Composite resins sandwich technique

A. Lindberg, J.W.V. van Dijken, M. Lindberg, Nine-year evaluation of a polyacid-modified resin composite/resin composite open sandwich technique in Class II cavities, J. Dent. 35 (2007) 124-129. 

Mount, G. J. (1989). The wettability of bonding resins used in the composite resin/glass-ionomer sandwich technique. Australian Dental Journal, 34,... 

The two major categories of polymer composite used in aerospace are laminates and sandwich stmctures, which require some differences in NDT inspection methods. The inspection of choice at the time of manufacture may be different from the inspection of choice for in-service assessments. The form of the stmcture determines the types of features of concern and the NDT techniques that may be apphed to detect and measure them. Table 15.1 summarizes some general thoughts and considerations on NDT of polymer composite stmctures. American Society for Testing and Materials (ASTM) also provides guidance on NDT for polymer composites [12]. The primary concerns in laminates are voids and porosity, inclusions, delamination, the fiber-to-resin ratio, and wrinkles (wavy or out-of-plane ply). Ultrasound is the predominate method for composite laminate inspection. In sandwich structures, the core material-to-facesheet bond, core condition, and fluid ingress are the usual concerns. 

Compression Molding Compression molding is a molding technique for making composite materials under specific temperature and pressure. The unit cost is reduced by the faster cycle times that are possible when compression molding/ sheet molding compounds (SMC) are made. SMC is a sheet that sandwiches chopped fiber between two layers of resin paste. Chopped fiber drop onto the paste and a second film carrier faces another layer of resin down on top of the fiber. Rollers compact the sheet to saturate the fiber with resin and to squeeze out... 

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