Elessandra da Rosa Zavareze

Filmes biodegradáveis à base de proteínas miofibrilares de pescado

The objective of this work was to study the physical, mechanical and barrier properties of the films produced from different concentrations of myofibrillar proteins of fish. The fish used was croaker (Micropogonias furnieri), which was gutted and filleted. The myofibrillar proteins were obtained through the muscle with successive washes with distilled water. The films were made with 3, 4 and 5% of myofibrillar proteins by the method of casting. The films were analyzed by thickness, solubility, opacity, tensile strength, elongation and water vapor permeability (PVA). The increase of myofibrillar proteins concentration in the films increased thickness, opacity, tensile strength and water vapor permeability and reduced elongation at break of the film.

CHAPTER 4:Relation between Structural Anisotropy in Natural Fibres and Mechanical Properties in Composites

This chapter will review natural fibres and composite properties, emphasising the co-relation between the structural anisotropy of natural fibres and mechanical properties in composites. The importance and applications of natural fibre composites will also be discussed. As a result of the increasing demand for environmentally friendly materials and the desire to reduce the cost of traditional fibres (carbon, glass and aramid), reinforced petroleum-based composites and new bio-based composites have been developed. The selection of suitable fibres is determined by the required values of stiffness and tensile strength of a composite. Further criteria for the choice of suitable reinforcing fibres include the following: elongation at failure, thermal stability, adhesion of the fibres and matrix, dynamic behaviour, long-term behaviour and price and processing costs. A very important factor to consider is the effect of anisotropy in composites reinforced with natural fibres, i.e., the mechanical properties depend on the direction in which a force is applied. The fibres adopt a particular orientation under loading, which is responsible for the stiffness composites along the direction of flow. The mechanical performance of composites is mainly dependent on the properties of the matrix and reinforcement and the interaction between the matrix and reinforcement.