Polyacrylonitrile Nanofiber Mats Research Articles

Effect of stabilization and carbonization treatment on the chemical and physical transformation of polyacrylonitrile (PAN) based electrospun carbon nanofibers

The present study delves into the production of carbon nanofibers (CNFs) utilising electrospun polyacrylonitrile (PAN) nanofiber mats, with a specific focus on the influence of oxidative stabilisation and carbonisation treatments. This research aims to thoroughly understand how variations in stabilisation time and temperature, as well as carbonisation temperature, impact the CNFs properties. These properties include fiber size, morphology, chemical and crystal structure transformation, thermal behaviour, and surface characteristics. Our methodology involved a detailed examination of the thermal treatment processes, where we observed a significant decrease in fiber size, though the surface morphology of the fibers remained largely unaffected. We employed Fourier-transform infrared (FTIR) spectroscopy to track the transformation of nitrile groups in PAN to imine groups, which indicated the progression of cyclisation reactions. Complementary analyses through differential scanning calorimetry (DSC) confirmed a high degree of these reactions, particularly at stabilisation temperatures extending to 250 °C and beyond. The cyclisation process was found to be complete during the carbonisation phase, at temperatures reaching 450 °C and above. Further, x-ray diffraction (XRD) patterns offered insight into the changes in the crystal structure, particularly in the packing of the d(002) spacing because of the stabilisation and carbonisation processes. This findings from this study not only elucidate the intricate process of CNFs production from electrospun PAN nanofiber mats but also highlight the critical factors that influence their final properties. These insights are invaluable for the development of advanced CNFs with tailored properties suitable for a range of applications, including but not limited to energy storage, electronics, and as supporting materials in various technological domains.

Heat transport during drop impact onto a heated wall covered with an electrospun nanofiber mat: The influence of wall superheat, impact velocity, and mat thickness

Nanofiber surface coating is a promising method for the enhancement of heat transfer during spray cooling. In the present work, the drop dynamics as well as local and overall heat transfer during single drop impact onto a heated wall covered with a polyacrylonitrile (PAN) nanofiber mat are investigated to obtain insight into the mechanisms governing the heat transport enhancement. The influence of wall superheat, drop impact velocity, and mat thickness on the hydrodynamics and heat transfer from the heated wall to the fluid is studied. The experiments were conducted inside a temperature-controlled test cell with a pure vapor atmosphere maintained with refrigerant FC−72 (perfluorohexane). The temperature field at the solid-fluid interface was observed with a high-speed infrared camera, and the heat flux field was derived by solving a three-dimensional transient heat conduction equation within the substrate. The presence of the nanofiber mat on the heater surface suppresses the drop receding phase due to the pinning of the contact line at the end of the spreading phase. Two different heat transfer scenarios are observed depending on the wall superheat and drop impact velocity: scenario (I), in which the liquid drop completely penetrated through the porous nanofiber mat and made contact with the heater surface; and scenario (II) in which the vapor produced inside the pores of the nanofiber mat prevented the liquid drop from touching the heater surface. In scenario (I), an up 450% heat flow enhancement during the sessile drop evaporation stage has been observed. In scenario (II), a 80% heat flow enhancement at this stage has been registered.

Evaporation-Driven Energy Generation Using an Electrospun Polyacrylonitrile Nanofiber Mat with Different Support Substrates.

Water evaporation-driven energy harvesting is an emerging mechanism for contributing to green energy production with low cost. Herein, we developed polyacrylonitrile (PAN) nanofiber-based evaporation-driven electricity generators (PEEGs) to confirm the feasibility of utilizing electrospun PAN nanofiber mats in an evaporation-driven energy harvesting system. However, PAN nanofiber mats require a support substrate to enhance its durability and stability when it is applied to an evaporation-driven energy generator, which could have additional effects on generation performance. Accordingly, various support substrates, including fiberglass, copper, stainless mesh, and fabric screen, were applied to PEEGs and examined to understand their potential impacts on electrical generation outputs. As a result, the PAN nanofiber mats were successfully converted to a hydrophilic material for an evaporation-driven generator by dip-coating them in nanocarbon black (NCB) solution. Furthermore, specific electrokinetic performance trends were investigated and the peak electricity outputs of Voc were recorded to be 150.8, 6.5, 2.4, and 215.9 mV, and Isc outputs were recorded to be 143.8, 60.5, 103.8, and 121.4 μA, from PEEGs with fiberglass, copper, stainless mesh, and fabric screen substrates, respectively. Therefore, the implications of this study would provide further perspectives on the developing evaporation-induced electricity devices based on nanofiber materials.

