scholarly journals The Thermal Behavior of Lyocell Fibers Containing Bis(trimethylsilyl)acetylene

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 537
Author(s):  
Igor Makarov ◽  
Markel Vinogradov ◽  
Maria Mironova ◽  
Georgy Shandryuk ◽  
Yaroslav Golubev ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Behavior ◽  
Carbon Fibers ◽  
Coefficient Of Thermal Expansion ◽  
Structural Features ◽  
Amorphous Structure ◽  
Processing Temperature ◽  
Composite Fibers ◽  
Scanning Calorimetry ◽  
Lyocell Fibers

This study focuses on the preparation of carbon fiber precursors from solutions of cellulose in N-methylmorpholine-N-oxide with the addition of bis(trimethylsilyl)acetylene, studying their structural features and evaluating thermal behavior. The introduction of a silicon-containing additive into cellulose leads to an increase in the carbon yield during carbonization of composite precursors. The type of the observed peaks on the differential scanning calorimetry (DSC) curves cardinally changes from endo peaks intrinsic for cellulose fibers to the combination of endo and exo peaks for composite fibers. For the first time, coefficient of thermal expansion (CTE) values were obtained for Lyocell fibers and composite fibers with bis(trimethylsilyl)acetylene (BTMSA). The study of the dependence of linear dimensions of the heat treatment fibers on temperature made it possible to determine the relation between thermal expansion coefficients of carbonized fibers and thermogravimetric curves, as well as to reveal the relationship between fiber shrinkage and BTMSA bis(trimethylsilyl)acetylene content. Carbon fibers from composite precursors are obtained at a processing temperature of 1200 °C. A study of the structure of carbon fibers by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy made it possible to determine the amorphous structure of the fibers obtained.

scholarly journals Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1141
Author(s):  
Nevin Stephen Gupta ◽  
Kwan-Soo Lee ◽  
Andrea Labouriau
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Carbon Fibers ◽  
Coefficient Of Thermal Expansion ◽  
Mechanical And Thermal Properties ◽  
Mechanical Mixing ◽  
Scanning Calorimetry ◽  
Mechanical Hardness ◽  
Degradation Temperature ◽  
Cost Efficient

In order to meet the needs of constantly advancing technologies, fabricating materials with improved properties and predictable behavior has become vital. To that end, we have prepared polydimethylsiloxane (PDMS) polymer samples filled with carbon nanofibers (CFs) at 0, 0.5, 1.0, 2.0, and 4.0 CF loadings (w/w) to investigate and optimize the amount of filler needed for fabrication with improved mechanical properties. Samples were prepared using easy, cost-efficient mechanical mixing to combine the PDMS and CF filler and were then characterized by chemical (FTIR), mechanical (hardness and tension), and physical (swelling, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and coefficient of thermal expansion) analyses to determine the material properties. We found that hardness and thermal stability increased predictably, while the ultimate strength and toughness both decreased. Repeated tension caused the CF-filled PDMS samples to lose significant toughness with increasing CF loadings. The hardness and thermal degradation temperature with 4 wt.% CF loading in PDMS increased more than 40% and 25 °C, respectively, compared with the pristine PDMS sample. Additionally, dilatometer measurements showed a 20% decrease in the coefficient of thermal expansion (CTE) with a small amount of CF filler in PDMS. In this study, we were able to show the mechanical and thermal properties of PDMS can be tuned with good confidence using CFs.

Friction and Wearing Behaviour of Sintered Composites Made from Copper Mixed with Carbon Fibers

2015 ◽  
Vol 660 ◽  
pp. 81-85 ◽  
Author(s):  
Radu Caliman
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Composite Materials ◽  
Friction Coefficient ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Coefficient Of Thermal Expansion ◽  
Density Ratio ◽  
Point Of View ◽  
Short Carbon

This paper presents a study regarding friction and wear comportment of sintered composite materials obtained by mixture of copper with short carbon fibers. Sintered composites are gaining importance because the reinforcement serves to reduce the coefficient of thermal expansion and increase the strength and modulus. In case of composites form by carbon fiber and copper, the thermal conductivity can also be enhanced. The combination of low thermal expansion and high thermal conductivity makes them very attractive for electronic packaging. Besides good thermal properties, their low density makes them particularly desirable for aerospace electronics and orbiting space structures. Compared to the metal itself, a carbon fiber-copper composite is characterized by a higher strength-to-density ratio, a higher modulus-to-density ratio, better fatigue resistance, better high-temperature mechanical properties and better wear resistance. Varying the percentage of short carbon fibers from 7,8% to 2,4%, and the percentage of copper from 92,2% to 97,6%, five dissimilar composite materials have been made and tested from the wear point of view. Friction tests are carried out, at room temperature, in dry conditions, on a pin-on-disc machine. The friction coefficient was measured using abrasive discs made from steel 4340 having the average hardness of 40 HRC, and sliding velocity of 0,6 m/sec. The primary goal of this study work it was to distinguish a mixture of materials with enhanced friction and wearing behaviour. The load applied on the specimen during the tests, is playing a very important role regarding friction coefficient and also the wearing speed.

