Fabrication of large‐scale superhydrophobic composite films with enhanced tensile properties by multinozzle conveyor belt electrospinning

Large‐scale superhydrophobic composite films with enhanced tensile properties were prepared by multinozzle conveyor belt electrospinning. First, a strategy of conveyor belt electrospinning was introduced for large‐scale fabrication since the conveyor belt can expand the electrospinning area unlimitedly. During the electrospinning (or electrospraying) process, certain kinds of fibers are combined on the conveyor belt in one electrospinning (or electrospraying) step. The superhydrophobicity of electrospun film can be achieved by the presence of PS beads and bead‐on‐string PVDF fibers, while submicron PAN fibers are responsible for the improvement of mechanical properties. The result shows that CA value of the surface comprising of PS beads and bead‐on‐string PVDF fibers could reach up to 155.0°. As the submicron PAN fibers increased, the value of CA decreased, changing from 155.0° to 140.0°, meanwhile the tensile strength of composite film was enhanced from 1.14 to 4.12 MPa correspondingly which is beneficial to putting the films into practice. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39735.     

Direct laser etching of hierarchical nanospheres on silicon rubber surface with robust dynamic superhydrophobic stability

Silicone rubbers with high dynamic superhydrophobic stability have an extensive application prospect. Applying direct laser etching technology, a fast and efficient method is proposed for the preparation of silicone rubber surfaces with hierarchical nanospheres and robust dynamic superhydrophobicity. A 4 μl water droplet on the laser modified silicone rubber surface exhibits a contact angle (CA) of 154 ± 3° and a roll-off angle (RA) of 5 ± 1°, there is a 65.6% increase in CA compared with the pristine silicon rubber. Moreover, the modified surface can stabilize its superhydrophobic state under a dynamic pressure of 1960.2 Pa. Interestingly, no significant change in the contacting time for the droplets with different impacting speed is found, which means that the stabilized contact time and robust dynamic superhydrophobicity are induced on the modified silicone rubber surface. The self-cleaning and anti-icing properties on the modified surface can effectively reduce the damage caused by surface pollution, ice formation, and other natural factors when applied to power lines, sealing elements, and automotive.     

Preceramic polymer‐derived SiOC fibers by electrospinning

Silicon oxycarbide (SiOC) fibers with different chemical compositions were successfully fabricated by electrospinning a mixture of polyvinylpyrrolidone (PVP) and commercially available polymethylsilsesquioxane (MK) or polymethylphenylsilsesquioxane (H44) preceramic polymers, followed by cross‐linking and pyrolysis at 1000°C in Argon. The influence of the processing procedure (solvent selection, cross‐linking catalyst and additives) on the morphology of the produced fibers was investigated. For the MK/isopropanol system, the introduction of 20 vol% N,N‐dimethylformamide (DMF) enabled to decrease the diameter of the as‐spun fibers from 2.72 ± 0.12 μm to 1.65 ± 0.09 μm. For the H44/DMF systems, beads‐free fibers were obtained by adding 50 vol% choloroform. After pyrolysis, the resultant SiOC fibers derived from MK and H44 resins possessed uniform morphology, with an average diameter of 0.97 ± 0.07 μm and 1.07 ± 0.08 μm, respectively. Due to their different chemical compositions, the MK‐derived and H44‐derived SiOC ceramic fibers could find different potential applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39836.     

Effect of fiber size on structural and tensile properties of electrospun polyvinylidene fluoride fibers

We use electrospinning to obtain polyvinylidene fluoride (PVDF) fibers and demonstrate simultaneous improvements in β‐crystal microstructure and in tensile properties of fibers with reduction of their diameter. PVDF fibers with average diameters ranging from 70 to 400 nm are obtained by controlling the concentration of the polymer in the electrospinning solution. The amount of β‐crystals present is found to be greater for finer diameter fibers, yielding a maximum β‐phase fraction of 0.86 in the 70‐nm fibers. Moreover, the deformation behavior of the fibers reveals that the tensile modulus and strength improve with reductions in fiber size. Sharp increases in tensile properties are demonstrated when the size of the fibers is reduced below 175 nm. We attribute the enhanced concentration of β‐crystals and the tensile behavior of finer diameter fibers to the extensional forces experienced by the material during electrospinning. POLYM. ENG. SCI., 55:1812–1817, 2015. © 2014 Society of Plastics Engineers     

