Nanofibrous Sheets Research Articles

Effect of human heart valve-derived ECM and NP/PCL electrospun nanofibrous sheet on mice bone marrow mononuclear cells and cardiac repair

BackgroundBiomaterials can improve cardiac repair combined with transplantation of bone marrow mononuclear cells (BMMNCs). In this study, we compared the phenotype and cardiac repair between human heart valve-derived scaffold (hHVS) and natural protein/polycaprolactone (NP/PCL) anchored BMNNCs. Methods and resultsBMMNCs were obtained from mice five days following myocardial infarction. Subsequently, BMMNCs were separately cultured on hHVS and PCL. Proliferation and cardiomyogenic differentiation were detected in vitro. Cardiac function was measured after transplantation of cell-seeded cardiac patch on MI mice. After that, the BMMNCs were collected for mRNA sequencing after culturing on the scaffolds. Upon anchoring onto hHVS or PCL, BMMNCs exhibited an increased capacity for proliferation in vitro, however, the cells on hHVS exhibited superior cardiomyogenic differentiation ability. Moreover, both BMMNCs-seeded biomaterials effectively improved cardiac function after 4 weeks of transplantation, with reduced infarction area and restricted LV remodeling. Cell-seeded hHVS was superior to cell-seeded PCL. ConclusionBMMNCs on hHVS showed better capacity in both cell cardiac repairing and improvement for cardiac function than on PCL. Compared with seeded onto PCL, BMMNCs on hHVS had 253 genes up regulated and 189 genes down regulated. The reason for hHVS’ better performance than PCL as a scaffold for BMMNCs might be due to the fact that optimized method of decellularization let more cytokines in ECM retained.

Novel pyrenylbenzylidene-malononitrile derivative mixed with cellulose acetate electrospun nanofibrous sheets for hydrazine detection

A new pyrenylbenzylidene–malononitrile (P2) was successfully synthesized via the Suzuki coupling reaction and Knoevenagel condensation using nano Cu as a catalyst. Nanofiber sheet mixed with compound 2 detects and responds to hydrazine vapor with a detection limit of 0.005% (w/v).

Hygromachines: Humidity-Powered Wheels, Seesaws, and Vehicles.

Hygroscopic soft actuators offer an attractive means to convert environmental energy to mechanical motions as they use water vapor, a ubiquitous substance in the atmosphere. To overcome the limits of existing hygroactuators, such as simplistic actuation mode, slow response, and low efficiency, here we present three kinds of humidity-powered soft machines adopting directionally electrospun hygroresponsive nanofibrous sheets. The wheels, seesaws, and vehicles developed in this work utilize spatial humidity gradient naturally established near moist surfaces such as human skin, so that they operate spontaneously, realizing energy scavenging or harvesting. We also constructed a theoretical framework to mechanically analyze their dynamics, which allowed us to optimize their design to obtain the highest motion speed physically possible.

Fabrication and characterization of anti-rosacea 3D nanofibrous customized sheet masks as a novel scaffold for repurposed use of spironolactone with pre-clinical studies

The repurposed oral use of spironolactone (SP) as an anti-rosacea drug faces many challenges that hinder its efficacy and compliance. In this study, a topically applied nanofibers (NFs) scaffold was evaluated as a promising nanocarrier that enhances SP activity and avoids the friction routine that exaggerates rosacea patients’ inflamed, sensitive skin. SP-loaded poly-vinylpyrrolidone (40% PVP) nanofibers (SP-PVP NFs) were electrospun. Scanning electron microscopy showed that SP-PVP NFs have a smooth homogenous surface with a diameter of about 426.60 nm. Wettability, solid state, and mechanical properties of NFs were evaluated. Encapsulation efficiency and drug loading were 96.34% ± 1.20 and 11.89% ± 0.15, respectively. The in vitro release study showed a higher amount of SP released over pure SP with a controlled release pattern. Ex vivo results showed that the permeated amount of SP from SP-PVP NFs sheets was 4.1 times greater than that of pure SP gel. A higher percentage of SP was retained in different skin layers. Moreover, the in vivo anti-rosacea efficacy of SP-PVP NFs using croton oil challenge showed a significant reduction in erythema score compared to the pure SP. The stability and safety of NFs mats were proved, indicating that SP-PVP NFs are promising carriers of SP.

