Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and lowdensity polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0-25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP.

Summary: Eri cocoons were prepared into short fibers and subsequently blended with cotton fiber in order to develop the new fiber blended yarn in the short spinning system. The Eri and cotton fibers were blended using the drawframe blending with varying blending factors, viz. blending composition (0-100%) and yarn counts (30 and 50 tex). The results showed that Eri fiber which was longer and stronger than cotton fiber, affected the fiber distribution in the yarn cross-section. The mechanical properties of the blended fibers and yarns increased with increasing silk content. Longer fibers of Eri silk tended to move towards the yarn core, especially at silk content higher than 50%. Moreover, stronger and more extensible Eri silk fiber gave an advantage to the improvement of mechanical properties of those blended yarns with silk content higher than 50%. However, with increasing silk content, the blended yarns were more irregular as shown in %CV. Concerning the yarn count effect, the higher yarn count of 50 tex resulted in a more regular yarn with higher yarn strength than that of 30 tex. The plain-woven fabrics were prepared using the blended yarns as a weft yarn and the cotton yarn or silk yarn as a warp yarn. The mechanical properties of those woven fabrics were characterized in order to study the influence of silk contents. The results showed that tensile strength, %elongation and tear strength of woven fabrics using the blended yarn were increased with an increase in silk content. This is an advantage of Eri silk in the aspect of rendering the strength to the blended yarns and fabrics.

This research aimed to study the dyeing properties on the PLA and silk yarns of the natural dyes obtained from various materials, viz. marigold petals (Tagetes erecta L.), rhubarb rhizomes (Radix et Rhizoma Rhei), garcinia barks (Garcinia Dulcis Kurz), turmeric rhizomes (Curcuma Longa Linn.), sappan barks (Caesalpinia sappan Linn.) and catechu barks (Acacia catechu Willd.). The color properties of the dyed yarns was determined and compared. The results observed the different color properties (L*, a* and b* values) and a shift of λmaxof the dyes on the PLA and silk yarns. This change in color properties of each natural dye was expected to be affected by the types of substrate (textile fiber) and also the chemical nature of the natural dyes. The study of the build-up properties indicated that the turmeric dye is the only natural dye which showed an outstanding performance on PLA and silk. A high degree of color yield of turmeric dye was obtained on both yarns, whereas a poor build-up was observed for the rest of the dyes.

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This research studied the optimized dyeing conditions for natural indigo dye (Indigofera tinctoria) on silk yarn. Vatting of natural indigo dye was investigated under different temperatures and times and the natural dyeing auxiliaries were used i.e. tamarind and ash solutions. The results informed the optimum vatting condition for the indigo dye at 90°C for 30 minutes and the optimum pH was 12. The sugars in tamarind solution was expected to work as a reducing agent for dye vatting whereas the ash solution derived from banana barks was used as an alkalinity controller. Dyeing silk yarns with leuco indigo dye under a short time (5 minutes) provided a complete dye distribution with satisfactory color strength on silk and very good fastness properties.