PBAT/PVA复合涂布膜阻隔性研究

目的 为改善PBAT膜的阻隔性,通过以戊二酸为交联剂改性PVA制备涂膜液,利用涂布法制备了具有高阻隔性的PBAT/PVA复合薄膜。方法 采用红外光谱、差示扫描量热仪、接触角测试仪、水蒸气透过率测试仪等对改性PVA单膜、PBAT/PVA复合膜的结构和性能进行研究。结果 表明由于戊二酸与PVA之间有一定的酯化作用,消耗PVA中部分羟基,从而提高了PVA的耐水性。戊二酸改性提高了PVA膜的疏水性,其接触角从11.3°提高到60.6°。与PBAT纯膜相比,涂覆了戊二酸的PVA涂膜液改性3 h后复合膜水蒸气透过率由647.95 g/(m².24 h)降低到132.07 g/(m².24 h)、氧气透过量由17 730.3 cm³/ (m².d.MPa)降低到396.6 cm³/(m².d.MPa),证明改性3 h的PVA涂膜液对增加PBAT阻隔性最有帮助。结论 利用涂布法制备的PBAT/PVA复合薄膜具有较高阻隔性,为PBAT的广泛应用打下了基础。     

环烯烃共聚物对聚丙烯五层共挤出软管阻隔性能的影响

目的 在聚丙烯(PP)五层共挤出软管的外层中引入一定质量分数环烯烃共聚物(COC)材料,研究其对软管阻隔性能的影响。方法 将不同质量分数的COC与PP共混造粒,对共混物进行熔融行为分析,并测试软管的阻氧与阻水性能,共混材料的拉伸强度、弯曲模量、缺口冲击强度等。结果 随着COC添加量的增加,软管管身的氧气透过速率与水蒸气透过速率降低。当COC质量分数为20%时,氧气透过率低至3.3 cm³/(d.m²),水蒸气透过率为0.6 g/(d.m²),此时其他性能也能实现较好的平衡。结论 在PP五层共挤出软管的外层中引入COC可以有效地提升软管阻水与阻氧性能。     

硬脂酸改性聚乙烯醇/纳米纤维素复合阻隔涂料的制备

目的 为了以安全环保的方式提高聚乙烯醇(PVA)阻水阻气性,制备高阻隔PVA涂料,提高PVA的性能与应用范围。方法 在聚乙烯醇中填充纳米纤维素(Cellulose Nanofiber,CNF),并在此基础上添加硬脂酸进行耐水改性,探究对阻隔性能的影响,利用傅里叶红外光谱,X射线衍射,氧气、水蒸气透过率测试仪对其进行结构性能表征。结果 硬脂酸与PVA的酯化反应可以提高涂层的耐水性,PVA与CNF间能产生氢键,提高涂层结晶性能与阻隔性能,适量的硬脂酸的加入未降低CNF的结晶度,只降低了PVA的结晶性能,硬脂酸添加量为16%时涂层水蒸气透过率达到最低2.2 g/(m².d),氧气透过率达到1.3 cm³/(m².d)。结论 利用CNF填充与硬脂酸酯化协同改性制备的PVA阻隔涂料具有较高的阻隔性能,使其在阻隔涂层方面具有广阔的应用前景。     

探究温度对复合膜阻隔性和力学性能的影响

目的 探究温度变化对几种包装用复合膜阻隔性和力学性能的影响。方法 采用4种不同材质的复合膜为研究对象，通过调节温度变化，分别对复合膜进行拉伸强度、断裂伸长率、穿刺强度、直角撕裂力、氧气透过量、水蒸气透过量测试。结果 随着温度的升高，复合膜的拉伸强度、穿刺强度、直角撕裂力呈现逐渐变小的趋势，断裂伸长率呈现先增大后减小的趋势，氧气透过量、水蒸气透过量呈现逐渐变大的趋势。温度从15 ℃升至55 ℃，BOPP/EVOH复合膜的力学性能和阻隔性能受温度影响小，其中拉伸强度降低了5.2 MPa，断裂伸长率增加了10%，穿刺强度降低了4.4 N，直角撕裂力降低了5.0 N，水蒸气透过量提高了2.34 g/(m².d)，氧气透过量增加了12.5 cm³/(m².d.0.1 MPa)。结论 根据实验探究，温度是影响包装复合材料性能的重要因素，为不同温度条件下不同材质复合膜的性能变化提供了数据指导，BOPP/EVOH复合膜的综合性能受温度变化影响最小。     

氧化纳米纤维素增强再生纤维素全纤维素复合薄膜的制备及性能

以2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)氧化松木粉纳米纤维素(TOCNs)为增强相、α-纤维素粉制备再生纤维素(RC)为基体,采用溶胶-凝胶法制备氧化纳米纤维素增强再生纤维素(TOCNs/RC)全纤维素复合薄膜。对不同TOCNs添加量下TOCNs/RC全纤维素复合薄膜的力学性能、光学性能、氧气阻隔性能和热稳定性能进行研究,并通过FTIR、SEM、TEM、XRD和流变仪对TOCNs和TOCNs/RC全纤维素复合薄膜的结构、形貌及纤维素溶液流变性能进行表征。结果表明,TOCNs添加量对TOCNs/RC全纤维素复合薄膜的力学性能有显著影响,当TOCNs添加量(与纤维素基体的质量比)为1.0%时,TOCNs/RC全纤维素复合薄膜的拉伸强度和断裂能分别可达134.3 MPa和21.51 MJ·m?3,具有最佳的综合力学性能;TOCNs/RC全纤维素复合薄膜的透光率随TOCNs添加量的增加而下降,雾度随TOCNs添加量的增加而增大,但仍保持较高的透光率(>85%)和较低的雾度(<14%);TOCNs/RC全纤维素复合薄膜还具有优异的氧气阻隔性,TOCNs添加量为1.6%时,其透氧系数仅为1.47×10?17cm3·cm/cm2·s·Pa。TOCNs/RC全纤维素复合薄膜有优于一般塑料薄膜的拉伸强度和氧气阻隔性,并有可媲美于塑料薄膜的透明度,可作软包装复合材料的强度层和阻隔层,在绿色高性能包装材料领域具有广阔的应用前景。      

