用于CTCP技术的射频无电极放电氮气等离子体光源研究

本文报道了一种利用射频无极放电激励的氮气等离子体新型光源,成功地对“星光”PS版进行了曝光,光谱分析表明氮气射频放电光源的光谱结构较碘镓灯更适于传统PS版曝光。为此,进一步从射频功率、工作气压等方面探讨了光源的最佳运行参数,得到在230Pa、160W采用两个传输透镜聚焦后获得的光源功率密度是2.23mW/cm2。最后给出了运用此光源对PS版的曝光结果。     

印刷制版用N_2等离子体蓝紫光源的实验研究

我国的印刷制版行业目前正处于从传统PS版向计算机直接制版(Computertoplate)技术转变的进程之中,PS版的产销量十分可观,在CTP技术中继续使用传统的PS版对我国印刷包装行业意义重大。实现传统PS版的CTP技术关键在于解决曝光光源问题。本文采用连续直流源空心阴极放电方式产生氮气等离子体蓝紫光源,成功地对一种超感度重氮萘醌系PS版进行曝光,从注入功率、放电气压等方面探讨了氮气等离子光源的最佳工作条件,在工作气压70Pa、放电电压580V、电流1.8A下获得了0.46mW/cm2的蓝紫光输出。气体放电光源还可轻易实现高频大功率脉冲输出,本研究结果表明,新型空心阴极氮气等离子体光源在实现PS版CTP技术方面具有一定的发展前景。     

介质阻挡放电微等离子体分解二氧化碳研究

二氧化碳既是主要的温室气体之一,也是包含碳和氧的资源,把相对惰性的CO₂转化为易于利用的CO是其利用的方法之一。采用介质阻挡微等离子体反应器通过单变量和正交实验探究了反应器参数(放电区长度、放电间距、介质厚度)和工艺参数(输入功率、放电频率和停留时间)对CO₂分解为CO的转化率和能量效率的影响规律。研究结果表明,影响CO₂转化率的大小顺序依次为：放电间距>放电长度>输入功率≈停留时间>介质厚度>放电频率;输入功率60.0 W、放电频率9.0 kHz和停留时间1.5 s、放电区长度60 mm、放电间距0.5 m、介质厚度1.6 mm时,CO₂的转化率为10.6%,能量效率为4.1%。     

低温氩等离子体改善PTT织物吸湿性的研究

用氩低温等离子体对PTT织物进行表面改性,以提高PTT织物的吸湿性能。在不同等离子体处理工作参数(放电功率、放电时间、工作气压)下对PTT织物吸湿性变化进行了规律性和原理分析,并探讨等离子体对PTT织物的最佳处理工艺。实验结果表明:放电时间5min、放电功率200W、气体压强50Pa的处理条件使PTT织物得到最佳的吸湿性能;PTT织物的微观表面出现了明显的凹坑和裂纹,同时强力变化较小。     

ICP光源中射频功率测量装置的设计

阐述ICP光源中射频功率测量的意义,提出了测量范围为100~1 500 W,频率为27.12 MHz的功率测量装置的设计方案。详细分析了射频功率测量装置中的电路设计,包括采样互感器、功率合成电路、幅度相位分析电路和移相电路,并给出了判断ICP光源负载状态和性质的方法。在实验中,利用BIRD43型功率计和BIRD4304A型功率计对射频功率测量装置进行了参数校准。     

等离子体协同紫外光催化净化聚丙烯酰胺废水

采用低温等离子体协同紫外光催化净化聚丙烯酰胺(PAM)废水,系统研究了光催化参数(紫外光光强、波长、TiO_2投加量)、物化参数(废水初始pH值,曝气量)、放电参数(放电电压、放电时间)对PAM废水COD脱除率的影响。结果表明,紫外光光强5 200μW/cm~2,波长253.7 nm,TiO_2投加量2.0%,废水pH值6.5,曝气量2.0 L/min,放电电压35 k V,放电时间2.5 h时,废水净化效果最好,PAM废水COD脱除率达84.6%。     