A Novel Method to Enhance the Mechanical Properties of Polyacrylonitrile Nanofiber Mats: An Experimental and Numerical Investigation.

This study addresses the challenge of enhancing the transverse mechanical properties of oriented polyacrylonitrile (PAN) nanofibers, which are known for their excellent longitudinal tensile strength, without significantly compromising their inherent porosity, which is essential for effective filtration. This study explores the effects of doping PAN nanofiber composites with varying concentrations of polyvinyl alcohol (PVA) (0.5%, 1%, and 2%), introduced into the PAN matrix via a dip-coating method. This approach ensured a random distribution of PVA within the nanofiber mat, aiming to leverage the synergistic interactions between PAN fibers and PVA to improve the composite's overall performance. This synergy is primarily manifested in the structural and functional augmentation of the PAN nanofiber mats through localized PVA agglomerations, thin films between fibers, and coatings on the fibers themselves. Comprehensive evaluation techniques were employed, including scanning electron microscopy (SEM) for morphological insights; transverse and longitudinal mechanical testing; a thermogravimetric analysis (TGA) for thermal stability; and differential scanning calorimetry (DSC) for thermal behavior analyses. Additionally, a finite element method (FEM) analysis was conducted on a numerical simulation of the composite. Using our novel method, the results demonstrated that a minimal concentration of the PVA solution effectively preserved the porosity of the PAN matrix while significantly enhancing its mechanical strength. Moreover, the numerical simulations showed strong agreement with the experimental results, validating the effectiveness of PVA doping in enhancing the mechanical properties of PAN nanofiber mats without sacrificing their functional porosity.

Flexible and freestanding temperature sensors based on laser carbonization of carbon nanofibers

A new single-step, low-cost method for producing a wearable, flexible temperature sensor has been developed using laser writing technology. The process involves carbonizing and patterning polymeric nanofibers to create a standalone laser-carbonized nanofibers (LCNFs) substrate. A large-area polyacrylonitrile nanofibers mat is first prepared using electrospinning and then carbonized with a high-power CO2 laser beam. The resulting LCNFs are highly conductive and retain their fibrous structure. The near-complete disappearance of polyacrylonitrile peaks in the FTIR measurements and the high-intensity characteristic peaks of carbon materials obtained in the Raman scattering measurements of the LCNFs confirm their complete carbonization. SEM microscopy showed that the fibrous structure of the LCNFs remained intact after the laser carbonization process with no significant damage. Additionally, TEM microscopy revealed that the LCNFs are made up of axially ordered graphene sheets, which form their unique fibrous structure. LCNFs' temperature sensor exhibits >87% higher temperature coefficient of resistance (TCR) than laser-induced graphene (LIG) temperature sensor on a polyamide substrate when tested under the same experimental conditions. The LCNFs sensor also boasts excellent resistance stability, mechanical stability, and flexibility. To fit various wearable applications and enhance the temperature-sensing capabilities, three different sensor patterns of LCNFs were created: square, serpentine, and heater. Among these patterns, the heater design exhibited superior TCR and temperature response. However, it also had a higher thermal mass compared to the other patterns.

Synthesis and modification of poly (p‐phenylene terephthalamide) for production of light‐weight hybrid composite armors reinforced with polymer composite nanofiber mats

AbstractPoly (p‐phenylene terephthalamide) (PPTA) polymer was synthesized and then modified to eliminate the processing difficulties arising from its insolubility in organic solvents. The chemical structures of the synthesized PPTA and N‐butyl PPTA (BPPTA) were confirmed by elemental analysis, x‐ray diffraction, Fourier transform infrared (FTIR), and 13C‐NMR spectroscopy studies. As a result of modification, an aramid derivative that is soluble in some common solvents was obtained and added into polyacrylonitrile (PAN) matrix in solution. PAN/BPPTA composite nanofiber mats (CNMs) were fabricated by electrospinning. Mechanical tests showed that tensile strength increased by 119% with 3% BPPTA content. The fabricated CNMs were combined with aramid fabrics to produce laminated hybrid armors and ballistic tests were performed following the NATO Stanag 2920 standard. This is the first report about the integration of CNMs into multilayer armor configurations and resulted in improved ballistic limit velocity (V50) with a relatively very small weight gain and emergence of new energy absorption mechanisms.Highlights Alkylation of the para‐aramid yielded an organo‐soluble aramid derivative. Tensile strength of PAN nanofiber mat increased by 119% with 3% N‐butyl PPTA. Integration of the CNMs resulted in new ballistic impact absorption mechanisms. CNMs contribute to V50 with a very low mass gain due to their high surface area/mass.

