壳聚糖/海藻酸钙微胶囊的通透性能

以传统细胞培养的重要碳源葡萄糖与柠檬酸、氮源L-谷氨酸为小分子模型,以聚乙二醇为测定微囊膜截留相对分子质量的模型分子,研究了微胶囊通透性能,考察了制备条件对壳聚糖/海藻酸钙微胶囊通透性能的影响.结果说明:葡萄糖、柠檬酸和L-谷氨酸可以自由透过微囊膜扩散;采用20 mg/mL海藻酸钠溶液与相对分子质量5万、2 mg/mL壳聚糖溶液制备微胶囊,胶囊的截留相对分子质量为1500;降低成膜壳聚糖溶液浓度和壳聚糖分子量,增大微胶囊粒径均有利于提高壳聚糖/海藻酸钙微胶囊的通透性.     

载脂肪酶壳聚糖/海藻酸钙微胶囊的制备

针对固定化脂肪酶的研究背景,以壳聚糖、海藻酸钠为微载体制备材料,采用脉冲电场液滴工艺制备壳聚糖/海藻酸钙微胶囊。以脂肪酶为生物模型,系统考察了制备条件对载脂肪酶壳聚糖/海藻酸钙微胶囊酶活力的影响。结果表明:海藻酸钠质量浓度和酶与海藻酸钠载体配比是影响固定化酶活力的主要因素,载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL时载酶微胶囊酶活力最高,球形度好。通过改变壳聚糖质量浓度和相对分子质量,可以调控微胶囊膜的厚密程度进而影响固定化酶活力。成膜液pH值依次影响壳聚糖与海藻酸盐分子中官能团的电离状态、成膜反应静电络合程度、酶蛋白包封率,最终影响固定化酶活力。在载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL,壳聚糖相对分子质量、质量浓度和pH值依次为50kDa、1mg/mL和3.0的条件下,固定化酶活力为187IU/g。     

高载药量海藻酸钙/几丁聚糖微胶囊的性能

采用乳化固化法制备了平均粒径为820nm海藻酸钙微球,并制备了海藻酸钙/几丁聚糖微胶囊。以牛血清白蛋白(BSA)为模型药物,考察投药浓度、几丁聚糖分子量和浓度等对微胶囊载药量和药物释放的影响,发现其载药量最大可达40%以上,结果还显示这种微胶囊具有很好的体外缓释性能。     

海藻酸钠/壳聚糖/海藻酸钙微胶囊机械强度的研究

采用脱乙酰度≥95%的壳聚糖为原料,通过NaNO_2氧化法降解得到不同分子量的壳聚糖。通过单因素试验,考察不同反应条件对海藻酸钠/壳聚糖/海藻酸钙微胶囊机械强度的影响,再通过响应面试验优化微胶囊的制备工艺。研究结果表明,当成膜时间为32 min,壳聚糖浓度为6.1 g/L,壳聚糖分子量为58189,壳聚糖pH值为6.0时,海藻酸钠/壳聚糖/海藻酸钙微胶囊的机械强度最高。     

阻燃涤纶织物的现状及发展

概述了国内外涤纶阻燃改性的研究情况,综述了涤纶阻燃处理方法,分析了卤系和磷系阻燃剂及其对涤纶的阻燃改性的优缺点,介绍了涤纶的燃烧机制、阻燃机制、阻燃方法以及阻燃性能的测试方法。涤纶阻燃改性中所用的阻燃剂主要是通过吸热、覆盖和稀释等机制发挥阻燃作用的。分析了涤纶阻燃整理存在的问题,讨论了阻燃涤纶的发展趋势。     

涤纶织物的阻燃研究及发展

涤纶是一种发展最快、产量最高的合成纤维,有良好的性能且价格低廉,在国防、工业用布和人们生活的很多方面得到了广泛应用。介绍了涤纶的燃烧性能和燃烧过程,阐述了涤纶的阻燃机理,阻燃整理方法及整理方法的优缺点,给出了涤纶改善阻燃性能后的评测标准,影响涤纶阻燃整理效果的因素,综述了国内外涤纶阻燃研究进展情况。最后,指出环保、多功能型阻燃涤纶,聚酯纤维阻燃理论以及纳米层状硅酸盐／聚酯复合材料方面将具有良好的发展前景。     

乳化法制备海藻酸钙/聚组氮酸微胶囊

采用乳化法制备海藻酸钙微球及海藻酸钙/聚组氨酸载药微胶囊,并考察不同海藻酸钠浓度、氯化钙浓度对微球表面形态、粒径分布、载药性能及微胶囊控制释放性能的影响。结果表明海藻酸钠浓度主要影响微球的粒径大小,氯化钙浓度主要影响微球的分散程度及粒径分布,微球载药量均随海藻酸钠浓度及氯化钙浓度的增加而减小,所制备的微胶囊均无明显的突释现象。     

