昆布氨酸的吸湿保湿性及动力学研究

通过将自制的昆布氨酸与原料L-赖氨酸盐酸盐以及甘油和透明质酸进行对比,对昆布氨酸的吸湿性能和保湿性能进行了研究,并对其吸湿过程作了初步的动力学分析。结果表明:昆布氨酸在相对湿度43%时的最大吸湿率为43.7%,保湿率为100.7%;在相对湿度81%时的最大吸湿率为85.1%,保湿率为103.8%;其吸湿性和保湿性均优于L-赖氨酸盐酸盐、甘油和透明质酸;昆布氨酸的吸湿过程符合二级吸附动力学模型,相关系数达到0.99以上。     

牛毛水解物对PC12细胞氧化损伤的抑制

通过考察H₂O₂浓度和作用时间对细胞活力的影响,确定PC12细胞氧化损伤模型的建立条件;通过细胞活力及形态分析,测定牛毛水解物对H₂O₂致PC12细胞氧化损伤的抑制作用。结果表明,H₂O₂浓度0.15 mmol/L、作用时间2 h为建立PC12细胞氧化损伤模型的理想条件;不同质量浓度的牛毛水解物 (10、20、40、60、80 mg/L)可有效抑制H₂O₂对PC12细胞的氧化损伤,使细胞活力达到58.79%、67.53%、76.89%、85.96%、87.58%,也能在一定程度上修复氧化损伤的细胞,使其活力恢复至53.69%、57.18%、62.56%、65.68%、67.23%,还能有效地维持细胞原有的形态特征。     

常用二元醇的吸湿保湿性能研究

为了探知二元醇的吸湿保湿效果,在RH 81%和RH 43%环境下分别研究了二元醇中的甲基丙二醇,丁二醇,丙二醇(1,2-丙二醇),植物丙二醇(1,3-丙二醇),二丙二醇的吸湿性能。在干硅胶条件下分别研究各类二元醇的保湿功能。结果显示,二元醇具有一定的吸湿性能和持久的保湿性能,特别是在干燥环境中,甲基丙二醇比其他二元醇具有更好的吸湿性能和更出色的保湿功能。因此,二元醇保湿剂在化妆品中的应用具有一定的市场前景,特别是新型二元醇甲基丙二醇的市场前景将更加广阔。     

茯苓多糖吸湿保湿性能的研究

以海藻酸钠和甘油为参照物,分别在RH81%和RH43%条件下测试茯苓多糖的吸湿性能以及在干硅胶环境下测试茯苓多糖的保湿性能。结果表明,茯苓多糖具有一定的吸湿性和比较持久的保湿性,尤其是在干燥条件下,保湿性能优于海藻酸钠和甘油,因此,茯苓多糖作为化妆品保湿剂具有一定的应用前景。     

PVC树脂的吸湿能力及吸湿速率

实验测定了PVC树脂的吸湿曲线及在多种空气条件下的平衡水含量,结果表明：PVC树脂含水量越低,其吸湿速率越快,在空气相对湿度较宽的条件下,PVC树脂的平衡水含量均低于0.3％,在此基础上,分析得到了PVC干燥装置较为合理的产品含水量控制值以0.25%为宜。     

酶解褐藻胶寡糖的吸湿及保湿性能研究

以海藻酸钠为底物,在实验室自制的褐藻胶裂解酶的催化下,通过控制酶解时间,得到平均聚合度(DP)分别为3,4,6的3种褐藻胶寡糖DP3,DP4,DP6。通过干燥器控制湿度的方法对产物进行吸湿和保湿性能测试,并和化妆品常用保湿剂丙三醇、聚乙二醇600(PEG600)及原料海藻酸钠进行比较。结果表明,在0～64 h内,在相对湿度(RH)为43%的环境中的吸湿率大小为:DP3>丙三醇>DP4>DP6>PEG600>海藻酸钠;在RH为81%的环境中的吸湿率大小为:丙三醇>DP3>DP4>DP6>PEG600>海藻酸钠;在硅胶环境中保湿能力大小为:DP3>DP4>DP6>丙三醇>PEG600>海藻酸钠。64 h时DP3在RH为43%和81%环境下的吸湿率分别为66.4%和108.9%,在硅胶环境中的保湿率为46.1%。DP3表现出优良的吸湿和保湿性能,是一种很有开发潜力的天然保湿剂。     

