高聚物分子量分布的表征——对聚碳酸酯的应用

建议一种简单的用GPC曲线上淋出体积V_p;(V_(10)—V_p)及(V_p—V_(90))三参数来表征高聚物分子量分布的方法,其中V_p是GPC微分曲线上高峰的淋出体积值,V_(10)/V_(90)是GPC积分曲线上在累积分数10％及90％处的淋出体积值,V_p与高聚物的平均分子量有关,而(V_(10)—V_p);(V_p—V_(90))则表征分子量分布的高分子量及低分子量尾端所延伸的宽度,分子量分布对于高聚物加工性能及产品力学性能的影响常与高低分子量的尾端部分有着密切关系。 应用此方法比较了几个国内外聚碳酸酯试样的分子量分布变化和性能的关系,说明这种表征方式能够反映不同GPC曲线上的差异(即分子量分布的差异),也能够明确地反映聚碳酸酯的冲击韧性和应力开裂性质的优劣。     

基于四苯基卟啉铁敏感膜的玻璃光波导传感器对乙二胺的响应特性

为检测食品变质过程中产生的乙二胺气体,采用Alder法合成了四苯基卟啉和四苯基卟啉铁化合物,通过核磁(~1H NMR)、场发射扫描电子显微镜(FE-SEM)、红外光谱(IR)、紫外可见光谱(UV-Vis)等手段对其进行表征,并以四苯基卟啉铁作为敏感试剂,利用旋涂法制备了四苯基卟啉铁薄膜/K+交换玻璃光波导传感元件,对多种气体进行检测。结果表明:该传感元件对乙二胺气体具有较好的选择性响应,较高的灵敏度,在1×10~(-10)~1×10~(-4)(V/V_0;V:被检测气体体积,V0:空气体积)体积比范围内,体积比与输出光强度间线性关系良好(R=0.9940),响应时间和恢复时间分别为3 s和11 s,信噪比S/N=4.8,RSD=0.5%(V/V_0=1×10~(-7))。平行试验中,其结果也具有良好的线性关系(R=0.9985),证明该传感元件对乙二胺气体检测的准确性。该类传感元件在食品品质检测方面有很好的应用与发展。     

混合弱酸中各组分酸含量测定方法研究

离解常数之比小于10~4倍,但离解常数均大于10~(-7)的两种一元弱酸混合情况下,推导出V/V_0~T=(α_(A2)~--α_(A1)~-)Ve_2/Ve~T+α_(A1)~-公式。根据此公式提出混合酸中各组分酸含量测定方法—标准曲线法。     

CRYSTAL STRUCTURE OF POTASSIUM 9-MOLYBDO-3-VANADOPHOSPHATE

K_4H_2PMo_9V_3O_(40).18H_2O,Mr=2169.68,tetragonal,space group P4/mnc,a=b=12.515(3),c=17.636(7)A;z=2;V=2762(2)A~3;F(000)=2206;Dc=2.31g/cm~3;μ=28.8/cm(MoKa=0.71069 A).Thecentral PO_4 is disordered in the(PMo_9V_3O_(40))~(6).P-O=1.511A.M(M=Mo or V)is 7 coordinate,M-O=1.62-2.48A.K is 7 coordinate,K-O=2.85-3.10A.     

基于陶瓷/聚合物的准固态复合电解质的制备及电化学性能

采用聚碳酸亚丙酯(PPC)、偏氟乙烯-六氟丙烯共聚物(P(VDF-HFP))、双三氟甲烷磺酰亚胺锂(LiTFSI)、磷酸钛铝锂(Li_(1.4)Al_(0.4)Ti_(1.6)(PO_4)_3)和锂离子电池三元电解液(1 mol·L~(-1)LiPF_6的碳酸乙烯酯(EC)-碳酸二甲酯(DMC)-碳酸甲乙酯(EMC)溶液,V_(EC)∶V_(DMC)∶V_(EMC)=1∶1∶1)制得准固态复合电解质,其中液态电解质含量为9%(w/w)。准固态复合电解质膜在25℃下电导率达1.3×10~(-4) S·cm~(-1)。与LiFePO_4组装成准固态锂电池,0.5C倍率下首次放电比容量达128.4 mAh·g~(-1),充放电50次后容量保持率为80%。与纯聚合物准固态电解质相比,添加Li_(1.4)Al_(0.4)Ti_(1.6)(PO_4)_3可显著降低界面电阻。     

