In this study, novel route for the preparation of novel stacked structure and one-step fabrication of electrospun silica microbelt with controllable wettability by a combination of sol-gel chemistry and electrospinning techniques. The application field of the one-dimensional silica in different environmental conditions was controlled by functionalization of the hydroxyl groups and non-polar groups on the backbone. Experimental results reveal that the formation of one-dimensional stacked structure is strongly related to the conductive properties of collective substrate. The exploration of the one-dimensional stacked structure mechanism was also conducted.
The present work studies the synergistic effect of graphene and carbon nanofiber (CNF) in nanopaper on the electrical properties and electro-active recovery behavior of shape memory polymer (SMP) nanocomposite. The combination of graphene and CNF is used to improve the electrical and thermal conductivities of the SMP. Graphene is first employed to significantly improve the electrical conductivity along horizontal orientation, as well as CNFs were expected to bridge the gap among individual graphene and improve the through-thickness electrical performance of nanopaper. Furthermore, the conductive nanopaper is coated on the surface and improves the electrical properties of the SMP nanocomposite, resulting in the shape recovery can be achieved by electricity. Finally, the temperature distribution has been characterized to experimentally testify the effect of nanopaper on the SMP nanocomposite in the electro-responsive recovery process.
Shape-memory materials (SMMs) are fascinating materials, with the potential for application as “smart materials” and also as actively moving materials, which can change their shape in a predefined way between/among shapes in presence of an appropriate stimulus. The intention of this article is to present a systematic and up-to-date account of chemoresponsive amorphous shape-memory polymers (SMPs) from basic principles in phase transition to experiments. Based on the previous work, phase transition of the chemo-responsive SMPs. of which the transition temperature is originated from the glass transition, is presented. Studies have been explored for chemo-responsive SMPs in various design principles in water/solvent induced shape-memory effect. Some examples, including are also presented.
A new nanopaper that exhibits exciting electrical and electromagnetic performances is fabricated by incorporating
magnetically aligned carbon nanotube (CNT) with carbon nanofibers (CNFs). Electromagnetic CNTs were blended with
and aligned into the nanopaper using a magnetic field, to significantly improve the electrical and electromagnetic
performances of nanopaper and its enabled shape-memory polymer (SMP) composite. The morphology and structure of
the aligned CNT arrays in nanopaper were characterized with scanning electronic microscopy (SEM). A continuous and
compact network of CNFs and aligned CNTs indicated that the nanopaper could have highly conductive properties.
Furthermore, the electromagnetic interference (EMI) shielding efficiency of the SMP composites with different weight
content of aligned CNT arrays was characterized. Finally, the aligned CNT arrays in nanopapers were employed to
achieve the electrical actuation and accelerate the recovery speed of SMP composites.
The new structures and multifunctional materials is that it can achieve some other special functions while it has ability to
carry, such as wave-transparent, absorbing, anti-lightning, anti-heat, anti-nuclear etc. It represents the direction of future
development of structural materials. And graphene is the one of two-dimensional atomic crystal free substance only
found in the existence and shows great importance for fundamental studies and technological applications due to its
unique structure and a wide range of unusual properties. It exhibits great promise for potential applications in chemistry,
materials, and many other technological fields.
In this paper, we prepare nanopaper through physical vapor deposition (PVD) with a variety in the weight ratio between
graphene and nanofiber. Then prepare composite materials with nanopaper and T300/AG80 prepreg by the meaning of
autoclave molding. The morphology of nanopaper was characterized by transmission electron microscopy (TEM) and
scanning electron microscope (SEM). And the electrical properties and the EMI shielding performances of these
nanocomposites have been investigated experimentally by and four-point probe measurement and vector network
analyzer. The experimental results indicate that the composites made from graphene and nanofiber nanopaper have
highly electric capability, and the EMI shielding value of composites were all up to -15dB. In the same time the
conductivity and the EMI shielding performances were improved with increasing the ratio of graphene in nanopaper.
We tested the mechanical properties of composite materials at the same time. The average strength of composite
materials is about 2000MPa, the elastic modulus is 130GPa above. We are sure that it can be used as the load-bearing
structural material which has a multi-functional performance in the aviation field.
