Helicoidally Arranged Polyacrylonitrile Fiber-Reinforced Strong and Impact-Resistant Thin Polyvinyl Alcohol Film Enabled by Electrospinning-Based Additive Manufacturing.

Rahul Sahay,Komal Agarwal,Arief S Budiman,Anbazhagan Subramani,Avinash Baji,Nagarajan Raghavan

doi:10.3390/polym12102376

Rahul Sahay, Komal Agarwal + Show 4 more

Open Access

https://doi.org/10.3390/polym12102376

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Abstract

In this study, we demonstrate the use of parallel plate far field electrospinning (pp-FFES) based manufacturing system for the fabrication of polyacrylonitrile (PAN) fiber reinforced polyvinyl alcohol (PVA) strong polymer thin films (PVA SPTF). Parallel plate far field electrospinning (also known as the gap electrospinning) is generally used to produce uniaxially aligned fibers between the two parallel collector plates. In the first step, a disc containing PVA/H2O solution/bath (matrix material) was placed in between the two parallel plate collectors. Next, a layer of uniaxially aligned sub-micron PAN fibers (filler material) produced by pp-FFES was directly collected/embedded in the PVA/H2O solution by bringing the fibers in contact with the matrix. Next, the disc containing the matrix solution was rotated at 45° angular offset and then the next layer of the uniaxial fibers was collected/stacked on top of the previous layer with now 45° rotation between the two layers. This process was continued progressively by stacking the layers of uniaxially aligned arrays of fibers at 45° angular offsets, until a periodic pattern was achieved. In total, 13 such layers were laid within the matrix solution to make a helicoidal geometry with three pitches. The results demonstrate that embedding the helicoidal PAN fibers within the PVA enables efficient load transfer during high rate loading such as impact. The fabricated PVA strong polymer thin films with helicoidally arranged PAN fiber reinforcement (PVA SPTF-HA) show specific tensile strength 5 MPa·cm3·g−1 and can sustain specific impact energy (8 ± 0.9) mJ·cm3·g−1, which is superior to that of the pure PVA thin film (PVA TF) and PVA SPTF with randomly oriented PAN fiber reinforcement (PVA SPTF-RO). The novel fabrication methodology enables the further capability to produce even further smaller fibers (sub-micron down to even nanometer scales) and by the virtue of its layer-by-layer processing (in the manner of an additive manufacturing methodology) allowing further modulation of interfacial and inter-fiber adherence with the matrix materials. These parameters allow greater control and tunability of impact performances of the synthetic materials for various applications from army combat wear to sports and biomedical/wearable applications.

Highlights

Research has been ongoing to study the mechanical properties of micron/sub-micron thin polymer films due to their widespread applications such as protective and functional coatings, non-fouling surfaces, microfluidics, sensors, lubrication and friction modification [1,2,3,4]
The arrangement of layers consisting of aligned fibers one above the other at 45◦ angle within the polyvinyl alcohol (PVA) matrix is evident from these figures
This sample shows that the parallel plate far field electrospinning (pp-FFES) methodology gives better control in fiber orientation than compared to the electrospinning done without using parallel plate setup

Summary

Introduction

Research has been ongoing to study the mechanical properties of micron/sub-micron thin polymer films due to their widespread applications such as protective and functional coatings, non-fouling surfaces, microfluidics, sensors, lubrication and friction modification [1,2,3,4]. Common strategies used for the fabrication of strong polymer thin films (SPTFs) include the addition of inorganic material such as carbon tubes, carbon fibers, these methodologies may result in an increase in the specific weight, incompatibility with inorganic material, anisotropic mechanical properties due to nonuniform distribution of the filler material, void formations and/or high cost of the resultant composite [11], reducing their strength. It is known that structural hierarchical arrangement of nano/sub-micron fibers in thin films improves its tensile and impact properties [12,13,14]. Researchers are taking inspiration from the multiscale (nano/sub-micron) hierarchical architectures found in natural structural materials, such as in mantis shrimps’ dactyl club, nacre, lobster claw and butterfly wing, to design next-generation of strong and/or tough materials [15,16,17]

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