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clearly shows the conglutination of starch fiber mats caused by the plasticizing 134
Source publication
Electrospun starch fiber mats have many potential applications, but an improvement in their mechanical properties is required to realize them. In the present study, wet-electrospun starch fiber mats were subjected to post-drying conditioning at controlled equilibrium relative humidity and equilibration time. The weight-normalized ultimate tensile s...
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Context 1
... improvement, WNUTS of dried starch fiber mats without conditioning (the control), 148 with conditioning at RH=84% for 3 days, and re-dried after conditioning at RH=84% for 3 days 149 ( Figure 2) were measured. One-way ANOVA shows significant difference in WNUTS among 150 these samples (P=0.029). ...
Context 2
... starch fiber mats conditioned at higher RH 162 likely attained the mobility necessary for conglutination to occur resulting in higher WNUTS. 163 164 Figure 2. Scanning electron micrographs of starch fiber mats without conditioning (A), with 165 conditioning at RH=84% for 3 days (B), re-dried after conditioning at RH=84% for 3 days (C), 166 ...
Citations
... There are drawbacks to this technique: the drying step after wet electrospinning is time-consuming (?6 h), the fiber mat was fragile, and the fiber diameter was in the micron range (Kong & Ziegler, 2013, 2014a. The plasticizing effect of water during storage (Wang, Kong, & Ziegler, 2018), incorporating nanocellulose-cationic starch , and achieving fiber alignment with a rotating drum collector (Wang et al., 2019a) were all found to improve the tensile strength of starch fiber mats by a modest amount. Starch-based nanofibers (~146 nm) were electrospun from aqueous solvent with the addition of sodium palmitate and pullulan (PUL) . ...
We aimed to develop a greener process for dry-electrospinning food-grade modified starch through the elimination of organic solvents. The rheological properties and electrospinnability of aqueous dispersions of commercial octenylsuccinylated (OS) starches with various molecular weight (Mw) were investigated, yet only nanofibers with beads or defects could be obtained from OS starch with the highest Mw, i.e., Purity Gum@ Ultra (PGU). Further improvement in the fiber morphology was achieved by adding pullulan (PUL) as a minor component in the spinning dope. Smooth, continuous, and bead-free nanofibers (147−250 nm) were obtained from the PGU-PUL dispersions. Shown on an electrospinnability map, the successful electrospinning of 12 %, 15 %, and 20 % (w/v) aqueous PGU dispersions required a minimum addition of 6 %, 5 %, and 3 % (w/v) of PUL, respectively. The addition of PUL contributed to establishing sufficient molecular entanglement for electrospinning. This study provides a promising green process to produce starch-based nanofibers for use in various applications, e.g., drug delivery, wound dressing, and tissue engineering.
... Starch is one of the most abundant biopolymers on earth, widely used in food, pharmaceutical, paper, plastic, textile, and cosmetic industries [3,4] in liquid dispersion, granule, film, or gel forms. Recently, our lab used a wet-electrospinning process to make pure starch fibers [5][6][7]. Electrospinning is a technique to produce micro-to nano-scale fiber mats with high surface area, high porosity, and various matrix/ nanostructures [8]. Due to the versatility of electrospinning, starch fiber mats with random and aligned orientation have been developed [6]. ...
... Fiber mats with smooth continuous fibers were collected for further analysis. Pure starch fiber mats prepared from DMSO solution [7] and pure pullulan fiber mats from aqueous solution were used for comparison. The optimized operational parameters are listed in Table 1 [7]. ...
... Pure starch fiber mats prepared from DMSO solution [7] and pure pullulan fiber mats from aqueous solution were used for comparison. The optimized operational parameters are listed in Table 1 [7]. ...
