To improve the impact resistance and reduce the product cost, poly(lactic acid) (PLA) blends containing varying mass fraction of waste rubber powder (WRP) were fabricated via melt compounding. The effects of WRP contents on the mechanical properties, morphologies and thermal stabilities of PLA/WRP blends were investigated. Mechanical tests showed that WRP could increase the ductilities of PLA, leading to the significant improvements in the impact toughness and elongation at break. In contrast, the tensile strength was just heightened slightly, while elastic modulus declined gradually. Scanning electron microscopy observations indicated that well bonded interfacial morphologies were formed between PLA and WRP. From the results of thermo gravimetric analysis, WRP decreased the onset and peak decomposition temperatures of PLA phase and increased the char contents of samples significantly. Average activation energies of samples were increased first and then decreased with increasing WRP. Finally, theoretical lifetimes of PLA/WRP blends were also estimated. 1I ntroductionPoly(lactic acid) (PLA) was an authentic biodegradable thermoplastic resin, which has obtained extensive attentions in recent years. It was the excellent biodegradability and biocompatilibity that usually made PLA very popular in the applications of internal sutures, implant devices, tissue scaffold and drug delivery devices (Nampoothiri et al., 2010). For the environmentally aware, PLA should be an especially attractive candidate instead of petroleum-based polymers, due to its sources from renewable plants (such as corn and starch). Although PLA possessed competitive strength and stiffness to general resins of polypropylene (PP) and polyethylene (PE), its applications were largely limited by the high brittleness, poor impact resistance and the relatively higher cost of products.

To improve the performances of waste rubber powder filled polypropylene (PP/WRP) blends, WRP was modified by γ-aminopropyltriethoxysilane (APTES) via mechano-chemical method, and then maleic anhydride (MAH) grafted PP (mPP) and MAH grafted ethylene-α-octene copolymer (mEOC) were chosen as the interfacial compatibilizers. The PP/WRP blends were prepared by melt-compounding and compression, and their morphological structures, tensile properties and thermal behavior were investigated carefully. Results showed that modification of APTES decreased the surface energy of WRP and facilitated its compatibility to PP. Both mPP and mEOC could further enhance their interfacial bonding and mPP was superior to mEOC in increasing the tensile strength and elastic modulus. Thermal analysis revealed relative lower melting temperature and crystallinity but higher activation energy for PLA/WRP blends in comparison to pristine PP.

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The biocomposites of poly (lactic acid) (PLA) involving 15 % mass fraction of calcium sulfate whiskers (CSW) were prepared via melt-blending technology, in an effort of toughening PLA and enhancing the thermal stability. The morphological structure, impact toughness, thermal stability as well as kinetic analysis on thermal decomposition for PLA/CSW composites were performed thoroughly. The results showed that CSW was organized successfully via silanization, helping to form well-bonded interfaces, and accordingly, the impact toughness increased remarkably. The thermal stability was enhanced by adding whiskers, leading to increased decomposition temperature and decreased mass conversion rate. Kinetic analysis revealed the great dispersions on the reaction order and activation energy. Though, in comparison to pure PLA, the reaction order of PLA/CSW composites increased based on calculation methods except for Carrasco's, the activation energy of the composites declined independently of the applied mathematical models, meaning that thermal decomposition of PLA phase was accelerated by the introduced CSW.

Main contents and research results are as follows：First, unconventional emulsion explosives for synthesis of zinc and lithium oxides are designed firstly, and we also discuss mechanics of deflagration. In the final analysis, we succeeded in synthesizing nano-sheets of zinc and lithium oxides by deflagrating at the fist time. Second, we tested microstructures of nanometer thin sheets of lithium and zinc composite oxides.Third, by contrast to industrial emulsion explosives, we analyzed the deflagration mechanics of the unconventional emulsion explosives. Last, zinc and lithium nanooxides are successfully collected and validated by XRD, TEM and FTIR exactly.