Advanced Materials Research Vols. 399-401

Abstract: It is known that the rate of coagulation depends mainly on the stability of the colloidal particles and that the solution pH and potential are the main factors affecting the colloidal stability. The stability of dispersion (the ability of the dispersion to resist coagulation) may be related to its kinetic stability, which in turn depends on the force barrier preventing collision between the particles and thus preventing their coagulation. The addition of surfactant can change the pH and the potential of silica sol. So PEG is select to improve the stability of silica sol. The results presented here show that surfactant, PEG, has a strong consequence on the stability of silica dispersion. With the molecular weight increasing, the stability of silica sol is weakening.

Abstract: The ultimate objective of the current work is to examine the effect of thickness on fiberglass reinforced epoxy matrix subjected to high velocity impact loading. The composite material chosen for this research was from type C-glass/epoxy 200 g/m² and type C-glass/epoxy 600 g/m². This material is used as a composite reinforcement in high performance applications since it provides certain advantages of specific high strength and stiffness as compared to metallic materials. This study investigates the mechanical properties, damage characterisation and impact resistance of both composite structures, subjected to the changes of impact velocity and thickness. For mechanical properties testing, the Universal Testing Machine (UTM) was used while for the high velocity impact, a compressed gas gun equipped with a velocity measurement system was used. From the results, it is found that the mechanical properties, damage characterisation and impact resistance of type C-glass/Epoxy 600 g/m² posses better toughness, modulus and penetration compared to type C-glass/Epoxy 200 g/m². A general trend was observed on the overall ballistic test results which indicated that as the plate specimen thickness continues to increase, the damage at the lower skin decreases and could not be seen. Moreover, it is also found that, as the plate thickness increases, the maximum impact load and impact energy increases relatively. Impact damage was found to be in the form of perforation, fibre breakage and matrix cracking. Results from this research can be used as a reference in designing structural and body armour applications in developing a better understanding of test methods used to characterise impact behaviour.