Thermomechanical Stability of Interphases in Glass Reinforced Composites

Abstract

The thermomechanical stability of organosilane surface treatments for E-glass fibers used in fiber reinforced composites was evaluated. The effect of molecular structure of 40 to 80 namometer coatings on the force transmission across the fiber/matrix interface was measured as a function of temperature and exposure to water using a fiber fragmentation test. It was found that phenyl-substituted amino silanes exhibited better thermal stability, but were less resistant to boiling water, than the commierically available γ-amino propyl silanes. A bis-trimethoxy γ-amino propyl silane showed an increase in both the hydrolytic and thermal stability when compared to the commiercial product. A good balance of thermal and hydrolytic stability was also obtained with a methylaminopropyltrimethoxy silane coating.The strain energy released from the glass fibers upon decoupling from the poxy matrix or silane coating was found to be in the range of 145 to 186 g/m2 and varied no more than 20 percent over a temperature range of 25 to 75°C or when exposed to boiling water and then redried. It also varied very little with the silane coating used. In addition, the average shear stress attained at the fiber-matrix interface in an imbedded single fiber test at 25°C was as much as two times higher than the shear strength of the epoxy matrix and as much as five times higher at elevated temperature. These data lead one to the conclusion that the interphase failure in these composites is controlled by a plane strain fracture in the constrained region of the organic phase, near the fiber surface, rather than by the maximum shear strength in the interphase.

Jute-Reinforced Polymer Composite with HDDA Monomer by UV Radiation in the Presence of Additives

“…It is evident that the dielectric constant rapidly increases with increasing temperature up to transition temperature and above the transition temperature it decreases and reduces to almost room temperature and with further increase of temperature it remains almost constant. For 10,15,20,25,30, and 35 number of UV pass the transition temperatures are 55, 60, 60, 55, 60, and 608C, respectively. Loss tangent follows the similar trend like dielectric constant and increases up to the transition temperature and then decreases with increasing temperature and then remains almost constant (Figure 7).…”

“…To enhance the use of jute fibers, investigations are necessary to search for chemical modifiers and physical treatments of jute fibers for better adhesion between synthetic polymer and natural fiber (jute). Several processes, such as chemical [15] and photochemical [16][17][18][19][20] treatments have been developed to modify fiber surfaces. Improved physico-mechanical properties of natural fibers with different impregnating solutions under UV radiation have been reported [19][20][21].…”