Electrostrictive Grafr Elastomers and Applications

1999 ◽  
Vol 600 ◽  
Author(s):  
J. Su ◽  
J. S. Harrison ◽  
T. L. St. Clair ◽  
Y. Bar-Cohen ◽  
S. Leary
Keyword(s):  
Energy Density ◽  
Electric Field ◽  
High Performance ◽  
Mechanical Energy ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Electromechanical Properties ◽  
Scanning Calorimetry ◽  
Polyurethane Elastomers ◽  
New Class

AbstractEfficient actuators that are lightweight, high performance and compact are needed to support telerobotic requirements for future NASA missions. In this work, we present a new class of electromechanically active polymers that can potentially be used as actuators to meet many NASA needs. The materials are graft elastomers that offer high strain under an applied electric field. Due to its higher mechanical modulus, this elastomer also has a higher strain energy density as compared to previously reported electrostrictive polyurethane elastomers. The dielectric, mechanical and electromechanical properties of this new electrostrictive elastomer have been studied as a function of temperature and frequency. Combined with structural analysis using x-ray diffraction and differential scanning calorimetry on the new elastomer, structure-property interrelationship and mechanisms of the electric field induced strain in the graft elastomer have also been investigated. This electroactive polymer (EAP) has demonstrated high actuation strain and high mechanical energy density. The combination of these properties with its tailorable molecular composition and excellent processability makes it attractive for a variety of actuation tasks. The experimental results and applications will be presented.

scholarly journals Enhanced Water Solubility and Oral Bioavailability of Paclitaxel Crystal Powders through an Innovative Antisolvent Precipitation Process: Antisolvent Crystallization Using Ionic Liquids as Solvent

Pharmaceutics ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1008 ◽  
Author(s):  
Qilei Yang ◽  
Chang Zu ◽  
Wengang Li ◽  
Weiwei Wu ◽  
Yunlong Ge ◽  
...  
Keyword(s):  
Oral Bioavailability ◽  
High Performance ◽  
Water Solubility ◽  
Water Soluble ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Antisolvent Precipitation ◽  
Antisolvent Crystallization ◽  
Artificial Gastric Juice

Paclitaxel (PTX) is a poor water-soluble antineoplastic drug with significant antitumor activity. However, its low bioavailability is a major obstacle for its biomedical applications. Thus, this experiment is designed to prepare PTX crystal powders through an antisolvent precipitation process using 1-hexyl-3-methylimidazolium bromide (HMImBr) as solvent and water as an antisolvent. The factors influencing saturation solubility of PTX crystal powders in water in water were optimized using a single-factor design. The optimum conditions for the antisolvent precipitation process were as follows: 50 mg/mL concentration of the PTX solution, 25 °C temperature, and 1:7 solvent-to-antisolvent ratio. The PTX crystal powders were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, high-performance liquid chromatography–mass spectrometry, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Raman spectroscopy, solid-state nuclear magnetic resonance, and dissolution and oral bioavailability studies. Results showed that the chemical structure of PTX crystal powders were unchanged; however, precipitation of the crystalline structure changed. The dissolution test showed that the dissolution rate and solubility of PTX crystal powders were nearly 3.21-folds higher compared to raw PTX in water, and 1.27 times higher in artificial gastric juice. Meanwhile, the bioavailability of PTX crystal increased 10.88 times than raw PTX. These results suggested that PTX crystal powders might have potential value to become a new oral PTX formulation with high bioavailability.

scholarly journals Improved dielectric constant and energy density of P(VDF-HFP) composites using NBT-xST (x=0, 0.10, 0.26) whiskers

2018 ◽  
Vol 08 (06) ◽  
pp. 1850040 ◽  
Author(s):  
Xuefan Zhou ◽  
Lu Wang ◽  
Guoliang Xue ◽  
Kechao Zhou ◽  
Hang Luo ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Dielectric Constant ◽  
Energy Storage ◽  
Energy Density ◽  
Electric Field ◽  
High Performance ◽  
Volume Fraction ◽  
High Energy ◽  
High Energy Density ◽  
Surface Modified