海藻酸钙/聚精氨酸微胶囊的载药和缓释性能

采用乳化-固化法,制备海藻酸钙/聚精氨酸微胶囊。分别考察不同聚精氨酸相对分子质量、海藻酸钠浓度、氯化钙浓度对海藻酸钙-聚精氨酸微胶囊载药量以及牛血红蛋白缓释性能的影响。实验结果表明,中相对分子质量聚精氨酸制备的海藻酸钙/聚精氨微胶囊的载药量较高并且具有更好的缓释效果。随着海藻酸钠浓度的升高,海藻酸钙/聚精氨微胶囊的载药量降低;随着氯化钙浓度的升高,海藻酸钙/聚精氨微胶囊的载药量先升高后略有降低;然而,以上因素对海藻酸钙/聚精氨微胶囊的缓释性能均无明显影响。     

阻燃涤纶纺丝技术

探讨了磷系阻燃涤纶的生产工艺。试验表明 :采用含水率在 30μg/ g以下的阻燃切片 ,选择纺丝温度 2 70℃和纺丝速度 2 80 0 m / m in,合适的组件过滤砂配方、喷丝板孔径及纺丝冷却条件 ,可制得性能优良的阻燃 POY,所加工的 DTY织物的极限氧指数达 35 .2 %     

纳米银/石墨烯负载涤纶织物的制备及其结构与性能研究

采用浸渍烘干法在经碱减量处理后的涤纶织物表面负载氧化石墨烯(GO),再通过纳米银(Ag)自组装制备具有良好电热性能的纳米Ag/石墨烯负载涤纶织物,研究了GO水分散液浸渍次数、柠檬酸钠溶液浓度及硝酸银溶液浓度对织物电热性能的影响,并对织物的结构、热性能及力学性能进行表征。结果表明：制备纳米Ag/石墨烯负载涤纶织物的较佳工艺条件为GO水分散液浸渍5次、柠檬酸钠溶液浓度0.1 mol/L、硝酸银溶液浓度0.1 mol/L;在纳米Ag/石墨烯负载涤纶织物制备过程中,GO和Ag⁺被还原成石墨烯和纳米Ag,并在织物表面形成致密且完整的高纯度纳米Ag;纳米Ag/石墨烯负载涤纶织物与未处理涤纶织物相比,具有更好的热稳定性,断裂强力相当;在3 V电压条件下通电60 s时,纳米Ag/石墨烯负载涤纶织物表面发热温度达到113℃,具有优异的电热性能。     

Oxygen diffusivity in alginate/chitosan microcapsules

BACKGROUND: Oxygen diffusion properties affect the proliferation and metabolism of cells cultured in microcapsules with a polyelectrolyte complex membrane. The effective diffusion coefficient (De) of oxygen in alginate/chitosan (AC) microcapsules under different preparation conditions was calculated, and a mathematic model was developed to investigate the effect of oxygen diffusion on cell loading in the microcapsules. RESULTS: Oxygen De in AC microcapsules was independent of alginate solution concentration, intrinsic viscosity of alginate and different polyelectrolyte complex membranes. De decreased from 2.1 ± 0.3 × 10^?9 to 0.17 ± 0.01 × 10^?9 m² s^?1 as microcapsule diameter decreased from 1800 to 45 0 µm. Microcapsule density was increased from 1.013 ± 0.000 to 1.034 ± 0.003 g mL^?1 as diameter decreased from 1775 to 430 µm. The mathematic model results showed that critical CHO cell loadings were 1.8 × 10⁸ or 1.1 × 10⁸ cells mL^?1 in microcapsules with 450 or 1800 µm diameter, respectively. CONCLUSIONS: No significant difference was found of oxygen De between calcium alginate beads and AC microcapsules. The decrease of De with diameter was attributed to the increasing density and compact degree on the surface. The model results indicated that risk on necrosis rose with the increasing diameter. Microcapsules with smaller diameters may have more advantages on cell culture. © 2012 Society of Chemical Industry     

纳米分散染料胶囊的制备及其对涤纶织物轧染染色性能

针对涤纶织物浸轧染色存在浮色多、后水洗负担重的问题，通过乳液聚合法制备了以分散染料为核，甲基丙烯酸甲酯（MMA）-丙烯酸丁酯（BA）共聚物为壳的纳米分散染料胶囊（NDDM），探究了核壳投料比、软硬单体配比、固色温度和固色时间等因素对涤纶织物轧染染色性能的影响。结果表明，NDDM对涤纶织物轧染染色的色牢度和匀染性均优于C.I.分散紫93染色织物，当核壳质量投料比为1:2、MMA和BA质量投料比为1:1，焙烘温度180 ℃、焙烘时间5 min时，NDDM轧染染色织物的颜色深，手感变化小，且未水洗染色织物的各项色牢度达到4级及以上，还原清洗COD值为312.3 mg/L，COD值较C.I.分散紫93染色相比下降了58%。在高温条件下，NDDM内分散染料从聚丙烯酸酯壳层内迁移释放并上染纤维，聚丙烯酸酯壳将未进入纤维内的残余染料覆盖固着在纤维表面。     