Single-stage synthesis of electrospun polyurethane scaffold impregnated with zinc nitrate nanofibers for wound healing applications

In this study, a wound dressing scaffold was developed based on polyurethane (PU, 9 wt %) incorporated with zinc nitrate nanofibers (9 wt %) using an electrospinning technique. The morphological studies revealed that the electrospun nanocomposites showed smaller fiber (568 ± 136.69 nm) and pore diameters (703 ± 60.76 nm) than the pure PU (fiber diameter 1159 ± 147.48 nm and pore diameter 1087 ± 62.51 nm). Energy-dispersive X-ray spectroscopy confirmed the presence of zinc nitrate in the PU matrix. The formation of hydrogen bonds and the enhanced weight residue found by Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the interaction of PU with zinc nitrate. Moreover, the contact angle measurements revealed the hydrophilic nature of the electrospun nanocomposite (84° ± 4.041°) compared to the control (100° ± 0.5774°). Mechanical testing and atomic force microscopy showed an improvement in the tensile strength (15.98 MPa) and surface roughness (277 nm) of the fabricated nanocomposites compared to the PU membrane (tensile strength 7.12 MPa and surface roughness 216 nm). Further, incorporation of zinc nitrate into PU improved the blood compatibility, as demonstrated by the prolonged blood clotting time (APTT 188 ± 4 s and PT 102.7 ± 3.786 s) compared to the pure PU (APTT 147.7 ± 3.512 s and PT 84.67 ± 2.517 s), as revealed in coagulation assays. Moreover, the electrospun nanocomposites showed a low hemolytic index and enhanced fibroblast proliferation rates, as indicated in the hemolysis and cytocompatibility studies. The newly developed wound dressing displayed better physicochemical characteristics, prolonged blood clotting time, and enhanced fibroblast proliferation rates, indicating that it might be utilized as an alternate candidate for wound dressings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46942.     

Preparation and properties of TPU micro/nanofibers by a laser melt‐electrospinning system

Laser melt electrospinning is a novel technology to fabricate scaffolds in the tissue engineering applications. The melt electrospinning is much safer than the conventional solution electrospinning due to without solvent effect. In this study, thermoplastic polyurethane (TPU) micro/nanofibers were successfully prepared by using this method. The effects of laser current and applied voltage on the fibers morphologies were investigated by scanning electron microscopy. The thermal behaviors and crystallization conditions of the TPU under different states were demonstrated by differential scanning calorimetry and X‐ray diffraction analysis. The mechanical property and the specific surface area of the TPU fibers membranes were also studied. All the analysis results showed that the effects of laser current and applied voltage on the average fiber diameter were complicated, the average fiber diameter ranging from 1.70 to 2.53 µm; the TPU is not an easily crystallized material; the electrospun fibers exhibited an amorphous phase; the average elongation at break laser of the electrospun TPU fiber membranes is about 134%; the average tensile strength is about 1.02 MPa and the specific surface area of the electrospun TPU fiber membrane is about 199 m²/g. POLYM. ENG. SCI., 54:1412–1417, 2014. © 2013 Society of Plastics Engineers     

Facile and eco-friendly fabrication of hierarchical superhydrophobic coating from eggshell biowaste

