Influence of multi walled carbon nanotubes and silica nanoparticles on tensile properties of polyurethane

Reinforcing of polymers with nanoparticles can considerably improve the desired properties of the polymeric nanocomposite foams. Carbon nanotubes (CNT) as an interesting additive due to their superior properties such as low... [ view full abstract ]

Reinforcing of polymers with nanoparticles can considerably improve the desired properties of the polymeric nanocomposite foams. Carbon nanotubes (CNT) as an interesting additive due to their superior properties such as low density and high aspect ratio make them favorable fillers for reinforcement. In addition, SiO2 (silica) nanoparticles have been widely used with polymers to enhance the heat resistance, radiation resistance, mechanical and electrical properties. Polymeric foams such as Polyurethane (PU) are a group of lightweight materials, which are appropriate for a broad range of applications such as thermal and electrical insulation, shock and sound absorbents.
PU foams are produced via the polymerization reaction of a diisocyanate with a polyol. Prior to the synthesis of PU foams, CNTs were functionalized by treating with the hydrogen peroxide (H2O2). In the next step, CNTs or silica nanoparticles were added to polyol and were mixed for 10 min. Then, Isocyanate was added to the composition, which was mixed and poured into wooden mold. Nanocomposites with various content of CNTs, silica A and silica B nanoparticles were produced up to 1 wt%. Molded nanocomposites were cut in turning machine with thickness of 10 mm and test samples were prepared with CNC machine according to ISO 1926.
The aim of this work is investigating tensile properties of the nanocomposites with various percentages of CNTs and silica nanoparticles such as 0.25, 0.5, 0.75 and 1 wt %. Tensile tests will carry out and their results will discuss. In addition, the morphology of the nanocomposites will perform using scanning electron microscopy (SEM). As a result, neat PU presents lowest tensile strength, whereas highest strength can be seen in the nanocomposites containing 0.25 wt% Silica-A with 33 wt% improvement, but further Silica-A addition decreased strength of the PU/Silica-A foam. In addition, this phenomenon can be seen in adding of Silica-B and MWCNT into polymer matrix, which adding 0.25 wt% of Silica-B and MWCNT increased the tensile strength about 27% and 16%, respectively. In order to produce nanocomposites with higher CNT content and prevent appearance of large agglomerations, hybrid nanocomposite was produced, which could lessen large agglomerations.