自由基引发马来酸二丁酯熔融接枝低密度聚乙烯的研究

用马来酸二丁酯(DBM)为接枝单体,过氧化二枯基(DCPO)为引发剂,对低密度聚乙烯(LDPE)进行了熔融接枝功能化。样品的红外光谱表明接枝反应确已发生。通过对样品中酯基的皂化水解测定产物的接枝率,对产物进行萃取,用凝胶量间接表征产物的交联程度;用溶液的特性粘度从侧面显示样品的支化或降解情况。实验结果表明,产物的接枝率和凝胶量可以通过选择反应条件(温度、时间及反应混合物的组成)来控制;过量的DCPO是引起交联产生凝胶的主要原因;向体系中添加DMF可阻止交联反应的发生,但产物的接枝率也有所下降,以自由基机理对上述结果进行了讨论。     

聚丙烯/POE共混组成对材料断裂行为的影响

采用基本断裂功(EWF)方法对聚丙烯(PP)/聚烯烃弹性体(POE)共混物的注射双边缺口拉伸试样的断裂行为进行了研究,比较了不同POE含量对共混物各断裂参数的影响.结果表明,PP和用量为5phr POE的共混物都可完全满足EWF方法的要求,共混物的断裂韧性-比基本断裂功we,较PP有显著提高;POE用量为10phr以上的共混物则出现明显的成颈现象而限制了EWF方法的应用;PP和各种POE用量的共混物都得到了其屈服所需要的比基本断裂功we,y和比塑性功β′wp,y.     

界面作用对HDPE/POEg/CaCO_3三元复合材料韧性的影响

通过界面改性,制备了以CaCO3为核,马来酸酐接枝乙烯-辛烯共聚物弹性体(POEg)为壳的高密度聚乙烯(HDPEg)/弹性体(POE)/CaCO3的三元复合材料.由于“核-壳”结构的形成,弹性体和CaCO3表现出协同的增韧作用.同未经表面处理的CaCO3复合材料相比,在相同的CaCO3含量的情况下,表面处理的CaCO3由于与弹性体形成更强的界面粘结,使得三元复合材料的“脆-韧”转变发生在较低的弹性体含量.     

Aqueous Knoevenagel Condensation Catalyzed by Aminopropyl-functionalized MCM-41

Since much more attention has been paid to the sustainable development, many researchers try to improve conventional chemical process and find new and more, environmentally friendly routes1. Aqueous-phase reactions are of interest as environ- mentally ben…     

石墨烯的制备、功能化及在化学中的应用

石墨烯是最近发现的一种具有二维平面结构的碳纳米材料, 它的特殊单原子层结构使其具有许多独特的物理化学性质. 有关石墨烯的基础和应用研究已成为当前的前沿和热点课题之一. 本文仅就目前石墨烯的制备方法、功能化方法以及在化学领域中的应用作一综述, 重点阐述石墨烯应用于化学修饰电极、化学电源、催化剂和药物载体以及气体传感器等方面的研究进展, 并对石墨烯在相关领域的应用前景作了展望.     

Design and Theoretical Study of Nickel Catalysts for Syndiotactic Polyolefins

A nickel catalyst was nodeled with ligand L^2,[NH=CH-CH=CH-0]^-,which should have potential use as a syndiotactic plyolefin catalyst,and the reaction mechanism was studied by theoretical calculations using the density functinal method at the B3LYP/LANL2MB level.The mechanism involves the formation of the intermediate [NiL^2Me]^ ,in which the metal occupies a T-shaped geometry.This intermediate has two possible structures with the methyl group trans either to the oxygen or to the nitrogen atom of L^2.The results show that both structures can lead to the desired product via similar reaction paths,A and B.Thus,the polymerization could be considered as taking place either with the alkyl group occupying the position trans to the Ni-0 or trans to the Ni-N bond in the catalyst.The polymerization process thus favors the catalysis of syndiotactic polyolefins.The syndiotactic synthesis effects could also be enhanced by varations in the ligand substituents.From energy considerations,we can conclude that it is more favorable for the methyl ttrans-O position to form a complex than to occupy the trans-N position.From bond length considerations,it is also more favoured for ethene to occupy the trans-O position than to occupy the trans-N position.     

用TREF方法分离聚烯烃共混物

用ＴＲＥＦ方法分离聚烯烃共混物徐君庭，封麟先，杨士林（浙江大学高分子科学与工程学系，杭州，３１００２７）关键词升温淋洗分级，聚烯烃，共混物升温淋洗分级（ＴＲＥＦ）方法是８０年代发展起来的，它按结晶度将聚合物分级［１］，目前主要用于聚烯烃的分级［２，３...     

Dicyano-Functionalized MCM-41-Supported Palladium Complex as An Efficient Catalyst for Allylation of Aldehydes and Ketones

Dicyano-functionalized MCM-41-supported palladium complex was prepared from dicyano-functionalized MCM-41 and palladium chloride. This complex exhibited high catalytic activity in the allylation of aldehydes and ketones with allylic chlorides in the presence of SnCl2. This polymeric palladium complex can be recovered and reused without noticeable loss of activity.