LAUSR

Abstract In this study, the effect of surface modification (acid treatment and chemical modification) of multi-walled carbon nanotubes (MWCNT) on the non-isothermal crystallization kinetics of poly (butylene succinate) (PBS) was studied. The chemical modifications of MWCNTs were conducted by using alcohols having different molecular weights. A twin screw microcompounder was used to prepare the MWCNT based nanocomposites. The filler content was 0.50% and 1% by weight. Fourier transform infrared spectroscopy (FTIR) was used to analyze changes in the surface chemical bonding and structure of the MWCNT's before and after surface modification processes. Transmission electron microscopy (TEM) was used to evaluate the morphological structures on the surfaces of the functionalized MWCNTs. The dispersions of surface modified and unmodified MWCNTs in PBS matrix and different solvents were characterized by scanning electron microscope (SEM) and polarized optical microscopy (POM), respectively. Different kinetic approaches such as Avrami, Ozawa and combined Avrami and Ozawa were studied to examine the non-isothermal crystallization kinetics of PBS and its nanocomposites. The nucleation activity of MWCNT nanoparticles was investigated in terms of Dobreva and Gutzow models. Activation energies for crystallization of PBS and its nanocomposites were evaluated by Friedman model. Besides, POM equipped with a hot-stage was used to examine the morphology during the crystal growth. FTIR and TEM analysis showed that surface modification of MWCNTs successfully accomplished. It was obtained that chemically modified MWCNT nanoparticles were well dispersed in both organic solvent and PBS matrix. Kinetic analysis revealed that crystallization rate of PBS increased especially in the presence of pristine MWCNT and chemically modified MWCNT nanoparticles. Moreover, crystallization rate of PBS increased as the length of the alkyl chains grafted onto the surface of MWCNT increased after chemical modification with alcohols. Pristine MWCNT exhibited the highest nucleation activity for PBS. POM analysis showed that nucleation density was higher in the presence of both pristine and chemically modified MWCNT filled PBS nanocomposites.