Preparation and characterization of gradient refractive index plastic rods with small calibers

A series of gradient refractive index (GRIN) plastic rods with diameters of 2–4 mm were fabricated using the centrifugal diffusion polymerization (CDP) technique. Methyl methacrylate (MMA) was used as the monomer having a lower refractive index, and poly‐(methyl methacrylate) (PMMA) was used as a prepolymer dopant. The reactive benzyl methacrylate (BzMA), and an unreactive agent chosen from bromonaphthalene (BN) and diphenyl sulfide (DS) with higher refractive index were used as the second component of the feed mixture. Effects of feed composition, centrifugal conditions, and initiator concentration on the optical characteristics of plastic GRIN rods are investigated. Refractive index profiles and image transmission qualities of the GRIN rods prepared in this investigation are estimated.     

印刷具有梯度折射率微结构的硫卤玻璃衍射光学元件的研究

通过一种高效而廉价的显微热极化工艺,在硫卤玻璃中刻印出覆盖可见到中红外波长且具有梯度折射率(GRIN)微结构的衍射光学元件(DOE).研究了显微热极化的主要极化参数(极化电压U)对硫卤玻璃的微观形貌、微结构、衍射效果和梯度折射率的影响规律.在U为0.75～1.00 kV范围内发现了有效印刷GRIN微结构硫卤玻璃的形成区...     

梯度光学功能玻璃研究进展

梯度折射率(GRIN)玻璃是指具有梯度折射率分布的光学功能玻璃,其在光学及光电学领域中具有广阔的应用前景.介绍了GRIN玻璃的形成原理及分类,综述了GRIN玻璃的制备技术及发展现状,讨论了它们各自存在的问题,提出了今后GRIN玻璃的研究方向.     

Gradient-Index polymer materials and their optical devices

A gradient-index (GRIN) plastic optical fiber was prepared by a heat-drawing process of the GRIN preform rod obtained by a new interfacial-gel copolymerization technique. The attenuation loss of the GRIN fiber was 179 kB/km at 650-nm wave-length and its numerical aperture was 0.20-0.25. To attain low loss and highly dense integrated circuits, steric radial-GRIN optical waveguide components such as GRIN branching, star coupler, multi-coupler, and a 2-D GRIN lens array, were monolithically fabricated by this technique. A novel spherical GRIN sphere lens, whose index function is symmetrical about the center of the sphere, with a low spherical aberration, was prepared by a modified suspension polymerization technique. A W-shaped GRIN sphere has been newly proposed to further reduce the spherical aberration, compared with the parabolic GRIN sphere previously proposed.     

Multilayered chalcogenide glass with gradient index for reduced SWaP IR optical system

Gradient index (GRIN) lens could promote the lightweight and miniaturization of optical imaging system, but the development of IR GRIN lens is still in its infancy. A new series of As–S–Se chalcogenide glasses (ChGs) possessing similar glass transition temperature, excellent thermal stability, and large refractive index variation was developed, and these properties enabled them to become a good glass material catalog for co-molding multilayered GRIN IR lens. By employing precision molding, layer-stacked GRIN ChG was co-molded with a maximum refractive index variation of 0.47 at 4 μm, which was correlated to the variation of Raman intensity and elemental content. A mid-IR optical imaging system was designed and fabricated using the GRIN ChGs, and IR images were obtained. This multilayered GRIN ChG could lead to 18% smaller and 35% lighter SWaP IR optical system.     

Surface Analysis and Treatment of Extruded Fluoride Phosphate Glass Preforms for Optical Fiber Fabrication

Fabrication of fluoride phosphate glass optical fibers using the extrusion method for preform fabrication has been studied using the commercial Schott N‐FK51A glass. The extrusion step was found to create a surface layer of differing composition from the bulk glass material, leading to defects drawn down onto the optical fiber surface during fiber fabrication, resulting in high loss and fragile fibers. Similar phenomena have also been observed in other fluoride‐based glasses. Removal of this surface layer from preforms prior to fiber drawing was shown to improve optical fiber loss from >5 dB/m to 0.5–1.0 dB/m. The removal of this surface layer is therefore necessary to produce low‐loss fluoride phosphate optical fibers.     