V_2O_5/TiO_2界面固溶过程的红外特征

加热温度低于580℃时,V_2O_5/TiO_2催化剂体系内的V_2O_5在TiO_2表面上分散,此时虽有部分V_2O_5碎片渗入TiO_2表层,但还未形成固溶体。在此阶段,随温度的提高,无定形的V=O键伸缩振动(980cm~(-1))先是生成,后逐步消失;V—O—V键的伸缩振动(862cm~(-1))显著减弱,并紫移到885cm~(-1);新出现了1400cm~(-1)吸收峰,它是V_2O_5一级结构及其集合体的表征。同时,在TiO_2的宽频区出现了740,670和594cm(-1)三个吸收峰,这可能是Ti~(4+)d轨道在VO_4影响下能级分裂的结果。580℃到677℃,形成等一类固溶体,上述1400cm~(-1)吸收峰消失,740,670和594cm~(-1)三峰也逐步合一,这是固溶体中V-O-Ti键振动的象征。>677℃,第二类固溶体(V_xTi_(1-x)O_2)出现,其红外光谱同第一类固溶体,但TG有失重。     

固态高聚物状态方程的研究

本文从理论上导出了一个新的三参数固态高聚物的状态方程, 在不发生转变的温度区域内, 它适用于描述固态高聚物的压强-体积-温度关系。方程形式简单, 物理参数的意义较明确。     

Synthesis and crystal structure of [V_2(μ-S_2)_2(S_2CNEt_2)_4]·2CH_3Cl

[V_2(μ-S_2)_2(S_2CNEt_2)_4].2CH_3Cl was synthesized by the reaction of NaS_2CNEt_2,Li_2S andVOCl_3 at room temperature.Crystal data:M=1061.3,space group Pbca,with the orthorhombicparameters:a=20.123(3),b=20.485(4),c=10.911(3),V=4497.7,Z=4,D_c=1.57g/cm~3,Mo Kσradiation(λ=0.71069()?),μ=13.2 cm~(-1),F(000)=2168.Final R=0.041 and R_w=0.047 for 2288 ob-served reflections with I>3σ(1).The coordination sphere of each V atom in title compound is a dis-torted tetragonal prism composed of two bidentate dithiocarbamate and two S_(2~((2-)) ligands.The V—Vdistance is 2.890 while the V—S distances fall in the range of 2.422—2.505.     

固溶体MAX相(Ti0.5V0.5)3AlC2的制备及其对MgH2储氢性能的催化影响

通过无压烧结法制备了固溶体MAX相(Ti_(0.5)V_(0.5))_3AlC_2,研究了其添加对MgH_2储氢性能的影响。结果发现,固溶体MAX相(Ti_(0.5)V_(0.5))_3AlC_2中的Ti和V元素通过协同作用,呈现出更高的催化活性。添加质量分数10%(Ti_(0.5)V_(0.5))_3AlC_2的MgH_2样品的起始放氢温度为230℃,较原始MgH_2降低了60℃。在275℃下等温放氢,(Ti_(0.5)V_(0.5))_3AlC_2添加样品的放氢速率可达0.35%·min~(-1),是原始MgH_2样品的4倍左右。此外,完全放氢后的MgH_2-10%(Ti_(0.5)V_(0.5))_3AlC_2样品在150℃、5 MPa氢压下,可在60 s内吸收4.7%的氢。计算显示,MgH_2-10%(Ti_(0.5)V_(0.5))_3AlC_2样品的表观活化能为79.6 kJ·mol~(-1),较原始MgH_2(153.8 kJ·mol~(-1))降低了48%,这是MgH_2放氢性能得到改善的主要原因。     

