Thermo-oxidative ageing of a SBR rubber: effects on mechanical and chemical properties
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ORIGINAL PAPER
Thermo‑oxidative ageing of a SBR rubber: effects on mechanical and chemical properties Naima Rezig1 · Tassadit Bellahcene1 · Méziane Aberkane1 · Moussa Nait Abdelaziz2 Received: 24 May 2020 / Accepted: 16 October 2020 © The Polymer Society, Taipei 2020
Abstract In this work, the effects of thermo-oxidative ageing at different temperatures and for different exposure durations on the mechanical and the chemical properties of a styrene butadiene rubber (SBR) are presented. Uniaxial tensile tests, hardness measurements, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra analysis, and swelling tests are carried out on as-received and aged samples. Accelerated ageing process was conducted at different temperatures ( 50◦ C , 70◦ C , 90◦ C , and 100◦ C ) and for different exposure durations (7, 14, 21, 28, 35, 45 and 60 days).This work confirm that accelerated ageing lead to a decrease of the ultimate mechanical properties and of the molar mass between cross-links in one hand, and an increase of the cross-linking density and of the material hardness, in another hand. ATRFTIR analysis shows significant changes in the chemical structure of aged SBR samples dominated by the thermo-oxidative process, which is, mainly pronounced at high temperature and long exposure time. The ultimate mechanical properties are related to the average molar mass between cross-links. A threshold value of this property corresponding to a complete degradation of the rubber can be determined. Finally, the time–temperature equivalence principle is applied to build master curves describing the evolution of certain quantities such as molar mass between crosslinks, tensile strength, and strain at break versus the reduced time. A predictive modeling of the stress and strain at break as function of the effective ageing time is proposed which give satisfactory results. Keywords SBR · Thermal · Ageing · Cross-linking · ATR-FTIR · Arrhenius law
Introduction Elastomers are increasingly used in different industrial sectors as industrial machinery, medical equipment, electrical insulation, mechanical damping, etc.[1, 2]. They differ from other polymers by two main characteristics: large reversible strain and high resilience which improve their useful life [1]. Therefore, the prediction of the rubber material life time is a key issue to be addressed to ensure the safety and reliability of mechanical rubber components. Thus, failure-proof
* Méziane Aberkane [email protected] 1
Laboratoire d’Elaboration, de Caractérisation et Modélisation des Matériaux (LEC2M), Université Mouloud Mammeri, 15000 TIZI OUZOU, Algérie
Unité de Mécanique de Lille (UML), Université de Lille, Cité Scientifique, Boulevard Langevin 59655, Villeneuve d’Ascq Cedex, France
2
design of rubber components is one of the key issues for engineers [3]. The best choice of material compounds is a good balance between the polymer and the additives, this choice being guided by economic and technical constraints. Indeed, filled rubb
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