The high-performance energy-storage dielectric capacitors are increasingly important due to their wide applications in high power electronics. Here, we fabricated a novel P(VDF-HFP)-based capacitor with surface-modified NBT-[Formula: see text]ST ([Formula: see text], 0.10, 0.26) whiskers, denoted as Dop@NBT-[Formula: see text]ST/P(VDF-HFP). The influences of ST content, fillers’ volume fraction and electric field on the dielectric properties and energy-storage performance of the composites were investigated systematically. The results show that the dielectric constant monotonously increased with the increase of ST content and fillers’ volume fraction. The composite containing 10.0 vol% NBT-0.26ST whiskers possessed a dielectric constant of 39 at 1[Formula: see text]kHz, which was 5.6 times higher than that of pure P(VDF-HFP). It was noticed that the D-E loops of the composites became thinner and thinner with the increase of ST content. Due to the reduced remnant polarization, the composite with 5.0 vol% NBT-0.26ST whiskers achieved a high energy density of 6.18[Formula: see text]J/cm3 and energy efficiency of approximately 57% at a relatively low electric field of 200[Formula: see text]kV/mm. This work indicated that NBT-0.26ST whisker is a kind of potential ceramic filler in fabricating the dielectric capacitor with high discharged energy density and energy efficiency.

Preparation and Characterization of Wave-Absorbing Coated Radiation-Proof Composite Fabric

2013 ◽  
Vol 821-822 ◽  
pp. 1184-1188
Author(s):  
Jiao Wen ◽  
Zhi Rong Ding ◽  
Yan Qing Zhang ◽  
Rui Li Hao ◽  
Zhen Dong ◽  
...  
Keyword(s):  
Low Frequency ◽  
Network Analyzer ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Coating Technology ◽  
X Ray ◽  
Acetylene Carbon ◽  
Acetylene Carbon Black

Absorbing powders were covered on the surface of radiation-proof fabric by coating technology. Morphology, structure, property, electromagnetic parameters and reflectivity of the coated composite fabric were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD),differential scanning calorimetry (DSC) , thermogravimetry (TG) and microwave network analyzer respectively. The results showed that the coating on the surface of radiation-proof fabric was crystal, acetylene carbon black (ACB) and carbonyl iron powder (CIP) owned better stability of thermodynamics compared with alloy powder (AP). ACB coated composite fabric and CIP coated composite fabric has excellent absorbing effect on the radar X, Ku band, while AP coated composite fabric has absorbing effects on low-frequency.

Enhanced Energy Storage in Nanocomposites Through Aligned PZT Nanowires

2011 ◽  
Author(s):  
Haixiong Tang ◽  
Henry A. Sodano ◽  
Yirong Lin
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Dielectric Permittivity ◽  
Aspect Ratio ◽  
Electric Field ◽  
Applied Electric Field ◽  
Energy Storage And Conversion ◽  
Electromechanical Properties ◽  
Capacitive Energy Storage ◽  
Wide Range

Nanocomposites consisting of a piezoceramic inclusion and polymer matrix offer a combination of electromechanical coupling with high toughness and ductility inherent to polymers. There is a wide range of applications for these types of materials due to their intrinsic piezoelectric and dielectric properties, such as vibration sensing, actuation, energy harvesting and capacitive energy storage. However, the relatively low piezoelectric strain coefficient and dielectric permittivity of these nanocomposites significantly limit their application in energy conversion and energy storage applications. There are mainly two coupled to improve the dielectric permittivity and electromechanical properties of piezoceramic nanocomposites, namely higher aspect ratio active inclusions and alignment of inclusions in the direction of the applied electric field. Previously, we have demonstrated that using higher aspect ratio lead zirconate titanate (PZT) nanowires (NWs) could significantly enhance the energy density and d33 coupling as compared to the samples with lower aspect ratio PZT nanorods [11]. In this paper, we will show that orientation of PZT NWs also influences energy storage capability of nanocomposite. Nanocomposites with aligned PZT NWs in the direction of the applied electric field show increased dielectric permittivity and energy density as compared to those with randomly dispersed inclusions. PZT NWs are hydrothermally synthesized, dispersed into a polyvinylidene fluoride (PVDF), cast into a film and then aligned through uniaxial stretching. Scanning electric microscopy (SEM) shows the PZT NWs are successfully aligned in direction of stretching. This work demonstrates that the energy storage and conversion capability of the nanocomposite can be significantly enhanced through the alignment of PZT NWs in the direction of the applied electric field. The findings of this research could lead to broad interest due to demonstration of developing piezoceramic nanocomposites with enhanced dielectric and electromechanical properties for next generation energy storage and conversion devices.

