Alkaline‐developable and negative‐type photosensitive polyimide with high sensitivity and excellent mechanical properties using photo‐base generator

2020 ◽  
Vol 58 (17) ◽  
pp. 2366-2375 ◽  
Author(s):  
Ling‐Ya Tseng ◽  
Yan‐Cheng Lin ◽  
Chih‐Cheng Kuo ◽  
Chun‐Kai Chen ◽  
Chuan‐En Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Sensitivity ◽  
Negative Type

scholarly journals Core-Shell Structured HMX@Polydopamine Energetic Microspheres: Synergistically Enhanced Mechanical, Thermal, and Safety Performances

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 568 ◽  
Author(s):  
Congmei Lin ◽  
Feiyan Gong ◽  
Zhijian Yang ◽  
Xu Zhao ◽  
Yubin Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
In Situ Polymerization ◽  
Solid Phase ◽  
High Sensitivity ◽  
Practical Applications ◽  
Δ Phase ◽  
Polymer Bonded Explosives ◽  
Static Mechanical ◽  
Friction Sensitivity

The solid–solid phase transition, poor mechanical properties, and high sensitivity has impeded further practical applications of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based polymer bonded explosives (PBXs). To address these issues together, a facile and effective route was employed to achieve a coating of polydopamine (PDA) on the surface of explosive crystals via in situ polymerization of dopamine. Additionally, PBXs based on HMX@PDA microcapsules were prepared with a fluoropolymer as polymer binder. Improved storage modulus, static mechanical strength and toughness, and creep resistance has been achieved in as-prepared PDA modified PBXs. The β-δ phase transition temperature of as-obtained PBXs based on conventional HMX (C-HMX)@PDA was improved by 16.3 °C. The friction sensitivity of the C-HMX based PBXs showed a dramatic drop after the PDA coating. A favorable balance proposed in this paper among thermal stability, mechanical properties, and sensitivity was achieved for C-HMX based PBXs with the incorporation of PDA.

Naturally Derived Wearable Strain Sensors with Enhanced Mechanical Properties and High Sensitivity

2020 ◽  
Vol 12 (19) ◽  
pp. 22163-22169 ◽  
Author(s):  
Zhen Lv ◽  
Jize Liu ◽  
Xin Yang ◽  
Dongyang Fan ◽  
Jie Cao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Sensitivity ◽  
Strain Sensors

Optimization of Surface Properties for Nanoindentation Studies on Nuclear Structural Materials

2017 ◽  
Vol 891 ◽  
pp. 67-72
Author(s):  
Petra Bublíková ◽  
Hygreeva Kiran Namburi ◽  
Daniela Marušáková
Keyword(s):  
Mechanical Properties ◽  
Sample Preparation ◽  
Radiation Damage ◽  
High Sensitivity ◽  
Structural Materials ◽  
Thin Layers ◽  
Standard Methods ◽  
Electrolytic Polishing ◽  
Preparation Step ◽  
Extent Of Damage

Nanoindentation using static loading of indenter tip is one of versatile methods used for evaluation of materials in smaller volume. It includes investigation of structural phases and thin layers on substrates etc. In the field of nuclear core and structural materials, nanoindentation has become an important tool to assess mechanical properties and correlate to the level of radiation damage at elevated and room temperatures. Nanoindentation, ideally in combination with Transmission Electron Microscopy, can describe the extent of damage and behaviour from the nanoand micro scale. Due to the high sensitivity of nanoindentation system, that typically uses loads in the range of tens of nN up to several tens of mN, the precise sample preparation is challenging and to be performed especially to understand behaviour of bulk materials. In the current study, samples from Austenitic Stainless Steel (ASS) 321, which is the representative structural material used for reactor internals, were prepared by standard methods - fine polishing, chemical etching, electrolytic etching, electrolytic polishing, electrolytic polishing & etching and ion polishing. Firstly, non-irradiated samples were used for optimization of the sample preparation methodology and then it will be applied on irradiated samples to obtain local mechanical properties. After each preparation step, nanoindentation was performed and load was optimized leading to the minimum standard deviation, also taking into account an indent size and pile-up mechanism. Scanning Probe Microscopy (SPM imaging) and nanoindentation results showed the multi-grained austenitic structure with minimal roughness. Local mechanical properties can be measured according to the knowledge of radiation damage type and location, with focus on grain boundaries to be evaluated. This study shows that advanced methods such as ion polishing are not suitable for ASS preparation, but standard methods based on chemical reaction with structure, especially electrolytic polishing and etching, are highly recommended.

Determining the Area Function of Spherical Indenters for Nanoindentation.

2000 ◽  
Vol 649 ◽  
Author(s):  
Andrew J. Bushby ◽  
Nigel M. Jennett
Keyword(s):  
Mechanical Properties ◽  
Yield Point ◽  
Reference Materials ◽  
Mechanical Response ◽  
Permanent Deformation ◽  
Full Range ◽  
High Sensitivity ◽  
Powerful Technique ◽  
Test Parameters ◽  
Actual Shape

ABSTRACTNanoindentation with spherical tipped indenters provides a powerful technique for exploring surface mechanical properties through the application of Hertzian mechanics. The full range of mechanical response can be obtained from elastic, through the yield point to a range of permanent deformation. However, the successful application of the technique requires accurate calibration of the indenter tip geometry. In this paper methods based on indentation into a number of reference materials are used to characterise a range of spherical tipped indenters with nominal radii from 5 to 50 microns. A traceably calibrated metrological AFM is also used to determine the actual shape of one of the indenters. The sensitivity of each method to test parameters is discussed. Coincidence of the data from both methods validates the determined shape of the indenter and offers the opportunity to cross-correlate the calibration of both instruments with high sensitivity.

