Preparation of a hydrophobic recycled jute-based nonwoven using a titanium dioxide/stearic acid coating

This work aims at developing a hydrophobic treatment for jute fiber-based nonwovens. Three solutions of titanium dioxide (TiO₂) nanoparticles were prepared through a sol–gel method by varying the molar ratio of the various constituents. The nonwoven was pretreated with these solutions before being impregnated with different concentrations of stearic acid. The TiO₂ nanoparticles synthesized are amorphous; their size varies with the concentration of ethanol used as a solvent in the sol–gel method. The nanoparticle coating produced on the jute fibers is uniform. The nonwoven wettability was evaluated by measuring its water contact angle and retention time; the nonwoven became hydrophobic at the lowest fatty acid concentration tested. An increase in the stability of the hydrophobicity was observed when the TiO₂ nanoparticle pretreatment was used compared to the application of the stearic acid treatment only. No detrimental effect of the hydrophobic treatment on the nonwoven mechanical performance and thermal stability was observed. These results demonstrate the potential of the TiO₂ nanoparticle/stearic acid treatment as a fast method to provide a stable hydrophobicity to recycled jute-based nonwovens.     

Evaluation on some finishing properties of oil palm plywood

Oil palm is the largest and most important plantation crop in Malaysia. The oil palm generally lasts for 25–30 years before the next replantation is done. Substantial amount of biomass in the form of palm trunk results from plantation cycle. This resource is simply left on the ground to decay and is not used as raw material to manufacture any kind of value-added products. The objective of this study was to investigate the possibility of manufacturing plywood from oil palm trunks and to evaluate some of the finishing properties of such experimental panels in comparison to those from Shorea sp as control samples. Three-ply plywood samples were produced from 5 mm thick veneers of oil palm using urea formaldehyde adhesive. Three types of chemicals, namely nitrocellulose, pre-catalyzed lacquer and polyurethane were used to finish experimental panels. The surface finished with nitrocellulose had the lowest contact angle on raw surface of oil palm plywood and wood. The average cross cut tape index of oil palm plywood was comparable to Shorea sp. All finishing materials of oil palm plywood produced impact rating of 4 except for surface finished with nitrocellulose while finishing on wood indicated an impact rating of 3. Oil palm plywood had higher weight loss compared to Shorea sp. Based on results from contact angle, cross cut tape index, impact rate test, weathering, and soil burial test methods it appears that the samples showed acceptable finishing properties comparable to those of solid wood.     

Antioxidant constituents from Lawsonia inermis leaves: Isolation,structure elucidation and antioxidative capacity

The antioxidant potential of different fractions of Lawsonia inermis (Lythraceae) was investigated. The n-butanolic fraction showed the highest yield of extraction; it also exhibited a strong antioxidant activity in the DPPH assay and a potent capacity in preventing linoleic acid oxidation. Five phenolic glycosides were identified in this fraction. The structure of a new compound was established as 1,2,4-trihydroxynaphthalene-1-Ο-β-d-glucopyranoside. In addition, the known 2,4,6-trihydroxyacetophenone-2-Ο-β-d-glucopyranoside was described for the first time in this species. The three other compounds, lalioside (2,3,4,6-tetrahydroxyacetophenone-2-Ο-β-d-glucopyranoside), lawsoniaside (1,2,4-trihydroxynaphthalene-1,4-di-Ο-β-d-glucopyranoside) and luteolin-7-Ο-β-d-glucopyranoside, have been previously reported in L. inermis. The antioxidant activity of these glycosides was evaluated by DPPH and β-carotene assays, and compared to those of commercial standards. 1,2,4-Trihydroxynaphthalene-1-Ο-β-d-glucopyranoside was the most active in the DPPH free-radical scavenging test (EC₅₀ = 6.5 μg/ml) and showed a moderate inhibition in the β-carotene bleaching assay. Chemical components of L. inermis have good antioxidant capacities and this species could be used as a potential source of new natural antioxidants.