Issue 36, 2016, Issue in Progress

Rheological properties and crystallization behavior of comb-like graft poly(l-lactide): influences of graft length and graft density

Abstract

Three series of narrowly dispersed comb-like graft poly(L-lactide) (PLLA) with controlled graft length and graft density have been facilely synthesized and characterized. The structural information was determined by means of 1H NMR, GPC, and viscometry, demonstrating the well-defined grafted structure. The effects of grafting parameters on rheological properties, thermal and crystallization behaviors were investigated systematically to illustrate the structure–property relationships. By the analysis of the rheological behavior, the increase of graft length and graft density can both lead to an elevated value of zero-viscosity (η0), enhanced complex modulus (G*) and increased complex viscosity (η*). Comparatively, graft density contributes more to the improvement of rheological properties than graft length does. For thermal properties, DSC results show that the glass transition temperature (Tg), the melting temperature (Tm) and the crystallization enthalpy (ΔHm) of graft PLLA increase with the chain length and decrease with the graft density. Furthermore, spherulite morphologies and growth rates were studied by polarized microscopy (POM), and the observation revealed a remarkable improvement of radius growth rate of the spherulites (G) when graft density increased. The results indicate that G depends more on the molecular weight of each arm (Mn,arm) than the total Mn.

Graphical abstract: Rheological properties and crystallization behavior of comb-like graft poly(l-lactide): influences of graft length and graft density

Supplementary files

Article information

Article type
Paper
Submitted
29 Jan 2016
Accepted
08 Mar 2016
First published
11 Mar 2016

RSC Adv., 2016,6, 30320-30329

Rheological properties and crystallization behavior of comb-like graft poly(L-lactide): influences of graft length and graft density

X. Leng, Z. Wei, Y. Bian, Y. Ren, Y. Wang, Q. Wang and Y. Li, RSC Adv., 2016, 6, 30320 DOI: 10.1039/C6RA02697D

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