Improving the softness of BOPP films: From laboratory investigation to industrial processing

Young's modulus of biaxially oriented polypropylene (BOPP) films prepared with homemade film stretcher was investigated,which can be used to indicate the softness of fihns.It was found that the modulus of films was decreased by about 69％ as the content of polyethylene (PE) added into polypropylene (PP) reached 30％.Also,increasing draw temperature can induce lower stress level during stretching,which may lead to the formation of crystals with low orientation level and thus decreased modulus of films.Based on laboratory study,BOPP films produced on commercial line were studied by differential scanning calorimetry (DSC),wide and small-angle X-ray scattering (WAXS,SAXS) with varying contents of PE.SAXS results show that the crystals are oriented in both machine direction (MD) and transverse direction (TD),and the crystals are more oriented in TD than MD according to the WAXS results for all films.Also,the orientation parameter of crystal along TD increases from 0.68 to 0.83 as the contents of PE increase from 0％ to 25％.Meanwhile,the modulus of films in MD declines with increase of PE contents generally,improving the film softness.Orientation of crystals is thus an effective structure parameter to adjust the film softness.The relationship of processing-structure-property is also established.     

Analysis of temperature and stress field in Al alloy’s twin wire welding

By analyzing the shape of twin wire welding’s arcs and the track of droplets’ transition, the phenomenon that the twin wire welding’s fore arc and rear arc all deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can apply to calculate the twin wire welding’s temperature field is put forward. This model is testified by actual experiment of temperature sampling. By comparing the temperature field of twin wire welding and single wire welding, the results show that twin wire welding has slender weld pool the end part of which is ellipsoid, and its HAZ is narrower than that of single wire welding. So, twin wire welding can not only reduce the Al alloy generating hot crack, but can also weaken the “overaging” softened phenomenon of heat treated strengthening Al alloy. In the end, the evolving rules of 2219 Al alloy’s longitudinal and transverse stress when welded with twin wire welding are analyzed.     

Theoretical Studies on the Halogen Bond between Propargyl Radical and Dihalogen Molecules

MP2/aug‐cc‐pVDZ calculations are carried out on the geometries, vibrational frequencies, interaction energies and topological properties for the π‐type halogen‐bonded complexes between propargyl radical and dihalogen molecules ClF, BrF and BrCl. There are two kinds of geometries: complex ( a ) involves the interaction between the X (X=Cl, Br) atom and the midpoint of C(1) –C(2) bond, complex ( b ) involves the interaction between the X atom and C(3) atom. The lengths of the halogen bond, the frequencies of the halogen bond, the elongation extent of the X–Y (XY=ClF, BrF, BrCl) bond, topological parameters at the BCPs of the halogen bond and X–Y bond are all well consistent with the interaction energies. The interaction of complex ( a ) is stronger than that of complex ( b ); the interaction of propargyl···BrF is stronger than that of propargyl···ClF and propargyl···BrCl. For the complexes ( a ) and ( b ), the charge transfer is observed from propargyl radical to XY, the atomic energy, the dipolar polarization, and the volume of the halogen atom X decrease upon complex formation.     

Alkoxy substituted MeO-BIPHEP-type diphosphines ligands for asymmetric hydrogenation of aryl ketones

<正>In this paper,a series of optically active MeO-BIPHEP-type ligands,(S)-6,6′-dimethoxy-2,2'-bis(di-p-alkoxyphenylphosphine)- 1,1′-biphenyl were synthesized and used to prepare the ruthenium complex.The effects of para-substituted were observed,the results showed that the ruthenium catalysts[diphosphine RuCl_2 diamine]containing both t-Bu and i-Pr substitutions have better activities and enantioselectivities than the non-substituted ruthenium catalysts in the asymmetric hydrogenation of acetophenone.     

