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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Novel Biocide Based on Cationic Derivative of Psyllium: Surface Modification and Antibacterial Activity

To circumvent the problems (such as volatilization, photolytic decomposition, chemical instability, easy permeability through the skin) associated with low molecular weight antimicrobial agents, our strategy employed graft copolymerization of cationic monomer with the polymeric substrate viz. psyllium husk. The surface graft concentration of quaternary ammonium ion on psyllium was optimized by measuring the extent of grafting in the microwave-induced process. The surface modification of graft copolymers was evident by different physico–chemical techniques like {sup 13}C nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), Thermo gravimeteric analysis (TGA), and viscometric study. The synthesized water soluble product resulted good antibacterial activity against Gram positive Staphylococcus aureus and Bacillus anthracis but failed to produce any antibacterial activity against Gram negative Salmonella typhi and Escherichia coli. The reason to failure has been explained on the basis of differences in the electrokinetic property between Gram-positive and Gram-negative bacteria. Optimum minimum inhibitory concentration (MIC) for the polymeric grade which showed good biocidal effect evaluated by both zone of inhibition and absorbance is found at 1000 µg/ml.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Layer by Layer Photo-Cross-Linked Environmental Functional hydrogel Thin Films Based on Vanillin: Part 3

The present work emphasizes the preparation of new monomer from the family of vanillin acrylate. It has been prepared in two steps the name of the final product is [2-((ditert-butylamino) methyl)-4-formyl-6-methoxyphenyl acrylate] and abbreviated by TBAMVA, both products were evaluated by {sup 1}H, {sup 13}C NMR and FTIR and they were in the logic case with the chemical structure. The next step was the preparation of three different pH and temperature responsive copolymers by free radical polymerization of 5, 10, 20 mol% of TBAMVA and 5 mol% of maleimide photo-cross-linker with N-isopropylacrylamide. Polymers were chemically and physically characterized indicating the presence of the aldehyde group in the main chain. The lower critical solution temperature of polymers has been determined by two methods; the first one using turbidity measurements by UV–Vis Spectroscopy, another method using micro-DSC. The last step was the formation of pH-Temperature responsive hydrogel layer over gold and studying the swelling properties response to pH and temperature using surface plasmon resonance with the optical waveguide. In the present work, we focused on synthesizing new environmental functional polymers and hydrogel thin films used as biosensor as a target for many biological molecules in biosynthesis, drug delivery, and bio-separation.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Thermo-Oxidative Aging of LDPE/Stearoyl Chloride-Grafted Cellulose Nanocrystals Blown Films

The effect of the incorporation of pristine and stearoyl chloride grafted CNCs on the chemical, mechanical, thermal and microstructural properties, during the thermo-oxidative aging, of LDPE blown films at 60 °C was studied. The success of the pristine CNCs grafting was assessed by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Thermal-gravimetric analysis (TGA), Atomic Force Spectroscopy (AFM) and contact angle measurements. The results show that chemical modification decreases both, the CNCs thermal stability and the polar component of surface energy, i.e. increases the nanocrystals hydrophobicity. Also, it was found that neither CNCs crystalline structure nor its dimensions changed with grafting. The changes on the blown film properties during thermo-oxidative aging were monitored using FT-IR, DSC, DRX and tensile testing. It was found that the CNCs catalyzed the production of carboxylic acids as a final degradation by-product, whereas the CNC-g-C{sub 18} inhibits its formation, i.e. in presence of CNCs grafted with stearoyl chloride the catalytic effect attributed to the pristine CNCs was partially inhibited. The DSC, DRX and tensile testing results show the microstructural arrangements due to the annealing and the chains oxidation predominated during the first 30 days of aging and then chain scissions prevail. These findings suggest an analogous reduction in molecular weight at the end thermo-oxidative aging. In addition, the presence of a high concentration of carboxylic acid and the drop in molecular weight after LDPE aging will facilitate the biodegradation of these oxo-degradable films.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Production of Hydrogel Microneedles from Fish Scale Biopolymer