This study reports a facile and sustainable approach to fabricate superhydrophobic coating from eggshell biowaste. The coating was prepared by ball milling chicken eggshells, composed of hydrophilic calcium carbonate (CaCO₃), to microsized particles followed by surface hydrophobilizing with stearic acid (C₁₇H₃₅COOH) to form low surface energy nanosized calcium stearate ((C₁₇H₃₅COO)₂Ca) through the esterification of hydroxyl groups (-OH) absorbed on a surface of CaCO₃ with carboxyl groups (–COOH) of stearic acid. Then, a layer of modified eggshell particles dispersed in polystyrene (PS) binder was dip-coated on a substrate. A coated surface with water contact angles of 151° ± 1° on glass and 153° ± 1° on cotton fabric substrates was achieved when a 4:1 weight ratio of the modified eggshell:PS was used. The uniform distribution of the modified eggshell particles throughout the coating led to a surface with high degree of hierarchical micro-nanoscale roughness which resulted in superhydrophobicity. The superhydrophobic eggshell coating showed good environmental stability, self-cleaning, and oil/water separation properties. These results suggest that eggshell biowaste can be utilized for superhydrophobic applications.     

Point‐bonded electrospun polystyrene fibrous mats fabricated via the addition of poly(butylacrylate) adhesive

Because of poor mechanical strength, applications of electrospun polystyrene (PS) fibrous mats are quite limited. The introduction of various concentrations of poly (butylacrylate) adhesives (PBAs) into PS solutions led to the fabrication of point‐bonded electrospun PS fibrous mats with good mechanical strength. The morphologies of PS/PBA fibers with varying PBA content (0?50 wt%) were investigated using scanning electron microscopy (SEM), and the results were compared with pure PS and PBA fibers fabricated with various solvents. SEM images indicated that point‐bonded PS/PBA fibers were uniformly distributed with an average diameter of 1–2 μm. On increasing concentration of PBA up to 20 wt%, porous PS/PBA fibrous mats were obtained. However, solid films were formed at very high concentrations of PBA. The Young's modulus and tensile strength of PS/PBA fibrous mats increased up to 52.4 and 2.7 MPa, respectively. The resultant enhancement of the mechanical properties of PS fibrous mats on addition of PBA increases the number of potential applications of these materials. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Polypropylene microfibers via solution electrospinning under ambient conditions

Uniform beadless fibers of chlorinated polypropylene (PP-Cl) are prepared by electrospinning of PP-Cl solutions in tetrahydrofuran at different concentrations, feed rates, applied voltages, and tip-to-collector distances (TCDs) under ambient conditions for the first time. Average fiber diameter and morphology of the electrospun PP-Cl fibers are determined by scanning electron microscopy. On the other hand, the wettability of the fibers is examined by water contact angle (WCA) measurements. Furthermore, thermal behavior of fibers is investigated by differential scanning calorimetry and thermogravimetric analyses, respectively. Obtained results show that the higher concentrations and feed rates of polymer solutions not only enhance the average diameter of the electrospun fibers ranging from 2.2 ± 0.5 to 2.8 ± 0.3 μm but improve the hydrophobicity of the fiber surfaces from 128° ± 1.1 to 141° ± 1.0 as well. On the other hand, when applied voltage is increased or TCD is decreased, diameters of achieved fibers are enhanced. It is suggested that PP-Cl is an useful material for solution electrospinning process at under ambient conditions, exhibiting great scientific merit and good industrial expectation in the potential PP applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48199.     

熔体微分静电纺PBAT纤维膜的制备工艺研究

探究了聚己二酸对苯二甲酸丁二醇酯（PBAT）熔体静电纺性能,并研究了熔体微分静电纺工艺参数与PBAT纤维性能之间的关系。结果表明,随着纺丝温度的升高,纤维直径减小,纤维直径分布呈先减小后增大的趋势;随着纺丝电压的升高,纤维直径减小且分布均匀,纤维膜力学性能逐渐提高;当纺丝距离为9 cm,纺丝温度为260 ℃,纺丝电压为45 kV时,制备的纤维细度及均匀度最佳,其直径为4.31 μm,直径分布标准差为0.76,纤维膜拉伸强度为9.9 MPa、断裂伸长率为111.2 %。     

Organic–inorganic hybrid copolymer fibers and their use in silicone laminate composites

