Influence of operating parameters on plasma polymerization of acrylic acid in a mesh-to-plate dielectric barrier discharge

Plasma polymerization of acrylic acid is an interesting research subject, since the obtained coatings can have significant biomedical applications due to their high surface density of carboxylic acid groups. In this work, plasma-polymerized acrylic acid (PPAA) films are synthesized using a mesh-to-plate dielectric barrier discharge operated at medium pressure (10.0 kPa). Results clearly show that this reactor setup is able to deposit uniform PPAA films in contrast to the commonly used parallel plate reactor. Moreover, carefully planned experiments are conducted to study the influence of discharge power and monomer concentration on the chemical composition and thickness of the PPAA films. Results clearly show that input power strongly influences the properties of the deposited films: with increasing discharge power, monomer fragmentation in the discharge increases leading to a decrease in carboxylic acid functional groups and a lower polymer deposition rate. The effect of monomer concentration is less pronounced: only at very low monomer concentration (0.1 g/h), a decrease in carboxylic acid functional groups can be observed. The chemical composition and thickness of the PPAA films can thus be tailored by adjusting the operational parameters of the discharge.     

亚氨乙酸型螯合吸附材料IAA-PEI/SiO2对重金属离子的螯合吸附行为

将聚胺大分子聚乙烯亚胺(PEI)接枝于微米级硅胶微粒表面,制得接枝微粒PEI/SiO2,然后使氯乙酸与PEI大分子中的伯、仲胺基发生亲核取代反应,形成亚氨乙酸(IAA)型螯合吸附材料IAA-PEI/SiO2. 研究了IAA-PEI/SiO2对重金属离子的螯合吸附行为和吸附机理. 结果表明,由于亚氨乙酸基团与重金属离子之间的静电作用与配位螯合作用,IAA-PEI/SiO2对重金属离子可产生强的螯合吸附作用,对Ni2+的吸附容量可达1.4 mmol/g;吸附过程为放热过程;在可抑制重金属离子水解的pH范围内,pH值越高,吸附能力越强;IAA-PEI/SiO2对重金属离子的吸附容量顺序为Ni2+> Pb2+>Cu2+>Cd2+.     

Effects of acid pretreatments on some physicochemical properties of carrot undergoing hot air drying

Carrot is one of the important root crops cultivated worldwide. In many cases, carrot must be dried prior to its use. Although hot air drying is one of the most common methods for drying carrots, it is well known that hot air drying leads to much quality degradation of a dried product. To alleviate the adverse effect of hot air drying many pretreatment methods have been proposed. In this study, the effects of pretreatments with citric acid, which is used as an anti-darkening agent and a texture-modifier, were investigated. Carrots were soaked in citric acid to pH of either 4 or 5 or blanched in citric acid to pH of either 4 or 5 prior to hot air drying. Untreated carrots, carrots soaked in water and carrots blanched in water were used as control samples. The effects of pretreatments, in combination with hot air drying at 70, 80 and 90 °C, on selected physicochemical properties of dried carrots, namely, color, shrinkage, rehydration ability, β-carotene content and cis–trans isomerization of β-carotene, were evaluated. It was noted that carrots, which were soaked and blanched in citric acid, were redder than the untreated sample. Although shrinkage of pretreated carrots was higher, the rehydration ability of the pretreated carrots was higher than that of the untreated sample. The β-carotene content of carrots with no pretreatment decreased continuously, whereas the contents of β-carotene in citric acid soaked and blanched carrots tended to be unchanged. However, isomerization of β-carotene in all samples was not significantly different.     

铝合金硫酸阳极氧化膜层颜色的形成与控制

给出了铝合金化学除油及硫酸阳极氧化工艺条件.分析了影响铝合金硫酸阳极氧化膜层颜色的因素,如铝合金成分,机械加工方式,膜层均匀度和腐蚀等.     

