A new photopolymerizable holographic recording material based on acrylamide and N-hydroxymethyl acrylamide

A new polyvinylalcohol-based photopolymeric holographic recording material has been developed. The recording is obtained by the copolymerization of acrylamide and N-hydroxymethyl acrylamide. Diffraction efficiencies near 50% are obtained with energetic exposure of 80mJ/cm^2. N-hydroxymethyl acrylamide can improve the optical quality of the film. With the increase of the concentration of N-hydroxymethyl acrylamide, the flatness of the film increases, scattering reduces and the straight image is clearer with a small distortion. The postexposure effect on the grating is also studied. The diffraction efficiency of grating increases further during postexposure, gradient of monomer exists after exposure.

Dark diffusional enhancement of holographic multiplexed gratings in phenanthrenequinone doped poly(methyl methacrylate) photopolymer

In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly （methyl methacrylate） （PQ-PMMA） photopolymer. The possibility of improving the holographic characteristics of the material through the dark enhancement is demonstrated. The optimal preillumination exposure and the optimal time interval between exposures are extracted to obtain the optimized diffraction efficiency, and their values are 3.4×103 mJ/cm2 and 2 min, respectively. The dark enhancement of the multiplexed grating is presented as an effective method to improve the response region and the dynamic range and to prevent saturation of the material. The dependence of the phenanthrenequinone concentration on the increment of the refractive index modulation is quantitatively studied, which provides a significant basis for improving the homogeneity in the multiplexed gratings using a quantitative strategy. Finally, a simple experimental procedure using the dark enhancement is introduced to improve the homogeneity of the diffraction efficiency and to avoid the complex schedule exposure.

Holographic storage of three-dimensional image and data using photopolymer and polymer dispersed liquid crystal films

We present holographic storage of three-dimensional（3D） images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram of real object and image of digital information are recorded in the films.The photopolymer is compared with polymer dispersed liquid crystals as holographic materials.Besides holographic diffraction efficiency of the former is little lower than that of the latter,this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field.Therefore,our study proposes a potential holographic storage material to apply in large size static 3D holographic displays,including analog hologram displays,digital hologram prints,and holographic disks.

Discrimination conditions and process of water-resistant key strata

Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.

Water-resistant organic thermoelectric generator with >10μW output

Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability of n-type materials is essential to ensuring large temperature differences between device terminals and ambient stability.With the aim of improving the long-term stability of the n-type operation of carbon nanotubes(CNTs)in air and water,this study uses cationic surfactants,such as octylene-1,8-bis(dimethyldodecylammonium bromide)(12-8-12),a gemini surfactant,to stabilize the nanotubes in a coating,which retains the n-doped state for more than 28 days after exposure to air and water in experiments.TEGs with 10 p-n units of 12-8-12/CNT(n-type)and sodium dodecylbenzene sulfonate/CNT(p-type)layers are manufactured,and their water stability is evaluated.The initial maximum output of 16.1μW(75 K temperature difference)is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation.The excellent stability of these CNT-based TEGs makes them suitable for underwater applications,such as battery-free health monitoring and information gathering systems,and facilitates the development of soft electronics.

Holographic property of photopolymers with different amine photoinitiators

Holographic parameters and photobleaching kinetics of the photopolymers with five different amine photoinitiators are studied. The maximum values of diffraction efficiency, photobleaching coefficient and quantum yield follow the sequence： Triethanolamine （TEA）〉 Diethanolamine （DEA）〉 Ethanolamine （EA）〉 Triethylamine （TETN）〉 Diethylamine （DETN）. The holographic capabilities of photopolymer performances are determined by the number of functional groups in the amine molecular structure. There is an optimum proportion of the photoinitiator, the photosensitizer and the monomer in the test of holographic parameters with different amine concentrations. The maximum diffraction efficiency is 59.26／%, sensitivity is 1.72／times 10^{ - 3}~cm^{2}/mJ, and the maximum refractive modulation index is 4.64／times 10^{ - 4}.

