转移法真空镀铝纸

本文介绍一种新研制的用于香烟及食品包装的真空镀铝纸。它是以双拉伸聚丙烯薄膜为基材,经真空镀铝后,以热融性树脂为粘接剂,将镀铝层转移到纸张表面的一种新型包装材料,故称转移法真空镀铝纸。这种材料综合了压延铝箔纸与涂胶镀铝纸的优点,其性能在许多方面超过了前两者。(详见本刊87—5期封三)。本文简要介绍这种材料的生产过程、使用性能及其原材料的选择要点。     

真空喷铝纸转移涂层性能研究

目的 为了解决真空喷铝转移纸胶印掉墨问题,同时研究掉墨现象的原因机理。方法 通过实验对纸张表面转移涂层的油墨结合牢度、表面张力、涂层结合牢度、涂层耐温性和耐溶剂性进行测试,同时对比涂层红外谱图和X射线光电子能谱(XPS)。结果 真空喷铝转移纸放置12个月后会出现表面张力降低到真空镀铝纸行业标准(BB/T 0054—2010)以下,放置18个月后会出现大面积掉墨现象,但涂层牢度并未出现变化。6—15个月涂层表面硅原子数分数由0增至0.6%,18个月的涂层表面硅原子数分数剧增为3.5%;同时表面涂层的耐温性、耐溶剂性未随着时间出现明显变化。结论 纸张中的硅含量以及喷铝纸加工过程中水性背涂里面的硅含量逐步向纸张正面的转移涂层表面转移,造成硅物质富集,形成有机硅低分子物质的弱界面层,降低了涂层的表面张力,并使其印刷适性变差。研究所得结论对真空喷铝转移纸产业化生产具有指导意义。     

喷雾干燥制备P(MMA-BA)中空微球及其对苯酚的吸附性能研究

采用种子乳液聚合法合成聚甲基丙烯酸甲酯-丙烯酸丁酯(P(MMA-BA))乳液,再将乳液进行喷雾干燥制备了壳层由纳米粒子构成且具有中空形貌的单孔高分子微球。研究了微球形成机理,并着重探讨了预聚物用量、硬软单体配比m(MMA)∶m(BA)、交联剂用量对微球形貌、比表面积的影响。结果表明,当条件为乳液浓度2%,进口温度125℃,出口温度50℃,进料量250mL/h,预聚物用量为2%(质量分数),硬软单体比m(MMA)∶m(BA)约为7∶3,交联剂用量为10%～20%(质量分数)时,能够形成形状规整的中空微球,用BET法测得其比表面积约为28.8259m2/g。考察了中空微球对低浓度苯酚溶液的吸附性能,结果表明,微球对苯酚的最大吸附量可达7.8568mg/g;微球用量较少时,单位质量微球吸附的苯酚量较大;微球中硬单体比例越高,所得微球比表面积越大,对苯酚的吸附量越高。     

多糖-植物蜡-纳米二氧化硅防水防油包装纸制备与性能

随着社会的发展，人们对无毒环保食品包装材料的需求不断增加。现阶段，兼顾防水防油性能的无氟食品包装纸研究较少。本文以壳聚糖溶液与海藻酸钠溶液为原料，通过阿魏酸交联制备复合防油剂，并涂布在食品包装原纸上，制备防油纸；然后以巴西棕榈蜡与纳米二氧化硅为原料，制备复合防水剂，采用浸渍的方法，制备防水防油纸，探究不同配比及涂布量对纸张防水防油效果与纸张性能的影响。结果表明：当壳聚糖与海藻酸钠复配质量比为8∶2、涂布量为4 g/m²时，防油纸可达到最高防油等级(12级)；当巴西棕榈蜡与纳米二氧化硅复配质量比为4∶3、浸渍量为3 g/m²时，纸张表面吸水量(Cobb)值为5.93 g/m²，水接触角为158.40°，显著提升了原纸的防油性能与防水性能。此外，与未涂布纸相比，防水防油纸的抗张强度提升了30%，透气度下降了60%。本文制备工艺简单、原材料无氟环保、纸张防水防油性能较好，有望在食品包装得到应用。     

多层涂布制备石头纸基相纸的研究

目的研制吸墨性优良的多层涂布石头纸基喷墨打印相纸。方法文中采用表面改性技术改进石头纸基相纸表面结构并通过主观与客观对比评价不同涂层结构的改进效果的方法,研究强吸墨性的石头纸基喷墨打印相纸的造纸工艺。结果其配方如下:底层,m(PCC)∶m(白乳胶)为100∶12;中层,m(沉淀二氧化硅)∶m(胶体二氧化硅)∶m(白乳胶)∶m(PVA-1799)为70∶30∶10∶10;面层,m(胶体二氧化硅)∶m(纳米三氧化二铝)∶m(PVA-1799)为80∶20∶20。涂布量为15 g/m2,经压光工艺处理后的石头纸较石头纸原纸白度提高了6.9%,光泽度提高了151.1%,平滑度提高了976.9%,K色色密度提高了47.4%;较市售的260 g/m2高光相纸平滑度提高了1650%,K色色密度提高了14.3%。结论三层涂布配方效果最佳。     