scholarly journals Thermal analysis of metal-ceramic bonding using finite element method

2014 ◽  
Vol 3 (2) ◽  
pp. 216 ◽  
Author(s):  
S. Gopinath ◽  
R Sabarish ◽  
R. Sasidharan
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Bonding Strength ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Processing Temperature ◽  
Element Analysis ◽  
Metal Ceramic ◽  
The Difference

This paper reports a finite element study of effect of bonding strength between metal and ceramic. The bonding strength is evaluated with different processing temperature and holding time. The difference between the coefficients of linear thermal expansion (CTEs) of the metal and ceramic induces thermal stress at the interface. The mismatch thermal stress at the interface region plays an important role in improving bonding strength. Hence, it is essential to evaluate the interface bonding in metal-ceramics joints. The Al/SiC bonding was modeled and analyzed using finite element analysis in ANSYS (v.10). Keywords: Bonding Strength, Coefficient of Thermal Expansion, Thermal Stress, Interface, Al/Sic, FEA.

Zirconium tungstate reinforced cyanate ester composites with enhanced dimensional stability

2009 ◽  
Vol 24 (7) ◽  
pp. 2235-2242 ◽  
Author(s):  
Prashanth Badrinarayanan ◽  
Ben Mac Murray ◽  
Michael R. Kessler
Keyword(s):  
Thermal Expansion ◽  
Dimensional Stability ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Thermomechanical Analysis ◽  
Dynamic Mechanical Properties ◽  
Filler Loading ◽  
Cyanate Ester ◽  
Scanning Calorimetry ◽  
Zirconium Tungstate

Zirconium tungstate (ZrW2O8) is a unique ceramic material characterized by isotropic negative thermal expansion behavior over a wide temperature range. Incorporation of ZrW2O8 is expected to improve the dimensional stability of polymers by reducing the overall coefficient of thermal expansion (CTE). In this work, the thermal and dynamic mechanical properties of a bisphenol E cyanate ester reinforced with various loadings of ZrW2O8 are examined. Thermomechanical analysis indicates that the incorporation of ZrW2O8 results in a decrease in CTE at temperatures above and below the glass transition temperature (Tg) of the neat resin. The dynamic storage moduli of the composites reinforced with ZrW2O8 are found to increase with increasing filler loading. Furthermore, the various phase behaviors exhibited by ZrW2O8 are also examined by differential scanning calorimetry measurements.

Basic Research on Combinatorial Evaluation Method for Coefficient of Thermal Expansion

2007 ◽  
Vol 1024 ◽  
Author(s):  
Yuko Aono ◽  
Seiichi Hata ◽  
Junpei Sakurai ◽  
Ryusuke Yamauchi ◽  
Hiroyuki Tachikawa ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Behavior ◽  
Young’S Modulus ◽  
Evaluation Method ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Ccd Camera ◽  
Basic Research ◽  
Film Library ◽  
Combinatorial Methods

AbstractThe coefficient of thermal expansion (CTE) is one of the most important material properties for actuators driven by heat or structure over a wide temperature. The CTE of an alloy depends on its composition, and combinatorial methods are very effective for researching new alloys. A CTE evaluation method, which can be applied to combinatorial methods or a thin film library, is proposed in this paper. The thermal behavior of a bi-layer cantilever couple was used for the evaluation, and the Young's modulus, which is also an important property, was simultaneously obtained. Firstly, one bi-layer cantilever was fabricated and agreement of the thermal behavior with the theoretical behavior was confirmed. The estimated error of the measurement device (CCD camera) resolution was then analyzed. The results indicate that combinatorial evaluation does not enable an accurate evaluation of Young's modulus, but does allow the CTE be accurately determined.

scholarly journals Mechanical And Thermal Behavior of Carbon Nanotubes/Vinyl Ester Nanocomposites