Laser-induced carbonization of carbon nanofibers free-standing electrodes for flexible interdigitated micro-supercapacitors

A versatile one-step laser writing technique is introduced in this work for carbonizing and patterning polymeric nanofibers mat to produce a free-standing laser carbonized nanofibers (LCNFs) electrode for flexible interdigitated microsupercapacitors. A large-area polyacrylonitrile nanofibers mat was first prepared with the facile electrospinning technique on a collecting drum followed by a stabilizing step. A high-power CO2 laser beam is used to carbonize the stabilized nanofibers into highly conductive LCNFs at ambient atmospheric conditions and draw the interdigitated pattern at the same time. The complete carbonization of the nanofibers is confirmed by the nearly complete disappearance of polyacrylonitrile peaks in the FTIR measurements and from the high-intensity characteristic peaks of carbon materials obtained in the Raman scattering measurements of the LCNFs. The SEM microscopy showed that the LCNFs were able to survive their fibrous structure after the laser carbonization process and without any significant damage. Also, the TEM microscopy revealed that the LCNFs are composed of graphene sheets that are axially ordered to form such a unique fibrous structure. Owing to its outstanding structural and electrical properties, the LCNFs interdigitated supercapacitor attained an aerial specific capacitance of 20.38 mF/cm2, a high energy density of 0.64 μWh/cm2, and a high-power density of 224.6 μW/cm2 which are almost two-fold higher than those of the laser-induced graphene (LIG) on a polyamide substrate assembled with the same conditions. This was accompanied by an excellent capacitance retention of 95.3 % after 10,000 electrochemical cyclic stability and impressive mechanical stability and flexibility.

Mechanical and Thermal Characterization of Annealed Oriented PAN Nanofibers.

Polyacrylonitrile (PAN) nanofibers have extensive applications as filters in various fields, including air and water filtration, biofluid purification, and the removal of toxic compounds and hazardous pollutants from contaminated water. This research focuses on investigating the impacts of annealing on the mechanical and thermal characteristics of oriented PAN nanofibers produced through the electrospinning of a PAN solution. The nanofiber mats were subjected to annealing temperatures ranging from 70 °C to 350 °C and characterized using a tensile test machine, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy (SEM). The study aimed to examine the tensile strength in the transverse and longitudinal directions, Young's modulus, and glass transition temperatures of PAN nanofiber mats. The results indicate that, upon annealing, the diameter of the nanofibers decreased by approximately 20%, while the tensile strength increased in the longitudinal and transverse directions by 32% and 23%, respectively. Furthermore, the annealing temperature influenced the glass transition temperature of the nanofiber mats, which exhibited a 6% decrease at 280 °C, while the degradation temperature showed a slight increase of 3.5% at 280 °C. The findings contribute to a better understanding of the effects of annealing on PAN nanofiber mats, facilitating their potential for various filtration applications.

Single-platform, attomolar detection of multiple biomarkers by flexible SERS sensor.

Early detection of Alzheimer's disease (AD), is critical for better healthcare management. Herein, we demonstrate a Surface Enhanced Raman Spectroscopy (SERS) active sensor for highly sensitive and selective detection of β-Amyloid Peptide (Aβ1-42), a biomarker of Alzheimer's disease. Polyacrylonitrile (PAN) nanofiber mats, containing purine-based ligand (L; 0mg (P1), 50mg (P2), and 100mg (P3)) were prepared by electrospinning followed by functionalization with silver nanoparticles (AgNPs). The fabricated SERS sensors were employed for the detection of Rhodamine 6G (Rh-6G) dye for optimization and the highest sensitivity was achieved on P3/AgNPs SERS sensor. The P3/AgNPs sensor was chosen for the detection of Aβ1-42 and human Insulin (HI). The limit of detection (LoD) was found to be 76 × 10-18M and 26× 10-18M for Aβ1-42 and HI, respectively. The sensitivity achieved is one order improved for Aβ1-42 and four orders for HI when compared with reported values. Also, demonstrated the selectivity of the P3/AgNPs sensor by testing a simulated cerebrospinal fluid (CSF) and achieved easily identifiable peaks of Aβ1-42 among the noise of HI and BSA. This approach could be extended to develop ultra-sensitive flexible SERS sensors for the facile detection of multiple biomarkers on a single platform with excellent sensitivity, selectivity and stability.

