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

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.

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Alkali-deficiency driven charged out-of-phase boundaries for giant electromechanical response

Nature Communications ◽

10.1038/s41467-021-23107-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Haijun Wu ◽

Shoucong Ning ◽

Moaz Waqar ◽

Huajun Liu ◽

Yang Zhang ◽

...

Keyword(s):

Thin Films ◽

Temperature Stability ◽

Epitaxial Films ◽

Polarization Rotation ◽

Phase Boundaries ◽

Film Properties ◽

New Strategy ◽

The Matrix ◽

Opposing Effects ◽

Severe Deterioration

AbstractTraditional strategies for improving piezoelectric properties have focused on phase boundary engineering through complex chemical alloying and phase control. Although they have been successfully employed in bulk materials, they have not been effective in thin films due to the severe deterioration in epitaxy, which is critical to film properties. Contending with the opposing effects of alloying and epitaxy in thin films has been a long-standing issue. Herein we demonstrate a new strategy in alkali niobate epitaxial films, utilizing alkali vacancies without alloying to form nanopillars enclosed with out-of-phase boundaries that can give rise to a giant electromechanical response. Both atomically resolved polarization mapping and phase field simulations show that the boundaries are strained and charged, manifesting as head-head and tail-tail polarization bound charges. Such charged boundaries produce a giant local depolarization field, which facilitates a steady polarization rotation between the matrix and nanopillars. The local elastic strain and charge manipulation at out-of-phase boundaries, demonstrated here, can be used as an effective pathway to obtain large electromechanical response with good temperature stability in similar perovskite oxides.

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Structure–Property Relationship of Cellulose Nanocrystal–Polyvinyl Alcohol Thin Films for High Barrier Coating Applications

ACS Applied Materials & Interfaces ◽

10.1021/acsami.0c21525 ◽

2021 ◽

Author(s):

Md Nuruddin ◽

Reaz A. Chowdhury ◽

Ryan Szeto ◽

John A. Howarter ◽

Kendra A. Erk ◽

...

Keyword(s):

Thin Films ◽

Polyvinyl Alcohol ◽

Cellulose Nanocrystal ◽

Structure Property ◽

Property Relationship ◽

Barrier Coating ◽

Structure Property Relationship ◽

Relationship Of

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Thermal, structural, and mechanical effects of nanofibrillated cellulose in polylactic acid filaments for additive manufacturing

BioResources ◽

10.15376/biores.15.4.7954-7964 ◽

2020 ◽

Vol 15 (4) ◽

pp. 7954-7964

Author(s):

Diego Gomez-Maldonado ◽

Maria Soledad Peresin ◽

Christina Verdi ◽

Guillermo Velarde ◽

Daniel Saloni

Keyword(s):

Tensile Strength ◽

Additive Manufacturing ◽

3D Printing ◽

Polylactic Acid ◽

Modulus Of Elasticity ◽

Manufacturing Process ◽

Thermal Characterization ◽

Nanofibrillated Cellulose ◽

Small Decrease ◽

The Matrix

As the additive manufacturing process gains worldwide importance, the need for bio-based materials, especially for in-home polymeric use, also increases. This work aims to develop a composite of polylactic acid (PLA) and nanofibrillated cellulose (NFC) as a sustainable approach to reinforce the currently commercially available PLA. The studied materials were composites with 5 and 10% NFC that were blended and extruded. Mechanical, structural, and thermal characterization was made before its use for 3D printing. It was found that the inclusion of 10% NFC increased the modulus of elasticity in the filaments from 2.92 to 3.36 GPa. However, a small decrease in tensile strength was observed from 55.7 to 50.8 MPa, which was possibly due to the formation of NFC aggregates in the matrix. This work shows the potential of using PLA mixed with NFC for additive manufacturing.

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Properties of aluminum metal matrix composites manufactured by selective laser melting

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-8174 ◽

2021 ◽

Vol 112 (7) ◽

pp. 552-564

Author(s):

Christian Felber ◽

Florian Rödl ◽

Ferdinand Haider

Keyword(s):

Additive Manufacturing ◽

Aluminum Alloys ◽

Selective Laser Melting ◽

Metal Matrix ◽

High Hardness ◽

High Strength ◽

Laser Melting ◽

Scanning Calorimetry ◽

Particle Reinforcement ◽

The Matrix

Abstract The most promising metal processing additive manufacturing technique in industry is selective laser melting, but only a few alloys are commercially available, limiting the potential of this technique. In particular high strength aluminum alloys, which are of great importance in the automotive industry, are missing. An aluminum 2024 alloy, reinforced by Ti-6Al-4V and B4C particles, could be used as a high strength alternative for aluminum alloys. Heat treating can be used to improve the mechanical properties of the metal matrix composite. Dynamic scanning calorimetry shows the formation of Al2Cu precipitates in the matrix instead of the expected Al2CuMg phases due to the loss of magnesium during printing, and precipitation processes are accelerated due to particle reinforcement and additive manufacturing. Strong reactions between aluminum and Ti-6Al-4V are observed in the microstructure, while B4C shows no reaction with the matrix or the titanium. The material shows high hardness, high stiffness, and low ductility through precipitation and particle reinforcement.