等离子体协同紫外光催化净化聚丙烯酰胺废水

采用低温等离子体协同紫外光催化净化聚丙烯酰胺(PAM)废水,系统研究了光催化参数(紫外光光强、波长、TiO_2投加量)、物化参数(废水初始pH值,曝气量)、放电参数(放电电压、放电时间)对PAM废水COD脱除率的影响。结果表明,紫外光光强5 200μW/cm²,波长253.7 nm,TiO_2投加量2.0%,废水pH值6.5,曝气量2.0 L/min,放电电压35 k V,放电时间2.5 h时,废水净化效果最好,PAM废水COD脱除率达84.6%。     

碱性电池隔膜用丙纶非织造布的等离子体改性

利用低温等离子体技术对碱性电池隔膜用丙纶非织造布进行表面改性处理,探讨了影响电池隔膜性能的因素,利用红外光谱、扫描电镜对材料表面性能进行了表征分析。结果表明,不同气体的等离子体对丙纶非织造布进行表面处理的最佳工作参数放电气体、放电功率、放电时间、工作压强分别为:氩气,70 W,3 min,15 Pa;氧气,120 W,3 min,30 Pa;空气,100 W,3 min,50 Pa。通过等离子体表面活化处理,在丙纶表面引入了亲水性基团,同时产生了刻蚀,丙纶非织造布的吸碱速率可提高至每10 min 8 cm左右,吸碱率提高至250%,面电阻大幅降低至8 Ω/cm2左右。     

等离子体预处理对解淀粉芽孢杆菌生长和α-淀粉酶分泌的影响

采用低真空室温射频等离子体对解淀粉芽孢杆菌CICC 10035进行预处理,通过改变放电功率、处理时间和工作气压等参数筛选工艺条件,并使用蛋白质组学技术对差异蛋白质进行生物信息学分析,探讨等离子体预处理对菌体生长和产酶性能的影响.得到的等离子体预处理最佳工艺条件为:放电功率120 W,预处理时间15 s,工作气压135 Pa.在该条件下,发酵48 h后,α-淀粉酶酶活超过400 U/mL,与对照样相比提高约20％.蛋白组学分析表明,等离子体预处理对菌体的蛋白合成及代谢产生了较强的正效应,尤其在DNA修复和氨基酸合成上,一方面提高了菌体活性,延缓了其衰亡过程;另一方面促进了α-淀粉酶在菌体内的合成和分泌.     

分子链剪切技术制备超低分子量聚氧化乙烯

采用紫外光对黏均分子量为1.5×106的聚氧化乙烯(PEO)进行了分子链剪切,得到了黏均分子量低于2.0×105的超低分子量PEO。考察了紫外光波长、功率、光源距离和反应温、湿度等因素对PEO紫外剪切速率的影响,并对制备得到的不同低分子量PEO进行了结构分析和性能测试。结果表明:在紫外波长为185 nm、功率为75 W、光源距离为5 cm、环境温度为35℃、相对湿度为20%的较优反应条件下,反应2、3、4和5 h可分别制备黏均分子量为2.0×105、1.1×105、7.0×104和4.0×104的超低分子量PEO。随着降解时间的延长,PEO的分子量分布系数减小。PEO在紫外剪切过程中结构未发生明显改变,仅有少量甲酸酯生成。随着分子量的减小,PEO的熔点降低,结晶度增加。     

Pilot Plant Results with Three Different Types of UV Lamps for Advanced Oxidation

Three different types of ultraviolet lamps were tested for the advanced oxidation process application on pre-treated surface water in a pilot plant. The pilot setup consisted of three parallel reactors with either medium pressure, low pressure or dielectric barrier discharge UV lamps. Four model compounds (atrazine, bromacil, ibuprofen and N-nitroso-dimethylamine (NDMA)) and 0, 5 or 10 ppm hydrogen peroxide were dosed. Low pressure lamps were shown to have the lowest energy demand, calculated as electrical energy per order, followed by dielectric barrier discharge lamps and then medium pressure lamps. Medium pressure lamps gave the highest formation of genotoxic activity and nitrite formation, whereas no formation of genotoxic activity was observed for either of the other lamp types.     

