Internal Activation of Thermoplastic Polypropylene GFRTP Composite by Homogeneous Low Energy Electron Beam Irradiation (HLEBI) of the Interlayered Glass Fiber Chopped Strand Mats (GF-CSM) Prior to Assembly

Abstract

A new process of internal activation of glass fiber reinforced thermoplastic polymer (GFRTP) of Polypropylene (PP) was achieved by homogeneous low energy electron beam irradiation (HLEBI) to the interlayered glass fiber chopped strand mats (GF-CSM) prior to assembly. Panels were fabricated by hot-press consisting of 5 HELBI-treated GF-CSMs between 6 untreated PP sheets. HLEBI improved the Charpy impact value (a uc ) of the internally activated GFRTP. HLEBI from 0.22 to 0.86 MGy mostly improved the a uc at each accumulative probability of fracture (P f ). Based on the 3-parameter Weibull equation, the a uc value was defined as the statistically lowest impact value, a s estimated as the a uc at P f = zero. The highest a s values at more than 87 kJ/m 2 were found for GFRTP irradiated at 0.65 MGy which appears to be at or near the optimum HLEBI dose. Strengthening the adhesion force at the extremely broad surface area of the fibers increased interfacial friction force to prevent fiber pull out, fiber/matrix debonding and crack generation in the hard to adhere PP matrix GFRTP, resulting in increasing a uc of GFRTP with glass fiber surface-activated by HLEBI.

Improving Impact Value of Interlayered Glass Fiber Chopped Strand Mat Reinforced Thermoplastic Polypropylene Externally Irradiated by Homogeneous Low Potential Electron Beam

“…The purpose was to maximize the ber surface area ( ber diameter: d f = 10 μm) activated by HLEBI throughout the bulk thickness. Results shown Charpy impact value 9) were improved over untreated using internal method. Moreover, this shows theoretically CSM-GFRTPs samples with in nite thickness can be prepared by an internal HLEBI activation to GF prior to dipping into PP.…”

“…5, dangling bonds are not detected in pure PP sheet before treatment. On the other hand, applying the small HLEBI dose enhances the density of dangling bonds, and then increases mechanical properties in inorganic glass 4,6,7) and often enhances ductility and strengthening of polymer matrix 9,10) and other GFRPs. 5,[9][10][11] In addition, HLEBI is also reported to generate dangling bonds in silica glass.…”

“…On the other hand, applying the small HLEBI dose enhances the density of dangling bonds, and then increases mechanical properties in inorganic glass 4,6,7) and often enhances ductility and strengthening of polymer matrix 9,10) and other GFRPs. 5,[9][10][11] In addition, HLEBI is also reported to generate dangling bonds in silica glass. 27,30) Since small dose of HLEBI generates dangling bonds in the silica glass 27) , partial relaxation of residual strain probably occurs around these dangling bonds in the network structure.…”

“…When HLEBI irradiation generates active terminated atoms with dangling bonds at each surface of PP and GF, the strengthening of ber pull-out induced by adhesion also occurs at GF/Polymer interface 5,9) , partly resulting in improving impact resistance of CSM-GFRTP.…”

“…9) Each CSM ply of interlayered composite was irradiated by HLEBI prior to lamination assembly and hot press to couple with dif cult to adhere thermoplastic PP. 9) This was for the layup of thermoplastic [PP/GF/PP/GF/PP/GF/PP/GF/PP/GF/PP] referred to here as [PP] 6 [GF-CSM] 5 . The purpose was to maximize the ber surface area ( ber diameter: d f = 10 μm) activated by HLEBI throughout the bulk thickness.…”