酿酒酵母甘露聚糖的理化性质及吸湿保湿性

采用高温抽提和分级醇沉,制备出了大、中、小不同重均分子量的YM-30、YM-50和YM-90甘露聚糖,测定其溶解度、pH、重均分子量及黏度,研究了它们的吸湿性、保湿性。结果表明:YM-30、YM-50和YM-90的重均分子量分别为1.24×10~5Da,4.47×10~4Da和2.16×10~4Da。YM-30不溶或微溶于水,YM-50和YM-90则易溶于水。YM-30溶液偏碱性,YM-50溶液为中性,YM-90溶液则偏酸性。YM-50和YM-90水溶液的黏度很低,几乎与水的黏度一样,且其黏度不受甘露聚糖质量浓度和温度的影响。红外光谱分析表明,3种甘露聚糖的糖链均为β-D-吡喃结构。在低相对湿度(43%)下,YM-90吸湿性最强;而在高相对湿度(81%)下,YM-30吸湿性最强。在相对湿度43%下,YM-30保湿性最优,其保湿率达到了98.4%,稍高于透明质酸。酵母甘露聚糖具有优良的吸湿、保湿性能。     

壳聚糖衍生物有望作吸湿保湿剂

<正>中科院烟台海岸带研究所开发的羧甲基壳聚糖季铵盐作为吸湿保湿剂的应用成果日前获国家发明专利授权。该专利利用活性叠加原理和亚结构连接的方法,把羧甲基与季铵盐基同时接入壳聚糖以提高     

甲壳素壳聚糖及其衍生物吸湿保湿性研究进展

简要介绍了甲壳素,壳聚糖的物化性质,概述了壳聚糖常见的化学修饰方法,详细综述了甲壳素,壳聚糖及其羟基化化衍生物,羧化衍生物,酰化衍生物的吸湿性和保湿性的研究现状,对β-壳聚糖,甲壳低聚糖的吸湿性和保湿性也进行了介绍。     

紫外伤害培养对酵母水解液紫外吸收性能的影响

研究了紫外伤害培养对酵母菌生长繁殖的影响及紫外伤害培养后酵母细胞的酶水解条件和酵母水解液的紫外吸收性能.实验结果表明酵母菌紫外伤害培养时间为60h～72h.紫外伤害培养后酵母细胞的最佳酶水斛条件为质量分数为10%的酵母细胞悬浮液中添加质量分数为2%的蛋白酶(细胞干重),pH6.5,52℃振荡酶水斛26h.紫外伤害培养的酵母细胞经酶水解离心后,上清液稀释10倍测定OD365为0.349,是未经紫外伤害培养的酵母菌酶水解液的3.46倍.波长326Bm～400nm(防晒黑区)的紫外吸光率>95%.说明紫外伤害培养后的酵母细胞酶水解液是极具开发价值的UVA生物吸附剂.     

Moisture absorption and desorption in a UV cured urethane acrylate adhesive based on radiation source

A photopolymerizable urethane acrylate (UA) adhesive was cured using two different sources: a conventional UV‐lamp and a UV‐emitting light emitting diode (LED). Moisture uptake in cured specimens was characterized by immersion in deionized water at 21.8, 30, 37.5, and 45°C for a period of 6 months. Additionally, desorption experiments were performed for selected specimens under vacuum at room temperature. Material degradation in the form of mass loss was observed in all samples after attainment of a maximum water uptake level, with the phenomenon being more pronounced at higher immersion temperatures. This degradation is attributed to leaching and dissolution of uncured monomers and lower weight molecular species from the samples. A two stage moisture uptake model is proposed to account for mass loss and excellent agreement between the tested mass loss and the loss‐rate parameters determined from the model is shown. Performance of specimens was characterized with dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). It was found the LED source was not as effective in curing surfaces, due to which there is a higher level of mass and lower T_g from hygrothermal exposure as compared to the core regions of the LED cured specimens and the overall lamp cured specimens. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