Removal of particulate matter from an air stream by a packed dielectric barrier discharge

This study elucidates the feasibility of using a packed dielectric barrier discharge approach to remove particulate matter from an air stream. The experimental results reveal that the particle removal efficiency of the packed dielectric barrier discharge system rose to 92.2% for 0.3 μm particles as the discharge voltage was increased to 20 kV at an operating frequency of 60 Hz. Only when the discharge voltage was sufficiently high to remove particulate matter did the particle removal efficiency increase with the operating frequency. The power required to adjust the discharge voltage was less than that required to adjust the operating frequency at the particular removal efficiency. Accordingly, energy can be saved in a packed dielectric barrier discharge system by adjusting the discharge voltage rather than the operating frequency to remove particulate matter from the air stream.     

Microstructural,wetting, and dielectric properties of plasma polymerized polypyrrole thin films

Polypyrrole (PPy) thin films were synthesized by plasma polymerization technique and investigated the influence of discharge power on microstructural, optical, surface wettability, and dielectric properties of grown films. As deposited PPy films were characterized by X‐ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR), Atomic force microscopy, UV‐VIS spectroscopy and dielectric spectroscopy. The broad XRD peak present at 2θ = 23.5° revealed the amorphous nature of grown PPy films. The FTIR spectra displayed characteristic peaks in the wavenumbers regions 3300–3400 cm^?1 and 1635–1700 cm^?1 and respective peaks intensities decreased slightly as a function of discharge powers. Significant modifications in surface morphology of the films were observed as a function of discharge powers and PPy films synthesized at higher discharge power of 50 W demonstrated characteristic surface morphology composed of characteristic vertical cone shaped clusters provided with rms roughness of 3.42 nm. The UV‐VIS absorption spectra evidenced that the optical density values varied as a function of discharge power. The evaluated band gap energies decreased with an increase of discharge power and found to be 2.53 eV for PPy films prepared at higher discharge power of 50 W. The surface wettability studies evidenced that as prepared PPy films were found to be hydrophilic in nature. The dielectric measurements were carried out for “ITO/polymer/ITO” structures in the frequency range 10 mHz to 100 kHz. As evidenced from dielectric spectroscopic measurements, PPy films synthesized at 50 W were demonstrated conductivity value of 6.0 × 10^?12 S/m. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43982.     

Ozone Production in a Dielectric Barrier Discharge with Ultrasonic Irradiation

Ozone production has been investigated using an atmospheric pressure dielectric barrier discharge in pure O₂ at room temperature with and without ultrasonic irradiation. It was driven at a frequency of either 15 kHz or ～40 kHz. The ozone production was highly dependent on the O₂ flow rate and the discharge power. Furthermore, powerful ultrasonic irradiation at a fundamental frequency of ～30 kHz with the sound pressure level of ～150 dB into the discharge can improve the ozone production efficiency, particularly when operated at the frequency of 15 kHz at the flow rate of 15 L/min.     