Nonwoven organic–inorganic fiber mats of poly(methyl methacrylate)‐graft‐poly(dimethyl siloxane) copolymers with various PDMS contents were produced by the electrospinning process. The average fiber diameter increased from 0.7 to 3 μm with increasing PDMS content. The fiber mats were used in the preparation of silicone‐laminated composite materials by distributing them (single, double and triple layer mats) in a silicone matrix prior to thermal curing. The composites showed a remarkably good fiber distribution in the silicone matrix. In general the stiffness and strength increased in the presence of fiber, and surprisingly, so did the toughness/extensibility. An interesting feature was that the most silicon‐rich fibers showed clear signs of yielding after tensile testing and failure. This, together with the greater compatibility of the fibers with the matrix because of the higher PDMS content, most probably favored composite toughness. All composite fracture surfaces were characterized by clear signs of fiber pull‐out. Fracture initiation areas were difficult to locate, and this is accredited to an even distribution of the individual fibers in the matrix. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

有机硅/聚醚胺复合固化剂改性环氧树脂及其性能研究

以二甲基二乙氧基硅烷、γ-氨丙基三乙氧基硅烷、二苯基二甲氧基硅烷为单体,通过水解、缩聚制备了含有氨基活性功能基团的有机硅低聚物（PS）,然后以PS与聚醚胺与环氧树脂进行固化交联得到机硅改性环氧树脂,研究探讨了PS含量对改环氧树脂耐热性、力学性能及吸水性能的影响。结果表明：当PS添加量为基体树脂的30%时,改性树脂的耐热性能有明显提高,800oC残留量为26.45%,拉伸强度为68.27MPa,弯曲强度为81.68MPa,与水表面接触角为109.3°,吸水率为2.59%,比未改性树脂分别提高了17.24% ,6.6%,17.3%,21.3%和降低了0.12%。     

Geopolymer reinforced with E‐glass leno weaves

This study explores the viability of fiberglass‐geopolymer composites as an intermediate temperature structural ceramic composite. E‐glass fibers are cheap, readily available, resistant to heat, electricity and chemical attack. Geopolymers are refractory and can be processed at room temperature. However, pure geopolymers have low tensile strength and fracture toughness, as is typical of ceramics. In this work, tensile and flexure properties of metakaolin‐based sodium and potassium geopolymers reinforced with E‐glass leno weaves were measured and the data was analyzed by Weibull statistics. The average tensile and flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were 39.3 ± 7.2 MPa and 25.6 ± 4.8 MPa, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average tensile and flexural strengths were 40.7 ± 9.9 MPa and 15.9 ± 4.0 MPa, respectively. The composites were heat treated for one hour at two temperatures, 300°C and 550°C and their flexure properties were studied at room temperatures. The average flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were reduced to 6.6 ± 1.0 MPa after heat treatment at 300°C, and 1.2 ± 0.3 MPa after heat treatment at 550°C, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average flexural strengths were 6.1 ± 1.5 MPa and 1.3 ± 0.3 MPa after heat treatment at 300°C and 550°C, respectively. SEM and EDS were performed to observe the fiber‐matrix interface. XRD was done to check if the geopolymer was amorphous as expected.     

Fabrication of hollow and porous polystyrene fibrous membranes by electrospinning combined with freeze-drying for oil removal from water

A novel method was proposed to fabricate hollow and surface porous polystyrene (PS) fibrous membranes for the removal of oil from water. Spinning solutions were prepared by using camphene and tetraethoxysilane (TEOS) as pore-forming agents, and hollow PS fibers with 100–400 nm pores on the surface were fabricated by electrospinning and freeze-drying. The distribution and volatilization of camphene and TEOS, as well as the drying behavior of solvents in high relative humidity, were important factors in forming the porous structure of PS fibers. The specific surface area of obtained PS fibrous membranes was twice that of conventional electrospun PS fibrous membranes and displayed superhydrophobic properties. Moreover, the large adsorption storage space was formed due to the hollow structure and porous surface of PS fibers. The maximum oil adsorption capacity of the porous PS fibrous membrane was 105.4 g g⁻¹, and was larger than that of the conventional PS fibrous membrane after repeated five times, thus making it a promising tool for oil spill cleanups. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47262.     

