Studies on the rubber-filler interactions in tyre tread compounds

摘要

Due to the low mechanical properties of pure rubber, fillers are normally added to rubber compounds intended to provide reinforcement and improve their final properties. Several factors affect the reinforcing potential of fillers, including size, structure and surface activity.Carbon black and silica are the most common reinforcing fillers used in the rubber industry. Since the introduction of the “Green Tire Technology” in 1992 by Michelin, silica was found to offer reduced rolling resistance and enhanced wet grip properties compared to carbon black. However, silica presents many processing difficulties due to the polarity differences with rubber and requires the addition of silane coupling agents. Silane coupling agents reduces these polarity differences between silica and rubber providing strong filler-polymer linkages and thus, good final mechanical properties of rubber compounds. With the addition of silane coupling agents several reactions take place, such as the silanization reaction occurring between the silica and silane, the silane-rubber coupling and the linkages occurring between the polymer chains. All these reactions play an important role of the reinforcing potential of silica particles. Therefore, the dispersion of silica along with the filler-polymer interactions occurring within the rubber matrix are nowadays important concerns for the tyre industry. Silica particles tend to self-associate forming aggregates and lowering the mechanical properties of tyre tread compounds.Due to the importance of rubber reinforcement in tyre industry the main aim of this thesis is to use different measuring techniques to study filler-polymer interactions occurring within the rubber matrix. The effects of compounds composition and mixing times on filler-polymer interaction were studied.This thesis is divided into two parts: the literature review and the experimental part. The literature part consists of 5 chapters making a general overview of rubber technology, silica and silane coupling agents and the different techniques available to measure filler-polymer interactions. The experimental part contains the methods used to measure filler-polymer interactions.