Silvia Sizuka Oishi

Synthesis and characterization of polyarylacetylene for use in the monolithic vitreous carbon processing

In this work, polyarylacetylene (PAA) prepolymer obtained from 1,4-diethynylbenzene was evaluated as polymeric precursor of monolithic vitreous carbon (MVC). The monomer 1,4-diethynylbenzene was synthesized and the PAA prepolymer was prepared with 13, 16 and 19 wt % of nickel catalyst. The best percentage of nickel catalyst considered was 13 wt %, due to the lower molecular weight and polydispersity index and higher carbon yield. The traditional production of MVC is obtained from phenolic and poly(furfuryl alcohol) resins, which require many hours to pyrolyze due to the large quantity of gases generated. Furthermore, the porosity is hard to control using these conventional resins. Polyarylacetylene releases little volatiles due to the polyaddition reaction and the aromatic rings in PAA chain also provide a high thermal stability, therefore the heat treatment could be faster without cracking the carbon material. This would also lower the cost of fabrication of MVC, in addition to the low porosity observed, making this polymer a good matrix for MVC.

Analysis of chemical polymerization between functionalized MWCNT and poly(furfuryl alcohol) composite

In this study, the chemical interaction between functionalized carbon nanotuboes with carboxyl groups (CNT-f) and the subsequent addition of furfuryl alcohol (FA) and mixture with poly(furfuryl alcohol) (PFA) resin was evaluated. The FA with CNT-f was mixed in PFA resin to facilitate the chemical interaction of CNTs. The morphological and chemical interaction were studied by Transmission Electron Microcopies (MET), FTIR analyses, Raman Spectroscopy, viscosimetry and X-ray photoelectron spectroscopy (XPS). It was observed that a chemical interaction occurs through the opening of the hydroxyl polymer chain with a subsequent output of one water molecule. This interaction was evident from the FTIR and XPS data of the PFA composites. In this way, the mixture of functionalized carbon nanotubes with carboxyl groups in the FA, before adding this reinforcement into the PFA resin, can be considered a good procedure in order to obtain an appropriate chemical interaction between the CNT and PFA resin.