Co-Bonded Hybrid Thermoplastic-Thermoset Composite Interphase: Process-Microstructure-Property Correlation

Abstract

Co-bonding is an effective joining method for fiber-reinforced composites in which a prefabricated part bonds with a thermoset resin during the curing process. Manufacturing of co-bonded thermoset-thermoplastic hybrid composites is a challenging task due to the complexities of the interdiffusion of reactive thermoset resin and thermoplastic polymer at the interface between two plies. Herein, the interphase properties of co-bonded acrylonitrile butadiene styrene thermoplastic to unsaturated polyester thermoset are investigated for different processing conditions. The effect of processing temperature on the cure kinetics and interdiffusion kinetics are studied experimentally. The interphase thickness and microstructure are linked to the chemo-rheological properties of the materials. The interdiffusion mechanisms are explored and models are developed to predict the interphase thickness and microstructure for various process conditions. The temperature-dependent diffusivities were estimated by incorporating an inverse diffusion model. The mechanical response of interphases was analyzed by the Vickers microhardness test and was correlated to the processing condition and microstructure. It was observed that processing temperature has significant effect on the interdiffusion process and, consequently, on the interphase thickness, its microstructure and mechanical performance.

The Springer Model for Lifetime Prediction of Wind Turbine Blade Leading Edge Protection Systems: A Review and Sensitivity Study

“…The interphase for a thermoplastic LEP that is co-bonded to a thermoset substrate was studied extensively [ 45 , 46 ]. A delicate balance between inter-diffusion and cure-kinetics was observed and linked to processing conditions and interphase quality [ 47 ].…”

Thermoset/Thermoplastic Interphases: The Role of Initiator Concentration in Polymer Interdiffusion

“…While knowledge of the manufacturing of individual FRPC parts has reached a level of maturity, the integration and assembly of different FRPC parts is far less developed, particularly considering the co-bonding process. Co-bonding is a bonding technique in which a prefabricated part (in this case, a thermoplastic (TP) polymer) is bonded with a (neat or fiber-reinforced) thermoset polymer through a curing reaction of the thermoset resin [ 1 , 2 , 3 , 4 ]. The areas of application of this technique involve the bond between the pultruded profiles at the blade root, spar cap, and leading edge protection (LEP) layer and the over-infused main body of the wind turbine blade [ 5 , 6 ].…”

“…The areas of application of this technique involve the bond between the pultruded profiles at the blade root, spar cap, and leading edge protection (LEP) layer and the over-infused main body of the wind turbine blade [ 5 , 6 ]. Although co-bonding may refer to the bonding of two parts with or without an adhesive between them [ 1 , 2 , 3 , 4 , 7 ], in this work we will focus on co-bonding without adhesives, where bonding takes place by the interdiffusion of polymers that are in contact as the curing takes place. The interdiffusion of the bonded polymers, and, subsequently, the curing of the resin result in the formation of an interphase [ 2 , 4 , 8 , 9 , 10 , 11 , 12 ].…”

“…Although co-bonding may refer to the bonding of two parts with or without an adhesive between them [ 1 , 2 , 3 , 4 , 7 ], in this work we will focus on co-bonding without adhesives, where bonding takes place by the interdiffusion of polymers that are in contact as the curing takes place. The interdiffusion of the bonded polymers, and, subsequently, the curing of the resin result in the formation of an interphase [ 2 , 4 , 8 , 9 , 10 , 11 , 12 ]. The size and morphology of the interphase have been shown to depend on the gelation time and viscosity of the resin, the thermodynamic affinity between the polymers, and the physical state of the thermoplastic [ 2 , 4 , 8 , 9 , 10 ].…”

“…The interdiffusion of the bonded polymers, and, subsequently, the curing of the resin result in the formation of an interphase [ 2 , 4 , 8 , 9 , 10 , 11 , 12 ]. The size and morphology of the interphase have been shown to depend on the gelation time and viscosity of the resin, the thermodynamic affinity between the polymers, and the physical state of the thermoplastic [ 2 , 4 , 8 , 9 , 10 ]. For instance, high levels of thermodynamic affinity may promote homogeneous mixing, whereas phase separation may take place at lower levels of affinity [ 9 ].…”