scholarly journals Light-Induced Actuation of Poly(dimethylsiloxane) Filled with Graphene Oxide Grafted with Poly(2-(trimethylsilyloxy)ethyl Methacrylate)

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1059 ◽  
Author(s):  
Josef Osicka ◽  
Miroslav Mrlik ◽  
Markéta Ilčíková ◽  
Lukas Munster ◽  
Pavel Bazant ◽  
...  
Keyword(s):  
Surface Modification ◽  
Graphene Oxide ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Single Step ◽  
Point Of View ◽  
Inert Material ◽  
Ethyl Methacrylate ◽  
Transmission Electron ◽  
On Line

This study serves to combine two approaches into one single step, to achieve a significant improvement of the light-induced actuation capabilities. Graphene oxide (GO) is an inert material, from the electrical and thermal conductivity point of view, and is incompatible with the usually-used poly(dimethylsiloxane) (PDMS) matrix. During surface-modification by surface-initiated atom transfer radical polymerization, the GO was transformed into a conducting and compatible material with the PDMS showing enormous light-induced actuation capability. The GO surface-modification with poly(2-(trimethylsilyloxy)ethyl methacrylate) (PHEMATMS) chains was confirmed by transmission electron microscopy and thermogravimetric analysis, with an on-line monitoring of gasses using FTIR. The improved compatibility was elucidated using contact angle and dielectric properties measurements. The PHEMATMS shell was investigated using gel permeation chromatography and nuclear magnetic resonance. The improved electric conductivity was measured using the four-point probe method and by Raman spectroscopy. The very important mechanical properties were elucidated using dynamic mechanical analysis, and with the help of thermo-mechanic analysis for the light-induced actuation. The excellent actuation capabilities observed, with changes in the length of around 0.8% at 10% pre-strain, are very promising from the point of view of applications.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

scholarly journals Anchor Effect in Polymerization Kinetics: Case of Monofunctionalized POSS

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 515 ◽  
Author(s):  
Agnieszka Marcinkowska ◽  
Dawid Przadka ◽  
Beata Dudziec ◽  
Katarzyna Szczesniak ◽  
Ewa Andrzejewska
Keyword(s):  
Volume Fraction ◽  
Gel Permeation Chromatography ◽  
Polymerization Kinetics ◽  
Point Of View ◽  
Rate Coefficients ◽  
Anchor Effect ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Free Volume Fraction

The effect of the anchoring group on the detailed polymerization kinetics was investigated using monomethacryloxy-heptaisobutyl POSS (1M-POSS). This compound was copolymerized with lauryl methacrylate (LM) as the base monomer, at various molar ratios. The process was initiated photochemically. The polymerization kinetics were followed by photo-DSC and photorheology while the polymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). For comparison, a methacrylate containing the branched siloxy-silane group (TSM) was also studied. It was found that the modifiers with a bulky substituent have a dual effect on the termination process: (i) At low concentrations, they increase the molecular mobility by increasing the free volume fraction, which leads to an acceleration of the termination and slows the polymerization; while (ii) at higher concentrations, they retard molecular motions due to the “anchor effect” that suppresses the termination, leading to acceleration of the polymerization. The anchor effect can also be considered from a different point of view: The possibility of anchoring a monomer with a long substituent (LM) around the POSS cage, which can further enhance propagation. These conclusions were derived based on kinetic results, determination of polymerization rate coefficients, and copolymer analysis.

