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The objectives of this study were to generate fermentable xylose by sulfuric acid hydrolysis of wheat straw and investigate the effect of hemicellulose removal on the physical and chemical properties of the unhydrolyzed solid residue (USR). Different reaction conditions, including concentration of sulfuric acid (COS), temperature, and time, were tested for their effects on the yield of xylose and the USR. The ideal hydrolysis conditions for xylose production were 0.5% of COS at 140 °C for 90 min, with the xylose yield of 0.185 g/g wheat straw. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the acid hydrolysis only caused slight changes in the functional groups and the crystal form of wheat straw at mild conditions, while higher temperature or higher COS exacerbated these changes. [ABSTRACT FROM AUTHOR]

Polyamide 5,6 (PA 5,6) fibers were prepared using the melt-spinning method. The effects of draw ratio and temperature on the structure and properties of PA 5,6 fibers were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction, sonic velocity and tensile test measurements. DSC results revealed that the melting temperature showed no considerable variation, while the heat of fusion increased with increments with draw ratio and temperature. It was found that the crystallinity and crystal size of PA 5,6 fibers were directly proportional to the draw ratio and temperature and the orientation factor increases as expected upon drawing. The tenacity and Young's modulus were found to be increased, while the elongation at break decreased with the draw ratio and temperature. The improvement in mechanical properties may be attributed to the increase of orientation along the fiber axis and the crystallinity. [ABSTRACT FROM PUBLISHER]