Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Organic geochemistry of Cretaceous Lamza and Chikila coals, upper Benue trough, Nigeria

Some biomarkers and other compounds in the aliphatic and aromatic fractions of the Lamza and the Chikila coals were characterized and used in assessing the source input, maturity, hence the hydrocarbon generative potentials of the coals. The samples exhibit a slight n-alkanes odd carbon preference (CPI ∼ 1), high pristane/phytane ratios and a dominance of 20S epimer of C₂₉ sterane. The ratio of C₃₀ αβ/(αβ + βα) sterane and 22S/(22S + 22R) C₃₁-homohopane gave values of 0.77-0.83 and 0.58-0.60, respectively. The low Ts/Tm ratios are in agreement with the calculated vitrinite reflectance, R_c (0.60-0.70%). The methylphananthrenes maturity derived parameters (1-MP/9-MP; MPR; MPI-1; R_c) revealed a very slight variation and a consistent order of samples maturity with the exception of the R_c values. All these together with some other hopanoid ratios, show that the organic matter is terrestrially derived, deposited in an oxic environment and at marginal maturity for hydrocarbon generation.     

The effect of hexamethylene diisocyanate modified ALCELL lignin as a coupling agent on the flexural properties of oil palm empty fruit bunch – polypropylene composites

ALCELL lignin has been employed as a coupling agent in oil palm empty fruit bunch (EFB)–polypropylene (PP) composites. The lignin has been chemically modified with hexamethylene diisocyanate (HMDI). Evidence for the reaction between HMDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on the flexural properties has been studied. The results show that the HMDI‐modified lignin is able to impart greater compatibility between EFB and PP. This is reflected in the greater flexural strength shown by the composites with HMDI‐modified lignin than those with the unmodified lignin. Scanning electron microscopy studies show that HMDI‐modification of lignin results in a better blending and compatibility between lignin and PP matrix. The glass transition temperature of lignin increases as the level of HMDI modification is increased. © 2001 Society of Chemical Industry     

Preliminary studies on the use of modified ALCELL lignin as a coupling agent in the biofiber composites

ALCELL lignin has been employed as a coupling agent in empty fruit bunch fiber (EFBF)–polypropylene (PP) composites. The lignin has been chemically modified with toluene diisocyanate (TDI) to various weight loadings. The evidence of the reaction between TDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on mechanical properties has been studied. The results show that the TDI‐modified lignin is able to impart greater compatibility between EFBF and PP. This is reflected in the greater mechanical properties shown by the composites with TDI‐modified lignin than in those with the unmodified lignin. Scanning electron microscopy (SEM) studies showed that TDI modification of lignin resulted in a better blending and compatibility between lignin and PP matrix. The glass‐transition temperature of the lignin increases as the WPG is increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1333–1340, 2001     

Estimating genetic values for milk production in the tropics

Variance components and predicted sire values were estimated using 305-d projected and unprojected milk records of varying lengths. Original data consisted of 15,512 lactation records of daughters of 138 Jamaica Hope sires that calved between 1969 and 1981 in 38 commercial dairy herds in Jamaica. Classification of records had little effect on components of variance. Herd-year-season variance decreased from 36% using all lactations to 28% with first lactations only. Sire variance was consistently about 10%. Cow component of variance accounted for 17% of the total variation using all lactations and 36% using all lactations of cows with recorded first lactations. Heritabilities for milk by Henderson's method 1 were five to six times larger than estimated from method 3 due to sire by herd confounding. Predicted sire values were between +400 kg and -400 kg. Rankings of sires with at least 5 progeny were considerably influenced by record classification, especially for sires with highest predicted values. There was less influence on rankings when at least 10 progeny per sire were used while the range in predicted sire values was larger using first lactation records only.     

Using mouse and keyboard under time pressure: preference, strategies and learning

Visually based point-and-click user interfaces have become very common. This increases the need to understand the mechanics in learning and using pointing devices in order to design appropriate human-computer interaction and thereby to help alleviate musculosketetal symptoms. The paper reports a study of preference, strategies and learning in using keyboard and mouse in a tracking task under time pressure. The keyboard was preferred by 11 out of 12 subjects due primarily to comfort, frustration, and visual strain. One of the most distinguishing features in favour of the keyboard was the opportunity to develop a working strategy facilitating learning.