This work presents for the first time, a scalable, low cost method for producing hydrogel microneedles from fish scales derived biopolymer using a modified low temperature press method. The microneedles are made from cross-linked hydrolyzed collagen (HC). The suitability of the microneedles for drug loading were tested by loading with Ferrous gluconate. Force analysis carried out in compression mode showed that the microneedles could withstand up to 0.136 N per microneedle before fracture which is sufficient strength to pierce the skin. The cross-linked microneedles swelled to 340% of their original mass in PBS and within 24 h released 34.5% of the loaded drug, while the non cross-linked microneedles dissolved within minutes. Chemical testing of the released drug confirmed that the drug released retained its chemical structure by forming colored complex with acetylsalicylic acid and UV spectrometry was used to quantify the concentration released. FTIR analysis confirmed the modified structure of the polymer when cross-linked. This proposed method allows cross-linking at room temperature using a thermal press method which can be easily scaled up.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

The Effect of Citric Acid on Physicochemical Properties of Hydrophilic Carboxymethyl Starch-Based Films

The carboxymethyl starch-based films in a presence of citric acid were prepared by casting technique. The influence of citric acid content on physicochemical properties of obtained hydrophilic films were evaluated (solubility in water, moisture absorption, mechanical and thermal properties). The crosslinking of starch derivative chains has been confirmed by FTIR spectroscopy, however, an excess of citric acid could cause hydrolysis of carboxymethyl starch chains. The best mechanical performance has been noted for the system containing 30 wt% (the highest tensile strength as well Young modulus 160 kPa and 650 kPa, respectively) as well as the highest T{sub g} (ca. 58 °C). Additionally for the mentioned system the lowest solubility in water has been determined.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Synthesis and Characterization of a Novel pH-Sensitive Aluminum Crosslinked Carboxymethyl Tragacanth Beads for Extended and Enteric Drug Delivery

Carboxymethyl tragacanth (CM-TG) with a DS of 1.2 was synthesized and characterized for drug delivery using diclofenac sodium as a model drug. The mixture of CM-TG and drug was ionically crosslinked using aluminum chloride to form drug-loaded beads. The concentrations of 10 and 20% w/w solution of CM-TG were found to produce beads with acceptable qualities. The beads exhibited pH-dependent swelling. The highest swelling was observed at pH 6.8 which evidences the possibility to release the drug in the colon. FT-IR and TGA confirmed carboxymethylation of tragacanth and the absence of drug-polymer interaction. The diclofenac sodium entrapment efficiency was 30–35% while the loading varies from 4.5 to 18% w/w based upon the drug-polymer ratio. The beads could extend the drug release up to 180 min at pH 6.8. The pH-responsive CM-TG hydrogel beads are biocompatible and could be exploited as a new excipient in developing enteric release formulations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Application of Novel Adsorbent Prepared by Mucor hiemalis Biomass Impregnated with Calcium Alginate for Removal of Sr{sup 2+} from Aqueous Solutions

In this research, a novel biosorbent was prepared by Mucor hiemalis biomass combined with calcium alginate (Mucor hiemalis/Alg-Ca). The dead biomass was entrapped into alginate gel by curing method in the presence of Ca{sup 2+} ions. The synthesized biosorbent characterized by XRD, EDAX, BET, FTIR, and SEM techniques was used for removal of Sr{sup 2+} from aquatic streams under various experimental conditions and the optimized adsorption capacity of 140 mg g{sup −1} was obtained. The selectivity of the adsorbent towards Sr{sup 2+} studied in the presence of Na{sup +}, Cs{sup +}, Ca{sup 2+} and Mg{sup 2+} was reasonably high. The adsorption process was kinetically fast and the equilibrium was established within 60 min, and followed the pseudo-second order kinetics model. The equilibrium data was well described by Langmuir isotherm model. The thermodynamics parameters (∆G°, ∆H° and ∆S°) of the process were determined. Positive ∆H° and negative ∆G° were indicative of the endothermic and spontaneous nature of the adsorption process. Graphical Abstract: .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