Evaluation of high temperature polymers in nanolayered films and gradient refractive index (GRIN) lenses

A new polymer nanolayer gradient refractive index (GRIN) system with more robust thermal stability because of incorporation of a high glass transition temperature polyester, OKP4HT, was demonstrated. A combination of extruded nanolayered GRIN film systems, comprised of five unique polymer materials, were combined to produce laminate optics comprised of a large internal refractive index gradient distribution, n = 1.445 – 1.630, without degradation of optical transmissive properties. The optical performance of a series of varied magnitude GRIN lenses, ranging from Δn = 0 to 0.185, was evaluated. Increasing the lens refractive index range resulted in decreased optic sphericalaberrations that followed analytical predictions. An analytical approach was reported to correlate the polymer material upper service temperature (UST) to the onset of polymer material loss modulus as measured by DMTA. Thermo‐optical interferometry measurements of irreversible lens deformation confirmed the lenses UST at 125°C for the OKP4HT/PC system as compared to 75°C for a PMM/SAN17 system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42741.     

Effects of impact modifiers on the properties of rigid PVC/wood‐fiber composites

This study examined the effects of impact modifier types and addition levels on the mechanical properties of rigid PVC/wood‐fiber composites. The impact resistance of rigid PVC/wood‐fiber composites depends strongly on the type and content of impact modifier. With the proper choice of modifier type and concentration, the impact strength of rigid PVC/wood‐fiber composites can be significantly improved without degrading the tensile properties. Methacrylate‐butadiene‐styrene and all‐acrylic modifiers performed in a similar manner and were more effective and efficient in improving the impact resistance of rigid PVC/wood‐fiber composites than the chlorinated polyethylene modifier.     

Effect of halogen on imprinting gradient refractive index microstructure in GeS2–Ga2S3–NaX (X=F,Cl, Br,I) glasses for broadband infrared diffraction gratings

Chalcohalide glasses with a gradient refractive index (GRIN) microstructure were imprinted by microthermal poling for realizing diffractive optical elements covering the visible to middle-infrared wavelength range. The effect of halogen ions on the saturation poling voltage (U), surface profile, diffraction pattern, optical transmittance, GRIN microstructure, and structural rearrangement of poled glass is investigated. An effective imprinting formation region for a GRIN microstructure based on the U and glass composition is observed under fixed poling time and temperature. The onset U (60 V–150 V) and activation energy of mobile cations (0.449 eV–0.533 eV) decreases with the atomic number of the halogen from F to I, but the saturation diffractive order (8th to 11th levels) and phase difference (~0.08λ to 0.18λ) increases accordingly. The onset U and activation energy decrease with the deformability of the glass network and radius of the halogen ions. The phase difference and saturation diffractive orders decrease with the proportion and electronegativity of interval halogen atoms in the glass network. Thus, chalcohalide glasses with GRIN microstructures can be tailored by adjusting the type of halogen ions for realizing various diffraction optical elements.     

The grafting of methyl methacrylate onto cotton by tri-n-butylborane

Methyl Methacrylate was grafted onto cotton by tri-n-butylborane in the presence of water. No graft was obtained in organic solvents, i.e., in the absence of water. The percentage of grafting increased with increases in reaction time, cotton amount, and initiator concentration. Pretreatment of cotton with pyridine also enhanced the percentage of grafting. Glycidyl methacrylate and ethyl acrylate were grafted onto cotton by tri-n-butylborane, while no grafting occurred when vinyl acetate and 4-vinyl pyridine were used. Usual radical initiators, such as azobisisobutyronitrile and benzoyl peroxide/dimethyl-p-toluidine, were not effective under the same conditions.     

Morphology and Characterization of Epoxy-acrylate Composite Particles

Summary  Epoxy-acrylate sample was prepared by two-stage feed emulsion polymerization. Gel permeation chromatography (GPC) and Ultraviolet-Visible (UV-Vis) spectra indicated the acrylic and styrene monomer were grafted onto epoxy resin. Transmission electron microscope (TEM) showed that epoxy-acrylate composite particles with different epoxy resin content stained by pH1.5 phosphotungstic acid (PTA) had an obvious core-shell structure, with styrene-acrylate as the core and epoxy resin as the shell. TEM micrographs also showed the acrylate cores concentrically or eccentrically were positioned inside epoxy resin shells, which was consonant with the particle structures designed. But the Epoxy Resin/Methyl Methacrylate (EP/MMA) particles showed a strange quadrangle-like structure and Epoxy Resin/Methyl Methacrylate/ Butyl Acrylate (EP/MMA/BA) particles showed a hexagon-like structure, which were different from the normal particle structures.     

