Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was ...Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was modified with acetyl and hutyryl groups and films were prepared by blending acylated starch with low density polyethylene （LDPE）. Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS （2.5, 1.7） maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370℃ and 389℃ which were higher than the decomposition temperature of native starch film （349℃）. Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films （4.18% and 3.76%, respectively） was lower than that of native starch films （5%）. This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.展开更多
This work investigated and quantified the physicomechanical properties of flat-pressed wood plastic composites produced with recycled polyethylene terephthalate, recycled polyethylene and sawdust derived from selected...This work investigated and quantified the physicomechanical properties of flat-pressed wood plastic composites produced with recycled polyethylene terephthalate, recycled polyethylene and sawdust derived from selected tropical timbers, namely, Nauclea diderrichii, Brachystegia eurycoma, Erythrophleum suaveolens and Prosopis africana, for possible utilization in the wood industry. The compounding of the polymer blends of the precursor plastics, namely recycled PET (rPET) and recycled PE (rPE) with the sawdust (SD) from the selected timbers to produce the desired wood rPET/rPE composites was carried out via the flat press method. The characterization of the physicomechanical properties of the wood plastic composites (WPCs) produced, such as the density, hardness, flexural strength, ultimate tensile strength, elongation %, thickness swelling and water absorption capacity was carried out using methods based mainly on the European Committee for Standardization (CEN) and the American Society for Testing Materials (ASTM) standards. The results of the investigation on the resultant composites indicated that changes in the SD content affected the density of flat-pressed WPCs in line with literature. Generally, it was observed that as wood dust increased and PET content decreased, the density of composites decreased with some deviations as expected probably due to the anisotropic nature of the wood fillers. The analysis of variance (ANOVA) revealed that there was a statistically significant variation in the wood composites of Nuclea diderichii based on the physicomechanical values as the p-value (0.020) obtained was less than the critical level of α = 0.05. It was also observed that the composite, Wood 1 Sample 5 (W<sub>1</sub>S<sub>5</sub>) which was composed of 40% rPE, 40% rPET and 20% SD (derived from Nuclea diderichii), had the highest percentage elongation (26.84%);the highest flexural strength (14.995 N/mm<sup>2</sup>) and possibly the least carbon footprint in the environment. These properties of W<sub>1</sub>S<sub>5</sub> suggest that it could therefore be the best option for the production of building materials like ceiling boards or floor skirting in the wood plastic composite industry. The results of these investigations have therefore indicated that the fabrication of WPCs from sawdust and rPET/rPE was technically feasible and had prospects for large scale production in the wood industry.展开更多
The study was conducted to determine the influence of gratering and fermentation parameters on the physicochemical quality of starch obtained from two cassava varieties in Sierra Leone (i.e., SLICASS 11 and SLICASS 6)...The study was conducted to determine the influence of gratering and fermentation parameters on the physicochemical quality of starch obtained from two cassava varieties in Sierra Leone (i.e., SLICASS 11 and SLICASS 6). Fresh cassava roots harvested from the Department of Agricultural Engineering were peeled, washed and grated before fermentation and starch extraction. Fermentation was carried out under separate aerobic and anaerobic conditions for a period of Seven days. Physicochemical analyses were conducted at the Postharvest Food and Bioprocess Engineering Laboratory of the Department of Agricultural and Bio-System Engineering, Njala University to determine the solubility, water absorption capacity and swelling power of starch extracts obtained from various experimental treatments. Fermentation method and duration had significant effects on the solubility, water absorption capacity (WAC) and swelling power (SP) of starch extracts. Maximum solubility and WAC were recorded on the fifth day, for both cassava varieties tested, with apparent significant difference resulting from the two gratering bands (i.e., with 1.5-inch nail hole and 4-inch nail hole sizes, respectively). While swelling power increased consistently with temperature for starch obtained from SLICASS-11 variety, an irregular pattern was observed for SLICASS-6 variety. A multiple correlation analysis proposes a significant and weak correlation between temperature, WAC (+0.150) and swelling power (+0.048). Also multiple correlation analyses suggest a significant correlation between fermentation period, the functional properties of starch extracts obtained from both fermentation methods and cassava varieties (i.e., solubility (−0.226), water absorption capacity (+0.301) and swelling power (+0.329)).展开更多