Eco-friendly bioactive β-caryophyllene/halloysite nanotubes loaded nanofibrous sheets for active food packaging

We fabricated Zein/polycaprolactone (PCL) electrospun nanofiber sheets incorporated with different concentrations of β-caryophyllene loaded into halloysite (HNT) nanotubes as an eco-friendly, bioactive food packaging material. We obtained heterogeneous fibers with flat ribbon-like morphology. The loading of β-caryophyllene/HNT increased the fiber diameters from ∼900 nm to ∼1100 nm. The nanofiber showed improved thermal and mechanical performance upon incorporating β-caryophyllene/HNT. The water vapor permeability decreased due to a decrease in the porosity of the nanofiber sheets. The β-caryophyllene/HNT loaded nanofiber showed good DPPH free radical scavenging and was effective against both gram-positive B.subtilis and gram-negative E.coli bacteria subjected to agar disc diffusion test and time-kill study. The initial release of β-caryophyllene from the 5%, 10%, and 20% loaded nanofiber sheets was ∼22%, ∼25%, and ∼31% within 12 h, and ∼63%, ∼69%, and ∼77% after 120 h indicating a sustained slow release for long term bioactivity. The WST-1, LDH, and cell adhesion properties of β-caryophyllene/HNT-loaded nanofiber render them biocompatible and nontoxic. Composting experiment reveals the eco-friendly nature of the fabricated nanofiber sheets as they all lose their fibrous morphology after 21 days of composting and a mass loss of ∼65% for Zein/PCL nanofibers and ∼63%, ∼55%, and ∼48% for 5%, 10%, and 20% β-caryophyllene/HNT loaded Zein/PCL nanofiber sheets. During the application test for postharvest quality preservation of strawberries, the strawberries covered in Zein/PCL-20 showed the best-preserved quality after 4 days of storage at 25 °C in 40% humidity. The physicochemical, biological, and application tests demonstrated the potential of the prepared nanofiber sheets as a potential bioactive food packaging material.

Intermittent scavenging of storage lesion from stored red blood cells by electrospun nanofibrous sheets enhances their quality and shelf-life

Transfusion of healthy red blood cells (RBCs) is a lifesaving process. However, upon storing RBCs, a wide range of damage-associate molecular patterns (DAMPs), such as cell-free DNA, nucleosomes, free-hemoglobin, and poly-unsaturated-fatty-acids are generated. DAMPs can further damage RBCs; thus, the quality of stored RBCs declines during the storage and limits their shelf-life. Since these DAMPs consist of either positive or negative charged species, we developed taurine and acridine containing electrospun-nanofibrous-sheets (Tau-AcrNFS), featuring anionic, cationic charges and an DNA intercalating group on their surfaces. We show that Tau-AcrNFS are efficient in scavenging DAMPs from stored human and mice RBCs ex vivo. We find that intermittent scavenging of DAMPs by Tau-AcrNFS during the storage reduces the loss of RBC membrane integrity and reduces discocytes-to-spheroechinocytes transformation in stored-old-RBCs. We perform RBC-transfusion studies in mice to reveal that intermittent removal of DAMPs enhances the quality of stored-old-RBCs equivalent to freshly collected RBCs, and increases their shelf-life by ~22%. Such prophylactic technology may lead to the development of novel blood bags or medical device, and may therefore impact healthcare by reducing transfusion-related adverse effects.

A smart tri-layered nanofibrous hydrogel thin film with controlled release of dual drugs for chemo-thermal therapy of breast cancer

A tri-layered nanofibrous hydrogel thin film with temperature sensitivity is introduced as a new controlled drug release system to treat breast cancer. A simultaneous heat generation with the tunable release of dual drugs is observed in response to visible light radiation. A tri-layered nanofibrous sheet was fabricated through sequential electrospinning the blends of Au@Chit@DOX-loaded poly(N-isopropylacrylamide-co-N-methylol acrylamide) (poly (NIPAAm-co-NMA)) and Curcumin-loaded poly (vinyl alcohol) (Cu-loaded PVA), where the Cu-loaded PVA nanofibers (NFs) are sandwiched between two layers of Au@Chit@DOX-loaded poly (NIPAAm-co-NMA) NFs. After thermal crosslinking of the tri-layered nanofibrous sheet, the nanofibrous hydrogel thin film is obtained. FTIR/ATR, UV–Vis, Photoluminescence, and PXRD analyses were used for characterizing. PVA NFs and poly (NIPAAm-co-NMA) NFs were observed in the average diameters of 358 and 212 nm, respectively, and Au@Chit@DOX nanoparticles (NPs) appeared as local thickening inside the NFs. The distribution of drugs was visualized with confocal images. The thermal stability up to 295 °C and tensile strength of 0.65 MPa with 99.36% elongation were reported for the nanofibrous hydrogel thin film. Unlike the fast release of drugs from the nanofibrous sheet, a controlled release of drugs was observed from the nanofibrous hydrogel thin film at 45 °C and under visible light radiation. 52% at 45 °C and 55% under light radiation were reported for the Cur release and 86% at 45 °C and 88% under light radiation were observed for the release of DOX within 18 h. The in vitro cell viability results under light radiation displayed a chemo-thermal therapy over breast cancer cells.