肉桂醛及其复配体系在盐酸中对铁缓蚀作用的研究

主要通过失重法即测量金属试样浸入腐蚀介质一定时间后的质量变化来测定腐蚀速率,从而研究肉桂醛及其复配体系在盐酸介质中对铁的缓蚀性能,并讨论了用量、温度、时间、肉桂醛浓度对铁缓蚀性的影响,结果表明,肉桂醛、邻苯二胺与1,10-菲罗啉三者以1.2:1:1的质量比复配时,对铁丝的缓蚀效果最佳,缓蚀率为94.5%.     

3-脲基-2-氰基-2-丙烯酸乙酯的合成研究

在二甲苯中以氰乙酸乙酯、原甲酸三乙酯和尿素合成3-脲基-2-氰基-2-丙烯酸乙酯.产物用乙酸乙酯重结晶,通过1H NMR对产物结构进行了表征.并对合成工艺进行了优化,得到较适宜的工艺条件:n(氰乙酸乙酯):n(原甲酸三乙酯):n(尿素)=1.0:1.12:1.1,反应时间10 h,收率73.65 %.     

维生素C和水杨酸复合脂质体制备及影响因素的研究

以大豆磷脂为膜材,采用复乳-超声法制备同时含有脂溶性水杨酸和水溶性维生素C的复合脂质体。研究配方中不同成分的质量比、维生素C水溶液的pH、乳化温度、包衣等对脂质体包封率和稳定性的影响。结果表明,在m(大豆磷脂)∶m(胆固醇)∶m(水杨酸)∶m(维生素C)=4∶1∶0.75∶1,维生素C水溶液的pH为5,初乳和复乳化温度分别为25、45℃时制备的复合脂质体中维生素C和水杨酸的包封率分别为48.2%和55.4%;包衣处理使水杨酸/维生素C复合脂质体稳定性提高。     

松香丙烯酸加成物与HEMA酯化及溴化反应研究

为了提高松香的附加值,利用松香和丙烯酸的Diels-Alder反应得到加成物(RA),RA进一步与甲基丙烯酸-β-羟乙酯(HEMA)反应得到酯化物(RAH),RAH再与液溴反应得到溴化物(BRAH)。以酸值为衡量指标优选出酯化反应的最佳工艺条件,并采用红外光谱(FT-IR)法和热失重分析(TGA)法对产物结构进行了表征。结果表明:酯化反应的最佳工艺条件为n(RA)∶n(HEMA)=1∶2.0,反应温度230℃,反应时间4 h,催化剂是ZnO,w(ZnO)=2%(相对于RA质量而言);RAH的热稳定性优于RA,BRAH具有一定的阻燃性能。     

溶剂热合成纳米CeO2-TiO2粉体及其光催化性能的研究

以硝酸亚铈和三氯化钛为原料,采用溶剂热法制备了不同钛铈摩尔比的纳米CeO2-TiO2复合氧化物,并用X射线衍射仪和BET测试仪等分析手段对合成产物进行了表征。以酸性橙7为目标降解物,对合成产物的光催化性能进行了测试。结果表明:CeO2-TiO2复合氧化物具有高效、快速的催化性能,光催化反应50 min,Ce:Ti(mol.)=1:1的CeO2-TiO2复合氧化物在高压汞灯照射下对酸性橙7的降解率为88.5%,而单相TiO2对酸性橙7的降解率为62.5%。     

新型聚酯多元醇水分散体的制备

先采用间苯二甲酸-5-磺酸钠(5-SSIPA)与新戊二醇(NPG)反应制得聚酯中间体,再将一定量的聚酯中间体与多元羧酸和多元醇进行反应,同时引入叔碳酸缩水甘油酯(CARDURAE-10),制备了聚酯多元醇水分散体.用红外光谱(FT-IR)和激光粒度分析仪对产物结构及其稳定性进行了表征;并考察了5-SSIPA/NPG对聚酯中间体的影响及合成工艺、催化剂、聚酯中间体用量、叔碳酸缩水甘油酯对反应体系的影响.结果表明:选择合适的合成工艺或加入催化剂可明显缩短反应时间;聚酯中间体用量约为单体总质量的12%时,得到的产物稳定性较好;叔碳酸缩水甘油酯的引入能有效降低树脂的黏度、减小水分散体粒径,并提高涂膜最终的耐酸、耐碱及耐水性能.