A flexible carbon nanofiber and conjugated polymer-based electrode for glucose sensing

Herein, a specific and stable biosensor for glucose using a flexible, modified electrode with a carbon nanofiber (CNF) and a novel conjugated polymer including three moieties of benzotriazole, benzodithiophene, and benzenediamine (P-BDT-BTz:BDA) as a platform was designed. For this purpose, polyacrylonitrile (PAN) nanofiber mats were obtained by a solution-based electrospinning method. PAN nanofiber mats were stabilized and carbonized to turn into carbon nanofibers and the sensing platform was formed by combining the nanofibers on a defined area of a flexible polyethylene terephthalate (PET) substrate. In addition, a random conjugated polymer, P-BDT-BTz:BDA, was synthesized, characterized, and used as a modifier of a CNF-coated transducer surface for glucose detection. The effect of each parameter on biosensor response was evaluated. Under optimized conditions, the electrode responded to glucose in a linear concentration range of 20 µM to 500 µM with a detection limit of 8.5 µM. In addition, it was observed that the designed biosensor has a good sensing ability for glucose in beverages. The results of our study show that the proposed amperometric glucose oxidase (GOx)-based biosensor has high specificity, a low limit of detection, and an extended range of linear detection for glucose.

Effects of stabilization on structures and properties of Electrospun Polyacrylonitrile based carbon nanofibers as a binder free electrode for supercapacitor application

Electrospun nanofibers were produced with Polyacrylonitrile (PAN) precursor using the Electrospinning technique. Stabilization is an important heat treatment process before carbonization. A total of 2 samples were considered for the carbonization process. Electrospun Pure PAN nanofiber mat was used with aluminium foil substrate for the heat treatment process in a tube furnace. The first sample was stabilized at 290 °C temperature at a 2 °C/min heating rate and constant heating for 3 h. The second sample was directly used for carbonization without stabilization. Fibers were carbonized at 500 °C under a nitrogen atmosphere with a dwell time of 1 h. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the influence on structures and properties of carbon fibers of both samples. To investigate elemental concentration in samples Energy-dispersive X-ray spectroscopy (EDX) was used. EDX results showed 45 % and 60 % carbon atom non stabilized and stabilized carbon nanofibers respectively. An SEM result reveals a drastic fiber diameter reduction in a sample that was not stabilized before carbonization as compared with the sample which was stabilized before the carbonization process. FTIR results showed the complete conversion of CN to CN at a stabilization temperature of 290 °C. Also, FTIR results reveal that 500 °C temperature is too low for complete carbonization as some peaks are still there after the carbonization. Low temperature carbonization is necessary to avoid the melting of aluminium foil substrate during the carbonization process. Further CNF mat will be peeled off from the substrate and will be used directly as electrode material for electrochemical characterization.

Emerald-based polyaniline-modified polyacrylonitrile nanofiber mats based solid-phase extraction for efficient and simple detection of Sudan dyes in poultry feed

Emerald-based polyaniline-modified polyacrylonitrile nanofiber mats (emerald-based PANI-PAN NFMs) were prepared and their performance as solid-phase extraction (SPE) adsorbent for extracting four Sudan dyes (Sudan I–IV) from poultry feed was evaluated. After solvent extraction, the poultry feed samples extraction solution was directly used for SPE by diluted with ultra-high purity water without any other treatment. No washing step was needed before elution, and the eluent was directly detected by the high-performance liquid chromatography-diode array detector (HPLC-DAD) without conventional concentration and filtration. The results showed that emerald-based PANI-PAN NFMs could effectively adsorb Sudan dyes through π-π conjugation and hydrogen bond. The amount of adsorbent and eluent required for the entire SPE process was only 10 mg and 600 µL, respectively. Furthermore, the emerald-based PANI-PAN NFMs were easy to regenerate, and no performance degradation was found after at least 6 times reuses. The detection limits of Sudan I–IV were 6–15 μg·kg−1 and the recoveries were 88.48 % –101.88 % with relative standard deviations (RSDs) less than 15 %, indicating the method has good sensitivity, accuracy, and precision. Compared with existing methods, the proposed method has simpler processes with practical application potential.