海藻酸钠包埋高效菌种强化处理聚酯废水的试验研究

对海藻酸钠-氯化钙法包埋某高效微生物菌种用于强化聚酯废水的生物处理进行了试验研究,同时将其与普通系统和高效菌种的悬浮投加型强化系统作了相应比较.结果表明:相对普通系统,悬浮投加高效菌种可使出水COD降低100mg/L,处理率提高8%,而用海藻酸钠-氯化钙法包埋固定化之后投加则可使出水COD降低200mg/L,处理率提高14%,使最终出水COD达到100mg/L以下,达到出水的排放要求,且减少了废水中对人类和环境有较大危害的1,4-二氧杂环己烷的含量.     

Inkjet fabrication and characterization of calcium alginate microcapsules

The present work describes a method for producing calcium alginate hydrogel microcapsules in the size range of 50-70 μm by means of a piezoelectric drop-on-demand inkjet device. Particles were prepared by emitting droplets of 0.5% and 1% (w/w) sodium alginate solutions into a magnetically stirred pool of CaCl₂ solution of variable viscosity ranging from 1 to 100 mPas. The effect of viscosity on the morphology of the resulting microcapsules was systematically investigated — lower viscosity of the receiving solution has lead to the formation of elongated particles, medium viscosities lead to spherical capsules, and for higher viscosities flattened particles were obtained. The applied voltage used for driving the piezoelectric inkjet print-head was found to be the most significant parameter for influencing the droplet size. The duration of the voltage pulse or the droplet viscosity had only minor effects. The release rates of two model substances (methylene blue dye and vitamin B12) from alginate beads were measured and their effective diffusion coefficients determined as function of alginate concentration.     

Mechanical,electrical, and thermal properties of graphene nanosheet/aluminum nitride composites

Graphene nanosheet (GNS)/aluminum nitride (AlN) composites were prepared by hot-pressing and effects of GNSs on their microstructural, mechanical, thermal, and electrical properties were investigated. At 1.49 vol% GNSs content, the fracture toughness (5.09 MPa m^1/2) and flexural strength (441 MPa) of the composite were significantly increased by 30.17% and 17.28%, respectively, compared to monolithic AlN. The electrical conductivity of the composites was effectively enhanced with the addition of GNSs, and showed a typical percolation behavior with a low percolation threshold of 2.50±0.4 vol%. The thermal conductivity of the composites decreased with the addition of GNSs.     

膨胀型无卤阻燃PP/EVA电缆料的研制

介绍了膨胀型无卤阻燃PP/EVA电缆料的制备方法,采用氧指数仪、UL94垂直燃烧箱、电子万能试验机及TG热重分析仪等对其进行了表征。结果表明:经阻燃后氧指数已提高到34.5%;燃烧等级已达到UL94V0级;拉伸强度为15.11MPa,断裂伸长率为557.67%;600℃时,残炭量达到17.49%。     

Directional properties and microstructures of spark plasma sintered aluminum nitride containing graphene platelets

Graphene platelets (GPLs) containing aluminum nitride (AlN) composites were produced by using both pressureless sintering and spark plasma sintering (SPS). Poor densifications were obtained when composites were pressureless sintered whereas highly dense composites were successfully produced by using SPS. In addition, the applied uniaxial load in the SPS resulted in the orientation of GPLs in the microstructure of composites, indicating that composites would have anisotropic properties. All the mechanical, thermal and electrical properties in the in-plane direction were better than the through-plane direction. Fracture toughness of composites with the addition of 1 wt% GPLs were increased more than 30% compared to AlN matrix. Increased anisotropic effect with increasing amount of GPLs led to even larger differences on the thermal conductivities in through-plane and in-plane directions. AlN also became an electrically conducting material after ∼1 wt% GPLs addition in both through-plane and in-plane directions.     

Tailoring the properties of spark plasma sintered SiAlON containing graphene nanoplatelets by using different exfoliation and size reduction techniques: Anisotropic mechanical and thermal properties

SiAlON ceramics are intensively used in different areas but still there is a need to improve the mechanical and thermal properties as well as ease of machinability and reduce the weight. In this study, the effect of graphene nanoplatelets (GNPs) exfoliation and dispersion techniques on the microstructure and properties of SiAlON ceramics were investigated. For this purpose, 2, 4 and 8 wt% GNPs were dispersed by using traditional sonication and newly proposed microfluidization techniques. Then, composites were densified in spark plasma sintering (SPS) furnace. Scanning electron microscope (SEM), x-ray diffraction analyses (XRD) and property measurements were performed in through-plane and in-plane directions. The microfluidization technique found to be more effective than sonication for the exfoliation, size reduction and homogenization of GNPs. Addition of GNPs prepared by both techniques increased the fracture toughness and in-plane direction thermal conductivity whereas decreased the hardness and through-plane direction thermal conductivity of the SiAlON.