Adhesion interfacial width

Schnell, R., Stamm, M. and Creton, C., Direct correlation between interfacial width and adhesion in glassy polymers. Macromolecules, 31, 2284-2292 (1998). 

As binary PPE/SAN blends form the reference systems and the starting point for the foaming analysis, their miscibility will be considered first. As demonstrated in the literature [41, 42], both miscibility and phase adhesion of PPE/SAN blends are critically dependent on the composition of SAN, more precisely on the ratio between styrene and acrylonitrile (AN). Miscibility at all temperatures occurs up to 9.8 wt% of AN in SAN, whereas higher contents above 12.4 wt% lead to phase separation, independent of the temperature. Intermediate compositions exhibit a lower critical solution temperature behavior (LCST). Taking into account the technically relevant AN content SAN copolymers between 19 and 35 wt%, blends of SAN and PPE are not miscible. As the AN content of the SAN copolymer, selected in this work, is 19 wt%, the observed PPE/SAN blends show a distinct two-phase structure and an interfacial width of only 5 nm [42],... 

Polymer-polymer interfaces are an important area of study since the interfacial behaviour is fundamental to the bulk properties of the system. This is particularly true when two or more polymers are mixed to form a blend, but the interface also plays a dominant role in areas such as adhesion, welding, surface wetting and mechanical strength. To understand fully polymer behaviour in such applications, the interface must be characterised at a microscopic level. Through deuterium labelling the interface between otherwise indistinguishable polymers can be studied, and neutron reflectivity provides unprecedented detail on interfacial width and shape. In addition to the inherent interdiffusion between polymers at a polymer-polymer interface, the interface is further broadened by thermally driven capillary waves. Capillary waves... 

Figure 3.9 Adhesion energy of different samples of PS/PpMS plotted as a function of the interfacial width. Reproduced with permission from Ref [52] 1998, American Chemical Society.

Kulkarni et al. [83] studied the failure processes occurring at the micro-scale in heterogeneous adhesives using a multi-scale cohesive scheme. They also considered failure effect on the macroscopic cohesive response. Investigating the representative volume element (RVE) size has demonstrated that for the macroscopic response to represent the loading histories, the microscopic domain width needs to be 2 or 3 times the layer thickness. Additionally, they analyzed the effect of particle size, volume fraction and particle-matrix interfacial parameters on the failure response as well as effective... 

The first chapter of the book summarizes classical approaches, introduces the concept of ionicity, and describes the mixed iono-covalent character of the oxygen cation bond in bulk materials. The next three chapters focus on the characteristics of the atomic structure (relaxation, rumpling and reconstruction effects), the electronic structure (band width, gap width, etc.) and the excitations of clean surfaces. Metal-oxide interfaces are considered in the fifth chapter with special emphasis on the microscopic interfacial interactions responsible for adhesion. The last chapter develops the concepts underlying acid-base reactions on oxide surfaces, which are used in catalysis, in adhesion science, and in colloid physics, and discusses their applicability to the adsorption of hydroxyl groups. A comprehensive list of references is included. 

The effects of bonding temperature on (he apparent peel strength per unit width are shown in Figure 2. In the bonding experiments at 120 °C, adhesion of the EO-1 films caimot be obtained with which the T-peel test was not performed. Interfacial failmes were observed for the bonded films of EO-2 and EO-3 samples at 120 C. At the lowest peel rate tested, 2 mm/min, the apparent peel sfrength are about 0.11 + 0.02 and 0.25 + 0.02 N/mm for EO-2 and EO-3 samples, respectively. As the bonding temperature increased to 130 °C, interfacial failure was observed for EO-1 sample and cohesive failure for all the other two samples. The fractal analysis will be carried out only on the fractured surfaces resulted in interfacial failures imder these conditions. 

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