Environmental friendly Polyacrylonitrile nanofiber mats encapsulated and coated with green algae mediated Titanium oxide nanoparticles for efficient oil spill adsorption

Oil spill causes extreme environmental damage, from aquatic life to seabirds, disrupting the entire ecosystem. Herein, we have synthesized high scale, economical and bio-compatible, green algae mediated Titanium oxide (TiO2) nanoparticles and Polyacrylonitrile (PAN) nanofiber mats. We have studied the effect of encapsulation and coating of TiO2 nanoparticles over nanofiber mats for highly efficient oil spill adsorption. TiO2 encapsulated and coated PAN (TECP) nanofibers showed a maximum of 62.34 g g−1 adsorption capacity of petroleum oil from the water surface. Moreover, the composite mats show maximum adsorption within 45 s for up to 5 repeated cycles. Further, it has been observed that the adsorption capacity has increased by increasing the weight of the composite nanofiber mats, which confirms its commercial applicability. Thus, this work provides rapid, large-scale, economical, bio-compatible, and highly effective adsorbents for oil spill cleaning and extraction over natural waterbodies.

Magnetic Carbon Nanofiber Mats for Prospective Single Photon Avalanche Diode (SPAD) Sensing Applications.

Electrospinning enables simple and cost-effective production of magnetic nanofibers by adding nanoparticles to a polymer solution. In order to increase the electrical conductivity of such nanofibers, the carbonization process is crucial. In this study, the chemical and morphological properties of magnetic nanofiber mats prepared from polyacrylonitrile (PAN)/magnetite were investigated. In our previous studies, PAN/magnetite nanofiber mats were carbonized at 500 °C, 600 °C, and 800 °C. Here, PAN/magnetite nanofiber mats were carbonized at 1000 °C. The surface morphology of these PAN/magnetite nanofiber mats is not significantly different from nanofiber mats thermally treated at 800 °C and have remained relatively flexible at 1000 °C, which can be advantageous for various application fields. The addition of nanoparticles increased the average fiber diameter compared to pure PAN nanofiber mats and improved the dimensional stability during thermal processes. The high conductivity, the high magnetization properties, as well as shielding against electromagnetic interference of such carbonized nanofibers can be proposed for use in single photon avalanche diode (SPAD), where these properties are advantageous.

Study of the Optical Properties of Electrospun PAN/GO Nanocomposites

Polymer nanocomposites with unique optical properties are currently one of the materials most desired by the industry. An effective method of producing this type of materials is the method of electrospinning from a solution or melted polymers, which allows to obtain a nanocomposite in the form of a mat composed of nanofibers. This paper describes the process of producing nanofibers from polyacrylonitrile (PAN) and composite thin nanofiber mats from PAN with the addition of graphene oxide (GO) particles using the electrospinning method. In addition, the aim of the work was to investigate the influence of process parameters and filler on the morphology and optical properties of the nanomaterial. By changing the configuration of the distance between the nozzle and the collector (10 and 20 cm) and keeping the remaining parameters of the electrospinning process constant, two PAN polymer samples and two PAN/GO composite samples were manufactured. The analysis of the chemical composition and morphology of the obtained materials was performed using X-ray microanalysis (EDX) and scanning electron microscopy (SEM), respectively. In order to examine the chemical structure of the polymer and composite nanofibers, Fourier-Transform Infrared Spectroscopy (FTIR) was used. The analysis of the optical properties and the energy band gap of the prepared nanofibers was determined by spectral analysis using a UV–Vis spectrophotometer. The research showed a significant influence of the filler on the morphology.

Preparation of molecularly imprinted resin/polydopamine nanofibers mat for the highly efficient extraction and determination of sulfonamides in environmental water.

With polyacrylonitrile nanofibers mat (PAN NFsM) as a template, molecularly imprinted resin/polydopamine nanofibers mat (MIR/PDA NFsM) was synthesized for the extraction of sulfonamides (SAs) in water. The specific surface area and pore volume were increased obviously due to the functionalization of MIR. The adsorption efficiencies of MIR/PDA NFsM under optimized conditions for SAs were92.3-99.3%. Possible adsorption mechanisms of imprinting recognition and hydrogen bond interactions were also put forward. Compared with MIR particles, the MIR/PDA NFsM exhibited much superior adsorption performance. Particularly, the outstanding mass transfer efficiency of MIR/PDA NFsM was much higher than the other reported adsorbents for SAs. Finally, a new method based on the solid-phase extraction (SPE) of MIR/PDA NFsM was successfully developed for the detection of five SAs in environmental water with HPLC-MS/MS and applied to the analysis of actual samples. Under the selected conditions, the enrichment factors of MIR/PDA NFsM of SCP, SMT, SMZ, SMR, and SMX were between 23.0 and 25.0. Low detection limits (0.26-0.76ng L-1), broad linear range (1.0ng L-1 to 10.0μg L-1), and satisfactory recoveries (82.8-115.6%) and precisions (RSDs < 7.2%) were obtained. Moreover, the excellent reusability properties and storage stability endowed MIR/PDA NFsM with great value forpractical applications.

