琥珀酸酯磺酸盐的制备及性能

用月桂酸与聚乙二醇-400进行酯化反应,酯化产物顺酐化再与亚硫酸钠进行磺化反应生成聚乙二醇脂肪酸酯琥珀酸酯磺酸盐。采用FT-IR对产品的结构进行表征,并对其乳液粒径、表面张力、接触角、发泡力、抑菌性能进行检测;将合成产物应用于皮革加脂处理,利用SEM观察皮革加脂前后的微观状态和形貌,并测试皮革力学性能。结果表明:制备聚乙二醇脂肪酸酯琥珀酸酯磺酸盐的乳液粒径为4.77 μm,Zeta电位为97.26 mV,泡沫体积为646 mL,临界胶束浓度(cmc)为8.59×10~(-4) mol/L,接触角为63.1°;其对黑曲霉、铜绿假单胞菌和金色葡萄球菌较为敏感,最小抑菌浓度(MIC)分别为15,20和15 g/L;SEM结果表明,加脂后皮革的纤维束更细小,纤维间距变大;皮革抗张强度从22.07 MPa提高至28.24 MPa,断裂伸长率从64.7%降至36.4%。     

Effect of the presence of ethyl lauroyl arginate on the technological properties of edible fish gelatin films

Physical, chemical and antimicrobial properties of fish gelatin films with different concentrations of ethyl lauroyl arginate (LAE) were studied. Optical properties of film-forming solution did not vary with increased LAE content. However, pH and surface tension increased. The incorporation of LAE into the formulation increased moisture and solubility of the films. In addition, the presence of LAE affected mechanical properties, making films stronger and more flexible; it had no effect on water vapour permeability. Finally, films with LAE significantly increased antimicrobial properties against Listeria innocua, Shewanella putrefaciens and Pseudomonas fluorescens, but not against Aeromonas hydrophila. These antimicrobial films could be used as an alternative technology for extending shelf-life of fresh fish products.     

减压蒸发月桂酸制备焊条抗吸潮保护膜研究

为减少手工电弧焊焊条在舰船焊接及野外施工时,因吸潮而引起的焊缝扩散氢的增加,对减压蒸发月桂酸制备焊条抗吸潮膜的方法进行研究。将烘干的焊条放入溶有一定量月桂酸的石油醚溶液中,用减压蒸发法进行处理,使焊条表面形成具有抗吸潮性能的薄膜。对焊条进行熔敷金属扩散氢测试,并对其保护膜表面形貌进行分析。结果表明,从溶液中直接取出的焊条表面容易形成"蘑菇"结构,用减压蒸发法所得薄膜"蘑菇"状结构明显减少。将焊条烘干后迅速取出放入石油醚中进行反应,然后进行减压蒸发可使"蘑菇"状结构几乎消失。抗吸潮焊条扩散氢含量与原焊条含量相同,且在8 h内几乎保持不变。     

Experimental Study on Hybrid Organic Phase Change Materials Used for Solar Energy Storage

The solar energy utilization in built environment has been limited due to its low heat flux, uneven distribution in time and space and temporal difference in day and night. The phase change materials have been used to collect the fluctuant solar energy to form a stable energy source for the terminal equipment of the buildings. In this study, the hybrid organic phase change materials was prepared for the capillary radiant heating system which formed a cascade utilization of solar energy. Firstly, lauric acid and stearic acid were selected as the basic organic phase change materials and the binary equilibrium phase diagram was completed based on the method of step cooling curve according to the experimental tests data. The results showed that the phase transition temperature of the mixed acid at the lowest eutectic point was 31.2℃ and the latent heat value was 264.3 kJ/kg when the mass mixing ratio was 70% for lauric acid and 30% for stearic acid. Secondly, the expanded graphite was used as an additive to enwrap the mixed acid and enhance the heat conductivity. The experimental results showed that when the mass proportion of expanded graphite in the mixed acid was 10%, the mixed acid could be completely enclosed by expanded graphite and the stability of melting and solidification was optimal. Additionally, the phase transition temperature of the hybrid phase change material was 31.5℃ and the latent heat value was 217.4 kJ/kg. The novel hybrid phase change material has a lower eutectic point and a higher latent heat of phase change, so it has a large application space and is quite suitable for the cascade utilization of solar energy with capillary network heating system.     

月桂酸纤维素酯/聚乙二醇相变储能纤维的制备及其性能

为获得具有优良相变储能性能的超细纤维,将聚乙二醇(PEG)链接到月桂酸纤维素酯(LACE)上,得到LACE/PEG接枝聚合物溶液后,用静电纺制备了LACE/PEG相变储能纤维;研究了纺丝液中PEG质量分数对所得纤维形态、相变储能及力学性能的影响,并通过水洗及循环热稳定性实验,分析了所得纤维的使用性和有效性。结果表明:含有不同PEG质量分数的LACE/PEG溶液均可纺制光滑的圆柱状纤维,但随PEG质量分数增加,纤维直径及相变焓增加,均一性及力学性能下降;由于PEG与LACE均具有相变行为,且二者之间靠化学键链接,使LACE/PEG纤维不仅具有较高相变焓及适中的相变温度,而且相变过程可逆,热循环稳定性良好,是一种具有较高使用价值的相变储能纤维。     

