Abstract
In recent years, due to their high specific mechanical properties, the polymer matrix composites have been widely used. In particular, carbon nanotubes (CNTs) have been used as reinforcement due to its exceptional mechanical and electrical properties. In this work the mechanical behavior of polyvinyl alcohol (PVA) reinforced with different percentages of mechanically oriented CNTs was studied. The composite material was made starting with a solution of PVA+ distilled water, and then the CNTs were added to the solution and dispersed by magnetic stirring and ultrasonic agitation. During this step, a surfactant was added to help with the CNTs dispersion. This mixture was poured into a container and dried using a heat source to accelerate its polymerization and curing. The layers obtained were subjected to mechanical stretching at controlled temperature to align the CNTs in the loading direction. The mechanical properties were measured by tensile testing and nanoindentation. The results show a large increase in modulus and hardness compared with non-reinforced polymeric material, it was also found a significant increase in the tensile strength. The composite with the best properties was subjected to thermal stabilization by ethanol, obtaining an increase in the degradation temperature of about 100°C approximately, although in this case the mechanical stiffness and hardness were decreased compared to unstabilized material, the usefulness of this material is enhanced.
Highlights
Nowadays, the understanding and manipulation of the properties of composite materials at nanometer scale is the key for the development of this kind of materials
The composite material was made starting with a solution of polyvinyl alcohol (PVA)+ distilled water, and the carbon nanotubes (CNTs) were added to the solution and dispersed by magnetic stirring and ultrasonic agitation
The results show a large increase in modulus and hardness compared with nonreinforced polymeric material, it was found a significant increase in the tensile strength
Summary
The understanding and manipulation of the properties of composite materials at nanometer scale is the key for the development of this kind of materials. The CNTs [6] have been extensively used as reinforcement in metallic, ceramic and especially in polymeric materials (see Figure 1). In general this has been due to an increased availability and cost reductions in the polymer matrix composites (PMCs) due to its relative easy dispersion. Polymers which can be dissolved [7-16] are preferred Those CNTs are usually dispersed by ultrasonic agitation and the alignment of the CNTs is obtained by the imposition of an electric field during the curing period [17-25] or by stretching the composite [26]. Polyvinyl alcohol (PVA) is dissolved in water, so it is convenient for CNTs incorporation. Soaking PVA into ethanol [29] or methanol has been proved to remove the residual water in the polymer increasing the formation of crystallites [30]
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