Alessandra de Almeida Lucas

Bionanocompósitos preparados por incorporação de nanocristais de celulose em polímeros biodegradáveis por meio de evaporação de solvente, automontagem ou eletrofiação

This review reports the preparation and characterization of bionanocomposites based on biodegradable polymers reinforced with cellulose nanocrystals (CNC) described in the literature. The outstanding potential of cellulose nanocrystals as reinforcement fillers of biodegradable polymers is presented with an emphasis on the solution casting process, which is an appropriate method to investigate the physico-chemical effects of the incorporation of CNC into the polymeric matrices. Besides solution casting, other small scale methods such as electrospinning and layer-by-layer are also covered.

Polyethylene cellulose nanofibrils nanocomposites

This paper investigates the use of an aqueous dispersion of polyethylene copolymer with a relatively high content of acrylic acid as a compatibilizer and as an alternative medium to obtain polyethylene CNF nanocomposites. The CNF content was varied from 1 to 90wt% and the appearance, optical, thermal, mechanical and rheological properties, as well the morphology of the films were evaluated. The PE/CNF films are transparent up to 20wt% of NFC indicating a good dispersion of CNF, but a poor distribution, with PE-rich and CNF-rich regions observed by SEM. Improved mechanical properties were achieved, with a 100% and 15,900% increase in the Youngs modulus with 1wt% and 90wt% NFC, respectively. The rheological behavior indicated good melt processability. According to these results, aqueous polyolefin dispersions seem to be a promising, easy and relatively fast route for obtaining cellulose/polyolefins nanocomposites with low to high contents of cellulose nanofibrils.

Expanded graphite as a multifunctional filler for polymer nanocomposites

Nano-expanded graphite (nEG) can be used as multifunctional filler for polymer composites and nanocomposites. Since it is constituted of stacked graphene sheets, this material has a good potential for the production of stiff nanocomposites, allying characteristics such as impact and thermal resistance, with good electrical and/or thermal conductivity, as well as gas or fuel barrier characteristics. The greatest advantage for using nEG as multifunctional filler is its good balance of properties combined with its low price when compared with other similar commercially available nanofillers, like carbon nanotubes and graphene nanoplatelets. As for all nanocomposites, the aspect ratio of the nanofillers, their dispersion and distribution during processing, final orientation, and a good interface with the matrix contribute for the final performance. In this chapter, the main requirements for mechanical, barrier, electrical, and thermal properties will be presented and discussed, highlighting the possible synergy found in some set of properties, mainly considering the best compositions and processing strategies to reach a good balance of properties for each application. The application of these nanocomposites for tube coatings, fuel tanks, and electro-electronic products will be shown and the processing–morphology–properties relationship of the resulting composites and nanocomposites will be discussed.

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