TY - JOUR
T1 - Mechanistic investigations into the adhesion between RFL-treated cords and rubber
T2 - Part I: The influence of rubber curatives
AU - Wennekes, W.B.
AU - Noordermeer, J.W.M.
AU - Datta, R.N.
PY - 2007
Y1 - 2007
N2 - The adhesion between virgin textile cords and rubber is always weak, because of significant differences between fiber and rubber in modulus, elongation, polarity as well as reactivity. In order to improve the adhesion, it is customary to use adhesive systems, which act as bridges between elastomer and reinforcement. These are commonly based on Resorcinol/Formaldehyde/Latex (RFL) dips. For polyester and aramid fibers, two dip systems are applied. The first one is an epoxy pre-dip and the second dip is a RFL dip again. Although several mechanisms are proposed to explain the role of RFL, the majority of these explanations are based on assumptions rather than proper scientific investigations. In this paper an attempt is made to understand the role of the rubber vulcanization system on RFL-to-rubber bonding as judged by measuring the H-pullout force, Strap Peel Adhesion Force (SPAF) and the mechanical properties of the compounds. A positive correlation is found between the optimum cure time (t90) of the rubber compounds and the pullout and peel force. In literature this is commonly explained by the lack of curative migration from the rubber into the dip when t90 is low. In the present paper curative migration is monitored by scanning electron microscopy coupled to an energy dispersive X-ray spectrometer (SEM-EDX). A strong enrichment of curatives in the RFL dip near the interface is observed. A high accelerator loading results in a low t90 of the rubber compound as well as a more pronounced enrichment of curatives in the dip near the interface. Therefore the drop in adhesion does not occur because of lack of curative migration from rubber to the RFL layer, but more likely due to overcure of the latex in the dip, causing a brittle layer resulting in low pullout and peel strengths
AB - The adhesion between virgin textile cords and rubber is always weak, because of significant differences between fiber and rubber in modulus, elongation, polarity as well as reactivity. In order to improve the adhesion, it is customary to use adhesive systems, which act as bridges between elastomer and reinforcement. These are commonly based on Resorcinol/Formaldehyde/Latex (RFL) dips. For polyester and aramid fibers, two dip systems are applied. The first one is an epoxy pre-dip and the second dip is a RFL dip again. Although several mechanisms are proposed to explain the role of RFL, the majority of these explanations are based on assumptions rather than proper scientific investigations. In this paper an attempt is made to understand the role of the rubber vulcanization system on RFL-to-rubber bonding as judged by measuring the H-pullout force, Strap Peel Adhesion Force (SPAF) and the mechanical properties of the compounds. A positive correlation is found between the optimum cure time (t90) of the rubber compounds and the pullout and peel force. In literature this is commonly explained by the lack of curative migration from the rubber into the dip when t90 is low. In the present paper curative migration is monitored by scanning electron microscopy coupled to an energy dispersive X-ray spectrometer (SEM-EDX). A strong enrichment of curatives in the RFL dip near the interface is observed. A high accelerator loading results in a low t90 of the rubber compound as well as a more pronounced enrichment of curatives in the dip near the interface. Therefore the drop in adhesion does not occur because of lack of curative migration from rubber to the RFL layer, but more likely due to overcure of the latex in the dip, causing a brittle layer resulting in low pullout and peel strengths
U2 - 10.5254/1.3548180
DO - 10.5254/1.3548180
M3 - Article
VL - 80
SP - 545
EP - 564
JO - Rubber chemistry and technology
JF - Rubber chemistry and technology
SN - 0035-9475
IS - 4
ER -