高效液相色谱法测定全血中直链烷基苯磺酸钠

提出了高效液相色谱法测定全血中直链烷基苯磺酸钠同系物的含量。全血样品用酸性提取溶液稀释,过Bakerbond SPE C18固相萃取小柱,经甲醇-乙酸-水(49+2+49)混合溶液淋洗后用甲醇-氨水(98+2)混合溶液洗脱。经纯化后的洗脱液在Wakopak WS AS-Aqua(250 mm×4.6 mm,5μm)柱上进行分离,流动相为乙腈与水(60+40)混合溶液,检测波长为228 nm。5种n-ABS同系物的C10~C14的质量分数在10.0~100.0 ng.g-1范围内与其峰面积呈线性关系,全血中各同系物回收率为78%~107%;日内相对标准偏差(n=5)≤10%,日间相对标准偏差(n=5)≤13%。     

α-葡萄糖苷酶抑制剂Radicamine A的合成

天然产物Radicamines A和B是日本植物学家Kusano等从半边莲中分离到的两个新型吡咯烷型生物碱,发现它们是有效的α-葡萄糖苷酶抑制剂,根据各种光谱数据推断它们为全反式取代的吡咯烷结构,绝对构型为(2S,3S,4S,5S) [1].后来,本课题组[2]和其它课题组[3,4]分别采用不同的全合成方法纠正了Radicamines A和B的构型,确定其为(2R,3R,4R,5R)(图1).去年,另一课题组采用与我们相似的合成路线率先报道了Radicamines A和B的合成及其对三种糖苷酶的活性研究[5].     

GaN基异质外延膜中Al组分含量测试方法综述

介绍了目前可用于AlGaN半导体异质外延膜中Al组分含量测定的多种测试技术,包括高分辨X射线衍射技术、光致发光法、紫外-可见光透射光谱法、电子探针法、卢瑟福背散射法等,并对各种测试技术的原理和优缺点进行了概述。     

金属铜配合物催化氧化1-(3,4-二甲氧基苯)乙醇的动力学研究

合成了1-(3,4-二甲氧基苯)乙醇(DMPE)作为木质素模型物,并用初始速率法研究了40℃时在pH6.5～8.5磷酸缓冲溶液中N,N-双(2-乙基-5-甲基-咪唑-4-亚甲基)乙醇胺合铜、N,N-双(2-(2-羟乙基胺基)乙基)草酰胺合铜和5,7,12,14-四甲基-1,4,8,11-四氮杂环十四-4,7,11,14-四烯合铜催化氧化1-(3,4-二甲氧基苯)乙醇的动力学,提出了1-(3,4-二甲氧基苯)乙醇氧化反应动力学模型,并由此计算出不同pH值条件下催化反应动力学参数k2和Km.铜配合物的催化活性随着pH的增大而增大.具有大共轭体系的配体催化剂表现出更好的催化活性.提出并讨论了H2O2氧化DMPE的催化氧化反应机理.     

Electrophoretic sol–gel synthesis of SrBi<Subscript>2</Subscript>Ta<Subscript>2</Subscript>O<Subscript>9</Subscript> nanowires

We report the independent invention of perovskite ferroelectric nanowires strontium bismuth tantalate (SrBi₂Ta₂O₉, SBT). Electrophoretic sol–gel techniques have been used successfully. The morphology and structures are analyzed via SEM, TEM and XRD. SBT nanowires and nanoparticles filled template revealed 30 and 40 μm long, respectively. SBT are proved to be a single phase of orthorhombic perovskite structure. As it indicated, SBT nanowires has been crystallized at 700 °C. To minimize surface polarity, SBT nanowires oriented preferentially along the growing axis (c axis) by translation and rotation of atomic clusters of SBT.     

Iron/copper promoted oxidative homo-coupling reaction of terminal alkynes using air as the oxidant

An inexpensive catalytic system, which used a readily available Fe(acac)₃ and trace quantity of Cu(acac)₂ as the co-catalyst and air as the oxidant for the homo-coupling of terminal alkynes, has been developed. The catalytic system could also apply to the cross-coupling reaction of two different terminal alkynes.