Alfred Tcherbi-Narteh

Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.

Cellulose Nanofibers-Graphene Nanoplatelets Hybrids Nanofillers as High-Performance Multifunctional Reinforcements in Epoxy Composites

The objective of this study was to fabricate epoxy polymer composites modified with cellulose nanofibers (CNFs) and graphene nanoplatelets (GNPs) binary filler materials. Individual (0.2 wt.% GNPs or 2 wt.% CNFs) and binary nanofillers (mixture of 0.5 wt.% CNFs and 0.1% GNPs) were incorporated into an epoxy matrix system to investigate the synergistic effect of nanofillers on composites properties. Dynamic mechanical analysis (DMA) and three point bend tests were carried out to investigate the viscoelastic and flexural properties of neat epoxy and nanofiller-reinforced nanocomposites. Incorporation of binary nanofillers resulted in better flexure strength, modulus and storage modulus although there was no significance change in glass transition temperature (Tg). FTIR analysis was carried out to study the probable reaction mechanism of epoxy polymer with binary nanofillers. SEM images of the fracture surface of the samples revealed rougher failure surfaces for nanophased samples.

Effects of Different Montmorillonite Nanoclay Loading on Cure Behavior and Properties of Diglycidyl Ether of Bisphenol A Epoxy

The primary focus of this study was to understand the effects of different amounts of montmorillonite nanoclay MMT loading on viscosity, cure behavior, reaction mechanism, and properties of diglycidyl ether of bisphenol A DGEBA epoxy composites. Influence of 1–3 wt.% MMT on rheological and subsequent cure behavior of SC-15 epoxy resin was studied using nonisothermal and isothermal rheometry and differential scanning calorimetry DSC. Rheological properties were influenced by different amounts of MMT at lower shear rates prior to and during curing. Cure reaction mechanism was unaffected by different MMT concentration; however heat and activation energy of reactions increased with increasing MMT loading. Samples with 2 wt.% MMT showed highest reaction rate constant, indicative of catalytic behavior. X-ray diffraction XRD and transmission electron microscope TEM revealed mainly intercalated microstructure throughout the MMT infused epoxy composite samples irrespective of the percent loading.

Low Velocity Impact Characterization of Nanoclay and MWCNTs Binary Nanoparticles Modified Carbon/Epoxy Composites Subjected to Marine Environmental Conditioning

The use of carbon fiber reinforced polymeric composites (FRPC) for naval vessels has been increasingly recently, where high impact resistance is a major concern. Recent advancement in the use of nanoparticles has enabled the design of lighter, stronger and more durable FRPC structures compared to the traditional FRPC. In this study, carbon fiber reinforced epoxy composites were modified with binary (2 wt.% montmorillonite nanoclay and 0.1 wt. % MWCNT together) nanoparticles and subjected to marine environmental conditioning. Low velocity impact response of the modified samples were tested after 6 months of conditioning and compared with control carbon/epoxy composites. The composite laminates were subjected to impact loading at 30J and 40J energy levels. Load vs displacement characteristics were obtained and analyzed. The damage area for all control and modified samples were observed using thermography imaging technique and quantified. From experimental results, it was evident that durability of carbon fiber reinforced epoxy composites was significantly improved by modification with montmorillonite nanoclay along with slight amount of MWCNTs.Copyright

Durability Studies of Hybrid Composite of E-Glass/Carbon Fibers in Different Solvents for Bridge Deck Panel Application

Objective An experimental study was carried out to investigate the solvent uptake in E-glass/Carbon Fiber composites with two types of epoxy systems: SC-15 and 635 epoxy resins in water, saltwater and antifreeze. These resins were infused into carbon, E glass and a hybrid of carbon and E-glass fabrics. Unconditioned samples with 635 epoxy resin system showed better flexural properties in case of both carbon fiber and hybrid composites but poor response when used as a matrix for E-glass fibers compared to SC-15 epoxy resin. Flexural properties for conditioned samples were determined after an immersion period of 8 weeks at room temperature and results showed that the 635 epoxy resin has a poor retention of flexural properties compared to SC-15 epoxy resin with highest degradation recorded for samples fabricated using E-glass fabrics. Moisture absorption curves did not follow the Fick’s law of diffusion except for first week of immersion. Lowest solvent uptake was recorded in antifreeze while highest was recorded in saltwater. Low operation temperature was exhibited by 635 epoxy resin with lower values of glass transition temperature compared to SC-15 epoxy resin. Storage modulus and glass transition temperatures determined from dynamic mechanical analysis (DMA) showed that composites with 635 epoxy resin system had better storage modulus while those with SC-15 had higher glass transition temperatures. Highest degradation in storage modulus was seen in E-glass-635 epoxy samples when conditioned with salt water while the maximum reduction in the glass transition temperature was seen for E-glass-635 epoxy samples conditioned with water.Copyright

Compression and Flexural Response of Carbon/Epoxy-Nanoclay Nanocomposites Subjected to UV Radiation and Condensation

Compressive and flexural properties of carbon fiber reinforced composites (CFRC) infused with montmorillonite nanoclay exposed to UV radiation and condensation was examined in this study. Nanoclay contents in samples used in this study were 0 (control), 1, 2 and 3 wt%. Samples were exposed to 15 days UV radiation and condensation using QUV/SE accelerated weathering system. Compressive properties were characterized using quasi-static and dynamic loadings before and after exposure. Flexural properties were also characterized through three point bending test according to ASTM standards. Compressive and flexural properties were monitored every 5 days of exposure in each conditioning. UV exposed samples with nanoclay showed a different trend after 5 days compared to neat samples, showing an increase in strength and modulus after 10 days of exposure. Samples exposed to condensation did not follow any specific pattern, although there was a decrease in mechanical properties in all samples.Copyright