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 G0 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.

Figure optionsDownload as PowerPoint slideHighlights
► Isothermal crystallization of a star-branched DPA-11 and a linear PA-11 are compared.
► DPA-11 exhibits the much lower crystallization rate than PA-11.
► The Vyazovkin method shows that DPA-11 always has the higher activation energy EX.
► The star branching of DPA-11 causes the sharp rise in EX during a high crystallinity range.
► The secondary crystallization of DPA-11 seems suppressed by the star-chain branching.