The role of the terminal functional group of self‐assembled monolayers on fiber matrix adhesion

Adhesion at the fiber‐matrix interface of a composite is often influenced by a combination of factors such as mechanical interlocking, physicochemical interactions, and chemical bonding in the fiber‐matrix interphase region. We demonstrate the use of an approach using self‐assembled monolayers (SAMs) for studying the impact of one of the factors, chemical bonding, on the overall adhesion of the glass‐fiber/matrix interface. Transformation of these monolayer surfaces using conventional chemistry with a focus on the creation of a terminal functional group that interacts with epoxy resin is reported. The modified surfaces were characterized by ellipsometry, X‐ray photoelectron spectroscopy, and contact angle techniques for chlorosilane coverage, and in situ conversion. The adhesion of diglycidyl ether of bisphenol‐A resin to modified SAMs on E‐glass fibers was measured by performing single‐fiber fragmentation test. The extent of adhesion between the fiber and matrix was found to be dependent on the type of functional group at the terminal end of the SAM in contact with the epoxy matrix. Methyl terminal group resulted in the least adhesion, while amine terminal groups resulted in the most adhesion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and refractive index characterization of chalcogenide glasses with gradient refractive index

Infrared gradient refractive index (GRIN) lenses have great application value and potential in multispectral imaging systems. This study reports various chalcogenide axial GRIN glasses prepared using the hot-pressing diffusion method. It is worth noting that the S4–S60 GRIN sample has a difference in refractive index (RI) Δn of greater than 0.3 and a diffusion depth of about 5 mm, which is the deepest diffusion depth reported in chalcogenide glass to date. In addition, the linear portion in the profile of the GRIN sample has a RI difference of 0.15 and a thickness of 1.2 mm. The effects of the temperature, concentration difference, and diffusion time on the sample diffusion process are discussed. The dispersion properties of the GRIN samples were further calculated, providing a new option for correcting chromatic aberrations in optical systems. In addition, a method for the indirect nondestructive characterization of sample RI using the Raman intensity ratio is proposed, and the reliability of the method is verified by practical experiments, which is convenient for the subsequent measurement of the GRIN profile.     

玻璃纤维表面的聚甲基丙烯酸甲酯接枝

本文用臭氧对表面涂有ＭＡＣ试剂的玻璃纤维进行了处理，使玻纤表面产生活性中心，引发甲基丙烯酸甲酯在玻璃纤维表面上接枝聚合，接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上有聚甲基丙烯酸存在。     

Bismuth‐Doped Multicomponent Optical Fiber Fabricated by Melt‐in‐Tube Method

Bismuth‐doped multicomponent optical fiber was fabricated by a melt‐in‐tube method. The fiber was prepared at drawing temperature where the clad was softened, while the fiber core glass was melted. The obtained fiber was characterized by electroprobe microanalyzer and X‐ray diffraction. No obvious precipitation of crystals or bismuth metals was observed in the fiber. Excited by 808‐nm laser, intense broadband near‐infrared emission with full width at half maximum of about 325 nm was observed from the fiber. Consequently, this fiber is promising for broadband fiber amplification. The melt‐in‐tube method is generally applicable for fabricating bismuth‐doped multicomponent optical fiber.     

Experimental investigation on the effect of nanostructuration on the adherence properties of epoxy adhesives by a probe tack test

In this work, we aimed to characterize the energy of adherence of nanoscale structured epoxy adhesives Diglycidyl ether of bisphenol-A/Methylene–diethylaniline (DGEBA/MDEA) induced by phase separation triblock copolymers Poly (Methacrylate de Methyl)-b-Poly (Butyl Acrylate)-b-Poly (Methyl Methacrylate) (PMMA-b-PBA-b-PMMA) at gel state by a probe tack test, which is an original use of this kind of test for thermoset adhesives. For a set of mechanical parameters (probe’s roughness, contact time, contact pressure and debonding velocity), we measured the energy of adherence for both neat and filled adhesives. The probe tack test was performed at different steps of gelation. We compared the behavior of the adhesives and evaluated the dissipation contribution to the energy of adherence of the adhesives during the test. We finally discussed the nanoparticles׳ influence on the competition between cavitation and fibrillation. We report that the addition of nanoparticles leads to an overall improvement of the energy of adherence, with a significant increase of the dissipation contribution to the energy measured.     

