GREEN COMPOSITES- BY MOSES DHILIP KUMAR

                                      GREEN COMPOSITES-

                             Currently, most plastics are simply buried in landfills where they remain for thousands of years.  Fiber-reinforced composites have been used for many applications from sporting goods to automotive parts. Most commercial fiber-reinforced composites are made from petroleum based synthetic fibers and resins that are non-degradable. Waste disposal problems and rising petroleum prices necessitate that some of the dependency on plastics be shifted to new materials. Using plant-based short and continuous cellulosic fibers in soy-protein polymer resin, that is fully-degradable, environment-friendly, 'Green' composites. Green composites can be made by the combination of Bio-degradable Resin and Natural Fibers.

 The random short fiber composites have moderate mechanical properties and can be used in non-structural applications. The unidirectional continuous fiber composites have tensile properties close to steel. However, at a typical steel-to-composite density ratio of about 6, these green composites are significantly superior to steel on a per weight basis and used for indoor structural applications in housing, transportation and automobiles. In recent years there has been considerable interest in using natural plant fibers as reinforcements for plastics. The motivation includes cost, performance enhancement, weight reduction, and environment concerns. High performance flax fiber could be a substitute for glass or carbon fibers as reinforcements for plastics.

FROM PINEAPPLE FIBERS AND POLY (HYDROXYBUTYRATE-CO-VALERATE) RESIN

                            Tensile properties of pineapple fibers, like most natural fibers, show a large variation. The average interfacial shear strength between the pineapple fiber and poly (hydroxybutyrate-co-valerate) (PHBV) is about 8.23 MPa, Fully degradable and environment-friendly Green Composites are made by combining pineapple fibers and PHBV with 20 and 30% weight content of fibers placed in a 0°/90°/0 ° fiber arrangements. Even though tensile and flexural strength and moduli of these green composites are lower than those of some wood specimens tested in grain direction, but they are significantly higher in perpendicular to grain direction. Compared to PHBV virgin resin, both tensile and flexural strength and moduli of these green composites were significantly higher. SEM photomicrographs of the fracture surface of the green composites, in tensile mode, showed partial fiber pull-out indicating weak bonding between the fiber and the matrix.

FROM RECYCLED CELLULOSE AND POLY (LACTIC ACID)

                        Green Composites were prepared from poly (lactic acid) (PLA) and recycled cellulose fibers (from newsprint) by extrusion followed by injection molding processing. Compared to the neat resin, the tensile and flexural moduli of the green composites are significantly higher. This is due to higher modulus of the reinforcement added to the PLA matrix. Differential scanning calorimetry (DSC) and Thermo gravimetric analysis (TGA) show that the presence of cellulose fibers do not significantly affect the crystallinity, or the thermal decomposition of PLA matrix up to 30 wt% cellulose fiber content. Overall it was concluded that recycled cellulose fibers from newsprint could be a potential reinforcement for the high performance biodegradable polymer green composites

FROM RECYCLED CELLULOSE FIBER AND POLY (3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE) BIOPLASTIC

                        Green composites are successfully fabricated from recycled cellulose fibers and bacterial polyester, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by melt mixing techniques. Various weight contents (15%, 30%, and 40%) of the fibers were incorporated in the PHBV matrix. The tensile and storage moduli of the PHBV-based composites improves by 220% and 190%, respectively, by reinforcement with 40 wt % RCF and the heat deflection temperature (HDT) increases from 105 to 131 C, while the coefficient of linear thermal expansion (CLTE) value reduces by 70% upon reinforcement with 40 wt % RCF. The PHBV-based composites had also shown better tensile and storage moduli and lower CLTE values than PP-based composites.