Jonathan Trovillion

Processing and characterization of epoxy nanocomposites with Mwcnt's/Cnf's using thinky and 3-roll shear mixing techniques

In this work, thinky mixing method was used to disperse multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) in SC-1 epoxy either in isolation or in combination with 3-roll shear mixing. To achieve better dispersion, MWCNT mixing with SC-1 resin directly or pre-mixed with a solvent and then mixed with SC-1 resin after evaporating the solvent. Dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), flexural tests, electrical conductivity tests and micrographic analysis were performed on neat, 0.2 and 0.4wt% MWCNT/CNF infused SC-1 epoxy to observe the loading effect on thermo-mechanical properties of composites. DMA results indicated improvement on storage modulus and glass transition temperature, Tg, while flexural results exhibited enhanced flexural strength and modulus with up to 0.4wt% MWCNT/CNF infused epoxy resin over neat. TGA results revealed improved residue content but almost constant decomposition temperature for nanophased resin compared to neat. However, these enhancements were observed only up to 0.2 wt. % loading after which the properties were seen to either reduce or not significantly improve. These results indicate that the methods used for dispersion is suitable for low weight percent loading only.

Rheology, Flexure and Thermomechanical Characterization of Epoxy/CNF Nanocomposites: Effect of Dispersion Techniques

The aim of this study is to investigate the optimum technique to disperse vapour grown carbon nanofibres (VGCNFs) in SC-1 epoxy uniformly and to evaluate their effect on the performance of SC-1 epoxy. In this study, ultrasonication and Thinky mixing methods were used either in isolation or in combination with 3-roll shear mixing. To achieve better dispersion, VGCNF was tested either by mixing with SC-1 resin directly or premixed with a solvent and then mixed with SC-1 resin after evaporating the solvent. Flexural tests were performed to evaluate mechanical performances, and the results exhibited 25.60% and 8.88% improvement of flexural strength and modulus, respectively over neat epoxy with only 0.2 wt.% loading. Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) indicated improvement in storage modulus, Tg, inflection temperature and residue content respectively over neat SC-1 epoxy. The high viscosity found by rheological analysis prevents their ubiquitous use in fibre reinforced composites. Thermal and mechanical properties at higher loading conditions were seen either to reduce or not significantly improve. These results indicate that the methods used for dispersion are suitable for low weight percent loading only.

Predicting Hygrothermal Degradation of Composites in Accelerated Testing

Advanced fiber reinforced polymer (FRP) composite materials have been increasingly used in many applications relevant to the Army’s transformation. Many of these applications require the FRP composites to perform over long periods in harsh environments with extremes of temperature, humidity, water, and exposure to ultraviolet radiation and chemicals. It is important to understand the long term durability of FRP composites to environmental stimuli. This paper presents results of the hygrothermal degradation of E-glass/epoxy composites in accelerated tests and compares these results to predictions made using a modeling methodology based on Arrhenius-type reaction laws. To investigate the hygrothermal degradation behavior, E-glass/epoxy composites were subjected to accelerated tests at controlled temperatures and relative humidities. The specimens were exposed in an unloaded state and with a static tensile load of 2% of the ultimate transverse tensile strength. In the model predictions, three degradation mechanisms were considered: (1) post-curing, (2) thermal degradation, and (3) hygrothermal degradation.

Influence of Non-Functionalized and Functionalized MWCNTs on Mechanical and Thermal Properties of Epoxy Composites

In this work, SC-15 epoxy resin was modified using 0.1–0.3 wt. % of non-functionalized and functionalized multi-walled carbon nanotubes (MWCNTs) using conventional and solvent based methods. A high-intensity ultrasonic liquid processor was used to disperse MWCNTs in solvent and to obtain a homogeneous molecular mixture of epoxy resin and MWCNTs. Viscosity, dynamic mechanical analysis (DMA), thermo-gravimetric analysis (TGA), tensile and flexure tests were performed on unfilled and 0.1–0.3 wt. % MWCNTs filled SC-15 epoxy. Preliminary results indicate increase in viscosity with increase in MWCNTs wt. % loading and 0.2 wt. % MWCNTs epoxy samples showed the highest improvement in tensile and flexural properties as compared to the neat system. DMA studies also revealed that 0.2 wt. % doped system exhibit the highest storage modulus and Tg as compared to neat and other loading percentages. TGA results show that amino functionalized MWCNTs samples are more thermally stable.Copyright