Investigation of Synthesis and Processing of Cellulose, Cellulose Acetate and Poly(Ethylene Oxide) Nanofibers Incorporating Anti-Cancer/Tumor Drug Cis-Diammineplatinum (II) Dichloride Using Electrospinning Techniques

A model anti-cancer/tumor drug cis-diammineplatinum (II) dichloride (cisplatin) was loaded into micro- and nanofibers of cellulose, cellulose acetate (CA) and poly(ethylene oxide) (PEO), using various electrospinning techniques. Single-nozzle electrospinning was used to fabricate neat fibers of each category. Drug loading in cellulose fibers was performed using single-nozzle electrospinning. Encapsulation of cisplatin in CA and PEO-based fibers was performed using coaxial electrospinning. Morphological analysis of the fibers was performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The various categories of fibers exhibited diverse morphological features depending on the material compositions and applied process parameters. The drug-loaded cellulose nanofibers showed attached particles on the surface. These particles were composed of both the polymer and the drug. The CA-cisplatin fibers exhibited drug encapsulation within various diverse morphological conformations: hierarchical structures such as straw-sheaf-shaped particles, dendritic branched nanofibers and swollen fibers with large beads. However, in the case of PEO fibers, drug encapsulation was observed inside repeating dumbbell-shaped structures. Morphological development of the fibers and corresponding mode of drug encapsulation were correlated with process parameters such as applied voltage, concentrations and relative feed rates of the solutions and conductivities of the solvents

Synthesis and Characterization of Low Density Polyethylene (LDPE) Reinforced with Functionalized CNTs

Abstract A systematic approach was undertaken to increase strength, modulus, and toughness of low density polyethylene (LDPE) filaments through infusion of functionalized CNT and ultra high molecular weight polyethylene (UHMWPE). CNTs were functionalized with OH functional groups using chemical treatment. Functionalized CNTs and UHMWPE were first dry mixed with LDPE, and filaments were then drawn using a melt extrusion process. Loading of UHMWPE varied from 8-10 wt% while that of CNT was at 2-4 wt%. LDPE has been infused first with UHMWPE, and then with both UHMWPE and CNT, and filaments were extruded. Neat LDPE filaments were also extruded as control samples. Individual filaments from each category were tested under tension according to ASTM D3379-75. In addition, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies were also conducted to measure changes in thermal and crystalline behavior. Filament tests have revealed that the tensile elongation of LDPE can be increased by about 200% with the addition of 10 wt% UHMWPE. This is however, is accompanied by a loss of about 50% ultimate tensile strength. In the next step, when 2 wt% CNTs and 8 wt% UHMWPE are added, tensile strength of the composite filament is restored to the level of neat LDPE (∼ 25 MPa) with an increase in modulus by 44% and in ultimate fracture strain by about 60% compared to that of neat LDPE. The source of improvement has been traced as formation of copolymer between LDPE and UHMWPE and strong interfacial interaction between the CNT and the polymers. Introduction: This research effort was to utilize the unique attributes of both the UHMWPE and CNT to improve the properties of LDPE which are largely used in industries. Polyethylene (PE) is a polymer based only on carbon and hydrogen, originating from monomers containing a double bond. The generic chemical formula for polyethylene is -(C 2 H 4 ) n -where n is the degree of polymerization. The density of the polyethylene decreases with increased side group mole fraction. These polyethylene's generally have branched and linear chain structures each with a molecular weight of typically less than 50,000 g/mol. 1,2 Low density polyethylene is considered as one of the commercially important thermoplastics, especially for their low density, good processability, and easier mouldability for a wide range of applications . LDPE is more flexible than HDPE, which makes it a good choice for prosthetic devices. On the other hand Ultra high molecular weight polyethylene (UHMWPE) is a linear homopolymer with average molecular weight of 3-6million g/mole. For UHMWPE, the molecular chain can consists of as many as 200000 ethylene repeat units. Despite the relatively weak Van der Waals bonds between its molecules, the longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results i

Processing of Hybrid Nanocomposite High Performance Fibers (UHMWPE+NYLON 6+CNT+MAH) Using Solution Spinning Technique

Ultrahigh molecular weight polyethylene (UHMWPE) fiber blends with Nylon-6 and reinforced with single-walled carbon nanotubes (SWCNT) were produced using a solution spinning process. Polyethylene-graft-Maleic Anhydride (PE-g-MAH) was used as a compatibilizer to enhance the interfacial bonding between the polymer phases. The loading of Nylon-6, MAH, and SWCNTs with respect to UHMWPE was 20 wt.%, 10 wt.% and 2 wt.% respectively. The development of morphological characteristics due to the inclusion of a compatibilizer in an immiscible hybrid polymer nanocomposite fiber is hereby discussed. Characterization studies of the hybrid fibers were performed using scanning electron microscopy (SEM), Energy-dispersive X-Ray Spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR)

Experimental Study of Thermoelectric Properties of SWCNTs and SiC Nanoparticles and its Composites Doped with Sol-gel