Tailoring the surface energy and area surface resistance of solid-electrolyte polymer membrane for dendrite free, high-performance, and safe solid-state Li-batteries

Solid electrolyte polymer composite enabled solid-state lithium batteries have shown extensive viability for mass production and commerciality for advanced energy storage technology. Most studies of polymer composite electrolyte are produced by solution casting and free-standing methods, where ionic conductors are randomly distributed into the polymeric network, suffering from poor ionic conductivity and agglomeration during charge/discharge cycling. In this work, using the threshold percolation model and critical volume fraction requirement, we have designed a highly efficient garnet-type ion-conducting nanofibrous sheet where ionic conductors of different aspect ratios are dispersed to tune the surface roughness, area surface resistance, and wettability of the developed electrolyte membrane. Moreover, the impact of filler volume fraction and percolation threshold on the surface properties of the membrane, regulating the area interfacial resistance of the Li metal cell has also been examined, which has not been studied so far in the literature. The corresponding high potential cathode-based lithium assembled coin cells exhibit an excellent specific capacity of 170 mAh g −1 at 0.3C, with high capacity retention under ambient circumstances. By optimizing the critical aspect ratio of the fillers and the percolation threshold, a high-performing solid electrolyte membrane can be realized for advanced and safer Li-batteries technology.

Novel nanofibrous membrane-supporting stem cell sheets for plasmid delivery and cell activation to accelerate wound healing.

The integration of biomaterials with cells for high overall performances is vitally important in tissue engineering, as scaffold‐free cell sheet lacks enough mechanical performance and cell viability while cell‐free scaffold possesses limited biological functions. In this study, we propose a new strategy to strengthen cell sheets and enhance cell activity for accelerating wound healing based on a novel sandwich structure of cell sheet‐plasmid@membrane‐cell sheet (CpMC). Specifically, the CpMC contains two adipose‐derived stem cell (ADSC) sheets on outer surfaces and an electrospun gelatin/chitosan nanofibrous membrane (NFM) encapsulating vascular endothelial growth factor (VEGF) plasmids in between. The physicochemical properties of NFM including swelling, stiffness, strength, elasticity, and biodegradation can be tailored by simply adjusting the ratio between gelatin and chitosan to be 7:3 which is optimal for most effectively supporting ADSCs adhesion and proliferation. The swelling/biodegradation of NFM mediates the sustained release of encapsulated VEGF plasmids into adjacent ADSCs, and NFM assists VEGF plasmids to promote the differentiation of ADSCs into endothelial, epidermal, and fibroblast cells, in support of the neoangiogenesis and regeneration of cutaneous tissues within 2 weeks. The proposed membrane‐supporting cell sheet strategy provides a new route to tissue engineering, and the developed CpMC demonstrates a high potential for clinical translation.

Muscle Degeneration: Preparation of Stretchable Nanofibrous Sheets with Sacrificial Coaxial Electrospinning for Treatment of Traumatic Muscle Injury (Adv. Healthcare Mater. 8/2021)

In article number 2002228 by Byung-Jae Kang, Hyuk Sang Yoo, and co-workers, a new method of fabricating nano-scaled gelatin nanofibers is introduced for treatment of volumetric loss of muscle. Myoblasts experiencing stepwise stretching of the gelatin nanofibers exhibit enhanced transition to myotubes. Muscle transplanted with stem cells/gelatin nanofibers exhibit higher recovery efficacy of muscle functions.

Preparation of Stretchable Nanofibrous Sheets with Sacrificial Coaxial Electrospinning for Treatment of Traumatic Muscle Injury.