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ADDITIVE MANUFACTURING OF HIGH-LOADING POLYMER NANOCOMPOSITES WITH MULTISCALE ALIGNMENT

10.12783/asc36/35753 ◽

2021 ◽

Author(s):

SOYEON PARK ◽

KUN (KELVIN) FU

Keyword(s):

Additive Manufacturing ◽

Polymer Nanocomposites ◽

High Performance ◽

Energy Storage Devices ◽

Storage Devices ◽

High Productivity ◽

Macro Scale ◽

The Matrix ◽

Multiscale Structures ◽

Printing Direction

Polymer nanocomposites have advantages in mechanical, electrical, and optical properties compared to individual components. These unique properties of the nanocomposites have attracted attention in many applications, including electronics, robotics, biomedical fields, automotive industries. To achieve their high performance, it is crucial to control the orientation of nanomaterials within the polymer matrix. For example, the electric conductivity will be maximized in the ordered direction of conductive nanomaterials such as graphene and carbon nanotubes (CNTs). Conventional fabrication methods are commonly used to obtain polymer nanocomposites with the controlled alignment of nanomaterials using electric or magnetic fields, fluid flow, and shear forces. Such approaches may be complex in preparing a manufacturing system, have low fabrication rate, and even limited structure scalability and complexity required for customized functional products. Recently, additive manufacturing (AM), also called 3D printing, has been developed as a major fabrication technology for nanocomposites with aligned reinforcements. AM has the ability to control the orientation of nanoparticles and offers a great way to produce the composites with cost-efficiency, high productivity, scalability, and design flexibility. Herein, we propose a manufacturing process using AM for the architected structure of polymer nanocomposites with oriented nanomaterials using a polylactic acid polymer as the matrix and graphite and CNTs as fillers. AM can achieve the aligned orientation of the nanofillers along the printing direction. Thus, it enables the fabrication of multifunctional nanocomposites with complex shapes and higher precision, from micron to macro scale. This method will offer great opportunities in the advanced applications that require complex multiscale structures such as energy storage devices (e.g., batteries and supercapacitors) and structural electronic devices (e.g., circuits and sensors).

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Synthesis and Characterization of a Bioartificial Polymeric System with Potential Antibacterial Activity: Chitosan-Polyvinyl Alcohol-Ampicillin

Molecules ◽

10.3390/molecules23123109 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3109 ◽

Cited By ~ 3

Author(s):

Andres Bernal-Ballen ◽

Jorge Lopez-Garcia ◽

Martha-Andrea Merchan-Merchan ◽

Marian Lehocky

Keyword(s):

Antibacterial Activity ◽

Polyvinyl Alcohol ◽

Statistical Significance ◽

Antibacterial Properties ◽

Intermolecular Forces ◽

Polymeric System ◽

Bacterial Strains ◽

Natural Polymers ◽

The Matrix ◽

The Individual

Bio-artificial polymeric systems are a new class of polymeric constituents based on blends of synthetic and natural polymers, designed with the purpose of producing new materials that exhibit enhanced properties with respect to the individual components. In this frame, a combination of polyvinyl alcohol (PVA) and chitosan, blended with a widely used antibiotic, sodium ampicillin, has been developed showing a moderate behavior in terms of antibacterial properties. Thus, aqueous solutions of PVA at 1 wt.% were mixed with acid solutions of chitosan at 1 wt.%, followed by adding ampicillin ranging from 0.3 to 1.0 wt.% related to the total amount of the polymers. The prepared bio-artificial polymeric system was characterized by FTIR, SEM, DSC, contact angle measurements, antibacterial activity against Staphylococcus aureus and Escherichia coli and antibiotic release studies. The statistical significance of the antibacterial activity was determined using a multifactorial analysis of variance with ρ < 0.05 (ANOVA). The characterization techniques did not show alterations in the ampicillin structure and the interactions with polymers were limited to intermolecular forces. Therefore, the antibiotic was efficiently released from the matrix and its antibacterial activity was preserved. The system disclosed moderate antibacterial activity against bacterial strains without adding a high antibiotic concentration. The findings of this study suggest that the system may be effective against healthcare-associated infections, a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.

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Accelerated degradation of polyvinyl alcohol via a novel and cost effective heterogeneous system based on Na2S2O8 activated by Fe complex functionalized waste PAN fiber and visible LED irradiation

Chemical Engineering Journal ◽

10.1016/j.cej.2018.10.161 ◽

2019 ◽

Vol 358 ◽

pp. 1489-1498 ◽

Cited By ~ 4

Author(s):

Yongchun Dong ◽

Liran Bian ◽

Peng Wang

Keyword(s):

Polyvinyl Alcohol ◽

Heterogeneous System ◽

Cost Effective ◽

Accelerated Degradation ◽

Pan Fiber ◽

Fe Complex ◽

Led Irradiation

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Determination of the Force Constants of Non-linear XY2 Molecules in the Gas-Phase by the GF Matrix Method

Zeitschrift für Naturforschung A ◽

10.1515/zna-2004-0913 ◽

2004 ◽

Vol 59 (9) ◽

pp. 621-622 ◽

Cited By ~ 1

Author(s):

Fatih Ucun ◽

Vesile Gūçlü

Keyword(s):

Gas Phase ◽

Condensed Phase ◽

Matrix Method ◽

Solid Phase ◽

Force Constants ◽

Matrix Solution ◽

The Matrix ◽

Newton Raphson ◽

Raphson Method

The force constants of the internal coordinates of nonlinear XY2 molecules in the gas-phase were calculated by using the GF matrix method. The matrix solution was carried out by means a computer program built relative to the Newton-Raphson method and the calculations were listed in a table. The force constants of some molecules in the liquidand solid- phase were also found and compared with these ones, and it was seen that the force constants for more condensed phase are lower as in an agreement with having its lower frequency.

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