Water-Evaporation-Induced Electric Generator Built from Carbonized Electrospun Polyacrylonitrile Nanofiber Mats.

Electricity has been generated from evaporation-driven water flow in films of carbon soot particles and other porous media. This paper reports the placement of carbon nanofiber mats (CNMs) on fiberglass screens for the construction of efficient water-evaporation-induced generators (WEIGs). These CNMs are prepared from carbonizing electrospun polyacrylonitrile nanofiber mats and then treating them with oxygen plasma. After electrode attachment to the two ends of a CNM, one electrode is immersed into water. Water rises in the mat due to capillary action and evaporates from the mat surface due to thermal energy provided by the environment. The steady rise of water pushes the dissociated ions of the surface functionalities upward, resulting in a streaming current and an electric potential. This paper investigates how the generated short-circuit current, Is, and open-circuit voltage, Vo, of the WEIG change with structural parameters of the CNMs. Under optimized conditions, these CNMs produce electricity at an areal power density of 83 nW/cm2, which is almost 10 times those offered by some existing ones. Thus, the easy-to-handle CNMs are an attractive porous scaffold for WEIGs.

Electrospun ZrO2@carbon nanofiber mats and their epoxy composites as effective EMI shields in Ku band

Present work describes in detail the preparation and characterization of zirconia (ZrO2) incorporated polyacrylonitrile (PAN) based carbon nanofiber reinforced epoxy composites as effective electromagnetic interference (EMI) shielding material. Zirconia incorporated PAN nanofiber mat was prepared by electrospinning process in N, N-dimethylformamide solvent medium. These nanofiber mats were thermally treated at 1000˚C to form zirconia incorporated carbon nanofiber mats (CNFs). These mats were impregnated with epoxy resin, and ZrO2/CNF epoxy laminas were prepared. It was revealed that the storage modulus of ZrO2@CNF/epoxy composites was superior to that of neat CNF/epoxy composites. The total electromagnetic interference (EMI) shielding effectiveness of carbonized mats and CNF/epoxy composites was analyzed, and excellent specific shielding was observed. Stacking these ZrO2@CNF mats proved to be an excellent tactic, and (8 layers) displayed an outstanding EMI shielding effectiveness of more than -90 dB in the Ku band, which is very significant for potential industrial, radar, and military applications.

Improved performance of Bis-GMA dental composites reinforced with surface-modified PAN nanofibers

In the present work, polyacrylonitrile (PAN) nanofibers reinforced dental composites were investigated to achieve the improved interfacial adhesion between the PAN nanofiber and resin matrix using surface modification of nanofibers. PAN nanofibers mat were prepared by electrospinning and then, surface treated with the activated bisphenol A glycidyl methacrylate (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) (50/50 mass ratio) dental resin followed by photo-curing. Also, the treated nanofibers mat was milled into a powder to achieve the uniform distribution of nanofibers in the matrix resin. The reinforced dental composite were prepared by mixing the various mass fraction of the powder (0.5–15 wt%) with the Bis-GMA/TEGDMA dental monomers. The effect of weight ratio of surface-modified nanofibers to blend resin on the chemical structure, morphology, compression and flexural properties, color and polymerization shrinkage of dental composites was evaluated. The results showed that using surface-treated nanofibers with content of 5 wt% enhanced the compression strength, flexural strength, flexural modulus and work of rupture of the resultant dental composite by factors of 23%, 7%, 80%, and 145%, respectively, comparing to the unreinforced neat resin. Also, the polymerization shrinkage reduces by 37%. These significant improved properties of the dental composite could be due to the semi-interpenetration network formation between surface-modified nanofibers and resin matrix and well distribution of nanofibers in the dental resin. Further increasing the nanofiber content led to poor mechanical properties of obtained dental composites. The results also, revealed that the color of resin composite could be whiter using modified PAN nanofibers as the filler.

Radio Frequency Heating Response of Polyacrylonitrile (PAN) Films and Nanofiber Mats

Radio Frequency Heating Response of Polyacrylonitrile (PAN) Films and Nanofiber Mats