This work investigated and quantified the physicochemical, structural and morphological properties of four (4) tropical timbers as precursor raw materials for possible utilization in the wood plastic industry. The phy...This work investigated and quantified the physicochemical, structural and morphological properties of four (4) tropical timbers as precursor raw materials for possible utilization in the wood plastic industry. The physicochemical properties of the wood samples such as the bulk and tapped density, moisture content, water absorption capacity at 25°C, volatile content, fixed carbon, ash content, alpha cellulose, hemicellulose, lignin, and extractives contents were determined using standard methods like the European Committee for Standardization and (CEN/TS) and the American Society for Testing Materials (ASTM) standards. The structural and morphological properties of the samples were examined with Fourier Infrared Transform (FTIR) spectroscopy and scanning electron microscope (SEM). Results indicated that the bulk density values of the timbers ranged from 0.34 g/cm<sup>3</sup> in Brachystegia eurycoma (W<sub>3</sub>) to 0.47 g/cm<sup>3</sup> in Erythrophleum suaveolens (W<sub>2</sub>), with the other timbers, Nuclea diderichii (W<sub>1</sub>) and Prosopis africana (W<sub>4</sub>) having the same bulk density of 0.40 g/cm<sup>3</sup>. With respect to their moisture content, W<sub>2</sub> had the highest value (8.38%) while Nauclea diderrichii had the lowest value (6.52%). The water absorption capacities of the woods studied correlated with the cellulose composition of wood in the order of: W<sub>3</sub> > W<sub>1</sub> > W<sub>4</sub> > W<sub>2</sub>. The FTIR results showed that W<sub>2</sub> and W<sub>3</sub> presented a slightly more prominent and broader band than the other woods at 1731 cm<sup>-1</sup>, in agreement with the higher holocellulose content of these species, while W<sub>2</sub> and W<sub>4</sub> presented the most prominent peaks indicating higher lignin content than W<sub>1</sub> and W<sub>3</sub>. The SEM micrographs of the wood flour samples investigated indicated that the surfaces of the woods were rough and heterogeneous with irregular crystal and brick shaped particles. A two-way analysis of variance (ANOVA) carried out with respect to the chemical composition of the wood samples indicated that there was no statistically significant variation in the wood chemical composition between species as the p-value (0.852) obtained was greater than the critical level of α = 0.05.展开更多
文摘Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was modified with acetyl and hutyryl groups and films were prepared by blending acylated starch with low density polyethylene （LDPE）. Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS （2.5, 1.7） maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370℃ and 389℃ which were higher than the decomposition temperature of native starch film （349℃）. Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films （4.18% and 3.76%, respectively） was lower than that of native starch films （5%）. This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.
文摘This work investigated and quantified the physicomechanical properties of flat-pressed wood plastic composites produced with recycled polyethylene terephthalate, recycled polyethylene and sawdust derived from selected tropical timbers, namely, Nauclea diderrichii, Brachystegia eurycoma, Erythrophleum suaveolens and Prosopis africana, for possible utilization in the wood industry. The compounding of the polymer blends of the precursor plastics, namely recycled PET (rPET) and recycled PE (rPE) with the sawdust (SD) from the selected timbers to produce the desired wood rPET/rPE composites was carried out via the flat press method. The characterization of the physicomechanical properties of the wood plastic composites (WPCs) produced, such as the density, hardness, flexural strength, ultimate tensile strength, elongation %, thickness swelling and water absorption capacity was carried out using methods based mainly on the European Committee for Standardization (CEN) and the American Society for Testing Materials (ASTM) standards. The results of the investigation on the resultant composites indicated that changes in the SD content affected the density of flat-pressed WPCs in line with literature. Generally, it was observed that as wood dust increased and PET content decreased, the density of composites decreased with some deviations as expected probably due to the anisotropic nature of the wood fillers. The analysis of variance (ANOVA) revealed that there was a statistically significant variation in the wood composites of Nuclea diderichii based on the physicomechanical values as the p-value (0.020) obtained was less than the critical level of α = 0.05. It was also observed that the composite, Wood 1 Sample 5 (W<sub>1</sub>S<sub>5</sub>) which was composed of 40% rPE, 40% rPET and 20% SD (derived from Nuclea diderichii), had the highest percentage elongation (26.84%);the highest flexural strength (14.995 N/mm<sup>2</sup>) and possibly the least carbon footprint in the environment. These properties of W<sub>1</sub>S<sub>5</sub> suggest that it could therefore be the best option for the production of building materials like ceiling boards or floor skirting in the wood plastic composite industry. The results of these investigations have therefore indicated that the fabrication of WPCs from sawdust and rPET/rPE was technically feasible and had prospects for large scale production in the wood industry.