A Novel Rigid PU Foam Based on Modified Used Palm Oil as Sound Absorbing Material

Novel bio-polyol was successfully synthesized from used palm oil (UPO) and was further tested for preparing rigid polyurethane (PU) foams. In this work, the modified used palm oil (MUPO) was synthesized in a single step process, by epoxidation together with ring opening reactions. The reagent ratios and reaction time for MUPO synthesis were also studied. The chemical structure of MUPO was confirmed by {sup 1}H-NMR spectroscopy and FTIR. The hydroxyl value of MUPO increased with reaction time and depended also on reagent ratio. The GPC trace of MUPO showed a bimodal distribution and the molecular weight slightly decreased with OH value. New rigid PU foams were prepared from MUPO. The foam cell size and compressive strength at 10% strain increased with OH value. All the rigid PU foams had excellent sound absorption coefficients. The lowest OH value (OHV = 100 mg KOH/g) provided sound absorption from 2200 Hz. In addition, the flammability of PU foams was improved by adding 30% wt of triphosphate (TPP) as flame retardant. The investigations showed that a bio-polyol based on UPO was suitable for preparing rigid PU foams that could serve as alternative sound absorbing materials. Graphical Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Accelerated Weathering and UV Protection-Ability of Poly(lactic acid) Nanocomposites Containing Zinc Oxide Treated Halloysite Nanotube

The aim of this study is to investigate the effects of zinc oxide treated halloysite nanotube (HNT-ZnO) on the properties of poly(lactic acid) (PLA) nanocomposites. ZnO was immobilized on HNT using a solvent-free technique. PLA nanocomposites were prepared with different loading of HNT-ZnO (i.e., 3, 5 and 7 wt%) using melt compounding. The properties of the PLA/HNT-ZnO nanocomposites were investigated using tensile test, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermogravimetric analysis and UV–visible spectroscopy. In addition, the effects of accelerated weathering (duration 60 days) on the behaviour of PLA/HNT-ZnO nanocomposites were studied. It was found that HNT-ZnO is capable to enhance the reinforcing ability, thermal stability and UV barrier of PLA nanocomposites. The PLA/HNT-ZnO films showed less discoloration and chain scission, indicating its higher photo-stability as compared to PLA/HNT after exposed to accelerated weathering. In summary, this study provides a basis for further development of PLA/HNT-ZnO nanocomposites with desirable mechanical, thermal and UV protection properties for potential outdoor application.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Microcellular Foaming Behaviors of Poly (Lactic Acid)/Low-Density Polyethylene Blends Induced by Compatibilization Effect

A facile methodology for improving the crystallization ability, rheological properties and microcellular foaming behaviors of poly (lactic acid)/low-density polyethylene (PLA/LDPE) blends through compatibilization was proposed. Poly (ethylene octene) grafted with glycidyl methacrylate (GPOE) as reactive compatibilizer was introduced into PLA/LDPE blends and the resultant PLA/LDPE/GPOE blends were foamed by supercritical CO{sub 2}. Torque curves and Fourier transformation infrared spectroscopy results confirmed that GPOE reacted with PLA successfully. The crystallization ability and rheological properties of PLA was promoted obviously by the addition of LDPE and GPOE. The size of LDPE dispersion phase in PLA/LDPE blends decreased from 4.4 ± 0.1 to 1.2 ± 0.1 µm, owing to the compatibility effect. When the content of GPOE reach 8 phr, microcellular structure appeared in the PLA/LDPE/GPOE blending foam. An interesting flower-like cellular structure was observed in PLA/LDPE/GPOE blending foams, with the foaming temperature at 85 and 90 °C. Finally, the microcellular foaming mechanism for various PLA foams was proposed and clarified using schematic diagram.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Wholly Heterocycles-Based Polyamide–Sulfide Containing Pyridine and Thiazole Rings: A Super-Adsorbent Polymer for Lead Removal

