Water Absorption, Hydrothermal Expansion, and Thermomechanical Properties of a Vinylester Resin for Fiber-Reinforced Polymer Composites Subjected to Water or Alkaline Solution Immersion

Abstract

In the present paper, a vinyl ester (VE) resin, potentially used as a resin matrix for fiber-reinforced polymer (FRP) composite sucker rods in oil drilling, FRP bridge cables, or FRP marine structures, was investigated on its resistance to water and alkaline solution immersion in terms of water uptake, hydrothermal expansion, and mechanical properties. A two-stage diffusion model was applied to simulate the water uptake processes. Alkaline solution immersion led to a slightly higher mass loss (approx. 0.4%) compared to water immersion (approx. 0.23%) due to the hydrolysis and leaching of uncured small molecules (e.g., styrene). Water immersion caused the expansion of VE plates monitored with Fiber Bragg Grating (FBG). With the same water uptake, the expansion increased with immersion temperatures, which is attributed to the increased relaxation extent of the resin molecular networks. Although an obvious decrease of the glass transition temperatures (Tg) of VE due to water immersion (5.4 to 6.1 °C/1% water uptake), Tg can be recovered almost completely after drying. Tensile test results indicate that a short-term immersion (less than 6 months) enhances both the strength and elongation at break, while the extension of the immersion time degrades both the strength and elongation. The modulus of VE shows insensitive to the immersion even at elevated temperatures.

Falling Weight Impact Damage Characterisation of Flax and Flax Basalt Vinyl Ester Hybrid Composites

“…The maximum weight gain reported for vinyl ester matrix is 1.07% at room temperature [30]. The maximum weight gain percentages for flax/VE and flax/basalt/VE hybrid composites were approximately 4% and 3.5%, respectively.…”

“…This could be attributed to water absorption-induced plasticisation of the vinyl ester matrix leading to an increase of deformation and impact energy absorption [5,23]. The maximum weight gain reported for vinyl ester matrix is 1.07% at room temperature [30]. The maximum weight gain percentages for flax/VE and flax/basalt/VE hybrid composites were approximately 4% and 3.5%, respectively.…”

“…Chemical composition, and physical and mechanical properties of commonly used natural bast fibres[27][28][29][30].…”

Effects of Adhesive Coating on the Hygrothermal Aging Performance of Pultruded CFRP Plates

“…Moreover, fiber reinforced polymer plates have been widely used as strengthening materials of concrete members [2][3][4][5]. The long-term performance of FRP materials in harsh environments such as hygrothermal or alkaline environments is significant for their application [1] and has been widely investigated [6][7][8][9][10].…”

“…It is believed that the water uptake of FRP composites plays a key role in the degradation of their mechanical and thermal properties, especially in water [11,12], alkaline solution (simulation of concrete pore solution) [6,13] and salt solutions (simulation of seawater) [14,15]. Ficker's model [16] and a two-stage model [17] were proposed to simulate the water-uptake behavior of FRP composites [13,[18][19][20].…”