Fabrication of Surlyn ionomer fibers using a novel coextrusion approach and mechanical property characterization

We report the fabrication of poly (ethylene-co-methacrylic acid) sodium-neutralized ionomer (Surlyn 8940) fibers via a forced-assembly coextrusion and layer multiplication process with polystyrene (PS) as the matrix material. The PS separating materials were removed by toluene extraction to yield independent Surlyn fibers. The tensile properties of Surlyn fiber strands were studied under different strain rates. Surlyn fibers were oriented to 300% strain at different temperatures to study the effect of orientation on the tensile properties. The oriented Surlyn fibers were annealed after orientation to further enhance the mechanical properties. Further drawing of these oriented fiber mats to a draw ratio of 4 at 60 °C followed by annealing at 60 °C can afford moduli in excess of 350 MPa and tensile strengths in excess of 70 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48046.     

Insert injection molding of high‐density polyethylene single‐polymer composites

A process for making high‐density polyethylene (HDPE) single‐polymer composites (SPCs) by insert injection molding was investigated. HDPE SPCs with relatively good tensile and interfacial properties were prepared within a short cycle time within a temperature range of 40°C. Melt‐spun HDPE fibers were made from the same resin as the matrix. The fibers were heat treated in silicone oil, with and without tension, to study the changes of fiber properties upon exposure to high temperature. HDPE SPCs containing about 30 wt% lab‐made HDPE fabric achieved a tensile strength of 50 MPa, 2.8 times that of neat HDPE. The peel strength of HDPE SPCs increased with increasing injection temperature and achieved a maximum value of 16.7 N/cm. Optical micrographs of polished transverse cross‐sections of the SPC samples showed that higher injection temperature is beneficial to the wetting and permeation properties of the matrix. Scanning electronic microscope photographs suggested good bonding and compatibility between the fibers and the matrix. POLYM. ENG. SCI., 55:2448–2456, 2015. © 2015 Society of Plastics Engineers     

Deformation processing of PMMA into high-strength fibers

Poly(methyl methacrylate) was drawn into fibers by melt extrusion followed immediately by a transient temperature drawing process. By varying five processing variables, fibers ranging from 0.635 mm to 25 μm in diameter were produced. Heat-induced relaxation of the aligned structure was used to determine the draw ratio of the resultant fibers and therefore the degree of polymer chain alignment imposed by the deformation process. The resulting changes in length and diameter were measured and it was found that draw ratios of 5–20 had been achieved under the varying processing conditions. It was also observed that fiber diameter immediately after drawing is a good predictor of the degree of orientation present in the fiber irrespective of the processing conditions. To test the effect molecular orientation has on material properties, fibers with varying degrees of orientation were tested in tension. As expected, increasing alignment resulted in increasing tensile strength. The maximum observed true ultimate tensile strength was 225 ± 53 MPa and was seen in fibers with a draw ratio equal to 18.7 ± 4.5. Fibers with a lower degree of alignment, while not as strong in tension, exhibited significantly increased ductility. True strains of as high as 25% were observed.     

In vitro evaluation of electrospun gelatin‐bioactive glass hybrid scaffolds for bone regeneration

Organic–inorganic hybrid materials, composed of phases that interact on a nanoscale and a microstructure that mimics the extracellular matrix, can potentially provide attractive scaffolds for bone regeneration. In the present study, hybrid scaffolds of gelatin and bioactive glass (BG) with a fibrous microstructure were prepared by a combined sol–gel and electrospinning technique and evaluated in vitro. Structural and chemical analyses showed that the fibers consisted of gelatin and BG that were covalently linked by 3‐glycidoxypropyltrimethoxysilane to form a homogeneous phase. Immersion of the gelatin–BG hybrid scaffolds in a simulated body fluid (SBF) at 37°C resulted in the formation of a hydroxyapatite (HA)‐like material on the surface of the fibers within 12 h, showing the bioactivity of the scaffolds. After 5 days in SBF, the surface of the hybrid scaffolds was completely covered with an HA‐like layer. The gelatin–BG hybrid scaffolds had a tensile strength of 4.3 ± 1.2 MPa and an elongation to failure of 168 ± 14%, compared to values of 0.5 ± 0.2 MPa and 63 ± 2% for gelatin scaffolds with a similar microstructure. The hybrid scaffolds supported the proliferation of osteoblastic MC3T3‐E1 cells, alkaline phosphatase activity, and mineralization during in vitro culture, showing their biocompatibility. The results indicate that these gelatin–BG hybrid scaffolds prepared by a combination of sol–gel processing and electrospinning have potential for application in bone regeneration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication and characterisation of nanofibrous polyurethane scaffold incorporated with corn and neem oil using single stage electrospinning technique for bone tissue engineering applications

