Matrix adhesion

An EB-curable struetural adhesive formulation usually eonsists of one or more crosslinkable oligomeric resins or prepolymers, along with such additives as reactive diluents, plasticizers, and wetting agents. The oligomer is an important component in terms of the development of mechanical properties. The adhesive and cohesive properties depend on the crosslink density, chemical group substitution, and molecular organization within the polymer matrix. Adhesion is achieved... 

Interference with specific cell-cell and cell-matrix adhesion mechanisms is another rapidly advancing approach to therapeutically interfere with angiogenesis. Antagonistic antibodies (Vitaxin) to the integrin heterodimer av 33 have been shown to act on the blood vessels of tumors but not on the resting organ vasculature. Vitaxin demonstrated some promise in Phase II clinical trials. 

The basement membrane is a structure that supports overlying epithelial or endothelial cells. The primary fimction of the basement membrane is to anchor down the epithelium to its loose connective tissue underneath. This is achieved by cell-matrix adhesions through cell adhesion molecules. 

Another major drawback of polysaccharides is their hydrophilic nature leading to low degrees of adhesion between fiber and matrix [11]. Moisture absorption takes place by three types of mechanisms namely diffusion, capillarity, and transport via micro cracks [2]. Among the three, diffusion is considered to be the major mechanism. Water absorption largely depends on the water-soluble or hygroscopic components embedded in the matrix, which acts as a semipermeable membrane. While, fiber/matrix adhesion and fiber architecture also affect the moisture absorption. The results of the water sorption experiment showed an interesting trend. The extent of water uptake was not very significant and also did not increase linearly with amount of filler (Table-2). 

Biopolymers have diverse roles to play in the advancement of green nanotechnology. Nanosized derivatives of polysaccharides like starch and cellulose can be synthesized in bulk and can be used for the development of bionanocomposites. They can be promising substitutes of environment pollutant carbon black for reinforcement of rubbers even at higher loadings (upto SOphr) via commercially viable process. The combined effect of size reduction and organic modification improves filler-matrix adhesion and in turn the performance of polysaccharides. The study opens up a new and green alternative for reinforcement of rubbers. 

Ethylene-vinyl acetate Fetterman [37] reinforced compounded ethylene-vinyl acetate (EVA) copolymer by using short hbers and found that silane coupling agents were effective at establishing improved hber-matrix adhesion. Das et al. [38] prepared carbon fiber-filled conductive composites based on EVA and studied the electromagnetic interference shielding effectiveness of the composites. 

The aspect ratio, i.e., the length/diameter ratio (L/D) of the fibers is a major parameter that controls the fiber dispersion, fiber-matrix adhesion and optimum performance of short fiber-mbber... 

Proper reinforcement of rubber matrix using hllers can be achieved only if there exists adequate adhesion between the hller and the mbber. Rubber-mbber adhesion and rubber-hller adhesion both without and with adhesion promoters have been studied extensively [125-127]. Fiber-matrix adhesion in short fiber-rubber composites is always a field of extensive research. If the fibers are not bonded properly with the rubber matrix, fibers will shde past each other under tension deforming the matrix, thereby reducing the strength properties. In the case of short fiber-reinforced rubber composites, loads are not directly applied to the fibers, but are apphed to the matrix. To obtain a high-performance composite, the load must be effectively transferred to the fibers, which is possible only when the fiber-matrix interphase is sufficiently strong. In addition, the adhesion between the fiber and the matrix should be such that the failure occurs in the matrix rather than at the interphase [92]. 

The situation is more complex when various other ingredients are added to PBT. Glass fibers, for instance, may lose adhesion from the resin due to the action of water on the glass-PBT interface, independent of the PBT-matrix reaction. This action will depend on specific contact conditions such as time, temperature and pH. In some instances, fiber-to-matrix adhesion can be recovered when the sample is dried, resulting in the recovery of some mechanical properties (if the PBT matrix is not too severely degraded). Other additives can introduce additional complications. 

Scholtens, B. J. R. and Brackman, J. C., Influence of the film former on fibre-matrix adhesion and mechanical properties of glass-fibre reinforced thermoplastics, J. Adhes., 52, 115 (1995). 

The reinforcement/matrix adhesion is essential to the final properties. 

Drug/Polymer Matrix Adhesive Layer Backing Membrane... 

In vitro and in vivo studies have shown that stromal cells provide a rich environment of signals (cytokines, extracellular matrix, adhesion molecules etc.) that control proliferation, survival and differentiation of hematopoietic progenitor cells (Chailakhian, 1978 Verfaillie, 2002). Recently investigators incorporated stromal components into the expansion cultures (Rawano et al. 

Drzal, L.T. and Madhukar, M. (1993). Fiber-matrix adhesion and its relationship to composite mechanical properties. J. Mater. Sci. 28, 569-610. 

Bucher, R.A, and Hinkley, J.A. (1992). Fiber/matrix adhesion in graphite/peek composites. J. Thermoplastic Composite Mater. 5, 2-13. 

Gutowski, W. (1990). Effect of fiber-matrix adhesion on mechanical properties of composites. In Controlled Interfaces in Composite Materials (Proc. ICCI-III) (H. Ishida ed.), Elsevier, New York, pp. 505-520. 

Herrera-Franco, P.J. and Drzal, L.T. (1992). Comparison of methods for the measurement of fiber/matrix adhesion in composites. Composites, 23, 2-27. 

Madhukar, M.S. and Drzal, L.T. (1991). Fiber-matrix adhesion and its effects on composite mechanical properties II. Longitudinal (0°) and transverse (90°) tensile and flexural behaviour of graphite/epoxy composites. J. Composite Mater. 25, 958-991. 

Pally, 1, and Stevens, D, (1989). A fracture mechanics approach to the single fiber pull-out problem as applied to the evaluation of the adhesion strength between the fiber and the matrix. Adhesion Sci. Technol. 3, 141-153. 

Biro, D.A., Pleizeier, G, and Deslandes, Y. (1993b). Application of the microbond technique. IV. Improved fiber matrix adhesion by RF plasma treatment of organic fibers. J. Appl. Polym. Sci. 47. 883-894. 

Drown, E.K., Al-Moussawi. H. and Drzal, L.T. (1991). Glass fiber sizings and their role in fiber-matrix adhesion. J. Adhesion Sci. Techno . 5, 865-881. 

Different kinds of carbon-intense fibers are used, the most common being carbon and graphite fibers, and carbon black. As is the case with fibrous glass, surface voids are present. Carbon-intense fibers are often surface-treated with agents such as low molecular weight epoxy resins. Such surface treatments also aim at increasing the fiber-matrix adhesion. 

Cukierman E, Pankov R, Stevens DR et al (2001) Taking cell-matrix adhesions to the third dimension. Science 294 1708-1712... 

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