2019 ◽  
Vol 56 (4) ◽  
pp. 735-743 ◽  
Author(s):  
Adrian Cotet ◽  
Marian Bastiurea ◽  
Gabriel Andrei ◽  
Alina Cantaragiu ◽  
Anton Hadar
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Behavior ◽  
Vinyl Ester ◽  
Coefficient Of Thermal Expansion ◽  
Mechanical Tests ◽  
Bending Test ◽  
Vinyl Ester Resin ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Walled Carbon Nanotubes

Single walled carbon nanotubes (SWCNT) and multi walled carbon nanotubes (MWCNT)/ vinyl ester nanocomposites with three different contents of carbon nanotubes (CNTs) have been prepared by the simple melt-compounding method. A fine and homogeneous dispersion of CNTs throughout vinyl ester resin has been noticed by SEM images. Two mechanical tests (compression and three point bending test) show that, compared to neat vinyl ester resin, compression modulus and compression strength of the nanocomposites have been significantly improved by about 9% and 14%, respectively, when incorporating only 0.15 wt.% MWCNTs. Furthermore, thermal behavior of SWCNT and MWCNT/ vinyl ester nanocomposites has been investigated and discussed based on differential scanning calorimetry (DSC) and thermo- mechanical analysis (TMA). Glass transition temperature (Tg) and coefficient of thermal expansion (CTE) have been increased and decreased, respectively, with increasing of CNTs content.

Asymmetric bismaleimide-based high-performance resins with improved processability and high Tg over 400 °C

2019 ◽  
Vol 31 (9-10) ◽  
pp. 1132-1139
Author(s):  
Zhidong Ren ◽  
Sijia Hao ◽  
Yue Xing ◽  
Cheng Yang ◽  
Shenglong Dai
Keyword(s):  
Weight Loss ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
High Performance ◽  
Coefficient Of Thermal Expansion ◽  
Processing Temperature ◽  
The Matrix ◽  
Temperature Window

Asymmetric 2-(4′-maleimido)phenyl-2-(4′-maleimidophenoxyl)phenylbutane (EBA-BMI) was successfully mixed with N, N′-(4,4′-diphenylmethane)bismaleimide (DDM-BMI) to prepare the matrix resins for high-temperature fiber-reinforced polymeric composites (glass transition temperature ( Tg) > 400°C). Experimental results imply that DDM-BMI/EBA-BMI (DE-BMIs) show excellent melting performance with wide processing temperature window and low molten viscosity, suggesting excellent compatibility between DDM-BMI and EBA-BMI. For example, the viscosity of DE-BMI41 (DDM-BMI/EBA-BMI, 4/1) is about 474–51 mPa·s in the temperature range of 148–180 °C. In addition, cured DE-BMIs represent remarkable thermal properties with Tg over 400°C, under which the storage modulus could still reach as high as 3.2 GPa. Meanwhile, the coefficient of thermal expansion of these cured resins is about 36–40 ppm °C−1 at 50–250°C, and the 5% weight loss temperature is about 470°C.

scholarly journals Effect of Stir Casting Process Parameters on Properties of Aluminium Composites – Taguchi’s Analysis

2019 ◽  
Vol 25 (4) ◽  
pp. 401-406
Author(s):  
Hemalatha ARIHARAPUTHIRAN ◽  
Dhanalakshmi VENKADASAMY
Keyword(s):  
Compressive Strength ◽  
Thermal Expansion ◽  
Process Parameters ◽  
Sliding Wear ◽  
Coefficient Of Thermal Expansion ◽  
Stir Casting ◽  
Processing Temperature ◽  
Wear Property ◽  
Casting Method ◽  
Abrasion Wear

The need for lightweight materials in various industries, increased fuel price, requirement of improved mechanical, thermal properties leads to the development of aluminium metal matrix composites. Stir casting method is employed for preparing composite consisting of aluminium die casting -12 alloy and reinforcement of 10 % by weight proportion of silicon carbide. Taguchi’s experimental analysis is employed for varying the process parameters of stir casting method like process temperature, stirring time and stirring speed. Tests were conducted to measure mechanical property like compressive strength, wear property such as sliding wear, micro abrasion and thermal property like coefficient of thermal expansion.  An attempt has been made to study the unrelated properties like compressive strength, sliding wear resistance, micro abrasion wear and coefficient of thermal expansion of aluminium composites by Principal Component Analysis method. The experimental investigation shows that increase in processing temperature reduces sliding wear, micro abrasion wear and coefficient of thermal expansion and also increases compressive strength.

Sign in / Sign up

Export Citation Format

Share Document