稀释法测定CTAB／醇／正庚烷／水四组份微乳液体系的结构参数

采用稀释法求得CTAB／醇／正庚烷／水四组份微乳液体系在25℃时的结构参数：水内核半径Rw、颗粒有效半径Re、界面层厚度l、平均聚集数n、颗粒总数Nd以及分散相所占的总界厦面积Ad。结果表明：含水量增大,醇从连续相转移到界面层的自由能Gc→i降低,对微乳液体系的稳定不利,含水量越低,有利于微乳液的形成和稳定;醇碳链的增长,Gc→i线性递增,有利于微乳液的形成和稳定,为运用该体系提供了理论依据。     

CTAB／n－C_5H_11OH／H_2O／D_4微乳液研究

本文研究的微乳液，以十六烷基三甲基溴化铵（ＣＴＡＢ）为表面活性剂，正戊醇（ｎ－Ｃ５Ｈ１１ＯＨ）为助表面活性剂，八甲基环四硅氧烷（Ｄ４）为油相及水四组分组成。从微乳液拟三组分相图出发，确定微乳液区域，然后从接近相图油顶点的某一组成微乳液出发，滴加Ｄ４至微乳液破坏，再滴加醇恢复微乳液。如此连续八次，得到一系列微乳液形成的ｎａ／ｎｓ，ｎｏ／ｎｓ，（ｎａ、ｎｓ、ｎｏ分别为相应微乳体液体系中醇，表面活性剂和油的摩尔数），用计算机关联得到相应直线的斜率Ｋ和截距Ｉ，从ΔＧ０→ｉ＝－ＲＴｌｎＩ（Ｋ＋１）Ｋ（Ｉ＋１）公式，计算上述体系中醇从油相到微乳液液滴界面的标准自由能ΔＧ０→ｉ。另外，从ΔＧ０→ｉ随温度的变化，可得到该过程的ΔＨ０→ｉ和ΔＳ０→ｉ。本文对其结果进行理论分析和讨论，这些结果在制备有机硅微乳液、有机硅微乳聚合和化妆品生产中具有指导意义。     

SDS/正丁醇/正庚烷/水微乳液体系结构参数测定

用稀释法测定SDS/正丁醇/正庚烷/水体系W/O型微乳液的结构参数,求得不同ω(水和SDS的摩尔比)时体系的水内核半径Rw、颗粒有效半径Re、界面层厚度l、颗粒总数Nd、分散相所占总界面积Ad和平均聚集数(n).研究了不同水量时,醇从油连续相转移到界面层时自由能变化△G0c→i.     

不同醇对微乳液体系结构参数的影响及纳米BaF2的制备

采用稀释法测定了十六烷基三甲基溴化铵(CTAB)/醇/正庚烷/水四组分微乳液体系在不同醇时体系的结构参数。结果表明:随着醇碳原子数的增加,微乳液体系的结构参数水内核半径Rw、颗粒有效半径Re、界面层厚度l、平均聚集数珔n以及吉布斯自由能-ΔG0c→i增加,而颗粒总数Nd以及分散相所占的总界面面积Ad减小。采用CTAB/正丁醇/正庚烷/水微乳液体系制备了纳米BaF2。经SEM和XRD表征,BaF2为均匀的球形纳米粒子,粒径39 nm左右。     

阳离子表面活性剂中相微乳液的形成和特性（II）

溴代十六烷基吡啶嗡／醇／正庚烷／盐水体系能形成多相区微乳液，本文系统研究了盐度，表面活性剂的浓度（０．２５％～５．６％）醇的种类（丙醇，丁醇，戊醇和己醇）和丁醇浓度（２．０％～６．０％）以及油的种类对体系中相微乳液的形成，相态和其特性（最佳含直Ｓ，盐宽△Ｓ和界面张力等）的影响。     

