Cellulose reactive molding

These are very reactive with each other, with the remaining N-H bonds on melamine, with the hydroxyl groups in acrylic and polyester coatings, and with the hydroxyl groups in paper for countertops and in alpha-cellulose for molded dinnerware. 

This chapter explores the use of furfuryl alcohol (FA) both as the initial medium for dispersing nanopartides of cellulose whiskers (CW) or montmorUlonite (MMT) nanoclays and as the monomer precursor for in-situ polymerization of the PNC matrix. In general, nanopartides prepared from biomass or from minerals possess an abundance of built-in surface functionality, and this can be exploited in the reactive molding approach to achieve their dispersion in PNCs. 

In-situ intercalative polymerization of layered silicates is perhaps the best example of reactive molding of nanocomposites today. In-situ interactive polymerization of layered silicates, which was discussed above, can be achieved either with thermosetting matrices, such as polyurethane and epoxy, or with thermoplastic systems, such as nylon-6 [4, 23]. A general requirement for reactive molding of nanocomposites is that the particulate phase of a PNC is compatible with the monomer phase of the reactive molding system, which acts as a polymerizable solvent This makes it possible to achieve and maintain a fine dispersion of the particulate phase in the monomer during matrix consolidation, resulting in excellent particle distribution in the final PNC. Above, it was noted that the hydroxylated surface of cellulose makes it reactive to isocyanate. Cellulose whiskers may therefore represent the ideal particulate phase for a nano-RIM process. For this to be achieved, the whisker-polyurethane system needs to be better characterized, so that the RIM process can be adapted to fabrication of cellulose whisker PNCs. 

This section discusses the results of reactive molding of CW nanocomposites using FA as a polymerizable solvent medium to produce CW-PFA nanocomposites. Cellulose whiskers are not commercially available, and therefore, they were prepared by hydrolysis of MCC with sulfuric acid. The preparation of the CW was followed by their thorough morphology characterization, and finally, by the polymerization of FA to PFA in their presence. To characterize the polymerization behavior and to investigate how the presence of CW influences the polymerization of FA, FTIR spectra were collected before and during the resinification process. Finally, characterization of the thermal stability of the CW-PNC, as measured by TCA, is discussed and compared to the pure polymer. The results provide a useful qualitative measure of the CW dispersion in the cured PNC. 

U.S. Pat. Nos. 3,407,154 [16] and 3,407,155 [17] describe thermosetting urea-formaldehyde and aminoplast resinous molding composition comprising fusible reactive urea-formaldehyde and aminotriazine-formaldehyde resin, respectively, and purihed a-cellulose hbers (14-25% by weight) as a hller. 

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