Muneer Al-Qadhi

Mechanical properties and water uptake of epoxy–clay nanocomposites containing different clay loadings

Nanocomposites based on diglycidyl ether of bisphenol A (DGEBA) epoxy reinforced with 1–10 wt% I.30E nanoclay were fabricated using high shear mixing technique and characterized to determine the effects of clay loading on their mechanical, thermal, and water uptake properties. The XRD and TEM analyses revealed that the structures of the resultant nanocomposites were a combination of disordered intercalated and exfoliated morphologies. Tensile strength increased for nanocomposite containing 1xa0% clay loading and decreased for higher nanoclay loading. Unlike strength, the stiffness increased almost linearly with clay loading, showing 46xa0% improvement in modulus of elasticity for nanocomposites containing 5xa0% of nanoclay. Water uptake measurements indicated enhancement in the barrier properties of epoxy matrix as nanoclay loading increased from 1 up to 5 wt%.

Optimizing the Curing Process of Epoxy-Clay Nanocomposites

Epoxy resin is one of the most applied thermoset polymers as a matrix for Glass Fiber Reinforced Pipes (GFRP). Curing process of epoxy resin is important for the integrity of the GFRP. The present work has been conducted to determine the proper pre-curing and post-curing temperatures and duration to develop epoxy-clay nanocomposite. During this study a differential scanning calorimeter (DSC) was used to determine the glass transition temperature and hence the degree of curing. Several samples of epoxy were prepared at different pre-curing and post-curing temperatures and durations. Pre-curing temperatures ranging from 80 to 150°C and post-curing temperatures ranging from 150 to 200°C were studied. The results show that the optimum pre-curing and post-curing temperatures are 100 and 170°C, respectively. Regarding the effect of curing duration, several specimens were prepared at the same pre-curing and post-curing temperatures with different curing durations of 1, 2, and 3 hours. It was observed that beyond one hour curing, the changes in the Tg and the degree of crosslinking were negligible. Using these optimum conditions samples of epoxy-clay nanocomposites were prepared using ultrasonication. The results showed that the addition of nonoclay to epoxy resulted in a reduction of the Tg.

Effect of High Shear Mixing Parameters and Degassing Temperature on the Morphology of Epoxy-Clay Nanocomposites

Epoxy-clay nanocomposites were prepared by high shear mixing method using Nanomer I.30E nanoclay as nano-reinforcement in diglycidyl ether of bisphenol A (DGEBA). The effect of mixing speed and time on the nature and degree of clay dispersion were investigated by varying the mixing speed in the range of 500-8000 RPM and mixing time in the range of 15-90 minutes. The effect of degassing temperature on the morphology of the resultant nanocomposites was also studied. Scanning and transmission microscopy (SEM & TEM) along with x-ray diffraction (XRD) have been used to characterize the effect of shear mixing speed, mixing time and degassing temperature on the structure of the resultant nanocomposites. The SEM, TEM and XRD examinations demonstrated that the degree of clay dispersion was improved with increasing the high shear mixing speed and mixing time. The results showed that the optimum high shear mixing speed and mixing time were 6000 rpm and 60 min, respectively. It was observed that the structure of the nanocomposites that have been degassed at 65oC was dominated by ordered intercalated morphology while disordered intercalated with some exfoliated morphology was found for the sample degassed at 100oC for the first 2 hours of the degassing process.

Mechanical Behavior of Hybrid Glass Fibre/Epoxy Clay Nanocomposites

Addition of organoclay to polymer matrix has recently attracted industry attention due to improved physical properties with an overwhelming potential in crude oil and water pipe applications. In this work, electrical grade-corrosion resistant (E-CR) glass fiber mats were used to prepare glass fiber reinforced epoxy (GFRE) nanoclay composites using hand layup method. Three different hybrid GFRE composites were made using 0, 1.5 and 3 wt% loading of I.30E nanoclay. High shear mixing was used to prepare the epoxy/clay nanocomposite. XRD results revealed a disordered intercalated morphology. The effect of nanoclay on mechanical properties were investigated by carrying out flexural and fracture toughness tests. The test results showed that addition of nanoclay up to 1.5 wt% improved both flexural strength and fracture toughness. However, these properties deteriorated when the clay content increased to 3 wt%.

Influence of Degassing and Nanoclay Loading on Physical and Flexural Properties of Epoxy

The mechanical and physical properties of epoxy-clay nanocomposites are known to be significantly affected by the dispersion and distribution of the clay particles in the epoxy matrix. The degree of dispersion of the clay particles in the epoxy matrix depends mainly on the processing parameters used to synthesize the nanocomposite.In this paper, the optimized high shear mixing parameters determined in an earlier work were used to disperse five different loadings of Nanomer I.30E nanoclay (1, 1.5, 2, 3 and 5 wt%) into DGEBA epoxy matrix. A systematic approach was adopted to optimize the degassing process of the mixture. X-Ray Diffraction (XRD) analyses showed that the optimum nanoclay dispersion was achieved for a degassing temperature of 120 °C. The flexural strength of the developed nanoclay/epoxy composite is found to increase by 15% for 1.5 wt% and due to the high stiffness of the clay, as compared with epoxy resin, the flexural modulus improved continuously with clay loading. The observed reduction in strength and fracture strain at high clay loadings is mainly attributable to the presence of clay agglomerations and voids formation. The diffusion of water molecules and maximum moisture uptake of epoxy are reduced considerably by the presence of nanoclay.

Effects of Processing Techniques on Morphology and Mechanical Properties of Epoxy-Clay Nanocomposites

Proper dispersion of nano thin layered structure of nanoclay in polymer matrix offers new and greatly improved properties over pristine polymers. The degree of nanoclay dispersion and hence the improvements in the physical and mechanical properties depend greatly on the technique used and processing parameters. In this work, 2 wt.% epoxy-clay nanocomposites were fabricated using different mixing techniques to study the effect of mixing methods on the nanoclay dispersion and thus on the enhancement of the properties of the resultant nanocomposites. Three mixing techniques were explored: high shear mixing (HSM), ultrasonication and their combination as well as hand mixing. The effect of mixing techniques on morphology and mechanical properties of the resultant nanocomposites was investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and tensile testing. The results of XRD and TEM showed that both exfoliated and disordered intercalated morphology were developed for the nanocomposites synthesized by HSM, while ordered intercalated morphology was observed for samples prepared by sonication. The tensile test results show that among the mixing techniques considered in this study HSM results in the optimum mechanical properties as a whole while hand mixing resulted in the worst physical and mechanical properties.

Morphology and Mechanical Property of Epoxy-Clay Nanocomposites Prepared by Ultrasonication

Epoxy-clay nanocomposites have been synthesized using organically modified montmorillonite nanoclay, Nanomer I.30E as nanoreinforcement in diglycidyl ether of bisphenol A (DGEBA) epoxy using ultrasonication. X-ray diffraction and TEM analysis showed that the interlayer spacing of clay increased as a result of sonication mixing. It was observed that the morphology of the resultant nanocomposites were dominated by disordered intercalated morphology with some ordered intercalated structure. Tensile tests results illustrated that while the addition of nanoclay increased the modulus of elasticity, noticeable reduction in strength and failure strain was observed. Fractographic analysis was curried out for the tensile fracture surfaces using SEM which illustrated that the roughness of the nanocomposites surface were high compared with the smooth surfaces of the pure epoxy indicating an improvement in the fracture toughness. It also demonstrated that during tensile loading for nanocomposites the cracks were initiated at either clay aggregates or microvoids which explained the reduction in strength for nanocomposites.