Conductive Rubber Nanocomposites as Tensile and Pressure Sensors

2012 ◽  
Vol 217-219 ◽  
pp. 130-133 ◽  
Author(s):  
You Hong Tang ◽  
Nikolai Witt ◽  
Lin Ye
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Synergistic Effects ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Potential Applications ◽  
Milling Method ◽  
Rubber Nanocomposites ◽  
Conductive Silicone Rubber ◽  
Very High

A conductive silicone rubber (SR) composite, filled with both carbon nanotubes (CNT) and carbon black (CB) is prepared by a simple ball milling method. Because of the good dispersion and synergistic effects of CNT and CB, the SR composite shows improvement in mechanical properties. As well, due to the assembly of conductive pathways generated by the CNT and CB, the nanocomposite becomes highly conductive at a comparatively low concentration, with very high sensitivity for tensile and compressive stress. These outstanding properties show that the SR composite has potential applications in tensile and pressure sensors.

Influence of Electric Field on the Mechanical Properties of Hexagonal Boron-Nitride Sheets Using ab-initio Calculations

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550047 ◽  
Author(s):  
R. Ansari ◽  
S. Malakpour ◽  
M. Faghihnasiri ◽  
S. Ajori
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Electric Field ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
High Sensitivity ◽  
Functional Theory ◽  
Zigzag Direction ◽  
Electric Filed ◽  
Armchair Direction

In some cases such as assembling nanodevices and nanobiosensing, the effect of electric filed on the mechanical properties of nanomaterials is important and should be taken into account. The aim of this work is to investigate the effect of electric field on the mechanical properties of hexagonal boron-nitride (h-BN) using density functional theory (DFT) calculations. The results show the high sensitivity of mechanical properties to the magnitude and direction of electric field. It is observed that imposing the electric field on the armchair direction, unlike the zigzag direction, increases the magnitude of elastic properties of h-BN especially in the case of Poisson's ratio. It is further observed that the electric field perpendicular to h-BN has a negligible effect on its mechanical properties.

Influence of thermal aging on mechanical properties of fiber metal laminates hybridized with nanoclay

2019 ◽  
Vol 233 (19-20) ◽  
pp. 7003-7018
Author(s):  
Moslem Najafi ◽  
Reza Ansari ◽  
Abolfazl Darvizeh
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Thermal Aging ◽  
Polymer Matrix Composites ◽  
Thermal Conditions ◽  
High Sensitivity ◽  
Mechanical Degradation ◽  
Fiber Metal Laminates ◽  
Plain Weave ◽  
Fiber Metal

One of the main problems of polymer matrix composites in critical applications is their high sensitivity to thermal conditions. Therefore, an experimental study was performed to evaluate the thermal durability of traditional plain weave E-glass/epoxy as well as fiber metal laminates as a possible alternative in this case. In this way, both the laminate types were exposed to thermal aging at 130 ℃ for five weeks, and the plausible degradation is investigated through weight loss analyzes and mechanical testing. The possibility of improving the mechanical behavior of the studied laminates by nanoclay was also studied. The results demonstrated that the weight loss and mechanical degradation were more pronounced in thermally aged plain weave E-glass/epoxy composites. The results also indicated that nanoclay could enhance the mechanical properties of both laminates. On the basis of the results, the shielding role of aluminum layers and thermal resistance of nanoclay can synergistically offer a novel class of nano-fiber metal laminates with high thermal tolerance in thermo-oxidative conditions.

scholarly journals WELDING OF NITINOL BY SELECTED TECHNOLOGIES

2019 ◽  
Vol 59 (1) ◽  
pp. 42-50
Author(s):  
Tomáš Kramár ◽  
Jan Tauer ◽  
Petr Vondrouš
Keyword(s):  
Mechanical Properties ◽  
Welded Joint ◽  
High Sensitivity ◽  
Intermetallic Phases ◽  
Atmospheric Gases ◽  
Capacitor Discharge ◽  
Niti Phase ◽  
Niti Wires ◽  
Minimum Heat ◽  
Capacitor Discharge Welding

Nitinol is a perspective alloy that is difficult to weld because of its high sensitivity to heat, atmospheric gases and the NiTi phase instability. We evaluated several welding techniques with regard to their applicability to weld fine pseudoelastic NiTi wires. Namely, we tested the microplasma arc, laser, electron beam, resistance and capacitor discharge welding. In conclusion, the behaviour of the weld for any of the implemented welding techniques is similar; it leads to a loss of mechanical properties in the welded joint caused by a recrystallization and an increased amount of brittle intermetallic phases. Yet, under perfect shielding and with a minimum heat input, the welds could, as a whole, retain the majority of their properties, and, as such, have the desired properties close to the base metal.

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