Ammonium polyphosphate-aluminum trihydroxide antagonism in fire retarded butadiene-styrene block copolymer

In this paper the effect of aluminum trihydroxide (Al(OH)₃—ATH) on the surface protection from fire for a styrene butadiene rubber (SBR) provided by ammonium polyphosphate ([NH₄PO₃]_n—APP) is studied.The combustion behaviour is studied by means of Cone Calorimetric tests: a maximum fire retardant effect is observed with 10-12 wt.% of APP. ATH, less effective as fire retardant, has been added at 60 wt.% to reach comparable results as measured by cone calorimetry for 12 wt.% APP.Replacement of ATH in the best performing SBR + 12 wt.% of APP shows an antagonistic effect with as little as 1 wt.% of ATH.The combustion behaviour is explained with the mechanism of interaction between SBR, APP and ATH, in which formation of aluminum phosphates negatively affects the surface protection provided by the ultraphosphate surface coating formed on heating APP in SBR.     

Preparation of styrene/acrylic acid copolymer microspheres: polymerization mechanism and carboxyl group distribution

 Poly(styrene-co-acrylic acid) (St/AA) copolymer microspheres were prepared by batch emulsifier-free emulsion copolymerization of St with AA. The monomer conversion, the morphology and the composition of the particles along the polymerization process were monitored by a gravimetric method, transmission electron microscopy observation and Fourier transform IR analysis, respectively. A shift of the polymerization locus from inside the particles to “outside” the particles in the postnucleation stage was proposed. The results of the study of the distribution of carboxyl groups by a combination of elemental and X-ray photoelectron spectroscopy analyses implied a core/shell structure for the St/AA copolymer microspheres. By chemical metal deposition, nickel particles were formed and deposited on the surface of St/AA microspheres, forming polymer/metal composite particles. Received: 16 February 2001 Accepted: 8 August 2001     

聚氨酯型互穿网络聚合物的研究

以甲苯二异氰酸酯和蓖麻油反应，合成了一系列室温固化的蓖麻油型聚氨酯。分别研究了蓖麻油聚氨酯（ＣＯＰＵ）／聚苯乙烯（ＰＳｔ）ＩＰＮｓ、ＣＯＰＵ／聚丙烯腈（ＰＡＮ）ＩＰＮｓ的结构和性能。结果表明：ＣＯＰＵ／ＰＡＮ的力学性能较ＣＯＰＵ／ＰＳｔ的力学性能为好。为进一步改善聚合物之间的相容性，在聚苯乙烯网络中引入极性较大的丙烯腈制备了ＣＯＰＵ／Ｐ（Ｓｔ－ＣＯ－ＡＮ）ＩＰＮｓ，并对它的力学性能、热分析、动态力学性能、热稳定性等作了系统的研究。结果表明：当聚氨酯浓度为６０％时，改变Ｓｔ、ＡＮ的比例，随ＡＮ含量的增加，体系的微相分离程度降低。改变ＣＯＰＵ／Ｐ（Ｓｔ－ＣＯ－ＡＮ）的比例，ｔａｎδ－Ｔ曲线上均呈现一个较宽的玻璃化转变温度；热重分析表明，其初始分解温度可达２４４℃。     

TiCl4处理分子筛催化氧化苯乙烯

通过气相ＴｉＣｌ４对多种分子筛进行处理，用Ｈ２Ｏ２对苯乙烯的氧化反应作探针反应，考察了所得分子筛的催化活性，发现用ＺＳＭ－５制备的催化剂的催化性能最好，得到苯乙烯的转化率可达～１２％生成苯乙醛和环氧苯乙烷的选择性可达～５５．９％，并用ＩＲ对用于ＴｉＣｌ４处理过的ＺＳＭ－５进行了表征，证实了钛原子进入ＺＳＭ－５沸石骨架，生成了钛硅分子筛。     

