Effect of Anhydride Modification on the Thermal Stability of Cultivated Acacia mangium

Abstract

This paper tests the hypothesis that propionic and succinic anhydride modification will improve the thermal stability of cultivated Acacia mangium wood. The thermal stability of modified wood was characterized with thermogravimetric analysis. Evidence of modification was confirmed by Fourier transform infrared analysis. Our results show that chemical modification with anhydrides improves the thermal stability of the Acacia wood. The higher thermal stability of anhydride-modified Acacia wood compared with unmodified wood is attributed to the reduction in hydrophilic nature of the wood due to esterification. Succinylated wood has better thermal stability than propionylated wood based on the values of on-set degradation temperatures, the temperatures at which 30, 50, and 70% degradation occurred, and the activation energy. The improved thermal stability of modified wood compared with the unmodified wood will offer potential for better utilization of Acacia mangium.     

Synthesis and characterization of rubber‐seed‐oil‐based polyurethanes

Novel biobased polyurethanes were synthesized from rubber seed oil (RSO), a renewable resource. The RSO monoglyceride, together with xylene and hexamethylene diisocyanate (HMDI), was employed to synthesize the desired urethane‐based prepolymer with isocyanate (NCO)‐terminated end groups followed by curing. The degrees of crosslinking of the polyurethane after curing were assessed with their swelling behavior. The properties of the resulting polyurethanes were found to be dependent on the type of diisocyanate and their molar ratios to the RSO monoglyceride. The network structures, which were assessed through swelling studies, showed that networks based on HMDI with an NCO/OH ratio of 1.50 were better crosslinked than with those toluene diisocyanate. The thermal properties of the samples analyzed by thermogravimetric analysis showed two and three decomposition stages in aliphatic‐ and aromatic‐based RSO polyurethanes, respectively. The highest stability with initial decomposition temperature (253°C) and percentage residual at 500°C (11.4%) was achieved with an aliphatic‐based RSO polyurethane. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Composition and Pasting Properties of Breadfruit (Artocarpus communis Forst) from South-West States of Nigeria

Breadfruit (BF) is an underutilised crop in Nigeria. Information on its composition and the behaviour of its flour during cooking are important requirements for enhancing the utilisation of BF. Flours of BF obtained from three towns in South-West Nigeria were analysed for their chemical and pasting properties. Starch, crude fibre, ash, fat, protein and pasting properties were evaluated. Starch was the predominant carbohydrate, representing about 60.4 to 65.8% in the pulp and 47.5 to 57.5% in the peel. Crude fibre values varied from 6.31 to 9.04%. There was no significant difference between the crude fibre contents of the pulp and peels. Ash content ranged from 2.77 to 4.78% with the peels having significantly higher values than the pulp. Fat content ranged from 0.43 to 0.65%. The pulps had significantly higher protein content than the peels. Peak viscosity varied significantly across locations with the peels having significantly lower viscosity than the pulps. The peels were significantly hot stable with breakdown viscosity values of 6.92 to 7.95 RVU compared to the pulps (72.33 to 210.77RVU). Final viscosity of the pulp was higher than that of the peels. Higher setback viscosity values were observed in the pulps than the peels and the former cooked in significantly shorter time (3.67 to 3.77 min) than the peels (8.93 to 8.99 min). The study revealed considerable differences in the composition of breadfruit grown in different locations in Nigeria.