Title : The impact of short and long term ageing in glycol water mixture on mechanical behavior of polyamide 6/glass fibers materials and recovery of properties after desorption process
Abstract:
The current paper aims to study the behavior of Polyamide 6 (PA6) and Polyamide 6 reinforced with 30% of short glass fibers (PA6GF30) under glycol water (GW) mixture (20:80) used for cars as coolant fluid at 50°C and 90°C for up to 80 days. First of all, the reversibility of short-term ageing of both materials was studied. Afterwards, the impact of long term ageing on the bulk properties was measured. Samples were fully immersed in the mixture of GW and periodically weighted. After reaching saturation state, samples undergo desorption and reabsorption cycles at the same ageing conditions. On the other hand, other samples were kept till 80 days of ageing. Results revealed ageing temperature has a crucial role on the desorption process. Thus at 50°C, residual glycol water were measured for both materials. However, it was fully dried for samples aged at 90°C. Regarding, mechanical characterization it was noticed that absorption process is a reversible mechanism only for PA6 aged at 90°C. Indeed, IR spectroscopy pointed out that both studied materials underwent a chemical hydrolysis after the second immersion (reabsorption). After 80 days of ageing, results gathered revealed the occurrence of substantial changes and the ageing is no longer physical in nature especially for PA6. Thus, the long term ageing leads to the formation of ester species due to thermo-oxidation as pointed out by Infrared spectroscopy analysis. Indeed, an overall loss of mechanical properties with a significant embrittlement of PA6 was noticed that can be attributed to a decrease of the level of entanglements within the polymer.