Percolation threshold (PT) phenomena, existing in filler filled systems, play a central role in the insulator-to-conductor
transition of electrical properties. While PT problem is important for mathematical-physical search, it also contributes to
the sharp transition of other properties. In works published in previous researches in this issue, all PT problems were
investigated the role in the transition of properties from experiential profile. In this paper, a mathematical model is
developed to study the percolation of composites filled with randomly oriented particles. Special emphasis is given to
found the dependence of the PT on unit cells (UCs) partition. Moreover, developed model agrees quite well with the
experimental results and is expected being applicable to predict PT of composites using the motion coefficient as a fitting
parameter. An important advance to the subject matter is done to study the dependence of anisotropic electrical
properties on UCs partition with motion coefficient.
By adding randomly distributed short fiber into a shape memory polymer (SMP) matrix, both the mechanical properties
and the shape memory behavior are improved significantly, overcoming some traditional defects of SMP composite
reinforced by long fiber and particles. In this paper, the short fiber reinforced SMP composite are developed for the
improvement of the mechanical and thermal properties of styrene-based SMP bulk. The specimens with different
chopped fiber weight fractions are prepared, and then their mechanical behavior and electrical properties are
investigated. As a result, the resistance against mechanical and thermal mechanical loads in the developed materials
increases due to the role of reinforcement fiber. For the conducting composite filled with short carbon fiber, not only the
actuation of SMP composite can be driven by low voltage, but also its tensile, bending strength, glass transition temperature, storage modulus and thermal conductivity increase by a factor of filler content of carbon fiber increasing. The results show meaningful guidance for further design and the performance evaluation of such composite materials.
The synthesis of massive arrays of monodispersed carbon nanotubes that are self-assembled on hydrophilic
polycarbonate membrane is reported. This approach involves individual carbon nanotube manufacturing by non-ionic
surfactant to aid in dispersion and nanotubes self-assembled for three-dimensional orientation by high press filtration.
The inherent capability of carbon nanotube and microstructure of well-packed arrays predominate excellent conductive
properties of massive arrays. These potential applications of nanometer-sized sensor, probe and energy resistor have
been characterized in this study. Furthermore, the route toward application of self-assembled regular arrays, as heat
transmission intermedium, has been carried out by activating shape-memory polymer. The electrical conductivity of
insulating polymer is significantly improved by assembled carbon nanotubes, resulting in shape recovery behavior of
nanocomposite being driven by electrical resistive heating.
Through summarizing and analyzing the physical corrosion theories of polymer, a theoretical model is constructed to
depict the relationship between relaxation time with temperature, stress and humidity. The correlation between physical
corrosion behavior and external factors is predicted from semi-experimental profile. In sequence, the morphology of
polymer and fiber was investigated by the scanning electron microscopy (SEM) in comparison with that of nonimmersed
samples. The dynamic mechanical thermal analysis (DMTA) methods were used to study the evolution of
thermomechanical properties against immersed time. It is found that the glass transition temperature (Tg) and storage
modulus were significantly reduced with immersion time increase. Then the hardness, tensile strength and bending
strength of GFRP were tested by their corresponding mechanical measurements.
Currently aircraft structural composites are commonly protected using approaches such as laying of metallic meshes and
foils. However, these are not ideal solutions because they add significant weight and may be difficult to repair. In this
paper, we used multi-walled carbon nanotubes(MWNTs) and short carbon fiber(SCF) as reinforcement, and epoxy resin
as matrix, prepared conductive nanocomposites for lightning protection of aircraft. MWNTs and SCF as conductive
filler, they via acidification and surface treatment, mechanical milling, ultrasonic dispersion method, the CNTs/SCF
Epoxy (EP) conductive nanocomposites were prepared by casting method. The characterizations of materials
microstructure, electrical and mechanical properties were investigated by scanning electron microscope (SEM),
resistance instrument, and tensile test machine and indentation experiments. Result proved that surface treatment carbon
nanotubes and short carbon fiber can be evenly spread over the epoxy matrix, and form three-dimensional conductive
network in the epoxy matrix. This makes the resistance of composite materials greatly reduced, improved conductive
performance. The characterization of materials mechanical properties also showed that the addition of nano-conductive
filler, but also significantly enhanced the material elastic modulus and hardness.
A unique concept of shape-memory polymer (SMP) nanocomposites making up of carbon nanofiber paper was explored.
The essential element of this method was to design and fabricate nanopaper with well-controlled and optimized network
structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under ultrasonicated processing and
vapor press method, while the dispersion of nanofiber was treated by BYK-191 dispersant. The morphologies of carbon
nanofibers within the paper were characterized with scanning electron microscopy (SEM). In addition, the thermomechanical
properties of SMP coated with carbon nanofiber paper were measured by the dynamic mechanical thermal
analysis (DMTA). It was found that the glass transition temperature and thermomechanical properties of nanocomposites
were strongly determined by the dispersion of polymer in conductive paper. Subsequently, the electrical conductivity of
conductive paper and nanocomposites were measured, respectively. And experimental results revealed that the
conductive properties of nanocoposites were significantly improved by carbon nanopaper, resulting in actuation driven
by electrical resistive heating.
