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The paper provides some experimental data on the effects of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) grafted maleic anhydride (PHBV-g-MA) used as the compatibilizer for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/olive husk flour (OHF) composites prepared by melt compounding. The natural filler was added to PHBV at various contents, i.e. 10, 20, and 30 wt%, while the amount of PHBV-g-MA was 5 wt% based on neat PHBV. Morphology, contact angle measurements, water absorption (WA), mechanical, viscoelastic, and barrier properties of the various composites were investigated with and without the compatibilizer. The study showed through scanning electron microscopy that the addition of PHBV-g-MA to PHBV/OHF composites resulted in better and finer dispersion of the filler in the matrix, even at a higher content ratio, indicating improved affinity between the components. This is in agreement with the decrease in both surface energy and WA. Furthermore, tensile and dynamic mechanical measurements indicated a reinforcing effect of OHF in PHBV composites, being more pronounced in the presence of PHBV-g-MA. The barrier properties against oxygen and water vapor were also improved for the compatibilized composites. [ABSTRACT FROM AUTHOR]

PS/organo-modified clay (5% w/w) nanocomposite has been subjected to a series of eight processing cycles in a twin screw extruder. The influence of multiple recycling on the properties of the nanocomposite was studied by following the changes in the morphology, the molecular structure, the melt flow index (MFI) and the thermal properties. The WAXS results indicate a strong intercalation of PS chains between silicate layers of the organoclay and the extent of intercalation appears to increase with increasing the number of cycles. The main effects of recycling are a reduction in molecular weight due to chain scission, although the occurrence of a crosslinking fraction is probable after 8 cycles. The thermal properties remain almost stable during reprocessing. [ABSTRACT FROM PUBLISHER]

The paper reports some results of an experimental study on ethylene vinyl acetate (EVA) copolymer/olive husk flour (OHF) composites incorporated at various filler ratios (15, 30 and 45 wt%) in the absence and the presence of ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) terpolymer used as a compatibilizer. The composite samples have been prepared by melt blending and their chemical structure, as well as morphological, mechanical and water absorption properties investigated. It is shown that the compatibility of EVA/OHF composites is improved by the addition of EBAGMA terpolymer. Indeed, FT-IR analysis shows that chemical interactions have occurred between the compatibilizer and the base blend components. Morphological results from SEM shows better dispersion of the wood particles in the EVA matrix and the resulting composite samples exhibit better tensile properties at break and lower water absorption than the uncompatibilized ones. Moreover, the results indicate that the loading concentrations of both OHF and EBAGMA have an effect on the composite properties. [ABSTRACT FROM AUTHOR]

Photostability of low-density polyethylene (LDPE) films under natural weathering conditions was investigated in the absence and the presence of various structures of hindered amine light stabilizers (HALS) by chemiluminescence (CL) and Fourier transform infrared (FTIR) spectroscopy. The stabilizers studied were Sanduvor PR 31 (as grafted HALS) and Uvasil 299 and Tinuvin 123 (as non-grafted HALS). The HALS were added separately to LDPE at the same concentration, namely 0.3% (w/w). It was found that the weathered stabilized samples exhibited a relative long period during which the CL signal slowly increased, while for unstabilized samples, CL increased after a short induction period. This behavior could be explained by reduction in the rate of hydroperoxide decomposition caused by nitroxyl radicals. However, the very high increase in stability observed in the case of Sanduvor PR 31 sample could be assigned to the grafting effect of the HALS on the polymer chain. At longer exposure times, the oxidation induction time decreased slowly as a result of stabilizer consumption in the photooxidative process. These changes in CL parameters were found to correlate with carbonyl index determined by FTIR spectroscopy. [ABSTRACT FROM AUTHOR]