilization of plastic was increasing as well as the increasing its demand in wide range application. Consequently, the number of plastic litter will increase and make more serious environmental problems. This research concerns to minimize waste problems by designing biodegradable plastic. In this research, biodegradable plastic was made of poly lactic acid (PLA) and gondorukem (Gum rosin, Resina colophonium) as the plasticizer. The effect of gondorukem towards PLA properties such as rheology and degradability was investigated. The research divided into two steps: (i) the polycondensation of lactic acid (LA) and (ii) modification of obtained poly lactic acid. In the first step, polycondensation was done in N2 atmosphere (138°C) for 30 hours and added 0.1 %w of SnCl2 as catalyst. Bulk modification was conducted by blending of gondurukem in varied weight (0.5, 1, and 2 g in 10 g of PLA). Furthermore, the modified PLA was analyzed its molecular structure, biodegradability and rheological property. The pr...

The influences of elastomer toward degradability of poly (lactic acid)

Poly (lactic acid)/elastomer blends were prepared via direct injection molding with the different weight fractions of elastomer, namely: 0, 10, 20 and 30 wt%. Degradation test of poly (lactic acid) (PLA) was performed by burial in the soil. The physical appearance and thermal properties of the tested specimens were monitored periodically. The presence of elastomer tended to significantly increase the degradability of PLA after buried for 27 weeks. With 30 wt% elastomer, the color and the surface of specimens become more white and rougher due to the degradation. Differential scanning calorimetry (DSC) was used to evaluate thermal properties and crystallinity of all samples. It was found that the melting temperature decreased as the amount of elastomer increased. The crystallinity showed that the degradation of PLA is occurred firstly in amorphous phase.