Recently, there is increasing interest in triggering shape recovery of shape-memory polymers (SMPs) by novel inductive
effect. In this paper, many hard works have been carried out to make SMP induced while along with swelling effect.
Based on the Free-volume theory, Rubber Elasticity Theory and
Mooney-Rivlin Equation, it is theoretically and
experimentally demonstrated the feasibility of SMP activated by swelling effect. The mechanism behind it is solvent
acting as plasticizer, to reduce the glass transition temperature (Tg) and melting temperature (Tm) of polymers, make
them softer and more flexible, facilitating the diffusion of the molecules to polymer chains, and then separating them. In
addition to this physical action, the intermolecular interactions among the chains are weakened, because interactions are
hindered at the points where the plasticizer is located. Finally, the Dynamic mechanical analysis (DMA), FTIR study and
glass transition temperature measurement tests were used to exemplify the feasibility of SMP driven by swelling effect.
And it is qualitatively identified the role of swelling effect playing in influencing the transition temperature. Swelling
effect occurs due to the interaction between macromolecules and solvent molecules, leading to free volume of polymeric
chains increasing (namely the flexibility of polymer chains increasing), resulting in the Tg decreasing. All above
mentioned investigation can be used to confirm that the shape recovery is induced by swelling effect. This actuation
almost is applicable for all the SMP and SMP composite, as the swelling theory is almost applicable for all the polymeric
materials.
A new type of fiber reinforced thermoset styrene-based shape-memory polymer composite (SMPC) is developed and
analyzed. The main objective is to systematically characterize the shape recovery properties of SMPC, which is a
foundation for SMPC used in deployable structures. Firstly, the deployment dynamics of cured SMPC shell is presented.
Then, the shape recovery performance is investigated by finite element analysis (FEA). The deployment process of
curved SMPC shell (from 0-180 degree) is simulated by the geometrically nonlinear analysis. The deployment moment
increases with the increase of the thickness of curved shell, and the strain show somewhat uniform in the central part of
the curved shell. Furthermore, a hinge made of SMPC is fabricated, which consists of two curved SMPC shells in
opposite directs. The deployment of hinge can be achieved in about100s by applying a 20V voltage. The deployment
ratio approaches approximate 100 %. Finally the deployment of a prototype of solar array actuated by the hinge is
demonstrated.
This paper is concerned about the basic properties of deployment for shape memory polymer composite (SMPC) and its
application in deployable hinge for space structure. Shape-memory polymers (SMP) are an emerging class of active
polymers that have dual-shape capability. One of another advantage, compared with other traditional material hinge, the
SMPC carpenter type hinge is that it will not produce a large shock when it spring into the deployed position. There are
several kinds of shape memory polymer composite (fiber reinforced, powder reinforced, etc,). Epoxy SMPs, carbon fibre
fabric reinforced SMPC was introduced in this work. In order to investigate the basic performances of SMPC hinge, the
experimental methods are used as follows: dynamic mechanical analysis (DMA), three point bending test and the radio
of shape recovery. In the end, the structure of the carpenter type hinge is introduced. The carpenter type hinge is one
mechanism that has the advantage of high-reliability of the deployment; light weighted, and low cost. This SMPC
carpenter type hinge performs good deployment performances during numerous thermomechanical cycles. So the potential applications for such materials as active medical devices are highlighted.
This present paper is focused on the effect of conductive particulate and fibrous fillers on the characterized property of
styrene-based shape memory polymer incorporating carbon black (CB) and short carbon fiber (SCF). It was shown that
the particulate additives are dispersed homogeneously within matrix and served as interconnections between the fibers,
while the fibrous additives may be considered as a rigid long aggregate of carbon, leading to easy formation of
continuous conductive networks. The glass transition temperature of nanocomposites drops sharply as compared with
that of pure SMP from the differential scanning calorimetry (DSC). For the composite containing 5 wt% CB and 2 wt%
SCF, the storage modulus increases by 16.2% compared to that of the composite containing 5 wt% CB and 1 wt% SCF;
the peak of tangent delta curve is an alternative definition of Tg, thus Tg defined in such a way is determined as 69.44°C
from Dynamic Mechanical Analyzer (DMA) test which is higher than 25.78°C obtained from DSC test. The electrical
conductivity of the composite achieves 3 S/cm by four-point Van De Pauw method, and the shape recovery can be
activated with a constant voltage of 25 V through them.