Thermoelectric (TE) properties of Single wall carbon nanotubes (SWCNTs) and Silicon carbide (SiC) nanoparticles after treated with sol-gel dopants at elevated temperature. Different combinations of P and N type sol-gels were used. The combinations were Boron-Antimony, Aluminum-Antimony, Aluminum-Phosphorus and Boron–Phosphorus. The nanoparticles were randomly distributed on a nonconductive glass substrate and hot and cold junctions were created using silver epoxy and Alumel (Ni-Al) wire. The carbon nanotubes used were approximately 60% semiconducting and 40% metallic. Voltage (mV), current (μA) and resistance (Ω) were measured across the distributed nanoparticles within 160° C temperature difference. The Seebeck coefficient for pristine SWCNTs was 0.12 mV/oC. When doped with Boron-Antimony the Seebeck coefficient increased to 0.981 mV/°C. On the hand, SiC nanoparticles showed no TE effect at pristine form, but when infused with SWCNTs substantial TE effect was present. Even though the Seebeck coefficient was in a similar range with different SWCNT concentrations (wt%), current, resistance and Power factor (P.F.) changed with wt% of nanotubes. Resistance of the nanotube samples slightly decreased with the increase in temperature. Finally, the SiC+SWCNT composites were prepared using the sintering process at around 1500° C. Thermoelectric and Mechanical properties of the composites were tested. The structure-property relation was analyzed using SEM (scanning electron microscope) and XRD (X-ray diffraction). It was revealed that fiber like SWCNTs created randomly distributed network with Nano contact junctions inside the SiC matrix and enhance thermoelectric and mechanical properties in the combined SiC+SWCNTs material system

Investigation of MWCNT Reinforcement on the Strain Hardening Behavior of Ultrahigh Molecular Weight Polyethylene

We have investigated strain hardening behavior of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with 2.0 wt% loading of multiwalled carbon nanotubes (MWCNTs). A solution spinning process was used to produce neat and MWCNT-reinforced filaments of UHMWPE. Tensile tests of filaments showed 62% and 114% improvement in strength and modulus, respectively. Strain hardening tests on filaments revealed spectacular contribution by MWCNTs in enhancing strength and modulus by more than one order of magnitude. SEM micrographs showed sufficient coating of nanotube surface with the polymer that promoted interface adhesion. This intimate interfacial interaction enforced alignment of nanotubes during repeated loading-unloading sequences and allowed effective load transfer to nanotubes. Close interaction between UHMWPE and nanotubes was further evidenced by Raman spectral distribution as a positive shift in the D-band suggesting compressive stress on nanotubes by lateral compression of polymer. Nanotubes thus deformed induced the desired strain hardening ability in the UHMWPE filament. Differential scanning calorimetry (DSC) tests indicated around 15% increase in crystallinity after strain hardening—which together with nanotube alignment resulted in such dramatic improvement in properties

Morphological Characteristics of UHMWPE+Nylon- 6+SWCNT Solution-Spun Hybrid Nanocomposite Fibers Compatibilized with PE-g-MAH’

Hybrid nanocomposite fibers from a blend of Ultrahigh molecular weight polyethylene (UHM-WPE)+Nylon-6+single-walled carbon nanotubes (SWCNT) were produced using a solution spinning process, both with and without a compatibilizer, Polyethylene-graft-Maleic Anhydride (PEG-g-MAH). The loading of Nylon-6, PE-g-MAH and SWCNTs was 20, 3, and 2 wt% of UHMWPE. A comparative morphological study of the fibers was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis. SEM images of hybrid fiber cross-sections have shown polymer-coated SWCNTs aligned along the direction of extrusion inside the polymer. The blends with compatibilizer have shown rough and indistinct interfacial separation of the constituent phases, as seen in both cross-sectional and longitudinal views of fibers in SEM micrographs. Whereas, the samples without compatibilizer showed distinct minor polymer phase as droplets. DSC results indicate reduction of crystallinity, crystallization rate and lamellar size in the compatibilized blends. Comparative FTIR analysis of the fiber blends showed the presence of new absorbance peaks (at 1753.62 and 1210–990 cm–1) suggesting formation of imide linkages between the UHMWPE backbone and Nylon-6 chains in the blends with compatibilizer via reactive functional groups present in the PE-g-MAH. The appearance of these peaks were more prominent when nanotubes were present in the blend

Electrospinning of Cisplatin-Loaded Cellulose Nanofibers for Cancer Drug Delivery

Cellulosic nanofibers have been electrospun with an antitumor agent Cisplatin. Cellulose acetate (CA) and Cisplatin were co-electrospun using a coaxial electrospinning system. For the outer sheath, a solution of 7.5wt% CA in Acetone and DMAc (2:1) was used. The inner core consisted of Cisplatin dissolved in DMF at a concentration of 5mg/ml. Drug-loaded nanofibers from Cellulose pulp (2wt%) dissolved in NMMO. H2O were also produced. The solutions were electrospun in a high voltage electric field of 25–30 kV. Characterization of neat and drug-loaded nanofibers was performed using Scanning electron microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The characterization studies have shown the formation of nanofibers having both sporadic beads with internal agglomeration and conjugation of Cisplatin on the nanofiber surfaces

Enhanced Charge Carrier Concentration of SiC/CNT with N and P Type Doping Agents

Single-walled Carbon nanotubes (SWCNTs) have been shown to have excellent conductive properties. SWCNTs were dispersed in a SiC nanoparticle matrix to form a homogeneous mixture that is both mechanically durable and conductive. The SWCNT amount has been varied. SiC/SWCNT mixtures were then doped with various N- and P-type agents, and the resulting samples were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Raman spectra of the samples were also measured for evidence of structural changes. Seebeck coefficients were measured for the doped samples demonstrating the change in thermoelectric properties. Shifts in the G peak (1580.6 cm-1) of the Raman spectra of the samples provides evidence of an increase in charge carrier concentration in the doped samples, correlating well with the Seebeck coefficient results