苯乙烯类热塑性弹性体对IR／CR的增容作用

采用相差显微镜及Ｍｏｏｎｙ－Ｒｉｖｌｉｎ方程中的２Ｃ１和２Ｃ２等方法，研究了少量ＳＩＳ，ＳＢＳ，α－甲基苯乙烯和丁二烯的三嵌段共聚物（ＭＳＢＭＳ）对ＩＲ／ＣＲ共混物相态结构、交联行为和力学性能的影响。结果表明，加入ＳＩＳ，ＳＢＳ，ＭＳＢＭＳ厅明显降低分散相尺寸，使体系分布均匀，提高了硫化胶的交联密度和拉伸强度。降低节体系煌内部损耗。对ＩＲ／ＣＲ共混物的增容效果，以ＳＩＳ为最好，ＳＢＳ次之，ＭＳＢＭ     

对称型双端过渡态丁二烯/苯乙烯嵌段共聚物的研制Ⅱ.结构研究

以双锂为引发剂、环乙烷为溶剂,合成了对称型双渡态丁二烯／苯乙烯（Ｂ／Ｓ）嵌段共聚物Ｓ－（Ｓ／Ｂ）－Ｂ－（Ｂ／Ｓ）－Ｓ,并对其结构进行了研究。结果表明：随着Ｓ／Ｂ的增大、极性添加剂（２Ｇ）／Ｌｉ的增加,嵌段共聚物中苯乙烯含量增加;嵌段共聚物具有微观相分离结构,分子量分布约为１．２。     

共聚物相容作用的预测和初步验证

采用ＨａｒｋｉｎＨｏｂｂｓ方程中的分散系数λ对异戊二烯与苯乙烯的三元嵌段共聚物（ＳＩＳ）和丁二烯与苯乙烯的三元嵌段共聚物（ＳＢＳ）在ＩＲ／ＣＲ和ＩＲ／ＢＲ共混物中的相容作用做了预测，并通过实验进行了验证。结果表明，在ＩＲ／ＣＲ共混物中加入ＳＩＳ或ＳＢＳ后可明显地增大ＭｏｏｎｅｙＲｉｖｌｉｎ方程中的常数２Ｃ１，２Ｃ２以及橡胶在溶胀体系中的体积分数ｖｋ，同时改善共混物的力学性能；而在ＩＲ／ＢＲ共混物中加入ＳＩＳ后，对网络结构参数和共混物的力学性能没有明显影响，预测与验证结果显示出一致性，证实了该方法预测的正确性。     

CR/SBS/CEVA-g-MMA/n-BMA胶粘剂的研制

以ＣＲ、苯乙烯丁二烯苯乙烯嵌段共聚物（ＳＢＳ）和氯化乙烯乙酸乙烯酯共聚物（ＣＥＶＡ）３种固体物料为接枝母体,以甲基丙烯酸甲酯（ＭＭＡ）和甲基丙烯酸正丁酯（ｎＢＭＡ）为接枝单体,在溶剂回流温度下,空气氛围中,以过氧化二苯甲酰（ＢＰＯ）为引发剂进行接枝共聚,制得了共混接枝共聚胶粘剂。此种胶粘剂的单体转化率、接枝率、初粘强度都有较大的提高,其广谱性能也有所改善。     

BR／PVC／SBS动态硫经体系的增容技术

采用差示扫描量热分析、扫描电子显微镜和力学方法研究了在丙烯酸酰胺和引发剂过氧化二异丙苯（ＤＣＰ）存在下,顺丁二烯橡胶／聚氯乙烯－丁二烯－苯乙烯嵌段共聚物（ＢＲ／ＰＶＣ／ＳＢＳ）动态硫化挤出共混的结果。初步探讨了引入丙烯酸酰胺“就地”产生增容剂的机理。实验证明,采用该方法较以α－甲基苯乙烯为增容剂的相同体系具有更好的增容效果。     

