Chain orientation in poly(glycolic acid)/halloysite nanotube hybrid electrospun fibers

Abstract

Chain orientation of poly(glycolic acid) (PGA) induced by halloysite nanotubes (HNTs) in hybrid electrospun fibers was investigated. The well-aligned PGA/HNTs hybrid fibers were prepared by electrospinning. The influence of HNTs loading (0, 1, 5, 10 wt%) on the PGA molecular chain and crystallite orientation was characterized by polarized Fourier transform infrared spectroscopy (FT-IR) and wide angle X-ray diffraction (WAXD). The effect of HNTs loading to the thermal properties of PGA fibers was investigated by differential scanning calorimetry (DSC), and the reinforcement effect of HNTs for PGA fibers was evaluated by tensile test. High temperature FT-IR measurement revealed the presence of hydrogen bonding between PGA carbonyl groups and HNTs surface silanol groups, which induces the alignment of PGA crystallite along the HNTs long axis. At low HNTs loading, HNTs distributed and aligned along the fiber axis during electrospinning process, whereas at high HNTs loading, the aggregation and anisotropic alignment of HNTs in PGA fibers lead disordered PGA chain orientation. The PGA molecular chain and crystallite orientation achieved the highest orientation degree at 5 wt% HNT loading. Furthermore, DSC results indicated that HNTs act as nucleating agent for PGA fibers and further increase the crystallinity of PGA fibers. Besides, young's modulus of PGA fibers was enhanced significantly with the addition of HNTs, which indicates a high reinforcement effect of HNTs to PGA fibers.