阳离子表面活性剂中相微乳液的形成和特性（Ⅱ）

溴代十六烷基吡啶／醇／正庚烷／盐水体系能形成多相区微乳液。本文系统研究了盐度、表面活性剂的浓度（０．２５％～５．６％）、醇的种类（丙醇、丁醇、戊醇和己醇）和丁醇浓度（２．０％～６．０％）以及油的种类对体系中相微乳液的形成、相态和其特性（最佳含盐量Ｓ￣＊、盐宽△Ｓ和界面张力等）的影响。     

烷基聚葡糖苷表面活性剂形成微乳液的研究

以烷基聚葡糖苷(APG或CiGi)为表面活性剂，C4～C6正构醇为助表面活性剂，采用肉豆蔻酸异丙酯为油相，与水一起得到微乳液体系。研究了在不同烷基链长度的醇作用下，不同烷基碳链长度的烷基聚葡糖苷形成微乳液体系的拟三元相图以及δ—γ相图，并用HLB方程计算了微乳液界面的一些重要参数。发现使用较长碳链的醇以及用较长碳链的APG均有利于单相及中相微乳液的形成，并对此进行了解释，同时确定了单相微乳液效率最高的体系。     

烷基聚葡糖苷/辛二醇微乳液体系的研究

采用烷基聚葡糖苷(APG或CiCj)为表面活性剂，同时采用1，2-辛二醇为助剂，肉豆蔻酸异丙酯为油相得到了微乳液体系。测定了不同烷基碳链长度的烷基聚葡糖苷以及温度、电解质种类对微乳液相图的影响；对比了含1，2-辛二醇的微乳液体系与含其他短链脂肪醇微乳液体系的异同。通过8-r相图，结合HLB方程计算了此微乳液体系的一些重要参数，得出APG烷基链长、温度、电解质和醇类对体系微乳液效率、界面膜组成的影响规律，并对此进行了解释。     

蔗糖酯中相微乳液的研究

借助改进的ε-β“鱼状”相图研究了蔗糖酯/醇/豆油/H2O四组分微乳液体系的相行为。研究体系随醇浓度的增加,微乳液类型发生WinsorⅠ→Ⅲ→Ⅱ的转变,由各相体积以及中相微乳液形成和消失时醇的浓度,可绘制ε-β“鱼状”相图,并计算各种参数;比较了不同醇类、不同电解质对体系微乳效率,界面膜组成的影响规律。结果表明,以十六酸蔗糖酯和正己醇形成载药微乳体系时具有较高的增溶能力,形成单相微乳液效能较高。     

Triton X-100/正构醇/石油醚/水反相微乳液性质的研究

通过测定微乳液的电导率值,确定配制W/O型Triton X-100/正构醇/石油醚/水微乳液的最大增溶水量;根据微乳液含水量与电导率关系曲线及体系的拟三元相图,讨论了正构醇种类、正构醇含量、乳化剂与油相质量比对W/O型微乳液的结构、电导率、增溶水量的影响。结果表明:乳化剂与油相质量比大于1时,正戊醇、正己醇和正庚醇为助剂配制的Triton X-100/正构醇/石油醚/水体系微乳液有较大的增溶水量,而乳化剂与油相质量比大于1.5时,以正丁醇为助剂配制的Triton X-100/正构醇/石油醚/水体系微乳液才有较大的增溶水量;正构醇的链长及加入量影响微液滴界面膜的强度,从而影响微乳液的增溶水量、电导率及微乳液形成区域的大小;对于Triton X-100/正构醇/石油醚/水体系,正戊醇是形成W/O型微乳液的较好助剂,当正戊醇与Triton X-100的质量比为0.5时,W/O型微乳液的形成区域最大。     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.     

Synthetic routes to nanoscale BxCyNz architectures

B_xC_yN_z nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC₂N, BN, BC and CN_x systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources.     