Wholly heterocycles-based polyamide-sulfide (PAS) containing pyridine and thiazole rings with thioether linkage was synthesized and used as a novel adsorbent for lead ion removal from water. The polymer adsorbent was fully characterized via FTIR, NMR and scanning electron microscopy (SEM). The thermal properties of the synthesized polyamide were also studied by thermogravimetric analysis and the outcome showed that the polymer has a good to moderate thermal stability. The SEM was used to investigate the morphology of the wholly heterocycles-based polyamide and the outcomes displayed a porous and globular-like morphology, which guarantee effective metal adsorption. Pb(II) ion removal capacity of the synthesized polymer was studied by varying the contact time and the adsorbent concentration. The maximum removal of Pb(II) was obtained as 99%. Equilibrium behavior and kinetic of the adsorption were also investigated using prevalent isotherm and kinetic models. The adsorption capacity was obtained to be around 714 mg g{sup −1}. The Langmuir isotherm and the pseudo-second order kinetic model suggested superior agreement with the equilibrium and kinetic adsorption data, respectively. Generally, the results of this research demonstrated that the synthesized polymer is a super-adsorbent for heavy metal removal from water.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Adsorption of Iron(III) and Copper(II) by Bacterial Cellulose from Rhodococcus sp. MI 2

Modified cellulose from the pellicle produced by Rhodococcus sp. MI 2 was more efficient at removing Fe(III) and Cu(II) from aqueous solution than similarly modified cellulose from Komagataeibar xylinus TISTR 998. This study first describes the modification of the cellulose to produce mercerized bacterial cellulose (MBC), phosphorylated bacterial cellulose (PBC), acid–base cellulose and diethylenetriamine bacterial cellulose (EABC). Their efficacy as adsorbents to adsorb Fe(III) and Cu(II) was then determined. In aqueous solution at pH 4 at initial Fe(III) concentration of 20 mg/L, PBC reached adsorption equilibrium within 195 min. At pH 5 in an initial Cu(II) concentration of 75 mg/L, EABC reached adsorption equilibrium within 210 min. Molecular structures and chemical bonds were examined by Fourier transform infrared spectroscopy (FT-IR) and physical morphologies by scanning electron microscopy. The adsorption kinetics of MBC, PBC and EABC showed good agreement with the proposed pseudo-second order model and the adsorption isotherm was best described by the Freundlich model. Our study determined optimal conditions, molecular structures, physical morphologies and adsorption kinetics. The cellulose produced by the new strain Rhodococcus sp. MI 2 was highly efficient at adsorbing and removing metal ions from aqueous solution.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Novel Environmentally Friendly Superabsorbent Hydrogel Hybrids from Synthesized Star-Shaped Bio-based Monomers and Acrylic Acid

During the past decades, production and applications of petroleum-based superabsorbents have grown dramatically; currently, superabsorbents are produced from acrylic acid, which consequently increase the environmental concerns. The high consumption rate of superabsorbent on the one hand, and their persistence in the environment from the other hand would make the waste of this material a potential hazard for the environment. These materials are not biodegradable, and if degraded hazardous derivatives would be released into soil and water. The current work presents the synthesis and the performance of a novel superabsorbent hydrogel, based on star-shaped bio-based compartments and acrylic acid. Herein, the synthesis of two bio-based star-shaped monomers will be reported based on the condensation reaction between hydroxyl and carboxylic acid end groups of a bio-acid and a bio-alcohol. The first monomer was synthesized from glycerin, succinic acid, lactic acid, itaconic acid, and acrylic acid. The second monomer was synthesized from glycerin, lactic acid, and methacrylic acid. The monomers structures were characterized via FT-IR and {sup 1}HNMR spectroscopies. The different portions of biobased monomers (10, 30, 50, and 70 wt%) were used in combination with the acrylic acid monomer to form hybrid superabsorbents. The swelling properties and the absorbency under load (AUL) of superabsorbents were investigated in turn. The maximum absorption capacities (398.49 and 90.10 g g{sup −1} in water and saline solution, respectively) were observed when 30 wt% of acrylic acid backbone of the superabsorbent was replaced with the bio-based monomer. Moreover, economic and environmental profiles of the hybrid SAPs have been evaluated. The comparative environmental assessment performed using life cycle analysis method, based on the material and energy balances obtained from the available literature. While the economy of the hybrid SAPs production still suffers from the high price of the employed raw biomaterials during manufacturing, the better environmental profiles obtained for the hybrid SAPs.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Synthesis and Characterization of Magnetic Halloysite–Alginate Beads for the Removal of Lead(II) Ions from Aqueous Solutions

