Interphases, adhesion

Fig. 6. Four mechanisms of adhesion, (a) The adsorption mechanism (contact adhesion), (b) The diffusion mechanism (diffusion interphase adhesion), (c) The mechanical interlocking mechanism. (d) The electrostatic mechanism.

In what follows, particular attention is given to semi-empirical strategies for optimizing contact adhesion and diffusion interphase adhesion. The former centers around maximizing the strength of inteimolecular interactions across a true interface, while the latter seeks to maximize thermodynamic compatibility between the phases. 

General characteristics of diffusion interphase adhesion coupling agents... 

Whatever the specific system or situation, the key issue in diffusion interphase adhesion is physical compatibility. This is once again, a thermodynamic issue and may be quantified in terms of mutual solubility. Most of the strategies for predicting diffusion interphase adhesion are based on thermodynamic compatibility criteria. Thus it is appropriate to review briefly the relevant issues of solution thermodynamics and to seek quantitative measures of compatibility between the phases to be bonded. 

In developing criteria for the ranking of adhesive formulations or adherend surface treatments or primers, it is necessary to distinguish between two different situations. In one case (contact adhesion), a true interface is believed to exist across which intermolecular forces are engaged, while in the other, an interphase is formed by diffusive interpenetration or interdigitation between the adhesive and the adherend (diffusion interphase adhesion). Even in the case of contact adhesion, more often than not, an mi vphase of macroscopic thickness forms on... 

Examination of the fracture by SEM shows that although there is no interphase adhesion in uncompatibilized blends, adhesion between the phases increased and dispersed domains decreased... 

Keywords Silane interphase adhesive joint epoxy. 

Interphase Adhesion. Adhesion between phases must be excellent if a crack or craze traveling in the matrix is to propagate into the dis-... 

The graft rubber particle sizes for these MBAS and SA impact polymers are nearly equivalent hence they can be compared directly. Other variables which may affect strength properties such as the craze size of the resin matrix, the interphase adhesion, molecular weights and... 

First, the copolymer is automatically formed at the interface between the two immiscible polymers where it is needed to stabilize morphology. In contrast, when a compatibilizing copolymer is added as a separate entity to a polymer blend, it must diffuse to the polymer-polymer interface to be effective for promoting morphology stabilization and interphase adhesion. However, the added copolymer may prefer to form micelles as a separate phase that is useless for compatibilization. 

A copolymer of the two immiscible polymers themselves would seem to be ideally suited to act as a compatibilizing agent for an immiscible blend. If the copolymer is at the interface of the two phases, then the segments of the copolymer dissolve in the respective bulk phases of the same identity. The copolymer acts as emulsifying agent for the blend resulting in reduced interfacial energy and improved interphase adhesion. 

PP/LCP, PVC/LCP Tensile impact properties Mechanical properties varied with interphase adhesion and orientation of LCP domains Seppala a/., 1992 Lee, 1988... 

PP-g-SBH copolymers cocrystallize completely with bulk iPP, which increases PP crystaUinity degree part of the SBH component (SBH grafts of PP-g-SBH copolymers and bulk SBH) enters the mutual amorphous phase of the blends, leading to a decrease of the intensity of the SBH peak. That means each part of the compatibilizer is miscible with the corresponding bulk phase of the blend. The compatibilized iPP/LCP blends display improved crystallization kinetics, enhanced degree of crystallinity, and improved interphase adhesion (37,38). Consequently, an improvement of the mechanical characteristics should be expected for these blends. In fact, the investigation of the Vickers microhardness of uncompatibilized and... 

In this paper, detailed evidence is given concerning the fundamental aspects of mechanical tests as a means of evaluating interphase adhesion. 

Whilst it is difficult to see the small endotherm exhibited by the melting of the PET-rich phase, both Zhuang et al. [73, 74] and Jung et al [120] were able to observe with DSC that its position changed little with addition of the PC, even up to 90% PC addition. Interphase adhesion in the solid state seemed good between PC and PLC, with fracture surfaces of spun fibers with the PLC as the minority phase showing good extension with little fiber pull-out. 

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