The natural fiber (NF) reinforced composites, so called eco-composites, are subject of many scientific and research projects, as well as many commercial programs. The growing global environmental and social concern, high rate of depletion of petroleum resources, and new environmental regulations have forced the search for new composites and green materials, compatible with the environment. The aim of this article is to present a brief review of the most suitable and commonly used biodegradable polymer matrices and NF reinforcements in eco-composites, as well as some of the already produced and commercialized NF eco-composites. POLYM. COMPOS., 28:98 -107, 2007.
Poly(L-lactic acid)-titanium dioxide nanocomposites (with various loadings of TiO 2 : 0.5, 1, 2, 5, and 10 wt %) were produced by solution casting method. The influence of TiO 2 on thermal properties and crystallinity of PLA was investigated by DSC and FTIR spectroscopy. The TiO 2 nano filler has no significant influence on the characteristic temperatures (T g , T c , and T m ), but has high impact on the crystallinity of these systems. The degree of crystallinity X c significantly increases for PLA nanocomposites loaded with up to 5 wt % of TiO 2 , while for 10 wt % load of TiO 2 it drops below X c of the pure resin. The degradation of the prepared composites was evaluated hydrolytically in 1N NaOH, enzymatically in a-amylase solutions, and under UV irradiation. The catalytic effect of TiO 2 nano particles on the degradation processes under UV light exposure (k ¼ 365 nm) and hydrolytic degradation was confirmed with the increase of the filler content. The opposite effect was identified in enzymatic degradation experiments.
Biodegradable thermoplastic-based composites reinforced with kenaf fibers were prepared and characterized. Poly(lactic acid) (PLA) was selected as polymeric matrix. To improve PLA/fibers adhesion, low amount of a proper reactive coupling agent, obtained by grafting maleic anhydride onto PLA, was added during matrix/fibers melt mixing. Compared with uncompatibilized composites, this compatibilization strategy induces a strong interfacial adhesion and a pronounced improvement of the mechanical properties.
In recent years bio-based polymer composites have been the subject of many scientific and research projects, as well as many commercial programs. Growing global environmental and social concern, the high rate of depletion of petroleum resources and new environmental regulations have forced the search for new composites and green materials, compatible with the environment. The aim of this article is to present a brief review of the most suitable and commonly used biodegradable polymer matrices and NF reinforcements in eco-composites and nanocomposites, with special focus on PLA based materials.
A few 4-allyl/amino-5-aryl-1,2,4-triazoles were synthesized and tested for antibacterial and antifungal effects against Escherichia coli, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Aspergillus niger and Candida albicans. 4-Allyl-5-aryl-1,2,4-triazoles were obtained by the oxidative cyclization of the appropriate 1-substituted-4-allylthiosemicarbazides and 4-amino-5-aryl-1,2,4-triazoles were obtained by cyclization of the potassium salts of appropriately substituted dithiocarbazinic acids with hydrazine hydrate. The new synthesized compounds were characterized using IR, 1H- NMR, 13C-NMR and UV spectral data together with elemental analysis.
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