Block copolymer functionalized quartz fibers/cyanate ester wave-transparent laminated composites

A block copolymer of PDMS-b-PGMA is synthesized by polymerizing glycidyl methacrylate(GMA)via reversible addition-fragmentation chain transfer(RAFT)polymerization applying a polydimethylsiloxane(PDMS)based macro-RAFT agent,which is then performed to functionalize the quartz fibers(QFs@PDMS-b-PGMA)via a simple coating process.Finally,the QFs@PDMS-b-PGMA/bisphenol A dicyanate ester(BADCy)wave-transparent laminated composites are fabricated by high-temperature molding.Nuclear magnetic resonance(NMR)spectroscopy,Fourier transform infrared(FT-IR)spectroscopy and size ex-clusion chromatography(SEC)demonstrate the successful preparation of PDMS-b-PGMA with expected structure.When the molar mass and coating amount of PDMS-b-PGMA are respectively 8100 g/mol and 2.0 wt.%,QFs@PDMS-b-PGMA/BADCy wave-transparent laminated composites present optimal mechan-ical properties and wave-transparent performance.The interlaminar shear strength(ILSS)and flexural strength are 53.6 and 552.0 MPa,respectively.Meanwhile,the dielectric constant and dielectric loss val-ues are 2.61 and 0.0028 at 1 MHz(wave transmittance of 93.8%),showing good stability at different frequencies(102-106 Hz and 8.4-12.4 GHz)and temperatures(25-250℃).

Conformally anchoring nanocatalyst onto quartz fibers enables versatile microreactor platforms for continuous-flow catalysis

Continuous-flow microreactors offer increased reactivity and reusability via unique reaction pathways to address a wide range of practical nanocatalysis problems.However,only limited platforms exist to employ these microreactors for versatile nanocatalytic reactions.In this work,we conformally anchored nickel oxide(Ni O)nanosheets onto quartz fibers(QFs),which exhibited a high catalytic activity using the hydrogenation of 4-nitrophenol(4-NP)as a model reaction in a batch reaction study.More importantly,we demonstrated that fiber-based QF@Ni O composites(e.g.,cotton,fabric,belt,felt)can be integrated as versatile platforms to develop microreactors for continuous-flow catalytic applications including hydrogenation reactions and dyecatalyzed degradation.This fiber-based three-dimensional(3 D)nanocatalyst architecture effectively drives continuous-flow catalytic reactions with unprecedented efficiency due to the easy diffusion of reactant molecules into the fibrous structure,allowing contact with catalytic active sites.Our approach to continuous-flow microreactor design uses surface hybridization as a guideline to immobilize nanocatalysts onto the QFs.These QF-based platforms,coupled with rational design,are expected to be applied to a wide range of nanocatalytic reactions.

Preparation and Characterization of Alumina-coated Hollow Quartz Fiber Reinforced Al_(2)O_(3)-SiO_(2) Aerogel Composite

Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.

Stimulation of Rare Earths in Quartz Optical Fiber Surface Metallization by Electroless Plating and Electroplating

This research aims to use several kind of rare earth oxides, such as Nd2O3, Yb2O3, Ce2O3 and La2O3, to improve the electroless plating and electroplating processes for surface metallization of quartz optical fiber (silicon fiber) for its practical uses. The effects of the rare earth oxides on the deposition rate of Ni-P-B, the stability of the plating solution and the surface property of the film were investigated and the comparisons of their behaviours were made. The effects of rare earth oxide of La2O3 on the hardness and surface property of the Ni film prepared by electroplating process were studied. The surface morphonogies, compositions and hardness of the Ni-P-B and Ni films were characterized and analyzed by SEM, MSM, ICP and DIMHM, respectively. The experimental results showed that Ce2O3 with the concentration of 4 mg·L-1 was the best one among the four rare earth oxides with suitable concentrations in increasing the deposition rate, enhancing the stability of the electroless plating solution and improving the surface property of the Ni-P-B film. The improvements of the hardness and surface property of the Ni film prepared by electroplating with adding La2O3 were discovered. No obvious influences of Ce2O3 and La2O3 on the compositions of Ni-P-B and Ce free in the Ni-P-B film were found because of its much more nagative deposition potential than those of the used reducing agents in this experiment. The total diameter of the quartz optical fiber with deposited Ni-P-B film and Ni film was about 1.7 mm, which could be satisfactorily for the practical uses of quartz optical fiber in many fields.

A NEW METHOD FOR MEASURING LONG-TERMCREEP DEFORMATION IN A SMALL REGION

Creep deformation localization is generally found in structures at high temperamture,typically in weldments. As the heat affected zone (HAZ) in a weldment is very narrow, deformation in HAZ region can hardly be measured by conventional displacement gauge. A new method for measuring long-term local creep deformation was developed by quartz optical fiber and technique of digital image analysis. The creep deformations of base metal, weld metal and HAZ in weldments are thereby determined with crossweld specimens.

Preparation and Characterization of Nanosized CeO_2/γ-Al_2O_3 Composite Supports

The main purpose of this article is to use rare earths to modify the electroless plating process for metallizing the surface of quartz optical fibers (silicon fibers). The effects of Yb, Ce and La on the deposition rate of Ni-P, the stability of plating solution and the surface structure of Ni-P film were investigated and their mechanisms were discussed. The surface morphonogies and compositions of the Ni-P films were characterized and analyzed by SEM, MSM, XRD and ESM, respectively. The experimental results showed that Ce(SO4)2 with concentration of 40 mg·L-1 was proved to be the best choice for increasing the deposition rate, enhancing the stability of plating solution and improving the quality of deposited Ni-P film compared with the other two kind of rare earths. The detections of ESM exhibited no effect of Ce on film compositions and no Ce deposition being found in the film prepared by electroless plating with adding Ce because of its much more negative deposition potential than those of the reducing agents used in the experiment. The addition of Ce resulted in a transmission of the film surface structure from crystal structure into a microcrystallitic structure. The Ni-P film with thickness of about 45 μm prepared using electroless plating by adding Ce(SO4)2 with concentration of 40 mg·L-1 had good quality, which will be satisfactorily for the next Ni deposition by electroplating.