A New Generation of Boron-Based Ceramic Fibers: Design, Processing and Properties of SilicoBoron CarboNitride (SiBCN) Fibers from Boron-Modified Polyvinylsilazanes

2006 ◽  
Vol 50 ◽  
pp. 9-16 ◽  
Author(s):  
Samuel Bernard ◽  
Markus Weinmann ◽  
David Cornu ◽  
Philippe Miele
Keyword(s):  
Melt Spinning ◽  
Structural Changes ◽  
Fiber Strength ◽  
Xrd Analysis ◽  
Nitrogen Atmosphere ◽  
Ceramic Fibers ◽  
Ceramic Yield ◽  
Flexible Form ◽  
Shaping Process ◽  
Spinning Process

Boron-modified polyvinylsilazanes have been studied for suitability as fiber precursor. A melt-tractable polymer displaying Si- and N-bonded methyl groups was successfully processed into green fibers ~18μm in diameter via a melt-spinning process. After the shaping process, the use of an ammonia curing atmosphere at 200°C allowed to increase the ceramic yield of the polymer, then avoid inter-fiber fusion during the further increase of the temperature. As-cured fibers were annealed in the temperature range 1000-1800°C in a nitrogen atmosphere to provide SiBCN ceramic fibers black colored, of flexible form and ~12μm in diameter in different crystallinity states going from totally amorphous below 1600°C to well-crystallized at 1800°C. The excellent strength retention after heat-treatment at 1600°C (1.3-1.5GPa) is clearly related to the high amorphous stability of fibers. Elemental compositions of such amorphous fibers showed a typical chemical formula of Si3.0B1.0C5.0N2.4. Between 1600°C and 1700°C, the fiber strength decreased to 0.9GPa then dropped to about one-quarter the original value at 1800°C while structural changes were evident by XRD analysis.

Preparation and Characterisation of Polyborazine as Novel Precursor to Boron Nitride Ceramic

2011 ◽  
Vol 194-196 ◽  
pp. 1749-1754
Author(s):  
Cheng Deng ◽  
Yong Cai Song ◽  
Meng Fu Zhu ◽  
Hong Bo Su ◽  
Xiu Dong You ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Melt Spinning ◽  
Condensation Reaction ◽  
Average Molecular Weight ◽  
Nitrogen Atmosphere ◽  
Minor Amount ◽  
Ceramic Fibers ◽  
Ceramic Yield ◽  
Linear Arrangement ◽  
Element Analysis

A processable polyborazine precursor was synthesized via substitution reaction and deamine condensation reaction by using methylamine, propylamine and B-trichloroborazine (TCB) as the starting materials. The chemical composition, structure and properties of the obtained polymer were investigated using element analysis, FT-IR, NMR, XPS and TG. The results indicated that the backbone of the polymer was approximate linear arrangement of boron-nitride ring molecules with B-N(CH3)-B structure as bridge bond, meanwhile minor amount of methylamino and propylamino remained in polyborazine as the pendant or end group. The melting point, number average molecular weight and polydispersity index of polyborazine was 90°С , 1002 and 1.355, respectively. The polyborazine showed good processability and polyborazine precursor fibers with diameter of 10~15 µm could be obtained by melt-spinning in N2 atmosphere. The ceramic yield of the polyborazine at 1000°С in nitrogen atmosphere was 53.2 wt%, which suggested that the as-achieved polymer can be used as a precursor to boron nitride ceramic fibers and membranes.

Preparation of SiBCN Microtubes from Melt-Spinnable Polymers

2008 ◽  
Vol 368-372 ◽  
pp. 926-928 ◽  
Author(s):  
Laura Gottardo ◽  
Samuel Bernard ◽  
Marie Paule Berthet ◽  
Philippe Miele
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Nitrogen Atmosphere ◽  
Low Molecular Weight ◽  
Ceramic Fibers ◽  
Preceramic Polymers ◽  
Flexible Form ◽  
First Time

SiBCN microtubes were prepared for the first time by spinning a low molecular weight preceramic polymers of boron-modified polyvinylsilazanes into green fibers ~30 m in diameter which were subsequently thermolyzed under a nitrogen atmosphere. Hollow SiBCN ceramic fibers black colored, of flexible form, ~20 m in diameter and 0.8GPa in tensile strength were produced.

Synthesis and Characterization of Reduced Graphene Oxide

2013 ◽  
Vol 678 ◽  
pp. 56-60 ◽  
Author(s):  
Cherukutty Ramakrishnan Minitha ◽  
Ramasamy Thangavelu Rajendrakumar
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Graphite Oxide ◽  
High Performance ◽  
Structural Changes ◽  
Epoxy Group ◽  
Xrd Analysis ◽  
Si Substrates ◽  
Reduced Graphene ◽  
Reduced Graphite Oxide

Reduced graphene oxide is an excellent candidate for various electronic devices such as high performance gas sensors. In this work Graphene oxide was prepared by oxidizing graphite to form graphite oxide. From XRD analysis the peak around 11.5o confirmed that the oxygen was intercalated into graphite. By using hydrazine hydrate, the epoxy group in graphite oxide was reduced then the solution of reduced graphite oxide (rGO) is exfoliated. Raman spectrum of rGO contains both G band (1580 cm-1), D band (1350 cm-1). The remarkable structural changes reveals that reduction of graphene oxide from the values of ID/IG ratio that increase from 0.727 (GO) to 1.414 (rGO). The exfoliated reduced graphite oxide solution is spin coated on to the SiO2/Si substrates.

