Thais Sydenstricker Flores-Sahagun

Bio-composites of cassava starch-green coconut fiber: Part II—Structure and properties

Development of any new material requires its complete characterization to find potential applications. In that direction, preparation of bio-composites of cassava starch containing up to 30 wt.% green coconut fibers from Brazil by thermal molding process was reported earlier. Their characterization regarding physical and tensile properties of both untreated and treated matrices and their composites were also reported. Structural studies through FTIR and XRD and thermal stability of the above mentioned composites are presented in this paper. FT-IR studies revealed decomposition of components in the matrix; the starch was neither chemically affected nor modified by either glycerol or the amount of fiber. XRD studies indicated increasing crystallinity of the composites with increasing amount of fiber content. Thermal studies through TGA/DTA showed improvement of thermal stability with increasing amount of fiber incorporation, while DMTA showed increasing storage modulus, higher glass transition temperature and lower damping with increasing fiber content. Improved interfacial bonding between the matrix and fibers could be the cause for the above results.

Effect of domestic compatabilizer on the performance of polypropylene-sawdust composites

Greater concern for environmental safety and fuel economy has increased interest in the use of renewable resources for development of new materials. Wood–plastic composites, made of recycled plastic and wood wastes, are very attractive in this respect, making this one of the most dynamic areas of new developments in the plastics industry in the past decade. This paper presents the preparation and characterization of polypropylene-sawdust composites by compression molding using maleated polypropylene (MAPP) produced in Brazil by reactive extrusion, with different amounts of two types of peroxides. The MAPP was characterized for thermal properties, melt flow index, and chemical structure, while the composites containing both uncoated and MAPP-coated sawdust were characterized for mechanical properties to understand the effect of coating as well as to compare these properties with those of composites prepared with commercial MAPP. The MAPP was efficient as a compatabilizer for polypropylene/sawdust composites. Better impact and tensile properties were observed in composites prepared with medium and high melt flow index compatibilizer concentrations, respectively.

Effect of processing parameters on the properties of polypropylene–sawdust composites:

Considering the boom in the market for wood plastic composite (WPC) products due to their relatively high specific strength properties, low maintenance costs, and wide range of applications, many authors have studied the performance of these composites prepared by reactive extrusion with different compatibilizers and peroxide types. This paper presents the density, chemical composition, and morphology of sawdust and the preparation and characterization of WPC with polypropylene by compression molding using different amounts of sawdust with and without coating with compatibilizer. Good-quality WPCs were obtained, as evident from almost identical experimental and theoretical density values of these composites. The WPCs prepared without compatibilizer coating exhibited low tensile properties. Irrespective of coating by different compatibilizers, the maximum tensile strength of all the WPCs decreased with increasing amount of sawdust. The WPCs prepared with uncoated sawdust fibers absorbed much more water than those prepared with compatibilizer-coated fibers, the latter showing increasing water intake with increasing amount of sawdust. These results are discussed in terms of melt-flow index, density differences, and adhesion between the sawdust and polypropylene.

Evaluation of polypropylene/saw dust composites prepared with maleated polypropylene (mapp) produced by reactive extrusion

Considering the importance of the environment and fuel economy, the Brazilian automotive industry has focused on the development of lightweight materials based on renewable resources. Replacement of PPtalc composite by PP- saw dust composite is a promising possibility. This paper presents the preparation of maleated polypropylene (MAPP) through reactive extrusion using different amounts of peroxides and maleic anhydride as well its characterization. Using 20% of saw dust coated with different amounts of prepared MAPP, several composites were prepared including one with commercial MAPP. Injection molded samples of all these composites along with that without the compatibilizer were characterized for mechanical properties. These studies indicated fulfilling the proposed objectives: (i) finding the optimal reactive extrusion conditions to prepare MAPP samples; (ii) preparation of PP/saw dust composites with and without MAPP coating; (iii) to arrive at optimized composite to get the best performance through their characterization for various properties of all the produced composites.

Lignocellulosic Materials of Brazil––Their Characterization and Applications in Polymer Composites and Art Works

Growing environmental concerns in recent years have led to finding new resources to replace the synthetic materials such as glass and carbon fibers in the development of polymeric and cementitious matrices-based composites. One such material is lignocellulosic fibers, due to their inherent characteristics such as abundant availability and renewability, low weight, biodegradability, interesting specific properties, etc. Studies have been carried out throughout the world in the utilization of these fibers particularly in the development of light weight, but high-performance composites. Some of their products are already in use in many applications. Although these fibers have been used even in sculptures or in arts in general, there is no report on the characteristics required for such applications. This chapter focuses on the exploration of these aspects particularly about the appearance of some plant fibers as well as their texture and potential use in polymeric sculptures or in arts. While doing so, the chapter will also present availability, methodologies used for the characterization as well as the reported properties (chemical, physical, mechanical thermal, electrical, environmental, and moisture absorption) of various Brazilian-based lignocellulosic fibers. It is hoped this will be applicable to fibers from other parts of the world to open up new areas of their utilization in a scientific manner enabling new value-added application for these agro-industrial byproducts, which may otherwise go waste.