|M.Sc Student||Alhazov Dmitry|
|Subject||Energy Absorption Characterization of Laminated Glass|
Reinforced by Electrospun Fibers with Embedded
|Department||Department of Mechanical Engineering||Supervisor||Professor Eyal Zussman|
|Full Thesis text|
Laminated glass (LG) is widely used as an enveloping and protective element in the automotive and construction industries. It can be of critical value in providing impact damage resistance and in protecting the behind-target space from penetration of foreign objects. LG is typically comprised of two or more glass plies bonded together with a transparent, thermoplastic elastomeric interlayer, typically formed from polyvinyl butyral (PVB). Polymer deformation largely dictates the laminate’s energy-absorption capacity during loading to ultimate laminate failure LG behavior under ballistic impact has also been explored. Furthermore, tensile adhesion strength between the glass and polymer layer plays an important role in reducing the risk of delamination.
Based on the above mentioned principles, we chose to pursue a means of enhancing the energy absorption capacities of the LG interlayers by embedding carbon nanotubes (CNTs) within the polymer matrix without compromising the construct's optical properties. When considering the remarkable mechanical properties of CNTs, nanocomposites reinforced with CNTs feature improved stiffness, tensile strength and toughness. However, in order to achieve optimal results using CNTs, dispersion, characteristic of nanomaterials, as well as controlled assembly in the polymer matrix must be thoroughly addressed.
This research attempted to enhance the impact resistance of LG by increasing PVB interlayer toughness by embedding carbon nanotubes (CNTs). Interlayers were formed by electrospinning aligned PVB fibers embedded with various concentrations of CNTs. The CNTs were aligned along the fiber which could be deposited on a glass to form an anisotropic structure. Then, hot pressing at 120 °C for 2 hours was applied to obtain a uniform film. The resulting composite fibers were characterized using optical, SEM, and TEM microscopy. Mechanical and thermo-mechanical properties were determined by dynamic mechanical analysis (DMA). Impact resistance to low-velocity of LG with the nano-composite like interlayer was studied showing the potential of the proposed polymer interlayer in LG structure. A ~30% increase in composite fiber (CNT 1.5% wt.) strength was observed, along with a ~70% increase in elastic modulus, measured at a strain rate of 0.1 min-1, in comparison with CNT-free fibers. The energy absorption of a double-layered LG embedded with CNTs increased by nearly 341%. While transmission of visible light decreased by 60%. Ballistic tests show no improvement in ballistic limit energy in steel and full metal jacket (FMJ) projectiles. However, a decrease of 21% in damage area in specimens with CNTs compared to specimens without the CNTs was observed in FMJ tests.