In this study, alginate (ALG) hybrid spheres supported with magnetic halloysite nanotubes (MHNTs) were synthesized and used effectively in the removal of Pb(II) ions from aqueous solutions. MHNTs were prepared using the “co-precipitation” method. Afterward, magnetic halloysite–alginate (MHNT–ALG) hybrid beads were formed using ALG and MHNTs by the “extrusion dripping” method. The characterization of halloysite nanotubes (HNTs), ALG, MHNTs, and MHNT–ALG hydrogels was performed using FTIR, TGA, particle size analysis, SEM–EDX, TEM, VSM, and BET. According to VSM measurements, the saturation magnetization values of MHNTs and MHNT–ALG hybrid beads at a mass ratio of 1:2 were determined to be 22.7 emu/g and 8.17 emu/g, respectively. The BET surface area of MHNT–ALG hybrid beads was measured to be 81.3 m{sup 2}/g. The adsorption of Pb(II) ions on MHNT–ALG hydrogels was investigated as a function of the pH of the medium, amount of MHNT–ALG, the mass ratio of MHNT to ALG in the composite, and initial Pb(II) concentration in batch stirred vessels. The fit of the adsorption equilibrium of Pb(II) ions on MHNT–ALG hydrogels to the Langmuir type-I and type-II models, Freundlich model, and Redlich–Peterson model was investigated. The fit of the adsorption kinetics to the pseudo-second-order kinetics model was evaluated. Using the Weber and Morris model, the effect of internal and external diffusion limitations was discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2019

One-Pot Depolymerization and Polycondensation of PET Based Random Oligo- and Polyesters

The glycolysis of PET is a promising well-developed technique that could be utilized in a wide range of processes. Due to its equilibrial nature, the high ratio of reagents and the purification steps it is an expensive process. In this study our goal was to modify the standard glycolysis to an easily modulateable method (acido-alcoholysis) suited for one-pot oligoester, polyester synthesis. Adipic acid was added to the depolymerization reaction to connect low molecular weighed components into oligoesters. PET depolymerization reaction series were carried out with ethylene–glycol/adipic acid and butane-1,4-diol/adipic acid to demonstrate the tuneability of these systems. The reaction products were thoroughly characterized with NMR, FTIR, TGA, DSC and functional group analysis. One-pot depolymerization-polycondensation reactions were engineered to produce unsaturated and saturated polyesters. The unsaturated polyesters were dissolved in styrene, cross-linked and moulded to be characterized with DMA. A decreasing tendency of the glass transition temperature and cross-link density were found in the function of the ratio of adipic acid used during the depolymerization step. Acido-alcoholysis proved to be a versatile technique that could be used to engineer oligoesters and polyesters. The reagent use can be minimalized, and the raw reaction products can be directly applied as mid-products.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Biomass Derived Antimicrobial Hybrid Cellulose Hydrogel with Green ZnO Nanoparticles for Curcumin Delivery and its Kinetic Modelling

