Water absorption,biodegradation, thermal and morphological properties of Spartium junceum fiber-reinforced polyvinylchloride composites: effects of fibers content and surface modification

In this study, we want to investigate the effects of fibers content and surface modification of Spartium junceum (SJ) fibers on the water absorption characteristics, thermal degradation, and morphological properties of SJ-reinforced poly (vinyl chloride) (PVC) composites. In addition, the change in mechanical proprieties of the composites after biodegradation test was evaluated by tensile strength. In order to improve the interfacial interactions between the PVC matrix and the SJ fibers, SJ fibers were modified by sodium hydroxide (NaOH), vinyltrimethoxysilane (VTMS) and treated with sodium hydroxide solution followed by VTMS (NaOH+VTMS). The results show that the water uptake of PVC/SJ fibers composites increases with the increase in the fibers’ content. However, the surface modification reduces water uptake. Moreover, the results indicate that the kinetics of water absorption of the PVC/SJ fibers composites approaches the Fickian diffusion mechanism. Also, the results indicate that the tensile strength of the composites is affected by the biodegradation test and chemical treatments. The atomic force microscope pictures of the composites illustrate the reduction of roughness via surface treatments of fibers.     

Biocomposites based on date palm flour reinforced (70/30) polypropylene/thermoplastic starch blend: Effects of flour treatment and selective dispersion

In this work, biocomposites have been prepared from a matrix consisting of polypropylene (PP) and thermoplastic starch (TPS) compatibilized using maleic anhydride (MA) grafted PP (PP-g-MA) and flour obtained from local date palm trees (DPF). To mediate the high hydrophilic character of the filler and attain an optimal dispersion, MA treated DPF (MA-DPF) was prepared via DPF esterification. Pretreated and MA treated DPF composites have been prepared by incorporating 10, 20 and 30% of the flour. MA-DPF has also been dispersed according to a second method consisting of dispersing the flour into starch/glycerol mixture before plasticizing to obtain MA-DPF modified TPS batches that were incorporated into PP to get the same matrix composition and flour loadings as for the first composites. The study of the composites properties proved the MA-DPF efficiency in increasing their impact resilience and diminishing their aptitude to water absorption. This was possible due to the association of the MA-DPF/TPS existing interactions to the better affinity of the esterified flour for the PP phase through its reduced hydrophilic nature. Also, SEM analysis confirmed that the interesting impact and water resistances of MA-DPF modified TPS filled PP composites derive from the DPF reinforced TPS phase consisting the materials.     

Hybrid Harmony Search Combined with Stochastic Local Search for Feature Selection

Feature selection is a challenging task that has been the subject of a large amount of research, especially in relation to classification tasks. It permits to eliminate the redundant attributes and enhance the classification accuracy by keeping only the relevant attributes. In this paper, we propose a hybrid search method based on both harmony search algorithm (HSA) and stochastic local search (SLS) for feature selection in data classification. A novel probabilistic selection strategy is used in HSA–SLS to select the appropriate solutions to undergo stochastic local refinement, keeping a good compromise between exploration and exploitation. In addition, the HSA–SLS is combined with a support vector machine (SVM) classifier with optimized parameters. The proposed HSA–SLS method tries to find a subset of features that maximizes the classification accuracy rate of SVM. Experimental results show good performance in favor of our proposed method.