scholarly journals Dynamic Single-Fiber Pull-Out of Polypropylene Fibers Produced with Different Mechanical and Surface Properties for Concrete Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 722
Author(s):  
Enrico Wölfel ◽  
Harald Brünig ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Christina Scheffler
Keyword(s):  
Tensile Strength ◽  
Dynamic Loading ◽  
Melt Spinning ◽  
Structural Changes ◽  
High Surface ◽  
Single Fiber ◽  
Scanning Calorimetry ◽  
Matrix Interaction ◽  
Pull Out ◽  
Fiber Matrix

In strain-hardening cement-based composites (SHCC), polypropylene (PP) fibers are often used to provide ductility through micro crack-bridging, in particular when subjected to high loading rates. For the purposeful material design of SHCC, fundamental research is required to understand the failure mechanisms depending on the mechanical properties of the fibers and the fiber–matrix interaction. Hence, PP fibers with diameters between 10 and 30 µm, differing tensile strength levels and Young’s moduli, but also circular and trilobal cross-sections were produced using melt-spinning equipment. The structural changes induced by the drawing parameters during the spinning process and surface modification by sizing were assessed in single-fiber tensile experiments and differential scanning calorimetry (DSC) of the fiber material. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements were applied to determine the topographical and wetting properties of the fiber surface. The fiber–matrix interaction under quasi-static and dynamic loading was studied in single-fiber pull-out experiments (SFPO). The main findings of microscale characterization showed that increased fiber tensile strength in combination with enhanced mechanical interlocking caused by high surface roughness led to improved energy absorption under dynamic loading. Further enhancement could be observed in the change from a circular to a trilobal fiber cross-section.

scholarly journals Yttrium doped phosphate-based glasses: structural and degradation analyses

2020 ◽  
Vol 6 (1) ◽  
pp. 34-49
Author(s):  
Abul Arafat ◽  
Sabrin A. Samad ◽  
Jeremy J. Titman ◽  
Andrew L. Lewis ◽  
Emma R. Barney ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Xrd Analysis ◽  
Calcium Pyrophosphate ◽  
Ion Release ◽  
Subsequent Increase ◽  
Structural Characterisation ◽  
Release Studies ◽  
Degradation Properties

AbstractThis study investigates the role of yttrium in phosphate-based glasses in the system 45(P2O5)–25(CaO)– (30-x)(Na2O)–x(Y2O3) (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y2O3 content as metaphosphate units (Q2) decreased with subsequent increase in pyrophosphate species (Q1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca2P2O7) and sodium metaphosphate (NaPO3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y2O3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y2O3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yttrium (YO6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles.

Silicon Carbide Base Ceramic Fiber Synthesis from Polycarbosilane-Modified Polymethylsilane Blend Polymers by Melt Spinning

2011 ◽  
Vol 675-677 ◽  
pp. 139-142
Author(s):  
Xin Xing ◽  
Lin Liu ◽  
Feng Cao ◽  
Xiao Dong Li ◽  
Zeng Yong Chu ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Tensile Strength ◽  
Thermal Oxidation ◽  
Melt Spinning ◽  
Ceramic Fiber ◽  
Ceramic Yield ◽  
Base Ceramic

A melt-spinnable precursor for SiC based fibers was prepared from blend polymers of polycarbosilane (PCS) and modified polymethylsilane (M-PMS). The blend polymers cured at 320°C are different from M-PMS and PCS. The ceramic yield of these blend polymers is about 83%. The C/Si ratio of M-PMS/PCS derived ceramics (pyrolyzed at 1250°C) is linear to the content of MPMS in M-PMS/PCS. After melt spinning, thermal oxidation curing, and pyrolysis, Si-C-O fibers were obtained. The diameter and the tensile strength of the resulted fibers are 16.5μm and 1.62GPa, respectively.

Effect of Crucible Parameters on Planar Flow Melt Spinning Process

2015 ◽  
Vol 68 (6) ◽  
pp. 1125-1129 ◽  
Author(s):  
M. Swaroopa ◽  
L. Venu Gopal ◽  
T. Kishen Kumar Reddy ◽  
B. Majumdar
Keyword(s):  
Melt Spinning ◽  
Planar Flow ◽  
Spinning Process

PLA/Carbon Nanotubes Multifilament Yarns for Relative Humidity Textile Sensor

2011 ◽  
Vol 6 (3) ◽  
pp. 155892501100600 ◽  
Author(s):  
Eric Devaux ◽  
Carole Aubry ◽  
Christine Campagne ◽  
Maryline Rochery
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Relative Humidity ◽  
Melt Spinning ◽  
Flexible Sensor ◽  
Spinning Process ◽  
Textile Sensor ◽  
Multifilament Yarns

Polylactide (PLA) was mixed with 4 wt.% of carbon nanotubes (CNTs) to produce electrical conductive multifilament yarns by melt spinning process for humidity detection. Thanks to a variation of electrical conductivity, this flexible sensor could detect the moisture presence. The introduction of plasticizer was necessary to ensure higher fluidity and drawability of the blend during the spinning process. The plasticizer modifies the crystallinity and the mechanical properties of the yarns. The effectiveness of this sensor (PLA/4 wt.% CNTs fibres) sensitive to humidity, is optimal when the spinning conditions are adapted. In this way, the temperature and the rate of the drawing roll were reduced. The influence of these parameters on the crystallinity, the mechanical properties and the sensitivity of the yarns were studied. Once the appropriate spinning conditions found, one humidity sensitive yarn was processed and the repeatability and efficient reversibility of its sensitivity were highlighted.

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