成膜条件对NMMO工艺纤维素膜拉伸强度的影响

以纤维素为原料,N-甲基吗啉-N-氧化物(简写NMMO)为溶剂,采用相转化法制备非对称纤维素膜.对该工艺法成膜的拉伸强度的影响因素进行了研究,以期为提高薄膜性能提供理论基础.实验结果表明:随着溶解纤维素的温度的升高,薄膜拉伸强度降低;随着刮膜时所施加的外力的增大,薄膜的拉伸强度增强;随着凝固浴温度的升高,薄膜的拉伸强度降低;随着塑化剂(甘油)浓度的增加,薄膜拉伸强度降低.     

单轴拉伸PLLA/PBS共混薄膜的包装特性研究

目的提高聚乳酸(PLLA)的韧性、强度及阻氧性能。方法采用双螺杆挤出流延线制备单轴拉伸PLLA/聚丁二酸丁二醇酯(PLLA/PBS)共混薄膜,用万能拉伸试验机、差示扫描量热分析仪(DSC)和透氧仪,对不同拉伸比例的PLLA/PBS共混薄膜的力学性能、热学性能和阻氧性进行了评估。结果随着拉伸比例的增大,PLLA/PBS共混薄膜屈服强度和弹性模量增大,断裂伸长率呈先增大后降低的趋势。随拉伸比例的增大,PLLA/PBS共混薄膜结晶速率明显提高,其阻氧性也得到一定的改善。结论通过单轴拉伸和与PBS共混提高了PLLA的韧性和强度,中等拉伸比例的PLLA/PBS共混薄膜的阻氧性相对较好。     

大气压介质阻挡放电等离子体辅助原子层沉积氧化铝阻隔膜

为了研究纳米氧化铝对双向拉伸聚对苯二甲酸乙二醇酯薄膜(BOPET)阻隔性能的影响,利用自行设计加工的大气压介质阻挡放电(DBD)等离子辅助原子层沉积(PAALD)设备,使用三甲基铝(TMA)和氧气等离子体(O²)在厚度为120 μm的BOPET上生长氧化铝(Al₂O₃)无机层。采用椭圆偏振仪、原子力显微镜、红外光谱仪、X射线光电子能谱分析和透湿仪等分别对氧化铝薄膜的厚度、表面形貌、成分和水蒸气透过率等进行测量和表征。结果表明,大气压DBD等离子体辅助沉积 Al₂O₃薄膜具有ALD生长特性,生长速率为0.27 nm/周期,高于在低压下由等离子体辅助ALD沉积的Al₂O₃的生长速率;生长的氧化铝薄膜结构致密、表面粗糙度小,薄膜成分较纯;其水蒸气透过率(WVTR)由PET原膜的3.17 g/(m²·d)低至0.05 g/(m²·d)。     

微纤化纤维素/聚乳酸薄膜的制备及性能分析

目的将微纤化纤维素(MFC)和聚乳酸(PLA)共混成膜,以提高薄膜的透湿、透氧、阻光等性能,满足果蔬等食品的包装要求。方法采用酶解法与机械处理的方法制备MFC,使用硅烷偶联剂KH560对MFC进行疏水改性处理,再将改性处理的微纤化纤维素(MFC-S)与PLA共混制成薄膜。结果当MFC-S的质量分数为0.75%时,MFC-S/PLA共混包装膜的拉伸强度比纯PLA膜增加了13.3%,当MFC-S的质量分数为2%时,MFC-S/PLA共混包装膜的透氧系数为纯PLA膜的1.43倍,透湿系数为纯PLA膜的1.26倍,透光率降低了60%,阻光效果较好。结论 MFC-S的质量分数为0.75%时,包装膜的拉伸强度较好;MFC-S的质量分数为2%时,透氧、透湿、阻光性较好。     

PPC/PHB吹塑薄膜的相形态、力学和阻隔性能研究

采用挤出吹塑成型制备PPC/PHB复合材料薄膜,研究薄膜的微观形态与力学性能和阻隔性能之间的关系。结果表明,薄膜的拉伸强度随着PHB含量的增大逐渐增大,薄膜的纵向拉伸强度比横向拉伸强度高,横向直角撕裂强度比纵向略高,这与薄膜沿拉伸方向发生了一定的取向有关;薄膜的水蒸气渗透系数和氧气渗透系数均随着PHB含量的增大而不断减小,表明其阻水及阻氧性能得到提高;当PHB含量为30%(质量分数)时,与纯PPC相比,复合材料薄膜的氧气阻隔性能提升了约5倍。分别采用Fricke和Nielsen理论模型预测PPC/PHB复合材料薄膜的阻隔性能,探究影响PPC/PHB共混薄膜阻隔性能的作用机制,可为高阻隔性能的PPC/PHB复合材料制备提供理论指导。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.