IGC Characterization of PMMA Grafted onto CTMP Fiber

Abstract

Inverse Gas Chromatography (IGC) was used to characterize chemithermomechanical pulp (CTMP) wood fiber surfaces modified by polymer grafting. From the retention times at infinite dilution over a range of temperatures, the differential heat of adsorption, ΔH^oA, the standard free energy, ΔG^oA, and the standard entropy of adsorption, ΔS^oA, have been determined for the n-alkanes vapors C₈-C₁₁ on CTMP wood fibers grafted with poly(methylmethacrylate) (PMMA) at various polymer loadings (PL). The dispersive component of the surface free energy γ^LS (London) has also been calculated by using a method based on the increment of ΔG^oA per CH₂ group. Comparison of results for the original material, CTMP and PMMA, with those of the grafted fibers has allowed the evaluation of surface modification. Grafted samples at high PL show values of ΔH^oA, ΔG^oA, and γ^LS approaching those of the pure PMMA indicating a high density of polymer chains grafts on the CTMP wood fiber.