PB-g-PMMA核壳粒子的合成及其在PVC中的分散

聚丁二烯(PB)橡胶粒子与聚氯乙烯(PVC)不相容。采用乳液聚合手段,在聚丁二烯乳胶粒表层接枝与聚氯乙烯相容的聚甲基丙烯酸甲酯(PMMA)充当增容剂制备了聚丁二烯接枝聚甲基丙烯酸甲酯(PB g PMMA ,MB)核壳粒子。用熔融共混法制备了PVC/MB共混物。SEM照片表明,这种核壳结构的粒子在聚氯乙烯中的分散情况随着核壳比的不同而改变,当核壳质量比小于93/7时能够完全均匀地分散在PVC基体中,核壳质量比大于94/6时根本不能分散在PVC基体中,核壳质量比为93/7是粒子能否分散开的转折点。共混物的力学性能数据表明,当MB加入量改变时,共混物也存在脆韧转变点,但受MB粒子的核壳比影响。

ABS树脂合成中影响PB-g-SAN接枝共聚物接枝率的因素

采用种子乳液聚合方式 ,以 K2 S2 O8为引发剂引发聚合 ,合成了一系列 PB- g- SAN接枝共聚物。考察了引发剂用量、分子量调节剂 (TDDM)用量和橡胶 (PB)含量对 PB- g- SAN接枝共聚物接枝率的影响。并将 K2 S2 O8引发剂与氧化 -还原引发体系做了比较。结果表明 ,随着引发剂 K2 S2 O8用量逐渐增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。引发剂用量太少时 ,不能满足聚合要求 ,PB- g- SAN接枝共聚物的接枝率也会降低。随着分子量调节剂 (TDDM)用量的增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。随胶含量的增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。采用氧化 -还原引发体系引发聚合有利于接枝反应的进行 ,在 PB含量相同时 ,采用氧化 -还原引发体系合成的 PB- g- SAN接枝共聚物的接枝率比采用 K2 S2 O8合成的接枝共聚物接枝率高。

Bonding and Mossbauer isomer shifts in (Tl, Pb)-1223 cuprate

By using the clinical bond theory of dielectric description, the chemical bond parameters of (Tl.Pb) - 1223 was calculated. The results show that the Sr-O, Tl-O, and Ca-O types of bond have higher ionic character and the Cu-O types of bond have more covalent, character. Mossbauer isomer shifts of Fe-57 and Sn-119 doped in (Tl, Pb) -1223 were calculated by using the chemical environmental factor, h, defined by covalency and electronic polarizability. Four valence state tin and three valence iron sites were identified ill Fe-57, and Sn-119 doped (Tl, Pb) -1223 superconductor. We conclude that all of' the Fe atoms substitute the Cu at square planar Cu (H site, whereas Sn prefers to Substitute the square pyramidal Cu (2) site.

溶胶-凝胶法制备纳米Pb(Zr_(0.52)Ti_(0.48))O_3

以醋酸铅 ,硝酸氧锆 ,钛酸四丁酯为原料用溶胶 -凝胶法制备了纳米 Pb( Zr0 .52 Ti0 .48) O3 ( PZT)。结果表明 ,随溶剂中乙二醇单甲醚与水的比例的增大 ,PZT粉体的晶化温度增高 ,晶粒的粒径尺寸也增大 ,当V( C3 H8O2 ) / V( H2 O) =4 .4 7时 ,不仅凝胶完成时间短 ,且可得到粒度分布集中、晶化温度低的 PZT粉体。用原子力显微镜测定 PZT的粒径为 6 0～ 70 nm,用 TG-DTA分析确定在 4 43℃即可发生晶化反应 ,在 5 0 0℃下结晶完善。通过对不同温度下热处理的粉体的红外光谱和 X射线衍射的分析 ,对溶胶 -凝胶法制备 PZT粉体形成钙钛矿结构的过程进行了研究。