Regenerated cellulose obtained from sugarcane bagasse was used for hydrogel preparation using epichlorohydrin (crosslinker) and green zinc oxide nanoparticles (ZNPs) which were phytosynthesised from musk melon seed extract. The synthesised ZNPs were characterised using FESEM and EDAX. The swelling capacity of the hydrogel was determined by swelling measurements. For drug delivery studies from hydrogel, curcumin was selected as the model drug for its appealing anticancer and antimicrobial activity. The presence of ZNPs and curcumin in the hybrid hydrogel was analysed using FTIR, XRD, TGA and SEM analysis. The drug loading efficiency was optimised by Taguchi method. The drug release studies were performed under varying pH and initial drug loading concentration. The kinetic studies showed the best fit with case II type of transport with polymer swelling as the drug release mechanism. Antimicrobial activity for curcumin loaded hybrid hydrogel and pure cellulose hydrogel was performed using Staphylococcus aureus (bacteria) and Trichophyton rubrum (fungi). Thus, the developed curcumin loaded biomass derived hybrid hydrogel could find potential application towards skin infective applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Waste Eggshells for the Decoration of Carbon Nanotubes and Graphene Nanosheets with Hydroxyapatite for Preparation of LLDPE Nanocomposites

Waste eggshells were used to decorate functionalized carbon nanotubes (CNT) and graphene oxide (GO) by hydroxyapatite (HAP) using in situ synthesis. The HAP decorated CNT and GO were characterized by X-ray diffraction, SEM, and IR spectroscopic techniques. CNT-HAP and GO-HAP were further used to prepare polymer nanocomposites by addition of different percentages of synthesized CNT-HAP and GO-HAP as fillers into linear low density polyethylene (LLDPE). The prepared nanocomposites specimens were utilized for physical and thermo-mechanical analysis. Mechanical properties of the LLDPE nanocomposites were improved with increasing the percentage of CNT-HAP and GO-HAP fillers compared to the pristine LLDPE. Hardness of hybrid-CNT-HAP/LLDPE composite was increased as compared to the GO-HAP/LLDPE, where as tensile strength of the GO-HAP/LLDPE was higher than that of the CNT-HAP/LLDPE composite. Flammability of CNT-HAP and GO-HAP composites was decreased by 32% as compared to the pristine LLDPE. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Gelatin/Gelatinized Sago Starch Biomembranes as a Drug Delivery System Using Rubber Latex as Plasticizer

Preparation and properties of gelatin and gelatin/gelatinized sago starch biomembranes as a drug delivery system are presented. Deproteinized natural rubber latex (DNRL) was chosen to blend as a plasticizer in biomembranes due to its elasticity. The opaque biomembranes were formed, and the effect of DNRL amounts (10–50 part per hundred of gelatin; phg) on mechanical properties of biomembranes was investigated. It was discovered that increasing the amounts of DNRL could decrease the brittleness of biomembranes. However, these DNRL blended biomembranes still swelled, dissolved in water, and eroded within 2 h. The 50 phg DNRL was further chosen for biomembrane preparations. Then, the 5–30 phg gelatinized sago starch which was prepared in-house was added. These gelatin/gelatinized sago starch biomembranes were homogenous and opaque. They portrayed good water uptake properties, and the highest values occurred in 20–30 min, then these biomembranes eroded slowly. Increasing the amounts of sago starch in biomembranes raised the water uptake rates but reduced the erosion properties. Biomembranes with and without starch blends showed the same tensile strengths. Their elongations at break increased when the amounts of starch were raised but still were lower than that of gelatin/DNRL biomembranes. The morphology, scanning electron microscopy, atomic force electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimeter, and X-ray diffractometer confirmed the compatibility of ingredients in biomembranes. Lidocaine and its hydrochloride salt were successfully incorporated in these biomembranes with good properties. The drug release and permeation of biomembrane showed good drug controlled release and were able to permeate through the pig skin.

36 MATERIALS SCIENCE↗