Atmospheric corrosion of Nylon 6,6 in Mauritius

Abstract

Plastics are being more and more commonly used for outdoor applications in Mauritius. In this context, the atmospheric corrosion degradation behaviour of nylon 6,6 was observed in the Mauritian atmosphere, having a corrosivity category of C3, according to ISO 9223. The crack width, depth and extent of the cracks formed on the surface were investigated using micrometry and image analysis. The changes in the chemical composition of the nylon 6,6 were investigated using the Fourier Transform Infrared spectroscopy technique. It was observed that the nylon 6,6 surface showed a progressive discolouration and a sudden increase in the size of the cracks after around 2 years of exposure. The degree of crack formation in terms of crack width, the depth of degradation and the microhardness of the surface were evaluated and all showed significant degradation only after about 2 years of exposure. Degradation has penetrated the test material within 750 µm from the surface in 4.5 years of exposure. Using the FTIR technique, evidence of chain scission occurring among the polymer chains was observed.

Ageing of climbing ropes with and without hydrophobic coating

“…This provided important parameters for the near surface characterisation of the oxidative processes in the sheath. The focus was on the carbonyl region between 1770 and 1705 cm 21 , where formation of N-acylamides (imides), N-formamides (formimides) and aldehydes (Figure 2) can be observed. Spectra were obtained with a resolution of 4 cm 21 and 64 scans per measurement were obtained from five places along the rope pieces with each place containing four measurements distributed around the rope's circumference.…”

“…[16][17][18] It is known that polyamides change their chemical and physical properties when they are exposed to meteorological effects due to UV-induced photo-oxidative degradation, which leads to chain scission, crosslinking and change in morphology through a free radical process. [19][20][21][22][23][24][25] The degradation of polyamides leads to the formation of N-acylamides (imides), N-formamides (formimides) and aldehydes (Figure 2). 26 Carbonyl groups represented in the above-mentioned degradation products can be detected by using the Fourier transform infrared spectroscopy technique in the carbonyl region between 1770 and 1705 cm 21 .…”

“…[19][20][21][22][23][24][25] The degradation of polyamides leads to the formation of N-acylamides (imides), N-formamides (formimides) and aldehydes (Figure 2). 26 Carbonyl groups represented in the above-mentioned degradation products can be detected by using the Fourier transform infrared spectroscopy technique in the carbonyl region between 1770 and 1705 cm 21 . Even though polyamide fibres are UV-stabilised during production, [27][28][29] either by the inclusion of antioxidant products or the incorporation of UV protection agents, some degree of deterioration of physical and chemical properties is inevitable.…”