There is a strong interest in the use of conductive shape memory polymer (SMP) for actuation by passing an electrical
current. This paper presents a systematic study on the effect of multi-walled carbon nanotubes (MWCNTs) and carbon
nanoparticles on the electro activate shape memory polymer (SMP). The first is the fabrication and characterization of
styrene-based SMP filled with MWCNTs was investigated. Then the resistivity of 8 wt% MWNTs sample is 80 ohm•cm
obtained by using four-point probe Van De Pawn method, and for 8.0×2.0×0.2 cm3 rectangle sheet, it can be triggered by
passing an electrical current with a constant voltage of 200 V. The second is focused on the effect of conductive
particulate and fibrous fillers on the electrical property of composite. The electrical conductivity of the composites
achieves 8.73×10-2, 9.63×10-2 and 1.13×10-1 S/cm by DC measurement and 0.12, 1.05 and 3 S/cm by four-point probe
Van De Pauw method. Their shape recovery can be activated by passing an electrical current of 25 V voltages. In this
paper, the sensors using conducting SMP composites testified by the temperature-dependent resistance and strain-dependent
resistance tests. At the same time, the shape self-recovery of SMPs and their composites when heated above
transition temperature acts as actuator.
The fabrication and characterization, especially mechanical and electrical properties, of styrene-based shape memory
polymer mixed with multi-walled carbon nanotubes (MWNTs) are presented in this paper. It is found that
surface-modified MWNTs incorporated very well with resin processed by royal water, and dispersion was achieved by
high-energy sonication in the solution. Scanning Electron Microscope (SEM) is shown that the particulate additives were
dispersed homogeneously within matrix and served as local conductive paths. The glass transition temperature (Tg) of
the composite containing MWNTs is lower than that of the pure SMP obtained from Differential Scanning Calorimetry
(DSC). With the increasing filler content, resulting in the reduction of Tg increases. The composites have a better
thermodynamic stability awarding to the results of Thermal Gravity Analyzer (TGA). The vibration of MWNTs in
composite system was obtained from Raman spectrums. For the mechanical property of SMP composite with 8 wt%
MWNTs, its Young's modulus increases by 12.1% and the tensile strength by 8.1% as compared with that of the pure
SMP. Four-point Van De Pauw method is introduced to investigate the electrical property of composites. An electrical
conductivity of 1.25×10-3 S/cm is obtained for 8 wt% MWNTs composite.
This paper is concerned about an investigation of mechanical and electrical conductive properties of carbon fiber fabric
reinforced shape memory polymer composite (SMPC). The shape memory polymer (SMP) is a thermoset styrene-based
resin. SMP is a promising smart material, which is under intensive investigation at present. Its primary advantages over
other smart materials are the high strain capacity (200% reversible strain), low density and low cost etc.. But its major
drawbacks are low strength, low modulus and low recovery stress. So the fiber reinforced SMPC was naturally
considered to be investigated in this paper, which may overcome the disadvantages mentioned above. The investigation
was conducted with experimental methods: Dynamic Mechanical Analyzer (DMA), static and mechanical cycle loading
tests, microscope observation of microstructural deformation mechanism, conductivity and shape recovery tests. Results
indicated that SMPC showed higher glass transition temperature (Tg) than neat SMP and improved the storage modulus,
bending modulus, strength and resistance against relaxation and creep. Both fiber microbuckling and fracture of SMPC
were observed after the static 3-ponit bending test at the constant room temperature. SMPC showed favorable recovery
performances during thermomechanical cycles of the bending recovery test and the fiber microbuckling was obvious.
Moreover, the conductive SMPC of this study experienced low electrical resistivity and performed a good shape memory
effect during numerous thermomechanical cycles.
A moiré interferometer system based on single metrology grating (SMG) that can achieve nanometer resolution is presented. By properly selecting the diffraction beam, different resolution can be realized with different diffracting orders. The measuring principle is described in detail. A new moiré fringes subdividing method is developed. This method can accurately deal with input signals which deviate from the orthogonal state by dynamically tracing the joints of input signals. So the stringent requirement for orthogonality of input signals is loosen. With the combination of the SMG and new subdividing method, the system can easily achieve nanometer resolution. A displacement measuring system, which resolution is 1nm and measure range is 400mm, is set up. And the experiment results of the system are given. It shows that the system has better anti-jamming ability to the orthogonal error of input signals than conventional systems.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.