Baltus C. Bonse

Effect of calcium carbonate particle size and content on polyamide 6 processing and properties

Three different types of calcium carbonates, including a nanosize one, were incorporated into polyamide 6, at different contents (5, 10 and 20 wt%) using a corotating twin-screw extruder connected to a Haake torque rheometer. Spherical-like nanosize CaCO3 particles and needle-like precipitated CaCO3 showed to consist of calcite crystals, whereas needle-like naturally occurring CaCO3 particles consisted of both calcite and aragonite. Specimens were injection molded and subjected to tensile, bending and impact testing. XRD, SEM and DSC analyses were also carried out. Both conventional and nanocalcium carbonate reduced torque, with the nano resulting in lower values. All investigated calcium carbonates increased PA6 tensile and flexural strength and elastic modulus.

ZnO Micro and Nanofibers made by electrospinning: Fabrication and Characterization

In this study, the best conditions to obtain Zinc Oxide (ZnO) nanofibers were studied for further development of a composite with a biopolymer for application in scaffolds. Although the electrospinning of ZnO nanofiber is already known, there are still new aspects to be explored to optimize itsproduction. In this work were prepared six different solutions of poly(vinyl alcohol) - PVA with two different molecular weight, containing ZnO precursor, i.e. Zinc Acetate, using water or a mix of water and alcohol as solvents, and tested to understand how solution characteristics influence the final morphology of the ZnO nanofibres. This paper shows promising results for production ceramic nanofibers by electrospinning since parameters as viscosity, molecular weight, concentration, conductivity and surface tension are well controlled.

Natural Fiber Polymer Composites Technology Applied to the Recovery and Protection of Tropical Forests Allied to the Recycling of Industrial and Urban Residues

“Often when pursuing research into green composites we say we are protecting the environment, that we are working for nature. We may as well stop kidding ourselves – nature will be fine; nature will work out OK and adapt to changes. It s humans that will cease to exist if we continue the way we are at present. Some scientists and engineers have realized that they need to take responsibility for the outcome of their work. Researching ways of creating faster machines and bigger toys, without due consideration of the effects on the environment or on people, is irresponsible... We need to consider the impact that our material choice and design will have on the society and the environment”* Generation of residues is inherent to human activities. After the Industrialization Period, with modernization of the society, the amount of industrial and postconsumer residues, together with the associated environmental problems, has been increasing at alarming levels. Residue management has become a major problem in modern society. The search for innovative solutions for the reuse of solid residues increased in the late 20th century and has intensified with growing urgency for environmental preservation. Many residue management solutions aim to add value to residue through the development of new materials and processes. Natural fiber polymer composites basic technologies are already relatively well established. Excellent textbooks can be found on this theme (Klyosov, 2007; Niska & Sain, 2008; Mohanty et al., 2005). Its concepts can be extended to the reuse of solid industrial and urban residues. In these composites the matrix is a polymer, and wood, vegetable or animal fibers are used as fillers or reinforcements. Both polymer and fiber may have been generated as an industrial or postconsumer residue. Another environmental problem that must be accounted for is the huge amount of deforested areas worldwide, also a consequence of human activities. Important research has