THE ELECTROCHEMICAL BEHAVIOUR OF THE NEW VANADIUM BRONZE (Li_3V_5O_(15)) CATHODE IN SECONDARY LITHIUM BATTERY

A new kind of vanadium bronze with rich lithium (Li_5V_5O_(15))was prepared from Li_2CO_3 and V_2O_5 at 680℃ for 24 hrs. The charge and discharge curves of bronze electrode were determined in organic electrolyte. One mole of this material could be incorporated up to 4 mole lithium at 0.2mA/cm~2 and 1.0V cut-off voltage, corresponding capacity about 340Ah/kg. Compared with the cell of Li/Li_(1+x)V_3O_5 the cell of Li/new bronze had higher capacity, smoother discberge curve, but lower plateau voltage (about 1.8V). The cycling behaviour of this material was good. The electrode insertion reaction was controlled by the lithium diffusion process in the bronze. This new bronze could be used for low voltage rechargeable lithium battery.     

两类稀土钒酸盐的合成与结构

通过（１）ＬｎＯＣｌ／Ｖ＿２Ｏ＿５，（２）ＬｎＣｌ３／Ｖ及（３）ＬｎＯＣｌ／ＬｎＣｌ／Ｖ＿２Ｏ＿５／Ｖ的高温固态化学反应，得到两种稀土钒酸盐：Ｌｎ＿６Ｖ＿３Ｃｌ＿（１０）Ｏ＿（１２）（Ｌｎ＝Ｌａ）及Ｌｎ＿４Ｖ＿５Ｓｉ＿４Ｏ＿（２２）（Ｌｎ＝Ｌａ～Ｎｄ）。Ｌａ＿６Ｖ＿３Ｏ＿（１０）Ｏ＿（１２）晶体呈浅色透明片状，其结构可认为是由［Ｌａ＿３（ＶＯ＿４）＿３Ｃｌ］单元插入到ＬａＣｌ３结构单元中而形成的，在结构中沿ｃ轴方向存在一系列截面积为１９．１的空洞。Ｌｎ＿４Ｖ＿５Ｓｉ＿４Ｏ＿（２２）（Ｌｎ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ）晶体呈，黑色针状，其结构可认为是由交替的稀土钒硅酸盐薄层及钒氧金红石层沿ｃ轴堆叠而表现为准二维Ｃｈｅｖｋｉｎｉｔｅ型结构。     

分散体系中任意形状的胶粒模型与相互作用能——Ⅱ、不等同球颗粒

鉴于不等同球颗粒在胶体化学中的重要性,所以它一直引起人们在理论上的关注。Hogg、Healy和Fuerstenau(HHF)对Poisson-Boltzmann方程引用Debye-Hückl近似,得出不同平行平板型颗粒在恒电位表面时相互作用能计算公式,进而HHF用Derjaguin法得出不等同球颗粒相互作用能的表达式。虽然HHF的公式仅适用低电位的情况,但它的表达式特别简单,因而一直被广泛使用。Ohshima等(OCHW)对球颗粒做了曲率校正,Barouch等(BM)对Poisson-Boltzmann方程提出二维解法,使不等同球颗粒的相互作用能的计算有了改进和提高。本文根据我们提出的模型和方法,对HHF公式也做了曲率校正,结果表明它和OCHW的曲率校正结果相当,但它的表达式却要简单得多。     

Crystal Structure of La_4V_5Si_4O_（22）──A Mixed－Valence Lanthanum Vanadium（Ⅲ／Ⅳ） Oxosilicate

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆＬａ_４Ｖ_５Ｓｉ_４Ｏ_（２２）──ＡＭｉｘｅｄ－ＶａｌｅｎｃｅＬａｎｔｈａｎｕｍＶａｎａｄｉｕｍ（Ⅲ／Ⅳ）ＯｘｏｓｉｌｉｃａｔｅＣｈｅｎＪｉｕ－Ｔｏｎｇ；ＧｕｏＧｕｏ－Ｃｏｎｇ；ＺｈｕａｎｇＨｏｎｇ－Ｈｕｉ；Ｈｕａ...     

Gas-Phase NMR Spectroscopy

The Murnaghan-Hildebrand equation of state, an accurate equation of state for many solids and liquids, is introduced for use in the illustration of thermodynamic relationships. It is shown to meet the need for an equation of state accurate over a wide range of pressures. Parameters are given for four solid phases of iron and for the liquid, with which eleven thermodynamic functions including V, U, H, S, V, V/B, and G can be calculated at any specified temperature and pressure. The program for these calculations can be used to represent experimental values, to illustrate thermodynamic relationships, to calculate chemical and phase equilibria, and to stimulate student interest from the study of real systems, for instance, the form of iron in the core of the earth.     

