Structural, mechanical and morphological analysis of self assembled bionanocomposites

Abstract

The wide usage of polymeric materials in engineering is largely due to their valuable mechanical properties. Fracture is a rupture of the bonds between elements of a body (atoms, molecules or ions) resulting in breakage or cleavage of the specimen into parts. The resistance of a material to fracture is called strength or mechanical strength. Since the mechanical properties of polymers largely depend on their structure, it is necessary to create a structure ensuring an optimal set of mechanical properties which do not vary with time. The structure of the polymer is established during processing. Processing not only imparts certain shape to the material but also plays an important role in the creation and determination of its structure, i.e. microstructures. Structures are often conceived in the melts or solutions from which the polymers are fabricated. An interesting method of structure control is by introducing artificial nuclei into the polymer melt, which then becomes crystallization centers. Growing attention in PLA is because of some distinctiveness that is deficient in other polymers, specifically concerning renewability, biocompatibility, processability, and energy saving. PLA is derivative from renewable and biodegradable resources, and its degradation products are non-pollutant and non-toxic. Therefore, PLA may be a substitute for petrochemical plastics. Furthermore, PLA has several bio applications, such as biodegradable matrix for surgical implants, and in drug delivery systems. On the other hand, for structural use, it is required that some of its properties be improved, namely in terms of thermo-mechanical and electrical performance. To rise above these limitations, approaches, like blending with other polymers, functionalization, and adding of fillers, are practiced. Adding up of nanofillers is an appealing approach, as with small quantity of filler, it is achievable to improve desired features, keeping key properties of PLA unharmed. The most reported nanofillers are clays, silica’s, and carbon nanomaterials as incorporating nanofillers is a common approach to attain this goal. Exceptional properties of carbon-based nanomaterials have increased research works dealing with PLA composites. To discuss in brief, poly (lactic acid) originally is a brittle material with low impact strength and its elongation at break is similar to other brittle polymer such as polystyrene. On the contrary, its tensile strength and modulus are comparable to poly (ethylene terephthalate). The inability of poly (lactic acid) to plastically deform at high-stress levels limits its application; hence several modifying techniques have been used to enhance its deformation properties, as discussed above. From the available literature, has been confirmed that crystallinity is an important characteristic affecting the strength properties of poly (lactic acid) and its composites.