Traumatic muscle injury with massive loss of muscle volume requires intramuscular implantation of proper scaffolds for fast and successful recovery. Although many artificial scaffolds effectively accelerate formation and maturation of myotubes, limited studies are showing the therapeutic effect of artificial scaffolds in animal models with massive muscle injury. In this study, improved myotube differentiation is approved on stepwise stretched gelatin nanofibers and applied to damaged muscle recovery in an animal model. The gelatin nanofibers are fabricated by a two-step process composed of co-axial electrospinning of poly(ɛ-caprolactone) and gelatin and subsequent removal of the outer shells. When stepwise stretching is applied to the myoblasts on gelatin nanofibers for five days, enhanced myotube formation and polarized elongation are observed. Animal models with volumetric loss at quadriceps femoris muscles (>50%) are transplanted with the myotubes cultivated on thin and flexible gelatin nanofiber. Treated animals more efficiently recover exercising functions of the leg when myotubes and the gelatin nanofiber are co-implanted at the injury sites. This result suggests that mechanically stimulated myotubes on gelatin nanofiber is therapeutically feasible for the robust recovery of volumetric muscle loss.

Comparative Removal of Lead and Nickel Ions onto Nanofibrous Sheet of Activated Polyacrylonitrile in Batch Adsorption and Application of Conventional Kinetic and Isotherm Models.

We investigated the adsorption of lead (Pb2+) and nickel (Ni2+) ions by electrospun membranes of polyacrylonitrile (PAN) nanofiber activated with NaHCO3 (PANmod). Analysis by Fourier-transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX) validated the functionalization of PAN nanofibers with NaHCO3, and the successful agglomeration of Pb2+ and Ni2+ onto PANmod. After a rapid uptake of the heavy metal ions (15 min), the equilibrium contact time was attained (60 min) following a linear increase of both adsorption capacity and removal efficiency. PANmod showed a better affinity for Ni2+ than Pb2+. The adsorption on PANmod was best described by the pseudo-second-order kinetic model for both studied models, supporting chemisorption. By varying the solution pH from 2.0 to 9.0, we found that the adsorption capacity followed an increasing trend, reaching a maximum at the pH of 7.0. Despite increasing adsorption capacities, the removal efficiency of both heavy metal ions exhibited a decreasing trend with increase in initial concentrations. The amount of PANmod directly affects the removal efficiency, with 0.7 and 0.2 g being the optimum dose for maximum uptake of Pb2+ and Ni2+, respectively. The Langmuir model fitted well the Pb2+ adsorption data suggesting monolayer adsorption, and the Freundlich model perfectly fitted the Ni2+ adsorption data, indicating heterogeneous adsorption. The estimated values of the mean free energy of adsorption in the D–R isotherm indicated a physical adsorption of both heavy metal ions into the surface of the PANmod.

Hybrid silk fibroin–gelatin nanofibrous sheet for drug delivery and regenerative medicine: In‐vitro characterization and controlled release of simvastatin/protein

Blend drug‐loading method in electrospun scaffolds has gained much attention as a cost‐effective and simple delivery system in regenerative medicine. However, it has some drawbacks, such as the burst release of encapsulated drugs and denaturing active agents in harsh organic solvents. In this study, a new silk fibroin‐gelatin (SF–G) fibrous sheet has been introduced as an engineered scaffold and a straightforward drug delivery system for skin tissue engineering applications. The hybrid sheets have been prepared via co‐electrospinning and in‐situ crosslinking methods without corrosive solvents and toxic crosslinking agents. To evaluate the proposed scaffold as a controlled release system, the simvastatin (SIM), a poorly water‐soluble drug, and bovine serum albumin (BSA), a hydrophilic protein, have been selected as two model pharmaceutical ingredients. The physicochemical and mechanical properties, as well as the degradation profile of the hybrid sheets, indicate that the fabrication method, SF: G fibers volume ratio and degree of crosslinking are vital in controlling the different features of the prepared scaffolds. The obtained results demonstrate that the hybrid structure, type of fiber, and in‐situ crosslinking method provide an opportunity to adjust the release kinetics of encapsulated drug/protein within the fiber matrix. The in‐vitro analysis also demonstrates suitable bioactivity of the drug/protein‐loaded scaffolds. Therefore, this hybrid nanofibrous sheet may be considered a new candidate for biomedical applications and pharmaceutical science.