Structure Evolution from Pb(Mg1/3Nb2/3)O3 to La(Mg2/3Nb1/3)O3

The crystal structure of lanthanum-modified lead magnesium niobates having composition (Pb_{1− x} La _x ) (Mg_{(1+ x )/3}-Nb_{(2− x )/3})O₃ with X = 0 to 1 was investigated by X-ray powder diffraction. It was found that the fundamental reflections from perovskite structure remain in the whole range of composition. The superlattice reflections from the A(B'_1/2-B"_1/2)O₃ ordered structure are also well preserved for La content greater than 50 at.%; however, a series of extra peaks of mixing indices appears, with intensities gradually enhanced with the increase of La content. For the complete substitution of Pb by La, a splitting of some reflections can be observed in the diffraction pattern. The results indicate that the crystal structure evolves continuously with the La content, from disordered cubic perovskite of space group Pm 3 m for X = 0, to ordered cubic perovskite of space group Fm 3 m for X = 0.5, distorted cubic perovskite of space group Pa 3 for 0.5 < X < 0.9, and finally to a rhombohedral perovskite, possibly belonging to the space group R 3 , for X ≥ 0.9. In the evolution of structure, a linear reduction of the lattice constant of the perovskite cell from 4.048 to 3.964 Å was observed.     

Dielectric-State Analysis in Solid-Solution Pb(Yb1/2Ta1/2)O3–Pb(Lu1/2Nb1/2)O3

The structure and temperature dependence of complex lead perovskite dielectrics were investigated for the system (1 − x )Pb(Yb_1/2Ta_1/2)O₃– x Pb(Lu_1/2Nb_1/2)O₃. Superlattice reflections for the compositions 0.8 < x < 1.0 were observed by X-ray diffractometry, and the temperature-composition dielectric-state diagram was determined. In the present study, the disordered middle composition, with 0.2 < x < 0.8, showed a diffuse paraelectric–ferroelectric phase transition, whereas the ordered end compositions, with 0 ≤ x < 0.2 and 0.8 < x ≤ 1.0, revealed successive sharp paraelectric–antiferroelectric and weak antiferroelectric–ferroelectric phase transitions. The dielectric state was confirmed by examining the variation of polarization ( P ) with electric field ( E ).     

(Bi1/2Na1/2)TiO3–Ba(Cu1/2W1/2)O3 Lead-Free Piezoelectric Ceramics

(Bi_1/2Na_1/2)TiO₃ with 0–6 mol% Ba(Cu_1/2W_1/2)O₃ (BNT-BCW), a new member of the BNT-based group, has been prepared following the conventional mixed oxide route. The compacted bodies were sintered at 1130°C for 2 h to get dense ceramics. The addition of BCW into BNT ceramics facilitated the poling process because of a reduction in leakage current. 0.995BNT·0.005BCW ceramics exhibit a relatively high piezoelectric constant ( d ₃₃= 80 × 10⁻¹² C/N) and a relatively low dielectric loss (tan δ= 1.5%). Increased amount of BCW was found to increase the dielectric constant and loss of BNT-BCW ceramics and to suppress the grain growth. During sintering, some BCW diffuses into the lattice of BNT to form a solid solution and some remains on the grain boundaries.     

炭黑/煤矸石/碳纳米管复合填料体系对天然橡胶性能的影响研究*

利用硝酸氧化法对碳纳米管(CNTs)进行纯化,并用环氧天然橡胶(ENR)进行改性处理。结合胶质量分数测定结果表明, ENR用量15%(质量)时效果最佳。采用胶乳凝聚法制备CNTs/天然橡胶(NR)母料。煤矸石粉(CG)经高温煅烧和表面改性处理。 将CNTs/天然橡胶(NR)母料、CG和炭黑(CB)通过机械混炼法与天然橡胶及配合剂混合,制备CB/CG/CNTs/NR复合材料,并对复合材料进行硫化特性及物理机械性能。结果表明： CNTs延迟硫化效应明显;相比炭黑,CG对硫化具有促进作用。硫化特性和甲苯溶胀法测定结果表明,在填料份数相同的条件下,单独由CB填充的NR有最大的交联密度,CNTs对交联密度影响不明显。物理机械性能测试结果表明,当CG：CB：CNTs=17.5:16.5:1(Phr)时,NR硫化胶的300%定伸应力和扯断伸长率明显高于单独由CB填充NR,而拉伸强度与之接近,复合填料样填充NR具有较好的综合性能。扫描电镜测试结果表明,复合填料在NR基体中分布均匀。