不同管径碳纳米管电化学储氢性能的比较

比较了5种不同管径碳纳米管的电化学储氢能力.采用三电极体系,Ni(OH)2/NiOOH为对电极,CNTs-Ni(质量比为1:9)为工作电极,Hg/HgO为参比电极,30%的KOH作为电解液.实验结果显示:在同等制作条件和200mA/g的充放电电流密度,0.1V的放电终了电压下,10～30nm的碳管储氢能力最好,克容量最大为480.6mAh/g,相应的平台电压高达0.92V;20～40nm的最高克容量为430.5mAh/g,仅低于10～30nm的电化学储氢量.10～20nm、40～60nm和60～100nm碳管的电化学储氢量分别是:401.1mAh/g、384.7mAh/g和298.3mAh/g.由此可见碳纳米管的管径大小也是影响其电化学储氢性能的一大因素.纯镍电极在同等条件下的最高放电量只有17.8mAh/g,对整个电极放电量的影响可以忽略不计.     

改性PVA超滤膜的制备与性能研究

选用聚乙烯醇、水、乙酸、硫酸铁等为原料 ,用相转化法制备了亲水性超滤膜 .在一定范围内研究了各种不同浓度的膜液组成对超滤膜性能的影响 ,确定了较佳的铸膜液组成 (质量分数 )为 :8%PVA ,6 %乙酸 ,1 5 %～ 2 %硫酸铁 .用此铸膜液制备的超滤膜 ,在操作压力为0 30～ 0 4 5MPa下 ,处理浓度为 10 0 0mg·L- 1的O/W型乳化液 ,透液速率可达 4 3L/(m2 ·h)以上 ,其除油率可达 92 %以上 .研究还表明 ,PVA超滤膜中添加适量硫酸铁 ,可改善膜的结构和耐水性能 .     

烧结温度对Nb_2O_5掺杂TiO_2靶材性能的影响

采用真空烧结方法制备了Nb_2O_5∶TiO_2(NTO)的陶瓷靶材,研究了在7.5%(质量分数)掺杂量下不同烧结温度对NTO陶瓷靶材的微观结构、表面形貌、电学性能、致密度和抗弯强度的影响。通过对NTO靶材的各项性能进行了表征分析表征,实验结果表明,当烧结温度在1 150℃,掺杂量在7.5%(质量分数)时,所制备的陶瓷靶材各项性能最优,其各项性能指标均表现良好,其电阻率为3.420mΩ·cm,抗弯强度为129.24 MPa,其致密度为94.30%。表明此时所制备的NTO陶瓷靶材更加适合于实际工业应用。     

钴掺杂纳米花瓣状氢氧化镍的制备及其电化学性能研究

采用水热法制备了钴掺杂的纳米花瓣状Ni(OH)2,讨论了钴掺杂量对产物形貌、结构和电化学性能的影响。结果表明,不同钴摩尔分数掺杂的样品都呈现α/β混合相花瓣微球,其比表面积均在280m2/g以上,远高于普通球形氢氧化镍(5~10m2/g)。电化学性能测试表明,钴添加剂显著提高了氢氧化镍高倍率放电容量和循环稳定性能,1.0C倍率时钴摩尔分数10%的样品放电容量可达430.1mAh/g(以纯氢氧化镍计),接近-αNi(OH)2的理论容量(480mAh/g),3.0C倍率时其放电容量(367.1mAh/g)仅比0.2C时的放电容量(406.9mAh/g)衰减9.8%。     

可降解海绵的制备及性能研究

以氢氧化钠、氢氧化锂、硫脲、水为溶剂,通过前三者的协同效应制备了纤维素溶液,以Na2SO4为成孔剂,利用纤维素易于再生的特性,制备了纤维素海绵.研究了纤维素浓度、成孔剂用量对纤维素拉伸强度、撕裂强度和吸水性的影响,利用光学显微镜对产物表面进行观察.结果表明,溶剂最佳质量配比m(NaOH):m(LiOH):m(硫脲)约为7:2:7、纤维素质量分数为5%～5.5%、成孔剂用量为(26～28)g/50g纤维素溶液时,所制备的纤维素海绵综合性能较高.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.