Influence of finish treatment on the durability of aramid fibers aged under an alkaline environment

Abstract

Aramid fibers are high‐performance materials which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for ground reinforcement. The influence of the surface finish composition and content has been studied in the field of cables and textiles, but there is no published data concerning the effect of a finish treatment on the hydrolytic degradation. Aramid fibers with different finish contents have been aged in an alkaline environment. The degradation has been identified by FTIR, viscosimetry, TGA, SEM, and tensile tests. For Technora fibers, the presence of finish appears to limit the tensile strength loss of aramid fibers at pH 11 by limiting abrasion, as well as bulk and surface degradation. For Twaron fibers, higher finish content only has a slight influence on the fibers durability at pH 11 and pH 9, by limiting abrasion and bulk degradation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Degradation of Technora aramid fibres in alkaline and neutral environments

“…Indeed, it is likely that lower molecular weight chains are decomposed at lower temperature. Moreover, the presence of finish does not have any influence on the decomposition temperature [11]. The present results suggest that hydrolytic aging of Technora T240 fibres may involve some chain degradation at pH9 and at pH11, which could not be highlighted by viscosity measurements, but further analyses, such as Size Exclusion Chromatography for instance would be required to clarify this.…”

“…The polymer decomposition from 474 AE 4 C to w863 C consists of two slopes which may be attributed to the decomposition of the PPTA and the 3,4 0 -POP-T sequences, as reported by Ozawa [9]. This assumption is supported by the thermogravimetric curve of PPTA fibres which display only one slope for the main decomposition [11]. Table 2 groups the decomposition temperatures of Technora T240 fibres as-received and after one year aging in different conditions.…”

“…The reduced viscosity of Technora T240 increases slightly from w441 AE 60 mL/g to w497 mL/g after one year at pH11 and 80 C, to w450 mL/g after one year at pH9 and 80 C, and to w492 mL/g after one year in deionised water at 80 C. The influence of the finish on the reduced viscosity has been explained elsewhere [11]. It appeared that the presence of finish lowers the reduced viscosity significantly.…”

“…Table 2 groups the decomposition temperatures of Technora T240 fibres as-received and after one year aging in different conditions. The decomposition temperature decreases by w10 C after one year at pH11 and pH9 at 80 C, and does not decrease in deionised water at 80 C. The hypothesis suggesting that the lower the decomposition temperature the larger the chain degradation has been shown to be acceptable [11]. Indeed, it is likely that lower molecular weight chains are decomposed at lower temperature.…”

“…The presence of finish has been shown to have a significant influence on the density of the Technora fibres [11]. For instance, the density is 1.398 AE 0.002 for as-received fibres without finish (Technora T000) whereas it is 1.387 AE 0.003 for as-received fibres with 2.5 wt% finish content (Technora T240).…”