Effects of toughened polyester on fatigue behavior of glass fiber reinforced polyester composite for wind turbine blade

Abstract

Cured unsaturated polyester resins are often highly brittle. In this paper, to improve fatigue life of the glass fiber‐reinforced polyester composite (GFRP) used in the wind turbine blade, the unsaturated polyester resin was toughened by 2 wt% liquid carboxyl‐terminated butadiene acrylonitrile (CTBN) copolymer. CTBN liquid rubber has acidic OH of the carboxylic group, which causes incompatibility and poor solubility of CTBN in unsaturated polyester resins. In this study, to increase compatibility and solubility of CTBN liquid rubber in unsaturated polyester resins, 1,4‐Butanediol diglycidyl ether (1,4‐BDGE) was selected to react with carboxylic group of the CTBN liquid rubber which converted to ester functional group. The reactions between epoxy groups of 1,4‐BDGE and carboxyl groups of CTBN were investigated by Fourier‐transform infrared (FTIR) spectroscopy. Four polyester samples were prepared by mixing unsaturated polyester with 0 to 3 wt% of modified CTBN. Tensile tests of polymer samples have been performed to observe the effect of modified CTBN additive. According to the results of the tensile test, the highest tensile strength, elongation‐at‐break, and modulus of toughness were observed in polyester with 2 wt% rubber. Two polyester/glass fiber composite samples with and without 2 wt% rubber were prepared by the vacuum infusion process (VIP) and subjected to fatigue behavior analysis. According to the results of the static tension test, the same value of tensile strength was observed in both composites. The obtained tension‐tension fatigue results (R = 0.1) showed a reduction in maximum stress level enhanced the fatigue life improvement for the samples with 2 wt% rubber due to the increased toughness of the composite matrix. Examining the fracture surfaces of the specimens after fatigue tests, it was revealed that failure of the polyester containing 2 wt% rubber/glass fiber occurred at the interface, while the specimens without rubber showed that failure did not occur at the fiber/matrix interface.

Long Chopped Glass Fiber Reinforced Low-Density Unsaturated Polyester Resin under Different Initiation

“…Among them, low-density unsaturated polyester resin (LDUPR) and its composite materials have been well development and drawn attention due to light weight, high mechanical performance and precenting environmentally friendly. It coincides with the development of new lightweight reinforced materials [7][8][9][10].…”

Tensile behavior of the bolt‐jointed GFRP after low‐velocity impact

“…Fiber‐reinforced composite laminates are increasingly used in various fields, primarily because of their excellent high specific strength, high specific stiffness, and good fatigue resistance. [ 1–3 ] The laminated construction of fiber‐reinforced composites and the characteristics of their constituent properties (fiber and matrix) often make their structural performance sensitive to even transverse impact loading. [ 4–7 ]…”

“…Fiber-reinforced composite laminates are increasingly used in various fields, primarily because of their excellent high specific strength, high specific stiffness, and good fatigue resistance. [1][2][3] The laminated construction of fiber-reinforced composites and the characteristics of their constituent properties (fiber and matrix) often make their structural performance sensitive to even transverse impact loading. [4][5][6][7] Generally speaking, the damage caused by impact on the materials is not always visible on the surface of the laminate, resulting in unpredictable and unknown performance degradation.…”

Fatigue life and damage evaluation of Glass Fiber Reinforced Unsaturated Polyester Composite Materials Based on recycled Polyethylene terephthalate (rPET)

“…Over the last few decades, the glass ber reinforced composite (GFRP) is increased in several structural applications wind turbine blades, leisure boats, space frames, etc. Polyester resin is most commonly used as a matrix to manufacture the wind turbine blade [34]. The wind turbine blade mainly consists of laminate composite that is subjected to dynamic loading.…”