Improvement of Bending Modulus and Impact Value in Injection-Molded Short Carbon Fiber Reinforced Polyetheretherketone with Homogeneous Low-Voltage Electron Beam Irradiation

Abstract

In short carbon fiber reinforced polyetheretherketone (SCFRP-PEEK) composites, carbon fibers and PEEK matrix typically exhibit a weak adhesive force at the interface. However, applying 0.43 MGy dose of homogeneous low-voltage electron beam irradiation (HLEBI) was apparently shown to improve not only the bending modulus (E f ) 65.5% at the median-ranked cumulative probability evaluated as a distribution function (P E = 0.50) from 6.7 to 11.1 GPa, but also Charpy impact fracture value (a uc ) 17.5% at median-ranked cumulative probability (P f = 0.50) from 16.6 to 19.5 kJ m ¹2 . The 0.43 MGy HLEBI dose also remarkably improved the statistically lowest Charpy impact value a s at P f = 0 calculated by 3-parameter Weibull equation 80.0% from 8.0 to 14.4 kJ m ¹2. Penetration depth, D p of the HLEBI was calculated to be 153 to 226 µm (311%) into both side surfaces. SEM results of the HLEBI-treated Charpy impact sample fracture surfaces show more matrix sticking to the fibers and more matrix being held between fibers than the untreated increasing pullout resistance. The HLEBI appears to assist in strengthening the typically weak bonding between the carbon fiber and PEEK matrix improving mechanical properties.

Tensile Shear Strength Improvement of 18-8 Stainless Steel/CFRP Joint Irradiated by Electron Beam Prior to Lamination Assembly and Hot-Pressing

“…32) Applying 0.43 MGy dose of HLEBI has been found to decrease the carbon fiber dangling bond density as evidenced by reduction in peak intensity at B = ³322.4 mT. 33) It is assumed lower doses of 0.13 to 0.30 MGy in this work also decrease dangling bond density in carbon fiber. This annihilation of vacant sites with dangling bonds of carbon fiber has been found to enhance the tensile fracture strength and its strain of carbon fiber.…”

“…This phenomenon is similar to that reported for PEEK (polyetheretherketone) CFRP composites where HLEBI generates a signal in PEEK resin but not in PEEK CFRP attributed to possible charge migration. 33) Moreover, in the 18-8/CFRP joint dangling bonds may interact with the highly conductive 18-8 steel by charge dispersion rendering undetectable by ESR yet strengthening the joint.…”

Enhanced Tensile Strength of Titanium/Polycarbonate Joint Connected by Electron Beam Activated Cross-Weave Carbon Fiber Cloth Insert

“…0.43 MGy-HLEBI improved the bonding force at the CF/polymer interface. 47) Thus, the optimal dose of HLEBI to the polymer matrix was probably effective in creating stronger CF/polymer interface adhesion to suppress the pull out of carbon bers.…”

“…On the contrary, optimum dose of 0.43 MGy improved the a uc of short carbon ber reinforced thermoplastic polymers. 47) Since the polyetheretherketone adhering force to short carbon ber was stronger than the cohesive force in polymer matrix. 0.43 MGy-HLEBI improved the bonding force at the CF/polymer interface.…”

“…Here, lines and n values indicate deformation mechanism regions and hardening index, respectively. Carbon ber pull out 1,47) Heterogeneous deformation with start of CF fracture prior to sample fracture slippage, attaining signi cantly higher stresses and strains. A strength hierarchy exists from increased strain hardening 35) :…”