Adhesive silane treatments

Optimized grit blast/silane treatments can provide wedge test durability as good as PAA with failure entirely cohesive within the adhesive (Fig. 21) [89]. Maintaining the process parameters within acceptable tolerances is critical with the heat drying of the silane on the treated surface being the most sensitive process parameter. 

Added % Silane/treatment Wet adhesion b MPa/ % detached Recovered adhesion MPa/ % detached... 

What is accomplished by adhesion promotion treatments in IC manufacturing should actually be referred to as wafer substrate preparation, and not adhesion. Adhesion in the structural sense, as experienced in airplane composite material parts attachment, is not accomplished by silane wafer processing treatments except for the PI applications discussed early in this paper. The term adhesion, as it is used here, refers to a more practical definition—that is, resist image adhesion. Nevertheless, this type of adhesion is essential to the huge international semiconductor business, and the early silane work of Plueddemann and others was essential to early wafer adhesion process development. 

IFSS are much more striking, emphasizing the fact that the effectiveness of silane treatment is more important in retaining fiber-matrix adhesion under conditions of exposure to moisture. 

Adhesion between polymer systems and mineral surfaces is significantly increased when using silanes as coupling agents (Fig. 7). The chemical bond on the mineral surface leads to superior adhesion and thus moisture and temperature resistance. The perfect bonding is exemplified in Fig. 8, showing a glass sphere in a polymeric matrix before (left) and after silane treatment. 

Joseph et had also prepared the oil palm microfibril-reinforced NR composites by conventional mechanical blending. The used microfibrils were separated from the oil palm fibres by using the steam explosion method, and were subsequently subjected to treatments such as mercerization, benzoylation, and silane treatment. They found that the storage modulus value of untreated and treated microfibril-reinforced NR composites was higher than that of macrofibre-reinforced composites. The Tg values of microfibril-reinforced composites were slightly higher than that of macrofibre-reinforced composites. The treated microfibril-reinforced NR composites displayed better adhesion between fibre and NR matrix. 

Silanes are well recognized and very efficient coupling agents extensively used in composites and adhesive formulations. They have been successfully applied in inorganic filler reinforced polymer composites for years and extensively used for glass fibre reinforced polymer composites.In this chapter, only silane treatment is discussed in short which is as follows ... 

George et al. (1996) treated pineapple leaf fiber with polymethylene-polyphe-nyl-isocyanate (C15H10N2O2) solution at 50°C for 30 min to improve the fiber-matrix interfacial adhesion. Comparing silane and isocyanate-treated wood fiber-PS composites, it was reported that isocyanate treatment was more effective than silane treatment in enhancing the mechanical properties of cellulose fiber-PS composites (Maldas et al. 1989). 

Effect of fiber treatments Alkali treatment on OPFs significantly improved its interfacial shear strength in polyester matrix [14]. Alkali treatment washed out the outer skin, better exposing fiber to the polyester matrix, leading to proper interaction between their surfaces. In addition, the fine holes created on alkali treatment allowed the polyester to penetrate into the fiber bundles in a better way. Acetylation treatment to the fibers improved impact strength of OPF-polyester composites due to improved fiber wettability and resulting fewer void spaces [71]. The tensile stress of OPF-polyester composites increased slightly upon both acetylation and silane treatments on fibers and decreased upon titanate treatment [14]. The flexural modulus of OPF-PP composites also increased considerably upon acetylation treatment on fibers. Similarly the abrasion resistance of OPF-polyester composites was enhanced upon alkali treatment to fibers [13]. Treated fibers enhanced the adhesion resistance of polyester resin by 75-85%, while untreated fibers enhanced the abrasion resistance only by 50-60%. 

Sometimes, degree of adhesion between fiber and matrix achieved through various primary processing of biocomposites is weak which results in poor performance of developed composites. Natural fibers comprise of waxy and fatty materials on their surface which causes improper bonding between fiber and matrix. There are various chemical treatment techniques (such as alkali-treatment, silane treatment, Benzoylation, Acetylation, etc.) which can be applied to natural fibers before primary processing to condition the surface and consequently improve the fiber matrix adhesion to develop high performance biocomposites. 

In order to improve the interfacial adhesion, the addition of functionalized polymers, i.e., MAPP or MAPE to the composite is employed. The presence of these polymers slightly modifies stiffness, but significantly increases tensile yield stress, tensile strength, and in some cases deformabillty [69,70], The numerous other surface modification techniques like silane treatment [71,72], isocyanates [73,74], surfactants [75], and various monomers as well as chemical modification [76,77] are also utilized. 

The beneficial effects of surface treatments of filler particles, including silane treatments, are generally attributed to improved adhesion of the polymer to the filler surface. However, it should be realised that in many cases the changes in the degree of agglomeration brought about by the surface treatments are equally, or more, important [83]. 

BMI-based composites with exceptional mechanical properties were obtained using glass hollow microspheres that were previously submitted to a silane treatment (Koopman et al. 2006). All data indicated that interface adhesion between BMl and filler is strongly affected by the silylation reaction at the glass surface, which enhanced the compatibility. 

The main adhesives for bonding plastics to rubbers include cyanoacrylates, two-part urethanes, two-part epoxies, hot melt reactive urethane prepolymers, heat reactive contact cements and silane treatments. 

Increased adhesion, as indicated by peel tests, consistently improves certain mechanical properties in all rubbers, has little effect on some properties, and varies with the type of rubber in other properties. Each trend in properties is accentuated by increasing the level of silane treatment from 0.5% to 1.0%. 

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