Thermal analysis, statistical predicting, and optimization of the flexural properties of natural fiber biocomposites using Box–Behnken experimental design

The object of this study is to investigate the flexural properties of biocomposites based on polypropylene/kenaf fiber/polypropylene-grafted maleic anhydride (PP/kenaf/PP-g-MA) using the response surface methodology. A three-factor, three-level Box–Behnken design, which is the subset of the response surface methodology, has been applied to present mathematical models as a function of kenaf fiber load, fiber length, and PP-g-MA compatibilizer content for the prediction of flexural strength and modulus behavior of the natural fiber biocomposite. Three levels were chosen for the considered parameters as follows: kenaf fiber (10–30 wt%), fiber length (2–10 mm), and PP-g-MA (1–5 wt%). Optimum compositions for better flexural properties were obtained from contour plots and response surface methodology. The results obtained using the design expert software showed the optimal flexural strength and modulus to be 53.66 and 3442 MPa, respectively. The obtained $${R^2}$$ values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model. Finally, the morphology and thermal stability of the samples were evaluated by scanning electron microscopy and thermogravimetric analysis

Young's Modulus prediction of polyurethane and acrylonitrile butadiene styrene polymer blend based on phase morphology

Young's modulus of blends of thermoplastic polyurethane (TPU) and acrylonitrile butadiene styrene (ABS) are measured with different weight percentage (blend ratio). The results of the different micromechanical models prediction of Young's modulus, based on both droplet matrix and co-continuous morphology, are compared with experimental results. Both two-dimentisional models like series, parallel, Maxwell, Halpin-Tsai, Takayanagi, Davis, Coran and Patel, and three-dimensional models like Kolarik, Barentson and Nijhof are used for Young's modulus prediction of polymer blends. In this work, an emphasis was given to the effect of weight percentage on morphology and mechanical properties of the blend. Scanning electronic microscopy shows droplet matrix morphology in the presence of less than 20 wg% ABS in TPU matrix but in 70/30 TPU/ABS blend ratio, ABS phase dispersed like elongated elliptical and phase inversion happened. In the 95/5, 90/10 and 80/20 blend ratio  which ABS droplets dispersed uniformly throughout the TPU matrix, Parallel Takayanagi and Barentson series model of parallel parts, could predict Young's modulus with good accuracy. In the 70/30 blend ratio which phase inversion was observed and both phases are somehow continuous, Coran-Patel, series Nijhof and Kolarik models were accurate

Dynamic failure behavior of glass/epoxy composites under low temperature using Charpy impact test method

211-220This paper demonstrates results of an experimental study on glass/epoxy laminated composites subjected to low velocity impact at energy levels equal to 10, 15 and 30 J under variable temperatures in the range of -30°C to 23°C. The configuration of specimens is quasi-isotropic. The low temperature and its influence on the maximum absorbed energy, elastic energy, crack length and delamination are highlighted. Also, the effects of geometry index (span-to-depth) and notch orientation are studied. Failure mechanisms of specimens are examined using microscopic examinations. Results indicate that impact performance of these composites is affected over the range of temperature considered. Failure mechanism is changed from matrix cracking at room temperature to delamination and fiber breakage at low temperatures