Characterizing nonwoven materials via realistic microstructural modeling

In this research, polyolefin elastomers (POE)/starch blends were prepared using an internal mixer with 0 to 55 wt% starch content, and MAH was added into POE/starch blend to prepare a composite that improves its biodegradation, while tuning the viscoelastic behavior and morphology. The effect of the composition and the compatibilizer addition on properties, such as morphology, rheology, and the creep behavior, was investigated. The observations of microstructures through thescanning electron microscope (SEM) showed that in the incompatibilized blends, the interfacial adhesion of the phases was very weak. In contrast, in compatibilized samples, the broken surface of starch was observed confirming the enhanced interfacial tension. Additionally, the increase in the starch content led to the rise in the relaxation times. The creep test results revealed that with the increment of starch content, the creep of the blends increased. The compatibilizer improved the creep recovery of the blends. Moreover, by addition of the compatibilizer, the values of the creep parameters including η, E 1 , E 2, and τ R obtained from the standard linear solid model (SLS), was higher than those for the incompatibilized blends. The addition of POE-MA compatibilizer can improve the properties of POE/starch blends, while keeping their biocompatibility.

Section: Results and Discutionmentioning

confidence: 99%

Effect of starch ratio and compatibilization on the viscoelastic behavior of POE/starch blends

Bazli

Bagherian

Karrabi

et al. 2019

“…This causes the LEP and the contact angle to rise in the fibers. Moghadam et al 47,48 provide a model that calculates and uses air-water interface (AWI) in fibers to allow liquid entry pressure (LEP) estimation in a fiber structure. They showed that LEP had a direct relationship with the properties of fibers such as their diameter or contact angle.…”

Section: Wettabilitymentioning

confidence: 99%

Improvement of PAN separator properties using PVA/malonic acid by electrospinning in lithium ion‐batteries

Khodaverdi

Vaziri

Javanbakht

et al. 2020

The prominent objective of this study is to improve the thermal shrinkage and wettability of lithium-ion battery membrane separators based on Polyacrylonitrile (PAN) formed using an electrospinning technique. To achieve this goal, a PAN blended with highly hydrophilic Polyvinylalcohol (PVA) is formed, using malonic acid (MA) as a cross-linker. Due to the excellent hydrophilic properties of PVA and the network formation inside the separators (because of the MA crosslinker presence), the results show significant improvement in the separator properties. For this reason, at the optimum concentrations of 5 wt.% PVA and 5 wt.% MA (sample F4), an increase of wettability (contact angle from 85 for pure PAN to 42 for the F4 separator) is able to be seen. The electrolyte uptake was significantly increased, as for the F4 sample is increased to 1,150%, which is 2.67 times higher than the PAN with 430%. The improved separators showed higher porosity, better tensile strength, lower thermal shrinkage, and better electrochemical performance than the pure PAN separator. It showed an ion conductivity of 3.03 mS/cm, a wide electrochemical stability window of 5.2 V and an initial discharge capacity of 156.4 mAh/g.

“…Our MSD mat‐generation algorithm creates realistic 3D fibrous structures via a sequential deposition of fibers on top of one another . The model is based on treating the fibers as an array of beads connected to one another with springs and dampers arranged according to the Kelvin–Voigt model . Writing the balance of forces for each bead in the fiber, we obtain [see Figure (a),

{\overset{false\to}{f}}_{i}^{\sum} = {\overset{false\to}{f}}_{i, i - 2}^{s} + {\overset{false\to}{f}}_{i, i - 1}^{s} + {\overset{false\to}{f}}_{i, i + 1}^{s} + {\overset{false\to}{f}}_{i, i + 2}^{s} + {\overset{false\to}{f}}_{i, i - 2}^{d} + {\overset{false\to}{f}}_{i, i - 1}^{d} + {\overset{false\to}{f}}_{i, i + 1}^{d} + {\overset{false\to}{f}}_{i, i + 2}^{d} + {\overset{false\to}{f}}_{C, i}

…”

Section: Numerical Simulationsmentioning

confidence: 99%

Empirical model to simulate morphology of electrospun polycaprolactone mats

Yousefi

Tang

Tafreshi

et al. 2019

Self Cite

This work is the first to report a study aimed at generating 3D virtual geometries that represent the microstructure of an electrospun fibrous mat comprised curly fibers. Polycaprolactone (PCL) mats are considered in our study as an example of such fibrous structures. We started with simulating the formation of PCL filaments and observed good agreement between the predicted and measured fiber diameters. In the absence of quantitative information about the shape of a curly PCL fiber, we treated these fibers as arrays of beads arranged on epitrochoid profiles. We then used the fiber deposition diameter and velocity in a mass-spring-damper (MSD) model to generate 3D fibrous geometries comprised hundreds of such curly fibers. The damping and spring constants in the MSD model were obtained through calibration with experimental data reported for single electrospun PCL nanofibers. The size of the epitrochoid-like fibers was obtained empirically through matching the average thickness of the resulting mats with those measured experimentally. With the calibrated code, we studied the effects of electrospinning conditions on the porosity of PCL nanofiber mats. It was found that increasing the voltage or decreasing the needle-to-collector distance results in PCL mats with thicker fibers, and consequently, lower porosities.