A new cell model for equation of state of polyethylene melt and n-alkane

The connectivity of successive carbon atoms in polymer decreases the degrees of freedom, and hence, the external degrees of freedom should correspond only to translational motion. We therefore, introduce a coarse-grained particle of a few successive monomers. A cell model (or the hard core model with attractive potential) for the particles can accordingly be used for the derivation of the equation of state of polymers. Modifying the classical cell model by Lennard-Jones and Devonshire, we construct a new equation of state for polyethylene melt and for liquid n-alkane; the free volume term is modified by using the Sutherland potential instead of the Lennard-Jones potential. The characteristic quantities P*, V*0, and T* in the equation of state are almost independent of temperature; the principle of corresponding state holds well. Since our equation of state contains the external degrees of freedom explicitly, we can evaluate the external degrees of freedom, c, for CH2. The value of c for the coarse-grained particle is equal to 1, and hence the particle is composed of 1/c repeating units. The linear length of the particle evaluated, 4.09 A at 0 K, is consistent with that obtained by neutron and x-ray scatterings.     

氧化热处理对聚苯胺/V2O5杂化材料结构和性能的影响

采用原位氧化聚合法将聚苯胺分子链插入层状V2O5的片层中,制得了聚苯胺／五氧化二钒(PAn／V2O3)纳米杂化材料,并用氧气对杂化材料进行氧化热处理,用WAXD、FTIR、TGA、电导率及循环伏安测试等手段研究了氧化热处理对杂化材料结构与性能的影响。结果表明：氧化热处理对杂化材料的层状结构几乎没有影响,但将导致层闯客体聚苯胺分子链上醌式结构的比重略有增加,降低了电子的离域能力,从而使得电导率略有下降,同时伴随着部分V^4 氧化为V^5 ,使得嵌锂能力得到明显改善。     

五氧化二钒催化钾碱液吸收二氧化碳的机理

从五氧化二钒(V_2O_5)的物理化学性质出发,研究了V_2O_5加快CO_2在钾碱液(K_2CO_3)中的吸收速率的化学作用机理。实验证明: 当9相似文献   

Heat capacities and entropies of liquid polyfluoroethylenes and polychloroethylenes

Through new measurements and from literature data, the heat capacity of all liquid polyfluoroethylenes could be established as: above 480 k, and as below 480 K in J/(K mol), where N_F is the mole fraction of F atoms. In connection with previously established heat capacities of the solid polymers, enthalpies, entropies, and residual entropies of the glassy state at 0 K were computed. Data for liquid polychloroethylenes are much less complete, and the thermodynamic functions could only be established for liquid poly(vinyl chloride) and compared with the data for solid poly(vinyl chloride), poly(vinylidene chloride), and polychlorotrifluoroethylene.     

One-dimensional π-d conjugated coordination polymers: synthesis and their improved memory performance

Multilevel resistance random access memories(RRAMs) are intensively studied due to their potential applications in high density information storage. However, the low ternary device yields and high threshold voltages based on current materials cannot meet the requirement for applications. Improvement via material innovation remains desirable and challenging. Herein,five one-dimensional conjugated coordination polymers were synthesized via the reaction between metal ions(Zn~(2+), Cu~(2+), Ni~(2+),Pt~(2+) and Pd~(2+)) and 2,5-diaminobenzene-1,4-dithiol(DABDT) and fabricated into RRAM devices. The as-fabricated ternary memories have relatively low threshold voltages(V_(th1):-1 to-1.4 V, V_(th2):-1.8 to-2.2 V). Their ternary device yields were improved from 24% to 56%. The first and the second resistance switches are interpreted by the space charge limited current(SCLC) and grain boundary depletion limited current(GBLC) modes, respectively. The Pd-DABDT, which is of planar structure,smaller band gap and better crystallinity than others, shows the best performance among these five polymers. Our work paves a simple and efficient way to optimize the performance of ternary RRAM devices employing one-dimensional hybrid materials.