盐酸介质中 P_(507) 萃取 Pb(Ⅱ)的平衡

通过实验，研究了２－乙基已基膦酸单（２－乙基已基）酯，在盐酸介质中萃取铅的规律和机理，为荧光级稀土生产提供了理论依据。

Preparation of Pb-Ca-Na master alloy using molten chloride salt electrolysis

An electrolysis technique for co-deposition of Ca2+ and Na+ at the liquid lead cathode was put forward. The experiment was carried out at an electrolysis temperature below 650 degrees C and had a current efficiency of 98%, which are respectively 100 similar to 300 degrees C lower and 15% similar to 30% higher than those reported both at home and abroad.

Comparative study on the doping effect of 3d elements in Bi(1.5)Pb(0.2)Sr(2)Ca(2)Cu(2.8)M(0.2)O(y) (M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni, or Zn)

With XRD, R-T, and ac chi measurements a comparative study on the doping effects of 3d elements in Bi(1.5)Pb(0.2)Sr(2)Ca(2)Cu(2.8)M(0.2)O(y) (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, or Zn) has been carried out. The effects of the former five members are significantly different, both on phase formed and on T-c, from the latter four. It seems that the effect on phase stabilization correlates with the valency of the doped cation. In connection with the instability of the 2223 phase, the correlation has been discussed.

高Jc Ag-Bi-Pb-Sr-Ca-Cu-O超导材料

Bi_2Sr_2Ca_2Cu_3O_y-Ag_x、Bi_(1.7)Pb_(0.3)Sr_2Ca_2Cu_3O_y-Ag_x和Bi_(1.7)Pb_(0.3)Sr_2Ca_2Cu_(3.2)O_y-Ag_x系列的超导材料是用固相反应的方法合成的。原料为分析纯AgNO_3、PbO、Bi_2O_3、CaCO_3、SrCO~3和CuO。把试剂按所需配比混和研磨后,在800℃烧12h,研磨压片,片子在850℃烧结200h,破碎、研磨后,按配比加入AgNO_3·800℃灼烧12h,再次研磨、压片,850℃再烧结200h,炉冷至室温。

一种新型的铅钙板栅合金——Pb-Ca-Sn-Al-Na

钠加到Pb—Ca—Sn—Al合金中,可以改善它的延伸率和浇铸性能。对于Pb—Ca—Sn—Al合金来说,钠是有效的变晶剂,它的最佳含量是0.01～0.077％。

HDPE-g-PB接枝共聚物的合成及其与聚丁二烯的共混

利用~(60)Co辐照合成了HDPE与丁二烯的接枝共聚物,PE-g-PB。动态力学试验表明,它与PB较PE与PB有更好的相容性。PB含量相同时PB/PE-g-PB共混物比PB/PE共混物有较高的抗张强度和断裂伸长率。前者中两相分布较均匀,相区尺寸较小。

组成和制备条件对Bi-Pb-Sr-Ca-Cu-O材料超导电性的影响

制备了一系列 Bi—Pb—Sr—Ca—Cu—O 超导材料。在一定范围内,不同组分的 Bi—Pb—Sr—Ca—Cu—O 样品都能得到接近单110K 相的材料,但样品性能差别极大.性能的好坏极大地依赖着组成条件。烧结温度过高或过低都不利于提高样品的临界电流密度,850℃的烧结温度是较合适的,长时间烧结有利于110K 相的形成。样品烧结完成后,应缓慢降温退火,以保证材料充分吸氧。

钼系1,2-PB结构与性能的研究

本文利用DSC,红外光谱,核磁共振等方法研究了四价钼体系聚合所得1,2-PB的结构与性能,讨论了1,2-PB的分予链结构对物理性能的影响,并将玻璃化温度与链结构参数间的关系式修订为:T_s=91v+220S~2—106,该式能够很好地描述钼系催化合成的高乙烯基聚丁二烯。