SBS加氢动力学的研究

以三（三苯基膦）二氯化钌「ＲｕＣｌ２（ＰＰｈ３）」为催化剂,三苯基膦（ＰＰｈ３）为配体对苯乙烯－丁二烯嵌段共聚物（ＳＢＳ）加氢,在１５０℃下进行了ＳＢＳ加氢动力学研究,得到了加氢动力学方程：－ｄ「Ｃ＝Ｃ」／ｄｔ＝ｋ「ｈ２」＾１．１２「Ｃ＝Ｃ」「Ｒｕ＾＊」「ＰＰｈ３」＾－１,１３０￣１６０℃的加氢反应活化能力２２．７４ｋＪ／ｍｏｌ。     

马来酸酐接枝SBS增容PVC／SBS的研究

马来酸酐接枝苯乙烯－丁二烯＝苯乙嵌段共聚物（ＳＢＳ）用ＭＳＢＳ代表,以它为增容剂,研究了ＳＢＳ对聚氯乙烯（ＰＶＣ０的共混增韧改性。结果表明：ＭＳＢＳ能明显改善ＳＢＳ与ＰＶＣ的相容必 分散相ＳＢＳ相区尺寸明显减小,分布更均匀,共混物的玻璃化转变温度内移,常温和低温下缺口冲击强度增大。当ＰＶＣ／ＳＢＳ／ＭＳＢＳ为７５：２５：４时,共混物的常温缺口冲击强度为５８．３ｋＪ／ｍ＾２,低温（－２０℃）缺口冲击     

对称型双端过渡态丁二烯／苯乙烯嵌段共聚物的研制：Ⅰ.共聚合 …

以比卤代烷烃取代型双锂齐聚物为引发剂、环已烷为溶剂,丁二烯（Ｂ）、苯乙烯（Ｓ）单体采用１次加入的方法,合成了对称型双端过渡 丁二烯／苯乙烯嵌段共聚物Ｓ－（Ｓ／Ｂ）－Ｂ－（Ｂ／Ｓ）－Ｓ,并对双锂体系本二烯、苯乙烯共聚合反应过程进行了研究,将丁二烯、苯乙类共聚合反应动力学数据进行了分段处理,求得不同引发温度、不同单体配比、不同极性添加剂用量「二乙二醇二甲醚（２Ｇ）／Ｌｉ」下丁二烯聚合段、苯乙烯聚合段假     

乙酸乙烯酯嵌段共聚物的合成研究

以ＡＩＢＮ为引发剂，用ＣＣｌ４调节乙酸乙烯酯聚合制备了带三氯甲基端基的ＰＶＡｃ大分子引发剂（ＰＶＡｃ－ＣＣｌ３）。以ＣｕＣｌ－ｂｐｙ为催化剂，用ＰＶＡｃ－ＣＣｌ３引发Ｓｔ，ＭＭＡ和ＢＭＡ等单体的ＡＴＲＰ聚合，得到了一系列相对分子质量可控、相对分子质量分布较窄的ＰＶＡｃ嵌段共聚物。     

阳离子P（BA—St—MBDM）共聚物乳液的合成及其抗静电性能

以丙烯酸丁酯（ＢＡ）、苯乙烯（Ｓｔ）和甲基丙烯酰氧乙基，二甲基，丁基溴化铵盐（简称ＭＢＤＭ、（ＣＨ２＝ＣＣＨ３－ＣＯＯＣＨ２Ｎ（ＣＨ３）２－ｎＣ４Ｈ９）＾＋Ｂｒ＾－）为共聚单体，Ｎ－甲基－Ｎ－十六烷基吗啉硫酸甲酯盐作乳化剂进行自由基型乳液聚合，研究了影响聚合速度、共聚物［η］和乳液稳定性的因素，合成了一系列稳定的阳离子共聚物乳液。所得乳液经稀释后对不同织物进行处理，处理后的织物具有良好的抗静电性和     

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.     

(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.     

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.     

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。     

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 ).