Abstract

Cross-linked polymers are widely used in various industries in the modern era. Their usage could range from medical devices to electronic components. According to their usage in harsh environments, makes them susceptible to the so-called aging phenomena. Aging is a multi-physics phenomenon that induces microstructural changes to the polymer matrix morphology. In this respect, aging can be categorized into different clusters due to the active environmental elements which cause aging. These environmental factors could be present solo or concurrently in the aging domain. Thermo-oxidative and hydrolysis mainly refer to the single aging phenomenon due to the single available environmental element which is oxygen and water respectively. On the other hand, hygrothermal and photo-oxidative aging results from the presence of oxygen plus either water or UV radiation which could be classified as a dual aging mechanism. As oxygen is one of the main environmental elements in nature, and understanding the behavior of the material during thermo-oxidative aging is very important. Accordingly, in this paper, the effects of temperature on the constitutive response of Neoprene rubber material are investigated. In fact, Neoprene is a synthetic rubber that is in high demand and widely used in many applications. Accordingly, Neoprene rubber specimens were exposed to the various thermo-oxidative aging environments in controlled laboratory conditions to study the post-aging variations in the behavior of the material. To this end, the effect of different temperature profiles on Neoprene rubber material were considered. Here, the aging temperature (T) was considered as a function of the aging time (t). In this respect, the material was subjected to different aging temperature (T) profiles which were constructed from a summation of two different step functions. The study was conducted on samples that were aged in two different temperature levels T1 and T2 for different aging durations t1, tT in three cases as follows: i) T1 = T2, ii) T1 > T2, and iii) T1 < T2. It should be noted that this approach was utilized to investigate the path dependency of thermal aging phenomena. To this end, uniaxial tensile failure, Differential Scanning Calorimetry (DSC), and cross-linking density analysis (swelling tests) were carried out on the aged and unaged samples. Both mechanical and chemical tests results were in agreement which shows that the aging of Neoprene is a non-conservative phenomenon which means that the thermo-oxidative aging of Neoprene is mainly a function of the total energy that the material had absorbed during the storage process.

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