This paper presents the application of inverse gas chromatography (IGC) technique for characterization and comparison of the surface properties of the natural fibers as reinforcement fillers in wood plastic composites. The effects of chemical modification using 1% NaOH were also studied. The fibers used for this work were Iranian cultivated eucalyptus, spruce, bagasse, and wheat straw. Chemical composition of fibers was found to be modified after treatment as characterized by Fourier transform infrared spectroscopy (FTIR). The crystallinity of fibers and the specific interaction was improved by the alkaline treatment, with more relevance to the agro-fibers. The IGC shows also a general increase in the wettability of the modified fiber when compared with the raw (unmodified) samples. Alkaline treatment achieves the best overall improvement in the properties evaluated of the agro-fibers when compared to the wood fibers.

Beef tallow methyl esters (TMEs), pork lard methyl esters (LMEs), and chicken fat methyl esters (CMEs) were produced, purified, and characterized to evaluate their quality and compare two purification methods: (1) conventional neutralization, water washing, and drying and (2) purification using cationic exchange resins. Also, B20 blends [20% biodiesel (v/v) mixed with petroleum diesel] were characterized and evaluated. The conventional alkali-catalyzed transesterification process was used, with methanol as the reagent and KOH as the catalyst, yielding 76.8, 90.8, and 91.5% (w/w) CME, TME, and LME, respectively. The ester content of these biodiesels was below 96.5% (w/w), and the kinematic viscosity was high (ranging between 4.84 and 6.86 mm 2 /s), which poses restrictions to their use as fuel in vehicle engines, especially in low-temperature climates. Although it is not possible to use 100% biodiesel produced from these animal fats, blends of 20% biodiesel are viable with some advantages, such as the improved cold-flow properties [cold filter plugging point (CFPP) below À6 °C], lower kinematic viscosity (from 3.10 to 3.28 mm 2 /s), and higher heating value of the mixture (about 44.6 MJ/kg). Results also show that the resin purification helps to reduce biodiesel acidity and kinematic viscosity, while conventional water washing followed by adsorbent drying and filtration gives better results regarding water and alkaline metal (Na + K) content.

Agro-residues fibers are inexpensive environmentally friendly alternatives to synthetic fibers in fiberreinforced polymer composites. The natural fiber properties and bondability with adhesive can be modified by subjecting the fibers to a pre-treatment procedure. The knowledge of the modified fibers surface properties is essential to explain and predict their applications. The present study is focused on the effect of alkaline treatment on the surface characteristics of stalk fibers from rapeseed, tobacco, cotton, lemon balm and kiwi. The chemical composition of fibers and Fourier transform infrared spectroscopy show components extraction and the X-ray diffraction show improvement in the crystallinity index of the treated fibers. But only the IGC analysis allows us to know in detail the alterations on the fiber surface and the effect on the adhesion of the fibers. IGC shows that alkaline treatment produces changes in the nature and number of the active sites, responsible for the physico-chemical activity of the surface of the fibers. The fiber hydrophobicity was improved by the increase of more energetic and active sites in the surface. Also, the creation of new basic active sites and removal of acidic active sites from the fiber surface due to alkaline treatment has been clearly shown.

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