CURING PROCESS OF PHOTOPOLYMER RESIN BOND DIAMOND TOOLS

Analytical simulation and corresponding proof-test are adopted to study the principle of the curing process of photopolymer resin diamond tools. The influence of the diamond as abrasives in photopolymer resin owing to the absorptivity of the diamond for the UV light on the photopolymer resin curing process is discussed. Based on the above, a kind of diamond tool—dicing blade is selected to analyze the curing process of photopolymer bond diamond tools. An analytical model of curing process is developed and a correlation curve between the depth of polymerization of the photopolymer resin diamond tools and the exposure time to represent the curing process of photopolymer bond dicing blade. A test is done to proof-test the validity of the analytical model and the correlation curve. The simulated data fit the experimental results, which demonstrates the analytical models and numerical algorithm are of high reliability. The analytical simulation method could possibly be used to optimize the curing cycle and improve the quality of the photopolymers resin bond diamond tools.

Dynamic analysis of holographic gratings in a multi-wavelength visible light sensitive photopolymer

A dynamic theoretical model of photochemistry and hologram formation in holographic photopolymer is established, and the dynamic development process of holographic gratings in the photopolymer is discussed with the model. A novel multi-wavelength visible light sensitive photopolymer for holographic storage is prepared. The influence of exposure wavelength on holographic storage characteristics is analysed. By fitting the experimental data of transmittance and diffraction efficiency to a function of time with different exposure intensities and wavelengths, the variations of dynamic parameters of photochemistry and photopolymerization diffusion are presented.

Compact 2×2 parabolic multimode interference thermo–optic switches based on fluorinated photopolymer

In this work, a dual-side parabolic structural(DSPS) multimode interference(MMI) thermo–optic(TO) waveguide switch is designed and fabricated by using novel low-loss fluorinated photopolymer materials. Comparing with the traditional dual-side linear structural(DSLS) MMI device, the effective length of the MMI coupling region proposed can be effectively reduced by 40%. The thermal stability of the waveguide material is analyzed, and the optical characteristics of the switching chip are simulated. The actual performances of the entire MMI switch are measured with an insertion loss of7 dB, switching power of 15 m W and an extinction ratio of 28 dB. In contrast to the traditional MMI optical switch, the new type of parabolic structural MMI TO waveguide switch exhibits lower power consumption and larger extinction ratio. The compact fluorinated polymer MMI TO switches are suitable well for realizing miniaturization, high-properties, and lower cost of photonic integrated circuits.

Development of a Hybrid Photopolymer for Stereolithography

New liquid free radical-cationic hybrid photopolymer, consisting of acrylate-based photocurable resin and epoxy-based photosensitive resin for stereolithography by UV laser was developed. The experiment results indicated that the hybrid photopolymer exhibits advantages of both the acrylate-based photosensitive resin and the epoxy-based photosensitive polymer contained in the hybrid system with relatively high photospeed and low linear shrinkage. Stereolithography parts without obvious distortion were built on the stereolithography apparatus HRPLA- I from this hybrid resin successfully and efficiently.

Analysis of Water Insulating Effect of Compound Water-Resisting Key Strata in Deep Mining

The problem of water preservation in mining and the prevention of water-bursts has been one of the more important issues in deep mining. Based on the concept of water-resisting key strata, the mechanics model of the key strata is established given the structural characteristics and the mechanical properties of the roof rock layers of the working face in a particular coal mine. Four other models were derived from this model by rearranging the order of the layers in the key strata. The distribution characteristics of stress, deformation, pore pressure and the flow vector of all the models are computed using the analytical module of fluid-structure interaction in the FLAC software and the corresponding risks of a water-burst are analyzed. The results indicate that the water-insulating ability of the key strata is related to the arrangement of soft and hard rocks. The water-insulating ability of the compound water-resisting key strata (CWKS) with a hard-hard-soft-hard-soft compounding order is the best under the five given simulated conditions.

Simulation of Water-Resistance of a Clay Layer During Mining:Analysis of a Safe Water Head

Given previous research and prototypical geological conditions of a mining workface,we simulated fis-sure development in clay layers at the bottom of Quaternary strata and above bedrock,sand and water inrush during mining by model experiments. The results show that V-shaped fissures usually occur in the bottom clay layer at the front top of the active face and that the position of these fissures changes periodically with ground pressure intervals. These fissures occur exactly in the area where the horizontal strain is concentrated. The results also demonstrate that the permeability coefficient of the cracked clay decreases while fissures tend to close. The permeability of the cracked bottom clay layer increases rapidly after a turning point in the permeability coefficient-water head curve (K-H curve) under a certain vertical load. Under static water pressure,the permeability coefficient of cracked clay decreases when load increases. A turning point in the K-H curve showed up and can be seen as a cutoff point to de-cide water inrush under a certain load level. Under an instantaneous water head,the greatest ability of the cracked clay to avoid drastic water inflow is a little higher than that under static conditions.