Comparative behaviour of electrospun nanofibers fabricated from acid and alkaline hydrolysed gelatin: towards corneal tissue engineering

Gelatin is a hydrolysed form of collagen which is categorised as type A (acid hydrolysed) or type B (base hydrolysed), based on method of hydrolysis. In this work, we have studied the comparative properties of electrospun nanofibers of gelatin A (GA) and gelatin B (GB) prepared using a ternary solvent (glacial acetic acid/ethyl acetate/water). In addition, silk fibroin was used to improve the integrity and stability of gelatin nanofibrous sheets. Silk fibroin is known to serve as a potential implantable biomaterial because of its optimal mechanical stability, transparency, cell proliferation and tunable degradability. GA scaffold and silk permeated gelatin A nanofibrous scaffold (SFG) showed 50-70% of transparency comparable to that of adult rat and goat cornea. ATR-FTIR analysis showed the presence of native functional groups and bonds. Scanning electron microscope (SEM) micrographs revealed the porous nature of the scaffolds i.e., 48.08± 3.35 and 51.38 ± 3.72 for GA and GB, respectively. GB nanofibrous scaffolds got dissolved instantly in phosphate buffer solution (PBS), while GA scaffolds remained stable up to ∼ 11 h at 25˚C, however got degraded within 12 h when incubated at 37˚C. Furthermore, SFG scaffolds physically cross-linked with ethanol vapour displayed relatively improved stability when examined for at least 6 days at 37°C, minor weight loss when incubated in a lysozyme solution and facilitated the cellular proliferation significantly. Liquid retention capacity of the electrospun GA nanofibrous scaffolds was found to be nearly 800% from its original weight within 48 h. The electrospun nanofibrous scaffolds i.e., SFG facilitated ~72% of cellular proliferation compared to the control for SIRC [Statens Seruminstitut Rabbit Cornea] fibroblasts cells by 5th day of cell culture. Comparative outcomes reveal that the electrospun GA nanofibers possess significantly better integrity and noted stability in an aqueous environment compared to GB nanofibrous scaffold. Moreover, owing to the enhanced integrity and better stability the GA nanofibrous scaffold in combination with silk fibroin could be exploited in corneal tissue engineering applications where transparency plays an indispensable characteristic.

High-Strength Hydrogel Attachment through Nanofibrous Reinforcement.

The repair of a cartilage lesion with a hydrogel requires a method for long-term fixation of the hydrogel in the defect site. Attachment of a hydrogel to a base that allows for integration with bone can enable long-term fixation of the hydrogel, but current methods of forming bonds to hydrogels have less than a tenth of the shear strength of the osteochondral junction. This communication describes a new method, nanofiber-enhanced sticking (NEST), for bonding a hydrogel to a base with an adhesive shear strength three times larger than the state-of-the-art. An example of NEST is described in which a nanofibrous bacterial cellulose sheet is bonded to a porous base with a hydroxyapatite-forming cement followed by infiltration of the nanofibrous sheet with hydrogel-forming polymeric materials. This approach creates a mineralized nanofiber bond that mimics the structure of the osteochondral junction, in which collagen nanofibers extend from cartilage into a mineralized region that anchors cartilage to bone.

Electrospun nanofibrous sheet doped with a novel triphenylamine based salicylaldehyde fluorophore for hydrazine vapor detection

Successful synthesis of a novel triphenylamine based salicylaldehyde fluorophore (compound 1) was performed via Suzuki cross-coupling reaction. Subsequently, the identification the hydrazine vapor of an electrospun nanofiber sheet combined with compound 1 depending on solid condition was described. Furthermore, cellulose acetate (CA) combined with the electrospun nanofiber sheet based on compound 1 was formed by applying the electrospinning technique where the average diameter was 324.6 ± 91.6 nm. The sensing nanofiber sheet exhibited a sensitive and selective reaction to hydrazine vapor with a linear concentration range of 0.2-1 %w/v in aqueous solution according to the analysis of fluorescence images using ImageJ. Moreover, it exhibited the elevated selectivity with hydrazine across 21 convenient interferences. Initial findings revealed the nanofibrous mat’s sensitivity and selectivity in terms of the identification of hydrazine via naked-eye detection under backlight 365 nm with fluorescent turn-off mode. Additionally, the generation of compound 1 and the hydrazone product (compound 1-HZ) was investigated through the use of 1H-NMR titration and HRMS, which affirmed the formation of hydrazine with a proton chemical shift at 7.95 ppm, HRMS of compound 1-HZ at m/z = 380.1764 [1-HZ+H]+). It has been demonstrated that the nanofibrous mat offers a basic and suitable method for detecting water vapour in water environments as well as industrial chemical setting.

