Microfluidization, time-effective and solvent free processing of nanoparticle containing thermosetting matrix resin suspensions for producing composites with enhanced thermal properties

Abstract

Dispersion of low content (0.1wt.%) of multi walled carbon nanotubes (MWCNTs) in an epoxy resin through microfluidization was brought under spotlight as a case study. For the sake of performance comparison, epoxy resin suspension with the same MWCNT content was also produced through sonication, and the energy consumed to disperse MWCNTs in the epoxy resin remained the same for the both processes. At the equal energy consumption level, preparing the resin suspension through microfluidization was determined to take approximately 4.5min, which is about 9 times lower than it takes for the same suspension to be prepared through sonication. Following cure of the prepared suspensions, thermal and thermo-mechanical properties of the resulting composites were systematically investigated. As a result, glass transition temperature (Tg) of the neat epoxy and its composites produced by sonication and microfluidization were determined to be 78±3, 83±5 and 88±4°C, respectively. Moreover, thermal expansion coefficient (CTE) of the epoxy resin was reduced by 7% when it was blended with MWCNTs through microfluidization, while no significant change was observed in the corresponding CTE value when through sonication. Thermomechanical testing findings implied about 5% and 10% improvement in storage and loss modulus values of the composites produced by microfluidization over by sonication. Transmission electron microscopy (TEM) examination showed that MWCNTs were more homogenously and individually dispersed in the epoxy resin by retaining their initial aspect ratio through microfluidization. Scanning electron microscopy (SEM) examination revealed that composite fracture surface morphology significantly varied, depending to large extent on the type of the process used. Based on the results obtained, it was proposed that microfluidization might pave the way for cost-and-time effective solvent-free processing of nanoparticle modified thermosetting resin suspensions, especially including those that could be promisingly used as matrix constituent for manufacturing fabric reinforced composites with multi-functional properties.