Polymeric matrices precursor

Given the vast number of possible matrix-reinforcement combinations in composites and the relative inability of current theories to describe the viscosity of even the most compositionally simple suspensions and solutions, it is fruitless to attempt to describe the momentum transport properties of composite precursors in a general manner. There are, however, two topics that can be addressed here in an introductory fashion flow properties of matrix/reinforcement mixtures and flow of matrix precursor materials through the reinforcement. In both cases, we will concentrate on the flow of molten polymeric materials or precursors, since the vast majority of high-performance composites are polymer-based. Fnrthermore, the principles here are general, and they apply to the flnid-based processing of most metal-, ceramic-, and polymer-matrix composites. 

Using furfuryl alcohol, recently Pranger and Tarmenbatrm (2008) employed an in situ polymerization approach to produce polyfurfuryl alcohol (PFA) nanocomposites without the use of solvents or surfactants. On the one hand, furfuryl alcohol (FA) has a dual function, serving both as an effective dispersant for MMT clay nanoparticles and as the matrix precursor for the in situ polymerization. 

The sol-gel synthesis of hybrid materials involves the occurrence of hydrolysis and condensation reactions in the presence of an organic polymer. Obviously, the selection of suitable polymer is of fundamental importance for the synthesis of the hybrid materials, as it should exhibit good miscibility with typical sol-gel precursors. The presence of suitable functional groups can facilitate the linkage between the polymer and the inorganic component. Also, the nature of the polymeric matrix is important because different properties of the matrix and, consequently, of the resulting nanohybrid material can be addressed for instance, the polymeric marix can be an elastomer (as in the case of polydimethylsiloxane) or thermoplastic (e.g., polytetrahydrofuran), amorphous, or (partially) crystalline [81]. 

A promising method for the in-situ growth of metal oxide NPs in the presence of a polymer is the thermal decomposition of precursors forming metal oxide NPs within the polymeric matrix. In the early 1990s, Ziolo et al. [155] used a one-step chemical method to synthesize finely dispersed Y-Fe203 NPs in a crosslinked PS... 

Colloidal dispersions of 33-nm-diameter trimetallic Au-Pb-Cd particles, containing gold core surroimded with a 18-nm-thick lead shell are formed by y-irradiation of corresponding metals salts." Nanocomposites with three or more different metals are multimetallic nanohybrids. Studies of their structures is a challenging task. Nevertheless, these materials have aheady been used as precursors in the production of superconducting ceramics, special multicomponent steels, etc. Traditionally, polymer is formed in a previously prepared inorganic matrix or the polymer is inserted into the latter. Multimetallic nanocomposites are prepared in situ within a polymeric matrix or simultaneously with polymer matrix formation. 

Liquid composite molding techniques, making use of the ring opening polymerization of various cyclic mono- and oligomers, wUl remain hot topics . Apart from CBT, cyclic lactones and lactams will be favored as matrix precursors. Gong et at [76] demonstrated the feasibihty of this method by producing PA-6 based SPC via infiltration of PA-6 fiber assembly with e-caprolactam followed by in situ polymerization of the latter. 

Polymerization of vinyl monomers intercalating into the montmorillonite (MMT) clay was first reported in the literature as early as 1961. The most recent methods to prepare polymer-layered-siUcate nanocomposites have primarily been developed by several other groups. In general these methods (shown in Fig. 5.1) are able to achieve molecular-level incorporation of the layered silicate (e.g. montmorillonite clay or synthetic layered silicate) in the polymer matrix by addition of a modified silicate either to a polymerization reaction (in situ method), to a solvent-swollen polymer (solution blending), or to a polymer melt (melt blending). Recently, a method has been developed to prepare the layered silicate by polymerizing silicate precursors in the presence of a polymer. ... 

In 2009, the same research group published the second paper in proton conducting membranes via the polymerization of microemulsions containing nanostructured Protic ILs (PILs) networks. PILs nanostructures formed in the precursor microemulsions could be preserved in the resultant polymeric matrix without macroscopic phase separation, even if the produced vinyl polymers are incompatible with PIL cores. 

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