文摘The study was conducted to determine the influence of gratering and fermentation parameters on the physicochemical quality of starch obtained from two cassava varieties in Sierra Leone (i.e., SLICASS 11 and SLICASS 6). Fresh cassava roots harvested from the Department of Agricultural Engineering were peeled, washed and grated before fermentation and starch extraction. Fermentation was carried out under separate aerobic and anaerobic conditions for a period of Seven days. Physicochemical analyses were conducted at the Postharvest Food and Bioprocess Engineering Laboratory of the Department of Agricultural and Bio-System Engineering, Njala University to determine the solubility, water absorption capacity and swelling power of starch extracts obtained from various experimental treatments. Fermentation method and duration had significant effects on the solubility, water absorption capacity (WAC) and swelling power (SP) of starch extracts. Maximum solubility and WAC were recorded on the fifth day, for both cassava varieties tested, with apparent significant difference resulting from the two gratering bands (i.e., with 1.5-inch nail hole and 4-inch nail hole sizes, respectively). While swelling power increased consistently with temperature for starch obtained from SLICASS-11 variety, an irregular pattern was observed for SLICASS-6 variety. A multiple correlation analysis proposes a significant and weak correlation between temperature, WAC (+0.150) and swelling power (+0.048). Also multiple correlation analyses suggest a significant correlation between fermentation period, the functional properties of starch extracts obtained from both fermentation methods and cassava varieties (i.e., solubility (−0.226), water absorption capacity (+0.301) and swelling power (+0.329)).
文摘This work investigated and quantified the physicochemical, structural and morphological properties of four (4) tropical timbers as precursor raw materials for possible utilization in the wood plastic industry. The physicochemical properties of the wood samples such as the bulk and tapped density, moisture content, water absorption capacity at 25°C, volatile content, fixed carbon, ash content, alpha cellulose, hemicellulose, lignin, and extractives contents were determined using standard methods like the European Committee for Standardization and (CEN/TS) and the American Society for Testing Materials (ASTM) standards. The structural and morphological properties of the samples were examined with Fourier Infrared Transform (FTIR) spectroscopy and scanning electron microscope (SEM). Results indicated that the bulk density values of the timbers ranged from 0.34 g/cm<sup>3</sup> in Brachystegia eurycoma (W<sub>3</sub>) to 0.47 g/cm<sup>3</sup> in Erythrophleum suaveolens (W<sub>2</sub>), with the other timbers, Nuclea diderichii (W<sub>1</sub>) and Prosopis africana (W<sub>4</sub>) having the same bulk density of 0.40 g/cm<sup>3</sup>. With respect to their moisture content, W<sub>2</sub> had the highest value (8.38%) while Nauclea diderrichii had the lowest value (6.52%). The water absorption capacities of the woods studied correlated with the cellulose composition of wood in the order of: W<sub>3</sub> > W<sub>1</sub> > W<sub>4</sub> > W<sub>2</sub>. The FTIR results showed that W<sub>2</sub> and W<sub>3</sub> presented a slightly more prominent and broader band than the other woods at 1731 cm<sup>-1</sup>, in agreement with the higher holocellulose content of these species, while W<sub>2</sub> and W<sub>4</sub> presented the most prominent peaks indicating higher lignin content than W<sub>1</sub> and W<sub>3</sub>. The SEM micrographs of the wood flour samples investigated indicated that the surfaces of the woods were rough and heterogeneous with irregular crystal and brick shaped particles. A two-way analysis of variance (ANOVA) carried out with respect to the chemical composition of the wood samples indicated that there was no statistically significant variation in the wood chemical composition between species as the p-value (0.852) obtained was greater than the critical level of α = 0.05.