In bone tissue engineering, the design of scaffolds with ECM is still challenging now-a-days. The objective of the study to develop an electrospun scaffold based on polyurethane (PU) blended with corn oil and neem oil. The electrospun nanocomposites were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement, atomic force microscopy (AFM) and tensile strength. The assays activated prothrombin time (APTT), partial thromboplastin time (PT) and hemolysis assay were performed to determine the blood compatibility parameters of the electrospun PU and their blends of corn oil and neem oil. Further, the cytocompatibility studies were performed using HDF cells to evaluate their proliferation rates in the electrospun PU and their blends. The morphology of the electrospun PU blends showed that the addition of corn oil and corn/neem oil resulted in reduced fiber diameter of about 845?±?117.86?nm and 735?±?126.49 nm compared to control (890?±?116.911?nm). The FTIR confirmed the presence of corn oil and neem oil in PU matrix through hydrogen bond formation. The PU blended with corn oil showed hydrophobic (112°?±?1) while the PU together with corn/neem oil was observed to hydrophilic (64°?±?1.732) as indicated in the measurements of contact angle. The thermal behavior of prepared PU/corn oil and PU/corn/neem oil nanocomposites were enhanced and their surface roughness were decreased compared to control as revealed in the AFM analysis. The mechanical analysis indicated the enhanced tensile strength of the developed nanocomposites (PU/corn oil - 11.88 MPa and PU/corn/neem oil - 12. 96 MPa) than the pristine PU (7.12 MPa). Further, the blood compatibility assessments revealed that the developed nanocomposites possess enhanced anticoagulant nature compared to the polyurethane. Moreover, the developed nanocomposites was non-toxic to red blood cells (RBC) and human fibroblast cells (HDF) cells as shown in the hemolytic assay and cytocompatibility studies. Finally, this study concluded that the newly developed nanocomposites with better physio-chemical characteristics and biological properties enabled them as potential candidate for bone tissue engineering.     

Fabrication and characterization of chitosan/PVA with hydroxyapatite biocomposite nanoscaffolds

Nanofibrous biocomposite scaffolds of chitosan (CS), PVA, and hydroxyapatite (HA) were prepared by electrospinning. The scaffolds were characterized by FTIR, SEM, TEM, and XRD techniques. Tensile testing was used for the characterization of mechanical properties. Mouse fibroblasts (L929) attachment and proliferation on the nanofibrous scaffold were investigated by MTT assay and SEM observation. FTIR, TEM, and XRD results showed the presence of nanoHA in the scaffolds. The scaffolds have porous nanofibrous morphology with random fibers in the range of 100–700 nm diameters. The CS/PVA (90/10) fibrous matrix (without HA) showed a tensile strength of 3.1 ± 0.2 MPa and a tensile modulus 10 ± 1 MPa with a strain at failure of 21.1 ± 0.6%. Increase the content of HA up to 2% increased the ultimate tensile strength and tensile modulus, but further increase HA up to 5–10% caused the decrease of tensile strength and tensile modulus. The attachment and growth of mouse fibroblast was on the surface of nanofibrous structure, and cells' morphology characteristics and viability were unaffected. A combination of nanofibrous CS/PVA and HA that mimics the nanoscale features of the extra cellular matrix could be promising for application as scaffolds for tissue regeneration, especially in low or nonload bearing areas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008