改性蒙脱土定型复合材料及热湿性能实验

利用十六烷基三甲基溴化铵(CTAB)对钠基蒙脱土进行改性,以优选改性蒙脱土为主体材料,以月桂酸为客体材料,通过熔融插层法制备定型复合材料.采用步冷曲线法和饱和盐溶液法分别测试复合材料的热性能和湿性能,利用“归一法”对热湿综合性能进行量化.利用XRD,FT-IR和SEM等技术对定型复合材料的孔径分布、微观形貌和组成结构进行测试和表征.结果表明:在改性阶段,改性剂(CTAB)与钠基蒙脱土的质量比为0.4∶1,加热温度70℃,加热时间为120 min时,改性效果最好;在熔融插层阶段,月桂酸质量百分比为28.6％、加热温度为70 ℃、加热时间为120 min时,定型复合材料的热湿综合性能最优.     

Short communication: Nα-Lauroyl-l-arginine ethylester monohydrochloride reduces bacterial growth in pasteurized milk

Effective strategies for extending fluid milk product shelf-life by controlling bacterial growth are of economic interest to the dairy industry. To that end, the effects of addition of l-arginine, Nα-lauroyl ethylester monohydrochloride (LAE) on bacterial numbers in fluid milk products were measured. Specifically, LAE was added (125, 170, or 200 mg/L) to conventionally homogenized and pasteurized 3.25% fat chocolate or unflavored milk products. The treated milks and corresponding untreated controls were held at 6°C and plated on standard plate count agar within 24 h of processing and again at 7, 14, 17, and 21 d of storage. Bacterial counts in all unflavored milk samples treated with LAE remained below the Pasteurized Milk Ordinance limit for grade A pasteurized fluid milk of 4.3 log cfu/mL for the entire 21 d. Bacterial counts in unflavored samples containing 170 and 200 mg/L of LAE were significantly lower than those in the untreated unflavored milk at d 17 and 21 postprocessing. Specifically, bacterial counts in the milk treated with 200 mg/L of LAE were 5.77 log cfu/mL lower than in untreated milk at 21 d postprocessing. Bacterial counts in chocolate milk treated with 200 mg/L of LAE were significantly lower than those in the untreated chocolate milk at d 14, 17, and 21. In chocolate milk treated with 200 mg/L of LAE, bacterial counts were 0.9 log cfu/mL lower than in the untreated milk at 21 d postprocessing. Our results show that addition of LAE to milk can reduce bacterial growth. Addition of LAE is more effective at controlling bacterial growth in unflavored milk than in chocolate milk.     

三种晶型淀粉与月桂酸复合对其形貌结构和消化特性的影响

玉米淀粉、马铃薯淀粉和锥栗淀粉等糊化后的3种晶型淀粉通过高压均质与月桂酸作用形成淀粉-脂肪酸复合物,探讨它们的复合指数、形貌结构和消化特性的变化规律。结果表明,3种晶型淀粉均能与月桂酸复合,复合指数与复合物中直链淀粉含量呈显著正相关（P＜0.05）;电镜图可知3种晶型淀粉经糊化和高压均质处理后,淀粉表面变得凹凸不平,与月桂酸复合后体积增大,孔洞被填充,表面变得平滑;X-衍射显示3种晶型淀粉与脂肪酸的复合物在7.8°、13°和20°附近均出现新的衍射峰,说明已由A、B、C型均转为V型;玉米淀粉、马铃薯淀粉和锥栗淀粉与月桂酸复合后,其对应RDS含量分别降低了9.44%、9.01%和9.57%,SDS及RS含量显著增加（P＜0.05）,增强了抗消化性。     

Synthesis and Aqueous Solution Properties of α-Dimethyl Oxamino Dodecyl Acid

Starting from α-chloro-lauric acid which was obtained from lauric acid through selectively chlorinating at the α-position with chlorine, a novel surfactant α-dimethyl oxamino dodecyl acid was synthesized with high yield via an economic route. The structure of α-dimethyl oxamino dodecyl acid was confirmed by means of Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry and ¹H nuclear magnetic resonance spectroscopy. Surface tension, foaming properties and emulsifying measurements were performed to study the aqueous solution properties of the synthesized surfactant. The results showed that the behavior of the α-dimethyl oxamino dodecyl acid strongly depend on the pH of aqueous solution: it had high surface activity, excellent foaming properties and emulsion stability for paraffin oil at acid pH while the corresponding properties decrease substantially at alkaline pH.     

月桂酸/二氧化硅复合相变储能材料的制备与性能

以月桂酸为相变材料,二氧化硅为基体,采用溶胶-凝胶法将相变材料嵌入到SiO2网络空间内,制备出月桂酸/二氧化硅复合相变储能材料。采用IR,SEM及DSC对复合相变储能材料进行了结构、形貌以及热性能表征。结果表明:含相变材料69.1%质量分数的复合材料相变温度为43.1℃,相变潜热高达104.64J/g,相变材料均匀地嵌入到SiO2网络空间内,发生相变时不泄露。同时二氧化硅作为基体材料形成空间传热网格,较大提高了相变材料的导热性能。