Reinforcing of phenol formaldehyde resin by graphene oxide and lignin nanohybrids

2019 ◽  
Vol 31 (5) ◽  
pp. 590-599 ◽  
Author(s):  
Jianzheng Zhang ◽  
Wang Rumin ◽  
Pengpeng Chen
Keyword(s):  
Graphene Oxide ◽  
Storage Modulus ◽  
High Performance ◽  
Phenol Formaldehyde ◽  
Weight Ratio ◽  
Mechanical Analysis ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
X Ray Diffraction ◽  
Transmission Electron

Utilizing synergetic effects of different fillers was an important strategy to develop high-performance polymer nanocomposites. In this work, novel hybrid nanofillers composed of graphene oxide (GO) and alkali lignin (L) were obtained successfully, and their reinforcing effect of phenol formaldehyde (PF) resin was fully investigated. The structures, morphologies, and properties of the GO-L nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscope, thermal gravimetry analysis, and Raman spectra. Dynamic mechanical analysis results showed that the GO-L–reinforced PF resin is much better than the single added GO and lignin with the same weight ratio. The effect of the filling ratio of GO-L on the storage modulus of PF was also investigated. Results showed that the storage modulus of PF was increased from 2015 MPa to 3675 MPa with the addition of 2 wt% of GO-L (3:7) hybrids.

Highly aligned graphene oxide/waterborne polyurethane fabricated by in-situ polymerization at low temperature

e-Polymers ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Lei Sang ◽  
Wentao Hao ◽  
Yuanyuan Zhao ◽  
Lulu Yao ◽  
Peng Cui
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Low Temperature ◽  
In Situ Polymerization ◽  
Waterborne Polyurethane ◽  
Mechanical Analysis ◽  
Transmission Electron ◽  
Degree Of Orientation ◽  
The Fourier Transform

AbstractNanocomposites of waterborne polyurethane (WPU) containing graphene oxide sheets (GO) were prepared by an in-situ polymerization method at low temperature. The morphology and interface structure were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Without undergoing complicated functionalization processes, GO can be finely embed into a WPU matrix and present high degree of orientation at high GO contents, due to the formation of chemical bonds and hydrogen bonding. From the Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) results, incorporation of GO exists in two ways and shows inverse effects. At a content of 2.0 wt.% GO loading, the tensile elastic modulus of the GO-WPU film increased by 193% to neat WPU. The nanocomposites also displayed 30°C higher thermal stability than WPU in thermogravimetric (TG) curves. This environment-friendly method may pave the way to design graphene-based polymer composites.

Radiation Damage in Ceramics

1982 ◽  
Vol 40 ◽  
pp. 600-603
Author(s):  
T. E. Mitchell ◽  
M. R. Pascucci ◽  
R. A. Youngman
Keyword(s):  
Radiation Damage ◽  
Outer Space ◽  
Point Of View ◽  
Nuclear Waste Storage ◽  
Waste Storage ◽  
Storage Media ◽  
Transmission Electron ◽  
Fundamental Point ◽  
Small Defect ◽  
Present Understanding

1. Introduction. Studies of radiation damage in ceramics are of interest not only from a fundamental point of view but also because it is important to understand the behavior of ceramics in various practical radiation enyironments- fission and fusion reactors, nuclear waste storage media, ion-implantation devices, outer space, etc. A great deal of work has been done on the spectroscopy of point defects and small defect clusters in ceramics, but relatively little has been performed on defect agglomeration using transmission electron microscopy (TEM) in the same kind of detail that has been so successful in metals. This article will assess our present understanding of radiation damage in ceramics with illustrations using results obtained from the authors' work.

Image registration with a computer driven S.T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 98-99
Author(s):  
A.M.H. Schepman ◽  
J.A.P. van der Voort ◽  
J.E. Mellema
Keyword(s):  
Spot Size ◽  
Scanning Transmission Electron Microscope ◽  
Small Computer ◽  
Structural Studies ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Specimen Area ◽  
On Line ◽  
Minimum Distances

A Scanning Transmission Electron Microscope (STEM) was coupled to a small computer. The system (see Fig. 1) has been built using a Philips EM400, equipped with a scanning attachment and a DEC PDP11/34 computer with 34K memory. The gun (Fig. 2) consists of a continuously renewed tip of radius 0.2 to 0.4 μm of a tungsten wire heated just below its melting point by a focussed laser beam (1). On-line operation procedures were developped aiming at the reduction of the amount of radiation of the specimen area of interest, while selecting the various imaging parameters and upon registration of the information content. Whereas the theoretical limiting spot size is 0.75 nm (2), routine resolution checks showed minimum distances in the order 1.2 to 1.5 nm between corresponding intensity maxima in successive scans. This value is sufficient for structural studies of regular biological material to test the performance of STEM over high resolution CTEM.

