Investigating the mechanical properties and degradability of bioplastics made from wheat straw cellulose and date palm fiber

During the past two decades، the use of bioplastics as an alternative to regular plastics has received much attention in many different industries. The mechanical and degradable properties of bioplastic are important for their utilization. In this research cellulose of wheat straw and glycerol were mixed by different weight ratios and then reinforced by using date palm fibers. To prepare the bioplastic plates، the materials were poured in molds and pressed by means of a hydraulic press and simultaneously heating of the molds. The experiments were performed based on a 3×3 factorial design with three levels: 50%، 60% and 70% of wheat cellulose and three types of reinforcement methods، namely: no-reinforcement، network reinforcement and parallel string reinforcement. The effect of the two factors on tensile strength، tensile strain، bending strength، modulus of elasticity and modulus of bending were investigated. The results indicated that the two factors and their interactions had significant effects on the mentioned properties of bioplastics (at α=0. 05 level). The comparison of the means of the tests showed that the network reinforcement type with 50% cellulose had the highest tensile and bending strengths with 1992. 02 and 28. 71 MPa، respectively. The maximum modulus of elasticity and modulus bending were 40. 4 and 2. 3 MPa، respectively for parallel string arrangement and 70% of cellulose. The degradability tests of bioplastic using a fistulated sheep indicated that with increasing the percentage of cellulose، the degradability rate deceased. The maximum degradability rate، after 48 h holding in the sheep rumen، was 74% that belonged to bioplastics with 50% cellulose. The degradability data were well fitted to a mathematical model (R2=0. 97).