The effect of temperature on the impact behaviour of glass/polycarbonate laminates

The invention relates to a transparent plastic composite made of PMMA and TPU with excellent mechanical properties.

Transparent plastic composite

The effect of polyacrylate microstructure on the impact response of PMMA/PC multi-laminates

A similitude approach towards the understanding of low velocity impact characteristics of bi-layered hybrid composite structures

The main purpose of this thesis is the systematic, experimental investigation of how a soft interlayer affects the impact response and energy dissipation mechanisms of all-polymer multilaminates. An instrumented, intermediate impact velocity experimental setup with strain rates on the order of 100 s -1 , is used to assess the impact mechanics of three-layered samples consisting of a poly(methyl methacrylate) (PMMA) front, polymer interlayer or adhesive, and polycarbonate (PC) back layer. Instrumentation of the gas gun is achieved with a shock accelerometer measuring contact force and optical displacement sensors recording deflection. Previous impact research utilizing instrumented gas guns by Levy and Goldsmith, and Delfosse et al. have measured contact force, but did not record simultaneous out-of-plane displacement. Signals acquired are temporally aligned allowing for insight into the response of the multilaminate during impact, which is inaccessible with typical gas guns. Impact testing is completed on bonded and unbonded sample configurations, with two thermoplastic polyurethane and four polyacrylate interlayers. Quantitative metrics from force and displacement signals, along with post-impact damage observations, are used to compare impact performance between configurations and impact velocities (12 and 22 m/s). In general, the presence and bonding of an interlayer increases impact resistance by mitigating and localizing the impact load. The interlayers are characterized at various strain rates in tension, compression, and shear adhesion. In tension, all interlayers display rate dependence, nonlinearity, and hysteretic behavior showing varying degrees of increasing energy dissipation with strain rate. Several trends between sample fracture and energy absorption mechanisms, quasistatic and low rate interlayer response, and metric results are established and discussed.

Impact Mechanics of PMMA/PC Multi-Laminates with Soft Polymer Interlayers

Acrylic/polyurethane/polycarbonate laminates have demonstrated resistance to impact by high velocity projectiles up to 100 percent greater than monolithic polycarbonate, currently considered the best commercially available transparent impact-resistant material. The energy absorbed during impact was found to be dependent on the chemical composition and microstructure of the adhesive interlayer and varied by a factor of two over the range of variables investigated. Polyurethanes based on MDI-butanediol “hard” and block copolyether “soft” segments, used as the laminate interlayer, affect both impact resistance and optical clarity as chemical composition of the urethane is varied. Microstructure as seen in both the optical and transmission electron microscope changes from no visible structure in transparent materials, through few widely scattered isolated spherulitic structures in translucent materials, to densely packed interpenetrating spherulitic structures in opaque materials. Changes in microstructure accompany increased “hard” segment and are not affected by “soft” segment composition. Urethanes with increasing spherulitic content show decreasing tackiness accompanied by decreasing laminate impact resistance. Dynamic mechanical spectra show sharp low temperature loss peaks (240°K) ascribable to Tg of soft segments and an additional broad loss shoulder around 140°K which sharpens as impact resistance decreases and urethane content increases.

Effects of Adhesive Structure on Impact Resistance and Optical Properties of Acrylic/Polycarbonate Laminates

: This paper describes an investigation of the relationships be-tween microstructure of transparent segmented polyurethane (PU) ADHESIVES, THEIR OPTICAL PROPERTIES AND LAMINATE BALLISTIC PER-FORMANCE THAT HAS LED TO A FORTY- FIVE PERCENT ADVANCE IN THE STATE-OF-THE-ART OF BALLISTIC RESISTANCE OF TRANSPARENT PLASTICS.

https://apps.dtic.mil/sti/pdfs/AD0785634.pdf

Dennis B. Barr

Papers

Effects of Adhesive Structure on Impact Resistance and Optical Properties of Acrylic/Polycarbonate Laminates

Effect of Interlayer on Impact Resistance of Acrylic/Polycarbonate Laminates