Adhesion Optimization between Incompatible Polymers through Interfacial Engineering

Abstract

Additive manufacturing technologies such as fused filament fabrication (FFF) open many possibilities in terms of product functionality, including the possibility to integrate a sensor in FFF parts to perform structural health monitoring. In this context, embedding fiber Bragg grating (FBG) sensors into 3D-printed polymeric structures for strain or temperature measurements has attracted increasing attention in recent years. Indeed, offering structural health monitoring functionality can optimize the maintenance cost and increase security compared with conventional materials. However, the transmission of strain and temperature between the polymeric matrix and the FBG polymer jacket requires optimal bonding between them. In this work, the two polymers of interest are polyimide (PI) and poly(lactic acid) (PLA) for the FBG jacket and printed polymer, respectively. The current study investigates the influence of different surface treatment methods on the adhesion between a PI film and a plate of PLA, with PLA and PI being incompatible polymers. The adhesion promotion applied to the PI surface relies on cleaning, plasma activation, roughness modification, or the use of adhesive nanocoating. Bilayer samples of PI-PLA are processed by welding PLA against the treated PI by heating, whereas the adhesion between PI and PLA is measured by peel testing. It is observed that the highest adhesion between PI and PLA is achieved by a combination of mechanical abrasion increasing roughness and the use of polydopamine as an adhesive. This finding is discussed based on a synergetic effect between mechanical interlocking and chemical interaction between the two counterfaces.

Overprinting of TPU onto PA6 Substrates: The Influences of the Interfacial Area, Surface Roughness and Processing Parameters on the Adhesion between Components

“…Samples overprinted at substrates with varied surface roughnesses had tear-off strengths in a range of around 0.3 MPa to 0.4 MPa, with the highest value associated with the sample with the lowest surface roughness. Higher surface roughness should lead to better adhesion between the polymer surfaces due to a higher specific surface area and additional mechanical interlocking, which was not the case in our study [ 33 ]. Possible explanations for this are that the material viscosity being too high to effectively fill the pits of the rougher surface, the peaks melting due to heat transfer from the extruder material or the effect being so small that it was not visible due to high deviations in the measured values.…”

Biomimetic Polymer Adhesives

“…Very recently, Mashayekhi et al used coating of PDA to bind polyimide (PI) and polylactide (PLA), which are well-known to be incompatible with each other. 113 Han et al synthesized a polydopamine-claypolyacrylamide (PDA-clay-PAM) hydrogel adhesive film, capable of demonstrating strong adhesion with robust mechanical strength (Figure 15b). 114 The catechol groups generated by PDA in the composite hydrogel adhesive was responsible for the enhanced adhesion strength.…”

Modeling of Single-Process 3D-Printed Piezoelectric Sensors with Resistive Electrodes: The Low-Pass Filtering Effect

“…In recent years, the fabrication of sensory elements using additive manufacturing techniques received significant scientific attention [ 1 , 2 ]. The research of 3D-printed dynamic sensors is important since complex sensor shapes can be fabricated and embedded within structures already in the manufacturing stages [ 3 ].…”