Hydrothermal aging of polyimide film

Abstract

The hydrothermal aging of a commercial polyimide film, (poly[pyromellitic dianhydride‐co‐4,4′‐oxydianiline]) is investigated, providing further insight into the well‐known loss of properties that can occur for these materials in the presence of moisture. The study involved measuring ATR‐FTIR, ultimate tensile strength, and percent elongation at break, under accelerated hydrothermal aging conditions at three different temperatures (70, 80, and 90°C). ATR‐FTIR data was analyzed using chemometrics in order to identify significant trends that develop upon the accelerated aging conditions. The most dramatic changes were observed for the aging at 90°C. Changes in the ATR‐FTIR spectra for aging at all three temperatures can be attributed to hydrolysis of the imide groups. Ultimate tensile strength was also used to monitor the hydrothermal aging process. This data was used to construct an Arrhenius plot from which an activation energy of 71.8 KJ/mol was determined for the hydrothermal aging process. This value is comparable to that of textiles used in fire protective clothing, suggesting that polyimide is a viable candidate for modeling the degradation of these textiles. This paper also shows the large potential of chemometrics for polymer aging studies as it allows identifying degradation mechanisms from subtle chemical changes in the materials.

Towards commercialization of graphene-based end-of-life sensors for fire-protective fabrics

“…The sacrificial polymers behave similarly to the outer shell fabrics of firefighters' protective garments when exposed to the ageing conditions of heat, UV light, and moisture [9][10]. The exposure to ageing conditions will initiate a degradation in the sacrificial polymer layer of the sensor, ultimately disrupting the conductivity of the conductive track [8].…”

New Research Trends for Textiles

“…Results showed that conductive tracks prepared on a meta-aramid woven fabric using reduced graphene oxide (Figure 6) resisted water immersion and the equivalent of 10 domestic launderings, while the conductivity was progressively lost as a result of abrasion [170]. Potential sacrificial polymers were successfully identified for thermal [171] and moisture [172] end-of-life sensors.…”

“…An innovative field for metalized fibers is products like wearable E-textiles [167]. Another important application is antimicrobial textiles, mainly based on silver-coated fibers [168][169][170][171][172]. However, copper containing textile materials is also offered for antimicrobial purposes [173,174].…”

Relationship between recovered enthalpy and the shape‐memory effect in shape memory polymers

“…[20][21][22] In addition, physical aging can cause changes to the characteristic relaxation time of the polymer. 15,23 Unlike the irreversible processes of chemical 24,25 and hydrothermal aging, 26,27 physical aging can be reversed through thermal rejuvenation mechanisms like super-T g reheating. 28,29 During thermal rejuvenation, the polymer chains are brought to an equilibrium state with their surrounding by raising their temperature above T g and any previous effects of aging and mechanical loading are erased.…”