UV absorption spectra of polystyrene

Summary Polystyrene (PSt) exhibits a new UV absorption band at around 290nm in comparison with ethylbenzene, which is attributed to associative interaction between pendant phenyl groups. Similar absorption bands are also observed for polymers of styrene derivatives. The UV spectra suggest charge-transfer complex formation between the polymeric and monomeric donors with electron-acceptor tetracyanoethylene (TCNE) and the equilibrium constants were estimated to be in the sequence of ethylbenzene > PSt > copolymer of St with methylmethacrylate.     

紫外线伤害皮肤的机理与防护

论述了由于人们对臭氧层的破坏导致紫外线对人体皮肤的伤害以及防晒化妆品的防晒机理,人们应该如何科学选用防晒化妆品,同时介绍了防晒化妆品的相关规定。     

Moisture absorption modeling using design of experiments

The effect of temperature and humidity on equilibrium moisture content of laminates was studied by response surface design. Two glass fabric‐reinforced laminated composite materials with different epoxy matrix resins, laminates A and B, were studied. Laminates A and B used are cyanate ester and polyphenylene oxide modified epoxy based laminate, respectively. The results show that the response surface profiles of moisture absorption for the two laminate materials are similar though their amounts of moisture absorption are different. The temperature‐humidity interaction effect and the quadratic effect of temperature are significant for laminate A. However, only the linear effects of temperature and humidity are significant for laminate B. Predictive models relating the important factors to the equilibrium moisture content were proposed in the article. The models developed can be used to predict and assess the reliability of the laminates for moisture related failures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1539–1543, 2007     

Corrosion protection performance of nanocomposite coatings under static,UV, and dynamic conditions

Silicone-modified epoxy polymeric matrix was successfully fabricated and reinforced with 1–2 wt% SiO₂, TiO₂, and TiSiO₄ nanoparticles. Fourier-transform infrared spectroscopy, contact angle measurements, differential scanning calorimetry, and field-emission scanning electron microscopy together with energy-dispersive X-ray spectroscopy were employed to investigate different characteristics of the prepared coatings. To simulate operating conditions, all samples were characterized via electrochemical impedance spectroscopy (EIS) after being subjected to different conditions. Corrosion under static conditions, in which the samples were exposed to a static electrolyte without further change in other parameters, was investigated. Furthermore, to study the effects of ultraviolet (UV) radiation in accelerating the degradation of the coatings, samples were characterized after being subjected to UV while immersed statically in the electrolyte. Additionally, the corrosion protection performance was investigated after subjecting the coated substrates to dynamic conditions involving continuous movement of the sample in the electrolyte, simulating continuous wear of the coated surfaces. Compared with the static condition, the EIS results revealed the vital role of the silicone resin and nanoparticles in improving the stability of the coating film against corrosion degradation in the presence of UV radiation, while poor performance in dynamic condition was recorded for all the coating systems.     

Moisture diffusion coefficients of mortars in absorption and desorption

Water vapor diffusion coefficients have been determined with a new set-up of the cup method for mortars with three binders (OPC, OPC + 70% slag, OPC + 10% silica fume) and two water/binder-ratios (0.4, 0.5). The measurements were made as a function of relative humidity with samples on both the absorption and desorption limbs of the sorption isotherm. For OPC samples the results show a clear difference between absorption and desorption. For the samples with supplementary cementitious materials the dependence on RH is small.     

紫外光/潮气双重固化聚氨酯杂化树脂的制备及其性能研究

以TDI、PEG400、KH550、HEA和环氧氯丙烷为原料,合成了紫外光/潮气双重固化聚氨酯杂化树脂,红外光谱(FT-IR)和核磁共振(1H-NMR)结果证明成功合成了预期产物.以其为预聚物,配制光/潮气双重固化涂料,对涂层的固化工艺和基本性能进行研究,结果表明涂层在30 s内光固化完全,经过100 h潮气固化后,涂层的硬度、附着力有明显提高,同时热稳定性能也有明显提高.