Synthesis and Liquid Crystalline Properties of New Chiral Monomers and Polysiloxanes

2013 ◽  
Vol 815 ◽  
pp. 747-751
Author(s):  
Jian She Hu ◽  
Yi Nan Liu ◽  
Ya Ting Song ◽  
Di Wang
Keyword(s):  
Liquid Crystalline ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Crystalline Materials ◽  
H Nmr ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Liquid Crystalline Materials

To study the structure-property relationships of new chiral liquid crystalline materials based on menthol and explore their potential applications, a monomer 4-(4-allyloxybenzoyloxy) phenyl-4-menthyl-oxyacetyloxybiphenyl-4-carboxylate (LCM) and the corresponding homopolymer (LCP) were synthesized. The chemical structure was characterized by FT-IR and 1H NMR. The liquid crystalline properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The monomer LCM formed a cholesteric phase when a flexible linkage chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. The homopolymer LCP exhibited a batonnet texture of a smectic A phase.

Crosslinking and Mechanical Properties of Liquid Rubber. I. Curative Effect of Aliphatic DIOLS

1979 ◽  
Vol 52 (5) ◽  
pp. 920-948 ◽  
Author(s):  
Yuji Minoura ◽  
Shinzo Yamashita ◽  
Hiroshi Okamoto ◽  
Tadao Matsuo ◽  
Michiaki Izawa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Low Molecular Weight ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Curative Effect ◽  
Polyurethane Elastomers ◽  
X Ray ◽  
Structure Property Relationships ◽  
The Difference

Abstract The structure-property relationships of polyurethane elastomers derived from a liquid hydroxyl-terminated polybutadiene/low molecular weight aliphatic diol/diisocyanate system were studied. The effects of the amount of low molecular weight diol on the mechanical properties of the elastomer were discussed on the basis of the results of stress-strain, swelling, dynamic viscoelasticity, x-ray diffraction, etc. It was found that some particular combinations of low molecular weight diol and diisocyanate specifically affect the properties of elastomers. When the mechanical properties of the elastomers were plotted against the number of methylene carbons in the low molecular weight diol, characteristic zigzag patterns were obtained. These patterns were explained by the difference in the packing and the dependence of the strength of intermolecular hydrogen bonding on whether the number of the methylene carbons was even or odd. This assumption was confirmed by x-ray diffraction.

scholarly journals Use of Pulsed Electric Field as a Low-Temperature and High-Performance “Green” Extraction Technique for the Recovery of High Added Value Compounds from Olive Leaves

Beverages ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 45
Author(s):  
Vasileios M. Pappas ◽  
Achillia Lakka ◽  
Dimitrios Palaiogiannis ◽  
Eleni Bozinou ◽  
George Ntourtoglou ◽  
...  
Keyword(s):  
Electric Field ◽  
Pulse Duration ◽  
High Performance ◽  
Agricultural Waste ◽  
Pulsed Electric Field ◽  
Added Value ◽  
Green Solvents ◽  
Olive Leaves ◽  
Duration Of Treatment ◽  
Scanning Calorimetry