Mechanical characterization and fractography of glass fiber/polyamide (PA6) composites

The mechanical properties of the glass fiber reinforced Polyamide (PA6) composites made by prepreg tapes and commingled yarns were studied by in‐plane compression, short‐beam shear, and flexural tests. The composites were fabricated with different fiber volume contents (prepregs—47%, 55%, 60%, and commingled—48%, 48%, 49%, respectively) by using vacuum consolidation technique. To evaluate laminate quality in terms of fiber wet‐out at filament level, homogeneity of fiber/matrix distribution, and matrix/fiber bonding standard microscopic methods like optical microscopy and scanning electron microscopy (SEM) were used. Both commingled and prepreg glass fiber/PA6 composites (with V_f ∼ 48%) give mechanical properties such as compression strength (530–570 MPa), inter‐laminar shear strength (70–80 MPa), and transverse strength (80–90 MPa). By increasing small percentage in the fiber content show significant rise in compression strength, slight decrease in the ILSS and transverse strengths, whereas semipreg give very poor properties with the slight increase in fiber content. Overall comparison of mechanical properties indicates commingled glass fiber/PA6 composite shows much better performance compared with prepregs due to uniform distribution of fiber and matrix, better melt‐impregnation while processing, perfect alignment of glass fibers in the composite. This study proves again that the presence of voids and poor interface bonding between matrix/fiber leads to decrease in the mechanical properties. Fractographic characterization of post‐failure surfaces reveals information about the cause and sequence of failure. POLYM. COMPOS., 36:834–853, 2015. © 2014 Society of Plastics Engineers     

Development of formulations based on acrylate monomers for optical cable applications

Methyl methacrylate and 2‐ethyl hexyl acrylate were copolymerized in the presence of different crosslinkers with free‐radical initiation. The double‐bond conversion was monitored with in situ Fourier transform near‐infrared spectroscopic techniques. Dynamic mechanical properties of the resultant polymers were measured, and the curves were interpreted on the basis of the heterogeneity and flexibility of the samples. The optical properties of the cables made out of these systems were measured with transmission spectra. The effect of the addition of additives on the optical properties was demonstrated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3001–3012, 2001     

Real‐Time damage detection in thermoplastic‐based composite materials with embedded multi‐mode optical fiber sensors

In this paper we describe the use of an inexpensive standard communication‐grade optical fiber for the purpose of detecting damage in glass fiber reinforced thermoplastic composite materials and hybrid fiber metal laminates based on the same composite constituent. These multi‐mode, step‐index optical fibers were embedded at different locations within the composite structure to assess their ability for structural health monitoring. In this study, the specimens were loaded under a three‐point bend test configuration, Results from the investigation have shown that these optical fibers are capable of detecting the peak failure load in the host material when embedded at locations where structural failure initiates at peak load. The output from the optical fibers was shown to be sensitive to the applied loading conditions suggesting that they can also be used to monitor structural loading. Optical micrographs of selected specimens were obtained by sectioning the specimens at the fracture location to provide confirmation of the optical fiber results.     

环保型水性印刷光油的研究

以甲基丙烯酸甲酯（MMA）、丙烯酸丁酯（BA）、丙烯酸甲酯（MA）、苯乙烯（St）等为单体,以过硫酸钾为引发剂,以十二烷基硫酸钠（SDS）、聚乙二醇辛基苯基醚（OP-10）为乳化剂,通过预乳化种子聚合法获得水性乳液型上光油。探讨了乳化剂用量和配比、引发剂用量、反应温度和时间、后续单体滴加时间、保温反应时间、搅拌速度及中和剂对乳液综合性能的影响。通过固化成膜试验对水性上光油的光泽度、耐磨性、耐水性等性能测定。结果表明：乳化剂用量为乳液的2．0％～3．0％（质量分数）,阴/非离子乳化剂配比为1：2,引发剂质量分数为单体的0．55％,反应温度78—84℃,反应时间4h,后续滴加单体时间为90min,保温时间2．0h,搅拌速率为120r／min,使用NaHCO3作为中和剂时乳液性能最佳。主要技术指标：光泽度为92;固含量为46％。