Dynamics of liquid imbibition through partially soluble porous sheets

We investigate the dynamics of liquid imbibition through partially soluble porous sheets. Using a polymeric porous sheet composed of polyethylene oxide (PEO) nanofibers, we examine the imbibition of mixtures of ethylene glycol (EG) that does not dissolve PEO and water that dissolves PEO. For aqueous EG mixtures with a concentration of greater than 70 wt% that only partially dissolves a PEO nanofibrous sheet, imbibition with dissolution is markedly slower than without dissolution. By developing a mathematical model to predict the imbibition velocity, we elucidate how dissolution changes the viscosity of the invading liquid and affects the dynamics of imbibition. This study guides us to extend the classical theoretical framework for liquid imbibition through porous media to complex porous media involving dissolution. Thus, a useful background is provided for long-term drug delivery using partially soluble porous materials and for engineering processes, such as geological sequestration and exploration, and coffee percolation.

A novel polycaprolactone/carbon nanofiber composite as a conductive neural guidance channel: an in vitro and in vivo study

The current study aimed to investigate the potential of carbon nanofibers to promote peripheral nerve regeneration. The carbon nanofiber-imbedded scaffolds were produced from polycaprolactone and carbon nanofibers using thermally induced phase separation method. Electrospinning technique was utilized to fabricate polycaprolactone/collagen nanofibrous sheets. The incorporation of carbon nanofibers into polycaprolactone’s matrix significantly reduced its electrical resistance from 4.3 × 109 ± 0.34 × 109 Ω to 8.7 × 104 ± 1.2 × 104 Ω. Further in vitro studies showed that polycaprolactone/carbon nanofiber scaffolds had the porosity of 82.9 ± 3.7% and degradation rate of 1.84 ± 0.37% after 30 days and 3.58 ± 0.39% after 60 days. The fabricated scaffolds were favorable for PC-12 cells attachment and proliferation. Neural guidance channels were produced from the polycaprolactone/carbon nanofiber composites using water jet cutter machine then incorporated with PCL/collagen nanofibrous sheets. The composites were implanted into severed rat sciatic nerve. After 12 weeks, the results of histopathological examinations and functional analysis proved that conductive conduit out-performed the non-conductive type and induced no toxicity or immunogenic reactions, suggesting its potential applicability to treat peripheral nerve damage in the clinic.

Dilute solvent welding: A quick and scalable approach for enhancing the mechanical properties and narrowing the pore size distribution of electrospun nanofibrous membrane

Major limitations to the practical use of nanofibrous membranes in water filtration are their weak mechanical properties and wide pore size distribution. This study describes a quick and scalable method to improve the mechanical properties and narrow the pore size distribution of nanofibrous membranes by welding the nanofibers at their junction points. The welding process involves a simple dilute solvent spraying step followed by heating, requiring only a few minutes. The polymer's solvent was diluted with a non-solvent to avoid excessive dissolution of the nanofibers. With that, the degree of welding can be controlled by the volume fraction of solvent, the heating temperature and heating temperature. Dilute solvent welding enhanced the mechanical properties of the nanofibrous membrane while slightly changed the fiber crystallinity and fiber size distribution. Furthermore, the membrane pore size distribution narrowed with welding while high porosity (~80%) was retained. In membrane distillation (MD) experiments, the welded nanofibrous membrane exhibited more robust MD performance than the pristine nanofibrous membrane with only slight decreases of vapor flux. This technique can be applied universally to treat both nanofibrous flat sheet and tubular membranes made from soluble polymers with their corresponding diluted solvents.

Improvement of Interlaminar Fracture Toughness in Glass Fiber Reinforced Plastic Laminates with Inorganic Nanofiber Sheet Interleaf

The present study developed a new type of nanofibrous structure-TiO2 nanofiber sheets (TNFS) to increase the interlaminar fracture toughness of glass fiber reinforced polymer (GFRP) laminates. SEM was employed to characterize the nanofibers before and after calcination. In order to quantify TNFS, the thickness and the crevice area of TNFS were analyzed, the results showed that the thickness and the proportion of crevice area were increased with the increase of TNFS contents. Mode I and Mode II interlaminar fracture toughness were investigated for GFRP laminates toughened by different mass fraction of TNFS. The highest Mode I fracture toughness value achieved by inserting 5 wt.% TNFS in the interleaf. GIc value was 74.35 % higher than those of base GFRP laminates. Meanwhile, with 6 wt.% addition of TNFS, the GFRP laminates showed the highest Mode II fracture toughness, which is 60.76 % higher than those of base GFRP laminates. The improvement mechanism of toughness was illustrated by the fracture surface analysis of TNFS interlayered laminates.