Olive leaves (OLL), an agricultural waste by-product, are considered a significant bioresource of polyphenols, known as bioactive compounds. This study evaluates the pulsed electric field (PEF) technique for the extraction of polyphenols from OLL. The study parameters included a series of “green” solvents (ethanol, water as well as mixtures of them at a 25% step gradient) and different input values for the pulse duration of PEF. The phytochemical extraction degree was evaluated using total phenol concentration (Folin–Ciocalteu method) and high-performance liquid chromatography (HPLC) analyses, while the antioxidant activity was assessed using differential scanning calorimetry (DSC). The results obtained from the PEF extracts were compared with those of the extracts produced without the PEF application. The highest PEF effect was observed for aqueous ethanol, 25% v/v, using a pulse duration of 10 μs. The increase in the total polyphenols reached 31.85%, while the increase in the specific metabolites reached 265.67%. The recovery in polyphenols was found to depend on the solvent, the pulse duration of treatment and the structure of the metabolites extracted.

Metal–organic framework structure–property relationships for high-performance multifunctional polymer nanocomposite applications

2021 ◽  
Vol 9 (8) ◽  
pp. 4348-4378
Author(s):  
Vishnu Unnikrishnan ◽  
Omid Zabihi ◽  
Mojtaba Ahmadi ◽  
Quanxiang Li ◽  
Patrick Blanchard ◽  
...  
Keyword(s):  
High Performance ◽  
Metal Organic Framework ◽  
Internal Surface ◽  
Polymer Nanocomposite ◽  
Structure Property ◽  
Framework Structure ◽  
New Class ◽  
Surface Areas ◽  
Structure Property Relationships ◽  
Metal Organic

Metal–organic frameworks (MOFs) have emerged as a new class of crystalline nanomaterials with ultrahigh porosities and high internal surface areas.

Lacidipine: review of analytical methods developed for pharmaceutical dosage forms and biological fluids

Bioanalysis ◽  
2021 ◽  
Author(s):  
Sai Tejasvini Chebrolu ◽  
Lalit Kumar ◽  
Ruchi Verma
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Ultra Violet ◽  
Analytical Techniques ◽  
Dosage Forms ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Limit Of Quantification ◽  
Pharmaceutical Dosage Forms

Lacidipine (LAC) is a calcium antagonist used in the treatment of hypertension. It is a lipophilic drug containing dihydropyridine ring that is responsible for the activity. This review article gives an overview of various analytical techniques proposed for the determination of LAC in pharmaceutical dosage forms, in pure form, in biological fluids and to determine characteristics of LAC in modified release dosage forms. Ultra violet/visible spectrophotometric, spectroflourimetric, high performance liquid chromatography, high performance thin layer chromatography, electro-analytical, bioanalytical and miscellaneous methods such as microbiological assay, X-ray diffraction, differential scanning calorimetry, were discussed. Various parameters such as system suitability, selectivity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness have been discussed for the employed methods.

Preparation and Thermal Properties of Polybenzoxazine/TiC Hybrids

2014 ◽  
Vol 887-888 ◽  
pp. 49-52 ◽  
Author(s):  
Noureddine Ramdani ◽  
Jun Wang ◽  
Wen Bin Liu
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
High Performance ◽  
Phenolic Resin ◽  
Scanning Calorimetry ◽  
New Class ◽  
Solution Blending ◽  
Tic Nanoparticles ◽  
Thermal Stability Of

In this work, typical polybenzoxazine, as new class of phenolic resin, has been used as a matrix for preparing a series of high performance hybrid materials using various amounts of titanium carbide (TiC) ranging between 0-10 wt% as fillers, via a solution blending technique. The thermal properties of bisphenol A-aniline base benzoxazine monomers (BA-a) and TiC mixtures have been studied by differential scanning calorimetry (DSC). The thermal stability of their cured hybrids has been tested by means of thermogravimetric analysis (TGA). The result showed that the glass transition temperature of the prepared composites increased with increasing the amount of TiC to reach a higher value at 194°C. Also, the incorporation of TiC nanoparticles has considerably improved the thermal stability of the hybrids including the char yield which increase by 50 % at 10 wt% TiC content.

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