UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical and Flame Retardant Properties

Abstract

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates.

Applicability of UV-Curable Binders in High Solid Suspensions for Direct-Ink-Write 3D Printing in Extremely Cold Temperatures

“…However, the enthalpy of cure can decrease with particles present due to light interaction with the particles, radical diffusion limitations, and heat conduction to the particles . Since the enthalpy of cure is approximately the same with and without particles at −10 °C and we know that the particles do reflect, absorb, and scatter light, this suggests that the high content of the glass microspheres in the particle-containing inks may provide a small extent of thermal shielding . This may help to maintain the suspension temperature above −10 °C around the particles, which would promote faster cure kinetics.…”

Polymer Composite Analysis and Characterization

“…The authors presented these new flame retardants as being viable and more environmentally friendly alternatives to existing materials. In addition, with the development of flame-retardant materials, Diego Pugliese and Giulio Malucelli published the paper "UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical, and Flame Retardant Properties" [2]. The authors evaluated the effects of the incorporation of a micrometer phosphate glass powder on the morphology, as well as the thermal, optical, mechanical, and flame-retardant properties of UV-LED curable acrylic films.…”