Recent developments in automated Transmission Electron MI

1989 ◽  
Vol 47 ◽  
pp. 46-47
Author(s):  
W.J. de Ruijter ◽  
P. Rez ◽  
David J. Smith
Keyword(s):  
Image Analysis ◽  
Computer Image ◽  
Lens Design ◽  
Computer Image Analysis ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Recent Developments ◽  
On Line ◽  
Routine Procedures ◽  
Near Future

There is growing interest in the on-line use of computers in high-resolution electron n which should reduce the demands on highly skilled operators and thereby extend the r of the technique. An on-line computer could obviously perform routine procedures hand, or else facilitate automation of various restoration, reconstruction and enhan These techniques are slow and cumbersome at present because of the need for cai micrographs and off-line processing. In low resolution microscopy (most biologic; primary incentive for automation and computer image analysis is to create a instrument, with standard programmed procedures. In HREM (materials researc computer image analysis should lead to better utilization of the microscope. Instru (improved lens design and higher accelerating voltages) have improved the interpretab the level of atomic dimensions (approximately 1.6 Å) and instrumental resolutior should become feasible in the near future.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

On-line alignment and astigmatism correction using a TV and personal computer

1993 ◽  
Vol 51 ◽  
pp. 202-203
Author(s):  
F. Hosokawa ◽  
Y. Kondo ◽  
T. Honda ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
High Resolution ◽  
Personal Computer ◽  
Block Diagram ◽  
Incident Beam ◽  
Ccd Camera ◽  
Alignment Procedure ◽  
Astigmatism Correction ◽  
Transmission Electron ◽  
Alignment System ◽  
On Line

High-resolution transmission electron microscopy must attain utmost accuracy in the alignment of incident beam direction and in astigmatism correction, and that, in the shortest possible time. As a method to eliminate this troublesome work, an automatic alignment system using the Slow-Scan CCD camera has been introduced recently. In this method, diffractograms of amorphous images are calculated and analyzed to detect misalignment and astigmatism automatically. In the present study, we also examined diffractogram analysis using a personal computer and digitized TV images, and found that TV images provided enough quality for the on-line alignment procedure of high-resolution work in TEM. Fig. 1 shows a block diagram of our system. The averaged image is digitized by a TV board and is transported to a computer memory, then a diffractogram is calculated using an FFT board, and the feedback parameters which are determined by diffractogram analysis are sent to the microscope(JEM- 2010) through the RS232C interface. The on-line correction system has the following three modes.

Confidentiality of Statistical Records: A Threat-Monitoring Scheme for On Line Dialogue

1976 ◽  
Vol 15 (01) ◽  
pp. 36-42 ◽  
Author(s):  
J. Schlörer
Keyword(s):  
Statistical Data ◽  
Cost Benefit ◽  
Data Bank ◽  
High Ratio ◽  
Point Of View ◽  
Data Sets ◽  
Monitoring Scheme ◽  
Access Controls ◽  
On Line ◽  
Bona Fide

From a statistical data bank containing only anonymous records, the records sometimes may be identified and then retrieved, as personal records, by on line dialogue. The risk mainly applies to statistical data sets representing populations, or samples with a high ratio n/N. On the other hand, access controls are unsatisfactory as a general means of protection for statistical data banks, which should be open to large user communities. A threat monitoring scheme is proposed, which will largely block the techniques for retrieval of complete records. If combined with additional measures (e.g., slight modifications of output), it may be expected to render, from a cost-benefit point of view, intrusion attempts by dialogue valueless, if not absolutely impossible. The bona fide user has to pay by some loss of information, but considerable flexibility in evaluation is retained. The proposal of controlled classification included in the scheme may also be useful for off line dialogue systems.

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