Structural motion of water-resisting key strata lying on overburden

Water-preserved mining is one of the important parts of the ‘Green Mining’ technological system. The purpose of wa-ter-preserved mining is to prevent water from bursting out in coal mines and thus to protect water resources. The principle of wa-ter-resisting key strata (WKS) is proposed to establish a model capable of guiding and developing water-preserved mining technol-ogy. The experimental model of the WKS is constructed following requirements of the Data Image Correlative Method (DICM). Five experimental schemes are designed according to different combined patterns of the WKS. The water-resisting performance of the WKS is analyzed from observation of structural stability. All of them provide referential value for water-preserved mining.

Water-resisting ability of cemented broken rocks

Using the self-designed testing system, the seepage tests for cemented broken rocks were conducted, and the impact of different factors on water-resisting ability was analyzed. The results show that(1) seepage process of the cemented broken rocks can be divided into two categories: in one category, seepage instability occurs after a period of time, in the other, the permeability decreases slowly and tends to be stable,and seepage instability does not occur;(2) cementing performance of cementing agent and grain size distribution are the decisive factors for water-resisting ability, with the increase of cementing performance and the mass percentage of large grains, the water-resisting ability of the specimen strengthens;(3)aggregate type has little effect on seepage stability, for the specimens with different aggregate types,the permeability and the duration of seepage instability have small difference;(4) initial porosity has a certain effect on the water-resisting ability of the specimen, but has no decisive role. With the increase of the initial porosity, the duration of seepage instability decreases.

Pore structure characteristics of the relative water-resisting layer on the top of the Ordovician in Longgu Coal Mine

In order to study the permeability and water-resisting ability of the strata on the top of the Ordovician in Longgu Coal Mine, this paper tested the permeability and porosity of the strata, investigated the fracture and pore structure features of the strata, and identified the main channels which govern the permeability and water-resisting ability of the strata. The permeability of the upper, central and lower strata shows as 2.0504 × 10^-3-2.782762× 10^-3, 4.1092 × 10^-3 -7.3387 × 10^-3 and 2.0891 ×10^-3-3.2705 × 10-3 μm^2, respectively, and porosity of that is 0.6786-0.9197%, 0.3109-0.3951% and 0.9829-1.8655%, respectively. The results indicate that： （I） the main channels of the relative water-resisting layer are the pore throats with a diameter more than 6 μm; （2） the major proportion of pore throats in the vertical flow channel and the permeability first increases and then sharply decreases; （3） the fractures occurring from the top to 20 m in depth of the strata were filled and there occurred almost no fracture under the depth of 40 m; and （4） the ratio of turning point of the main flow channel in the strata on top of Ordovician can be used to confirm the thickness of filled water-resisting lavers.

Numerical analysis of the destruction of water-resisting strata in a coal seam floor in mining above aquifers

With the increase in mining depth many mining areas in China have entered a period necessitating mining above aquifers. Production safety in coal mines in northern China is under serious threat from Ordovician karst water on coal seam floors, in order to analyze the destruction of water-resisting strata in floors of coal seams being mined and to achieve safe mining above deep aquifers, we established a numerical model of water-resisting strata, considering the structural characteristics and mechanical properties of a floor layered with hard and soft rock. We simulated the distribution characteristics of deformation, failure and seepage using the analytical module of fluid-structure interaction of FLAt：. We also obtained the corresponding stress distribution, deformation and flow vectors. Our results indi- cate that： （1） the advance of the working face causes water-resisting strata in goaf floors to form a deep double-clamped beam, subject to homogeneous loading at the bottom; （2） the two sides of the rock beam are subject 1~0 shear failure; （3） both sides of the rock seam at the bottom of the water-resisting strata are subject to tension and the greater the working face advance, the more serious the failure; C4） the original balance of the stress and seepage fields are broken and redistributed due to mining activities, especially the interaction of the abutment pressure in both sides of the goal; the lateral pressure on the goal floor and the water pressure on the floor of the aquifer promote floor heave and shear failure on both sides of the floor, forming a water-inrush passage. Our study results can provide references for the mechanism of water-inrush on mine floors.

