Effect Of Silicon Dioxide In The PHB Matrix Characteristics

Poly (3-hydroxybutyrate) is a biopolymer produced mainly by microorganisms of Alcaligenes, Azobacter, Bacillus and Pseudomonas genera. Due to its properties such as high degree of crystallinity, crystalline melting temperature and barrier properties this polymer has the potential to replace polyolefins, with the advantage of being biodegradable, biocompatible, and from a renewable source. In this this work were prepared a nanocomposites with two kinds of silicon dioxide (hydrophilic or hydrophobic) employing solution casting method. The nanocomposites obtained were characterized by XRD, DSC, and Low Field NMR (T1H). The incorporation of the two silicon dioxide types in the PHB matrix induced different and specific changes in the PHB matrix. It could be observed that silica A200 acted as nucleating agent for PHB, affecting its crystallization kinetics. On the other hand, silica R972 interacted chemically with the matrix, affecting more significantly the matrix crystalline planes. From thermal properties studied, only it was observed significant changes on the crystallization temperature for PHB/A200 systems. Evaluating the NMR relaxation data, they revealed that the PHB/R972 systems presented an interfacial chemical interaction with the matrix. On other hand, PHB/A200 systems presented a decrease of T1H relaxation time values that point to a decrease of crystal size, which shows in an increase in the molecular mobility. So, the systems analyses showed distinct characteristics and properties according to the nature of the nanoparticle incorporated in the polymer matrix, reflecting on the interaction nanoparticle/matrix degree and so on its morphologies and properties.