Modulating the Mechanical Properties of Electrospun PHB/PCL Materials by Using Different Types of Collectors and Heat Sealing.

Irena Borisova,Olya Stoilova,Nevena Manolova,Iliya Rashkov

doi:10.3390/polym12030693

Abstract

Two-component fibrous materials based on poly(3-hydroxybutyrate) (PHB, Tm = 160 °C) and poly(ε-caprolactone) (PCL, Tm = 60 °C) were successfully fabricated by dual-jet electrospinning of their separate spinning solutions. The desired alignment of the fibers that compose PHB/PCL mats was achieved by using three types of rotating collectors—drum (smooth), blade and grid. Additional fiber alignment in the direction of collector rotation was achieved by rotating at 2200 rpm. Moreover, the selected concentration of PCL spinning solution resulted in fibers with spindle-like defects along their length. Thus, “segment” sealing of the PHB (high-melting) fibers by the molten PCL (low-melting) fibers/defects sites was achieved after heating the PHB/PCL mats above the melting temperature (Tm) of PCL. The surface morphology, thermal behavior and mechanical properties of the PHB/PCL mats before and after thermal treatment were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and mechanical tests. The results indicated that regardless of the cutting direction of the specimens (0° or 90°), thermal treated PHB/PCL mats reveal enhanced mechanical properties. Therefore, this work provides an easily feasible route for the fabrication of electrospun PHB/PCL mats with tunable mechanical properties and improved performance.

Highlights

Electrospinning is a cutting-edge nanotechnology and currently the only technique that allows facile fabrication of non-woven textiles with unique features and versatile possible applications [1,2,3,4]
The surface morphology, thermal behavior and mechanical properties of the PHB/PCL mats before and after thermal treatment were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and mechanical tests
A key factor is the structure of the non-woven textile; mats composed of aligned fibers are characterized by better mechanical behavior compared to mats composed of randomly deposited fibers [5,6,7,8,9]

Summary

Introduction

Electrospinning is a cutting-edge nanotechnology and currently the only technique that allows facile fabrication of non-woven textiles (the so-called “mats”) with unique features and versatile possible applications [1,2,3,4]. Despite the progress gained in terms of the electrospinning process, finding possibilities for tuning and improving the mechanical properties of the mats still remains a major challenge. A key factor is the structure of the non-woven textile; mats composed of aligned fibers are characterized by better mechanical behavior compared to mats composed of randomly deposited fibers [5,6,7,8,9]. The achievement of a certain alignment of the fibers that compose the mats is a suitable approach for improving the strength of the mats. Another approach is the thermal treatment of the mats at temperatures close to or above their melting temperatures (Tm ). There are very few reports on the improvement of the mechanical behavior of mats by thermal treatment [10,11,12,13]

Methods

Results

Conclusion