Strong water-resistant Co-Mn solid solution derived from bimetallic metaleorganic frameworks for catalytic destruction of toluene

The construction of CoeMn mixed-metal oxide catalysts derived from bimetallic metaleorganic frameworks(MOFs)has great significance for catalytic destruction of toluene.Hence,a series of Co_(a)Mn_(b)O_(x)-MOFs with different physicochemical properties were successfully synthesized via pyrolysis of CoeMn bimetallic MOFs.Attributing to the higher specific surface area,more active sites(Co^(3+)and Mn^(3+)),stronger reducibility,and abundant defect sites,the as-prepared Co_(1)Mn_(1)O_(x)-MOFs displayed an optimal catalytic performance,especially the excellent water vapor resistance.The result of the in situ diffuse reflectance infrared Fourier transform spectroscopy demonstrated that toluene can be degraded at relatively low temperatures(<100℃).Benzyl alcohol,benzaldehyde,benzoic acid,and maleic anhydride were the main intermediate products in toluene degradation process.This work reveals the value of bimetallic MOFs derived Co-Mn oxides for toluene oxidation and presents a novel avenue for designing mixed-metal oxide catalysts with potential applications in volatile organic compounds(VOCs)catalytic oxidation.

Upcyclable thermosetting photopolymer containing degradable sulfite bonds for sustainable 3D printing

The advancement of photo-curing three-dimensional(3D)printing technology has significantly enhanced the capabilities of advanced manufacturing across various fields.However,the robust cross-linking network of photopolymers limits its application in information encryption and exacerbates environmental issues.In this study,a degradable thermosetting photopolymer platform for information encryption was proposed by incorporating sulfite bonds into the polymer structure.Due to the autocatalytic behavior of sulfite bonds during hydrolysis under acidic conditions,the photopolymer can achieve complete degradation at 50℃ within 45 min.Based on the degradability of the developed photopolymers,a highly secure degradation-UV dual information encryption system has been established using photo-curing-based 3D printing technology.Furthermore,the degradation products of these photopolymers,generated during the information decryption process,can be utilized to prepare high-performance solar thermoelectric generators with a power density of 325.7µW cm^(−2)(under one sun)after a simple one-step modification.This work not only inspires the development of multiple information encryption methods based on 3D printing but also provides a practical solution to address environmental challenges associated with plastic pollution.

富勒烯掺杂的光致聚合物的全息存储特性研究

研究了富勒烯对六官能团脂肪族聚氨酯丙烯酸酯/环氧树脂(RJ423/EPIKOTE 828)体系光致聚合物的全息性能的影响,分析了富勒烯(C_(60))材料以及曝光光强对光致聚合物衍射效率的影响。通过吸收光谱结合X射线衍射图谱分析,掺杂的富勒烯既没有和聚合物中的其他成分发生化学反应,也不影响材料本身的结构和结晶性能。实验结果表明,富勒烯掺杂提高了单体聚合反应的速率,并且参与活性单体分子之间的扩散。在光强20 mW/cm^(2)、时间40~50 s、厚度200µm时,光致聚合物的衍射效率提升到86%,感光灵敏度达到1.32 cm^(2)/J,收缩率降低了约80%。由于C_(60)促进聚合,抑制体积收缩,从而增强全息存储的稳定性,经过全息图像存储实验对比,证明该光致聚合物掺杂富勒烯之后具有优秀的全息存储性能,同时也表明富勒烯掺杂的光致聚合物在全息储存领域具有较大的应用前景。

苯乙烯基吡啶鎓盐的光二聚反应及其在丝网印刷中的应用

甲酰基苯乙烯基吡啶鎓盐(SBQ)是一种具有荧光的水溶性二芳基乙烯衍生物,在水溶液中,在365 nm紫外光照射下发生[2+2]的光二聚反应,得到没有荧光的二聚体。这种光二聚体在254 nm短波长紫外光照射下,可以发生光解开环反应,重新生成单体,恢复荧光。SBQ光二聚体可以作为光信息存储材料。在酸性水溶液中,通过缩醛化反应将SBQ单体接枝到聚乙烯醇骨架上,合成了一种水溶性的感光高分子材料,再与白乳胶复配得到单组分丝网印刷感光胶。同学们利用自己合成的产品不仅可以在纸张和实验服上印刷自己创作的图案,而且还可以动手制作印刷电路板以及开展更多的拓展应用。本实验的合成反应均在水溶液中开展,具有安全、环保和绿色的优点。