Grafting of maleic anhydride onto polypropylene: Synthesis and characterization
ABSTRACT Isotactic polypropylene was grafted with maleic anhydride using benzoyl peroxide as an initiator and toluene as a solvent. Effects of various parameters such as monomer and initiator concentration, reaction time, and reaction temperature on percentage grafting were studied. Effect of various solvents on extent of grafting was also studied. The maximum extent of grafting achieved was 5.3%. The graft copolymers were characterized by i.r., thermal, viscometric, and contact angle studies. Improved thermal stability and decreased intrinsic viscosity and critical surface tension were observed for graft copolymers. © 1994 John Wiley & Sons, Inc.
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ABSTRACT: Subcutaneous mycoses include diverse clinical syndromes, characterized by invasion of the skin and subcutaneous tissue by saprobic fungi. Individuals living in rural areas constantly suffer lesions or trauma; however, only a few of them develop disease. In this contribution, we describe recent advances in the understanding of the virulence of these organisms, focusing on the most prevalent infections, sporotrichosis, chromoblastomycosis, and mycetoma. Although these infectious diseases are considered neglected tropical diseases, modern molecular techniques have been able to identify the etiologic agents and observe variations in the former monolithic concept of the species, which was based mostly on morphologic characteristics. The complete genetic characterization of the causative agents, along with that of their host, will help in the understanding of the factors on which the development of these infections depends.Clinics in dermatology 07/2012; 30(4):382-8. · 3.11 Impact Factor
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ABSTRACT: In this work, the rheological, morphological and mechanical behaviors of nanocomposites based on blends of polypropylene and metallocene polyethylene (mPE), reinforced with organically modified montmorillonite and prepared through melt blending, are studied. Two different compatibilizing agents were employed: a PP grafted with maleic anhydride (AM) commercially available, and a PP grafted with the same monomer in our laboratory. The grafting degrees of both compatibilizers were determined through Fourier transformed infrared spectroscopy (FTIR). Additionally, the rheological properties in dynamic shear and the mechanical properties in tension of the composites were studied. The morphologies of the nanoparticles and of the dispersed phase were characterized using TEM and SEM microscopy, respectively. The compatibilizing agent prepared in our laboratory has a higher grafting degree than that of the commercial one. The dynamic rheological properties of the nanocomposites are higher than those of the corresponding analog blends, when mPE is at concentrations of 40%. Both the nanocomposites and the blends without the layered clay exhibit a pseudosolid behavior at low frequencies. The obtained morphology of the clay particles is mainly intercalated. The nanocomposites compatibilized with the agent prepared in the laboratory exhibit a smaller particle size of the polymeric dispersed phase. The mechanical properties remained almost unchanged with the addition of the nanoparticles, whereas a reduction both in the Young's modulus and in the tensile strength were obtained with the addition of the polymeric dispersed phase.Revista de la Facultad de Ingenieria 12/2010; 25(4):107-120.
Chapter: BIODEGRADABLE PLASTIC FROM BLOOD[Show abstract] [Hide abstract]
ABSTRACT: Most of today's synthetic polymers are produced from petrochemicals and these persistent polymer waste is evoking more concern regarding its environmental impact. Globally, 2.5 to 4 billion tons of waste was generated in 2006 and recycling is expensive, therefore an alternative solution is needed to solves this serious problems . In the search for sustainable materials from non-potential food sources, bloodmeal is one of the best candidates for bioplastic manufacture. It is one of the highest non-synthetic sources of nitrogen coming from meat.Meat is New Zealand's second-largest food export and is worth $5.14 billion. From the plastics industry's point of view, developing improved blended materials is a much more effective and cheaper compared to synthesizing new polymers. Blending reduces the number of different grades that need to be manufactured and stored, resulting in space and capital investment reduction.03/2013: pages 154; , ISBN: 978-0-475-12403-6