آسیه خزینی

Regarding the development and application of biocompatible composites in various sectors, including packaging industry and disposable containers, consideration of the methods for improving mechanical properties is essential. the purpose of this study was to make a bio composites with a mixture of polypropylene as a matrix, starch as a filler, and Nano/micro cellulose fibers as reinforcing agent. For this study, polypropylene was used as a matrix, starch as filler in two levels (30 and 40%) and cellulose nanofibers at three levels (0, 1 and 2%) and cellulose micro-fibers in three levels (0.5, And 10%) was used as a reinforcing agent. MAPP was used as a coupling agent and glycerol as a plasticizer. Raw materials were mixed in a co-rotating twin-screw extruder. In this stage, TPS produced and of Nano and micro-fibers of cellulose dispersed in polymeric matrix. Then the granules obtained from the extruder were transferred to the injection device to obtain test specimens. The morphology of the samples was studied by FE-SEM. Data obtained from the results of the experiments were analyzed by using a factorial design in a completely randomized block design with SPSS software; also, Duncan test was used to compare group mean. The results showed that the addition of Nano and micro-fibers of cellulose increased the flexural and tensile strength of the specimens. Samples made with 30% starch and 2% cellulose Nano-fibers had the most flexural and tensile strength.

Wheat straw particle boards were produced using a mixture of wheat straw and cotton bolls with Urea formaldehyde resin and its properties were reinforced with nanoclay. Cotton bolls and wheat straw particles were mixed at the ratio of 40:60, 60:40 and 80:20percents, respectively. Nanoclay was used at two levels of 0 and 2 percents based on oven dried weight of resin. Control samples were made of wheat straw particle. Mechanical and physical properties (modulus of rupture, modulus of elasticity, internal bonding, water absorption and thickness swelling after 2 and 24h soaking in water) of the produced boards were measured. The results revealed an increase in cotton bolls in the mixture particles, leads to an increment of the bending strength, modulus of rupture and modulus of elasticity of the boards. The results also indicated that water absorption and thickness swelling after 2 and 24h immersion in water decreased with increase in nano clay and cotton bolls percents.