具有预期结构的苯乙烯与丙烯酸丁酯接枝共聚物的合成与表征

通过苯乙烯 (St)与 4 对氯甲基苯乙烯 (CMS)进行氮氧稳定自由基共聚合反应 ,合成了二元共聚物P(St co CMS) ,并以此共聚物引发丙烯酸丁酯进行原子转移自由基聚合 ,成功地合成了结构明晰的以聚苯乙烯为主链、聚丙烯酸丁酯为支链的接枝共聚物 ,研究了共聚合反应动力学 .P(St co CMS)和接枝共聚物的结构通过1 H NMR得到确认 ,并表征了接枝共聚物平均侧链数目和平均侧链长度     

聚四氟乙烯微粉辐照接枝苯乙烯的XPS研究

聚四氟乙烯微粉辐照接枝苯乙烯的ＸＰＳ研究许观藩，罗云霞，杨弘（中国科学院长春应用化学研究所，长春，１３００２２）关键词聚四氟乙烯，苯乙烯，表面接枝，ＸＰＳ用辐照方法在疏水性高聚物材料表面接枝聚合亲水性单体，可以达到改性的目的．文献中所用的高聚物材料包...     

Preparation and characterization of three-dimensionally ordered macroporous styrene/p-methylstyrene syndiotactic copolymer

Three-dimensionally ordered macroporous (3DOM) styrene/p-methylstyrene syndiotactic copolymer (sPMS) with pore size 170 nm were fabricated by means of silica templates using (dbm)₂ Ti(OPh)₂/MAO catalytic system. The resulting materials were characterized by NMR, SEM, GPC and DSC. The results indicated that the 3DOM sPMS were highly syndiotacic, and the pore contraction was approximately 20.6%. Compared with bulk sPMS, 3DOM sPMS possessed the lower number-average molecular weight and broader molecular weight distribution. In terms of DSC results, the bulk sPMS exhibited the lower glass transition temperature than that of 3DOM one.     

非均相Schiff碱铬(Ⅲ)配合物的合成及催化苯乙烯环氧化性能的研究

将丙氨酸水杨醛Schiff碱铬(III)配合物嫁接到了介孔分子筛MCM-41上,并利用FTIR、UV-Vis、XRD、N2吸附和元素分析对所制备的非均相配合物结构进行了表征.以30%的H2O2为氧化剂,考察其对苯乙烯环氧化反应的催化性能.结果表明,均相配合物非均相化后,其催化活性明显提高.在较优的反应条件下,苯乙烯转化率可达75.5%,此时苯基环氧乙烷的选择性为68.5%,且该非均相催化剂重复使用四次后仍保持较高的催化活性.     

球壳烯与侧链含有给电子基团聚合物在光诱导下的电荷转移现象

球壳烯与侧链含有给电子基团聚合物在光诱导下的电荷转移现象喻凤银，周锡煌，李福绵（北京大学化学系，北京，１００８７１）关键词球壳烯，Ｃ＿（６０），电荷转移现象，含二甲氨基苯基的苯乙烯共聚物球壳烯是近年来发现的除金刚石、石墨以外碳的第三种同素异构体［１］...     

环状三过氧烷引发剂热分解和引发苯乙烯聚合

用气相色谱质谱联用仪 (GC MS) ,分析新型环状三过氧基团引发剂 (3,6 ,9 triethyl 3,6 ,9 trimethyl 1,4 ,7 triperoxonane ,简称TETMTPA)在乙苯和苯中的分解产物 .根据产物的分子结构 ,提出了涉及氧氧、碳碳和碳氧断键的分解机理 ;考察该引发剂引发苯乙烯本体聚合的速率和分子量 ,并与单过氧基团的过氧化二特丁基引发和热引发进行比较 ,发现用TETMTPA可以使分子量增加 ,对形成高分子量聚苯乙烯的原因作了解释 ;通过差示扫描量热仪 (DSC)和核磁共振仪 (NMR)聚合产物进行分析 ,验证了所提出的TETMTPA引发机理