Thermochimica Acta, Vol.544, 99-104, 2012
Elucidating isothermal crystallization behaviors of nylon-11s. Influence of star-chain branching
Star-branched polymers have being captured much research interest, yet impacts of the star-chain branching on the crystallization still need further elucidating. We originally report a comparative study of the isothermal crystallization kinetics of a star-branched DPA-11 and a linear nylon-11 (PA-11). Differential scanning calorimetry (DSC)confirms DPA-11 crystallizes at a much slower rate than PA-11. The kinetic analysis demonstrates the Avrami equation can generally well predict relative crystallinity X, and DPA-11 exhibits the higher Avrami exponents. The Hoffman-Lauritzen spherulitic growth analysis demonstrates DPA-11 has the decreased Go and Kg values, accounting for the appreciably lowered spherulitic growth rate. More interestingly, the advanced isoconversional (Vyazovkin) method reveals DPA-11 always manifests the higher activation energy than PA-11 and once X exceeding 0.85 the activation energy of DPA-11 rises sharply, whereas that of PA-11 tends to decrease. (c) 2012 Elsevier B.V. All rights reserved.