Colour and gloss properties of pigment‐printed synthetic leather using an ultraviolet‐curable water‐borne polyurethane acrylate binder and two photoinitiators at different ratios

This study reports on the colour and gloss properties of pigment‐printed polyurethane‐based synthetic leather using an ultraviolet (UV)‐curable water‐borne polyurethane acrylate binder and two types of photoinitiators (Omnirad 819 DW and Omnirad 500) at different ratios. The UV curing of printed synthetic leather samples was conducted with gallium and mercury lamps, either singly or in combination, at three different power levels. Chemical changes in the cured films because of the polymerisation of the UV‐curing process were analysed by Fourier Transform‐infrared spectroscopy, which showed that the polymerisation reaction occurred after UV curing in both the clear and in the pigmented films. The Omnirad 500 photoinitiator is more effective in surface curing and the Omnirad 819 DW photoinitiator is more effective in deep curing. The Omnirad 500 photoinitiator caused the gloss values to drop significantly, especially in the formulation including both photoinitiators, Omnirad 819 DW and Omnirad 500, at a 1:2 ratio, respectively. In the formulation including a higher ratio of the Omnirad 819 DW photoinitiator, higher gloss values were obtained compared with the formulation including a higher ratio of the Omnirad 500 photoinitiator. Considering all the results, the highest gloss value of 20.96 was obtained with samples printed with the formulation of the two photoinitiators at an equal ratio (1:1) cured under a gallium/mercury lamp combination at a power level of 90 W/cm. Moreover, the highest K/S value of 10.86 was obtained with samples printed with the formulation of the two photoinitiators at an equal ratio cured under the gallium lamp at 90 W/cm.     

Ozone formation with (V)UV‐enhanced dielectric barrier discharges in dry and humid gas mixtures of O2, N2/O2, and Ar/O2

The effect of (V)UV illumination at 172 run and 253.7 run on ozone formation with dielectric barrier discharges in air‐like mixtures of nitrogen/oxygen and argon/oxygen as function of the water concentration is presented. Although (V)UV at these wavelengths efficiently cleaves ozone, the ozone concentration in a combined (V)UV/dielectric barrier discharge in oxygen‐containing gases is reduced only very little. This corresponds to an enhanced concentration of atomic singlet oxygen, which, in presence of water, increases the production of hydroxyl radicals. This is confirmed by measurements of the removal rates of 2‐propanol and of its byproducts in dry and humid air in a combined (V)UV/dielectric barrier discharge treatment.     

Bromate Destruction by UV Irradiation and Electric Arc Discharge

Bromate ion destruction by UV irradiation using either a low pressure mercury lamp or a medium pressure mercury lamp has been evaluated. A low pressure lamp which emits radiation predominantly at < 200 nm was more effective than the UV lamp which emits radiation at 254 nm, since bromate ion has a peak absorbance of about 195 nm. Bromate ion was shown to be reduced to bromide ion with bromine as an intermediate. Bromate ion destruction using a low pressure mercury lamp (< 200 nm) ranged from 3 to 38% for doses ranging from 23 to 228 mW-s/cm²; 7-46% destruction was achieved using a medium pressure lamp with initial bromate ion concentrations of 11-38 μg/L and doses ranging from 60 to 550 mW-s/cm². A new innovative electric arc discharge method also has been evaluated and compared with UV irradiation. The electric arc discharge method destroyed 12-45% bromate ion for doses ranging from 130 to 1300 mW-s/cm².     

Continuous Generation of TiO 2 Nanoparticles by an Atmospheric Pressure Plasma-Enhanced Process

A novel method for the continuous generation of titanium dioxide (TiO₂) nanoparticles by dielectric barrier discharge process is presented using titanium tetraisopropoxide (TTIP) and water as precursors. The aerosol generator employs an atmospheric pressure plasma enhanced nanoparticle synthesis (APPENS) process of alternative current (AC). The influences of applied voltage, frequency and precursor molar ratio on the generated particles were described by the SEM, XRD, and SMPS analyses. The results showed that TiO₂ particles appear to be in a broad size range of bi-modal distribution when no voltage is applied. While after applying the AC plasma they become uni-modal distributed with average sizes range from around 30 to 60 nm. The applied electric frequency can be adjusted to either generate nanoparticles after the plasma reactor or develop a thin film in the reactor. An increase in the precursor molar ratio leads larger particles with a broader size distribution.