Moisture diffusion properties of HFPE‐II‐52 polyimide

Abstract

Moisture diffusion properties of the polyimide HFPE-II-52 were determined using weight gain, weight loss, and swelling experiments over a temperature range of 25-2008C. Below 1008C, diffusivity was measured using standard weight loss and weight gain methods. Above 1008C, diffusivity is found by weight loss experiments performed by placing moisture saturated samples in an oven and recording weight loss dynamically. The diffusivity of the polyimide was found to obey the Arrhenius relation over the entire range of temperature. Weight gain experiments were performed to determine the equilibrium level of moisture absorbed by the polyimide as a function of relative humidity. Swelling experiments were performed to measure swelling strain as a function of moisture absorption.

Fiber optic distributed temperature sensor mapping of a jet-mixing flow field

“…Polyimide is hygroscopic and swells with an increase in humidity (Bhargava et al 2006), an effect exploited to create fiber Bragg grating humidity sensors (Ding et al 2011;Berruti et al 2013). Swelling of the coating alters optical fiber dimensions and shifts the Bragg wavelength.…”

Phase-shifted fiber-Bragg-grating-based humidity sensor

“…The relationship between the humidity and water uptake is modeled by Peeyush et al [49] by using the Guggenheim-Anderson-de-Boer equation: 12) where M  is the weight gain, w a is the water activity, which is RH value, m M is the monolayer moisture content, and A and C are constants related to heat of sorption. Fitting the data to Eq.…”

High Temperature Shear Strength of T650-35/HFPE-II-52 Polyimide Matrix Unidirectional Composite

“…Linear viscoelastic properties of the matrix, moisture swelling and thermal expansion of the HFPE-II-52 polyimide matrix are given in [14,15]. The coefficient of thermal expansion of HFPE-II-52 measured using TMA (TA Instruments Q400EM Thermomechanical Analyzer) is 35: Â 10 À6 = C averaged over 50 C to 300 C. The T g of the laminate, measured using DMA (TA Instruments 2980 Dynamic Mechanical Analyzer) with three-point bending samples, is approximately 370 C. This is somewhat higher than T g % 358 C measured for the post-cured neat resin [14].…”

“…The 50% RH samples were conditioned in a temperature-humidity controlled environmental chamber at 85 C for 7 days. The matrix of the fully saturated, 100% RH samples absorbs 3.2% by weight of water at all temperatures [15].…”

“…This study focuses on composites made from T650-35 graphite fibers with HFPE-II-52 matrix, a polyimide developed for use in composite materials [12]. The limited published data available on HFPE-II-52 and its composites include [12][13][14][15].…”