Adhesive strength of bonds of polymers with carbon fibres at different loading rates

Abstract

The effect of the loading rate on the strength of the interface of bonds of UKN-5OOO-P carbon fibres ~ 7 #m in diameter with thermosetting (EDT-I O epoxy binder) and thermoplastic (PSK-1 polyarylene sulfone) matrices was investigated. The adhesive strength T 0 of the bonds was determined in shear ofStudying the properties of the interface between a polymer matrix and reinforcing filler under the effect of different service factors is one of the most important problems in composite science. Such studies are interesting from both theoretical and practical points of view. They would allow creating composites with defined and adjustable properties. In addition, they would make it possible to establish the mechanisms of changes in adhesive strength, compare them with the similar mechanisms of the change in the cohesive strength of the components of the system and the composites based on them, and determine their common character.The above also fully applies to the properties of the interface of bonds of polymers with fibres in different conditions of loading. However, this problem has been investigated for a very limited number of systems. In particular, it has not been investigated in general for bonds of polymers with very thin and brittle carbon fibres.We examined the effect of the loading rate on the adhesive strength of bonds of polymers with UKN-5000-P industrial carbon fibres. The fibre diameter was d = 6.8-7.1 btm and the strength was 3.5 GPa. EDT-10 epoxy binder and PSK-1 polyarylene sulfone were selected as the adhesives; the first one is a typical cross-linked binder and the second is a typical thermostable thermoplast (polyarylene sulfone was used in the form of powder).The adhesive shear strength, determined in pulling a fibre out of a layer of the polymer (pull-out method), was used as the measure of adhesion; the "three fibre" method was used [1][2][3][4][5][6][7][8]. The methods of fabrication of bonds of the carbon fibres with the polymer matrices were described in detail previously; with thermosetting matrices in [2,3] and with thermoplasts in [4].We know from studies of industrial fibres 7-20 btm in diameter that the fibre whose adhesion is determined can be pulled out of the adhesive if the thickness of the polymer layer l in which the fibre is loaded is no greater than 10-20 of its diameter: l/d< (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Otherwise, the fibre will break when the bonds are loaded, i.e., not adhesive, but cohesive failure will occur. For this reason, boron fibres 55 and 95 ~tm in diameter were used as the fibres on which the adhesive was applied and on whose diameter the average length of the adhesive bond depends in the "three fibre" method. The bonds were formed in ovens in air medium without using pressure. The temperature--time conditions of bond formation are reported in Table 1. The samples obtained were tested on an adhesiometer* which measures in a range of rates covering three orders of magnitude [2,3].

Interfacial Fracture Toughness Evaluation of Poly(L-lactide acid)/Natural Fiber Composite by Using Double Shear Test Method

“…As illustrated in Figure 7 and Figure 8, the mean interfacial shear stress, τ i of the model composite decreased with increasing in bonding area, A. Similar observations were found in other studies for kevlar fiber [9], glass fiber [29], carbon fiber [30], and steel wire [31] which bonded with either thermoplastic orthermosetting adhesives. The τ i -A relation can be explained as follows.…”

Evaluation of Interfacial Fracture Toughness and Interfacial Shear Strength of Typha Spp. Fiber/Polymer Composite by Double Shear Test Method

“…A similar trend was also seen in Figure 11d in which the interfacial shear strength value decreased with the increasing bonding area. Similar results were reported by Day and Cauich Rodrigez in a study on Kevlar fiber [31], Zhandarov and Mader on glass fiber [47], and Gorbatkina et al on carbon fiber [48] with thermosetting or thermoplastic as the matrix. The increasing bonding area enhanced the occasion probability of the critical flaws, therefore the probability of the initiated fracture upon loading was increasing [49].…”

Methods and models for fibre–matrix interface characterisation in fibre-reinforced polymers: a review

“…A variant of the fibre-bundle pull-out specimen is double-end specimen, with the matrix on either end of the free bundle length [396]. Another pull-out-like test is the three-fibre method (1983) [356,397,398], in which a vertical fibre (fibre of interest) is held between two horizontal fibres (support fibres), and the droplet is formed at the three fibres’ intersection (see Figure 37a). The IFSS can be estimated using Gorbatkina [402], Greszczuk [241] or Zhandarov et al [330] models.…”

“…Another pull-out-like test is the three-fibre method (1983) [356,397,398], in which a vertical fibre (fibre of interest) is held between two horizontal fibres (support fibres), and the droplet is formed at the three fibres’ intersection (see Figure 37a). The IFSS can be estimated using Gorbatkina [402], Greszczuk [241] or Zhandarov et al [330] models. This method, being experimentally challenging in the case of thermoplastic matrices, reportedly eliminates the microdrop slippage throughout the slit, featuring a uniform interfacial loading contrary to the microbond test, with the pulled-out fibre surface being matrix-free [210].…”