A green method to fabricate starch-based nanofibers is provided. High-temperature (≈162 °C) was used to destructure high-amylose starch in water. Sodium palmitate was added to enhance the stability of high-amylose starch in water at room temperature and increase the conductivity of the electrospinning dope. Flow properties and zeta potential of starch-palmitate dispersions were characterized by rheometer and dynamic light scattering, respectively. Pullulan was mixed in as a minor component of the starch-palmitate complex (starch:pullulan at a ca. 2:1 ratio) and the mixture electrospun. Pullulan hindered starch association and modified the dispersion properties, promoting molecular entanglement without gelation. The presence of sodium palmitate-starch inclusion complexes in the fiber was confirmed by differential scanning calorimetry and X-ray diffraction. Tensile strength of the nanofiber composite was found to be weaker than that of micro-sized pure starch fiber mats. This method provides future industry with lower cost by eliminating the use of organic chemicals.
... The electrospinning dope, 12% (w/v) HAMS (Kong & Ziegler, 2013;Wang, Kong, & Ziegler, 2018) dispersion in pure DMSO, was prepared by heating the dispersion in a boiling water bath with continuous stirring for about 1 h. ...
... Microscopic observation of electrospun starch fibers was performed using a Phenom G2 Pro scanning electron microscope (SEM, Phenom-World, Eindhoven, The Netherlands) at an accelerating voltage of 5 keV. Fiber diameter distributions were evaluated based on at least 8 SEM images using an open source software, ImageJ and Fityk 0.9.8 (Hotaling, Bharti, Kriel, & Simon, 2015;Wang et al., 2018). ...
... Uniaxial tension tests were carried out using a Q800 dynamic mechanical analyzer (DMA, TA Instruments, New Castle, DE), with a film tension clamp using controlled force mode at room temperature (20°C). The controlled force was applied parallel to the aligned direction at a rate of 0.05 N/min, with a preload force of 0.001 N. Weightnormalized ultimate tensile strength (WNUTS) was calculated (Wang et al., 2018). At least two samples for each of two treatment replicates were evaluated. ...
Electrospinning is a versatile technique to fabricate non-woven fiber mats with an average fiber diameter ranging from nanometers to micrometers. Fibers produced by electrospinning have potential application in numerous fields owing to their light weight, high surface area, and high porosity. In certain applications, anisotropic properties are desired, which may also improve mechanical strength. This study comprehensively documented the feasibility of directed fiber deposition in wet-electrospinning and offers an inexpensive setup for laboratory investigation. Aligned starch fiber mats were produced and the effects of three operational parameters, i.e., rotational speed, drum location, and coagulation bath composition, were evaluated. The alignment of starch fibers was affected by the ethanol concentration in the coagulation bath and drum rotational speed. Coherent fibers could be obtained in all trials except for the one at the lowest ethanol concentration (60% v/v) and highest rotational speed (500 rpm) when the drum was below the liquid. The tensile strength was influenced by the interaction of location and ethanol concentration, and that of rotational speed and ethanol concentration. This study set a promising example of making aligned biopolymer fiber mats and investigating fiber deposition in wet-electrospinning. Aligned starch fiber mats have potential applications in areas such as tissue engineering and as wound dressings.
... Uniaxial tensile test. 155Fiber mats were tested both with and without equilibration to 75% relative humidity for 23 156 days(Wang et al., 2018). The sample fiber mats were cut into 5.3 mm wide strips using a film 157 cutter (PN 984485.901, ...
Electrospinning has become an increasingly attractive technique to produce micro-to nano-scale fibers from bio-based polymers, including starch. Compared to their synthetic counterparts, fibers electrospun from bio-based polymers generally have inferior mechanical strength. In the present study, we aim to enhance the mechanical strength of electrospun starch-based fibers by using nanocellulose as a reinforcing filler and cationic starch as a binding agent. The potential ionic bonding between cationic starch and anionic nanocellulose, and the hydrogen bonding as well as macromolecular entanglement between the three components, are expected to improve the compatibility of polymers and the mechanical strength of their composite fibers. Rheological properties of nanocellulose, cationic starch, and their mixtures were studied to understand their conformation and interaction in DMSO dispersions. The rheological properties of the ternary systems were studied and correlated with their electrospinnability and the tensile strength of the composite fiber mats. Our results suggested that nanocellulose-cationic starch at its percolation concentration (≈2%, w/w, of starch) has the most profound influence on fiber strength, and CS:NC ratios of 1:2 and 1:1 created improved intermolecular ionic bonding for reinforcing the fiber structure.
