淀粉乙酸酯的阴离子接枝己内酯聚合研究

将淀粉在二甲基甲酰胺、吡啶存在下 ,以乙酸酐进行部分乙酰化 ,制备取代度为 0 7～ 1 9的淀粉乙酸酯 (St Ac) .以萘钠与淀粉乙酸酯中残余的羟基反应 ,将羟基转化为醇盐 (ONa) ,引发己内酯进行阴离子开环接枝聚合 ,合成了淀粉 聚己内酯接枝共聚物 (St g PCL) .采用凝胶渗透色谱法 (GPC)研究了接枝前后聚合物分子量的变化情况 ,并以接枝率、单体转化率对接枝反应进行了表征 .研究了接枝条件如温度、溶剂、引发剂和单体的用量对接枝率及单体转化率的影响 .研究发现随着反应温度升高 ,接枝率、单体转化率呈S曲线变化 ,单体浓度、引发剂浓度的增大有利于接枝反应的进行 .     

[Mn(H_2P_2O_7)_3]~(3-)引发淀粉与丙烯腈接枝聚合反应的动力学研究

以[Mn(H_2P_2O_7)_3]~(3-)为引发剂,研究了丙烯腈与玉米淀粉的接枝共聚反应。由实验结果求出了反应速率与引发剂浓度、单体浓度、淀粉浓度和反应温度的关系,推导并验证了接枝反应动力学模型,探讨了反应机理,求得了接枝反应活化能。     

三价锰离子引发烯类单体在聚乙烯醇上接枝聚合的研究

<正> 无论是淀粉;纤维素,还是聚乙烯醇(PVA)的接枝反应,Ce(Ⅳ)被认为是一个十分有效的引发剂,已有较详尽的研究。与Ce(Ⅳ)相类似,Mn(Ⅲ)也可以和一些高聚物组成氧化还原引发体系,由此产生自由基,引发烯类单体在高分子主干上进行接枝聚合。Ranby等人,以焦磷酸络合的三价锰离子引发烯类单体在纤维素和淀粉的接枝反应中,获得了高效的接枝产物。有用这种引发体系在淀粉上接枝丙烯腈获得吸水276     

焦磷酸络锰三价离子引发淀粉-丙烯酰胺的接枝共聚合

将带有极性基团的乙烯类单体通过化学接枝到淀粉或纤维素之类的天然多糖上,可作为絮凝剂、脱除剂和粘接剂^[1～3],近来已发展为高吸水性材料和石油分离剂^[4]。用Ce⁴⁺引发乙烯类单体接枝到淀粉和纤维素类已有报道^[5]。Rayonier用Mn³⁺的焦磷酸盐络合物引发接枝乙烯类单体至纤维素及其衍生物上^[6];Cenita等用Mn³⁺引发MMA、AN接枝淀粉^[7]。本文以焦磷酸络锰离子(Mn³⁺)作引发剂、丙烯酰胺(AM)为单体、淀粉为接枝基体进行接枝共聚,这一工作目前在国内外尚未见报道。     

烯类单体与可溶性淀粉的接技共聚

甲基丙烯酸与可溶性淀粉在硝酸铈氨(CAN)、高锰酸钾及Fenton’。试剂(Fe~(2+)—H_2O_2)引发下的接枝反应,经历了不同的反应历程。对可溶性淀粉而言,采用Fenotn‘s试剂为引发剂,水—丙酮混合液为介质,可以有效地控制反应,并获得高转化率和高接枝率的最佳效果。通过溶解度参数估算及拟均相反应设计,选择二甲基亚砜(DMSO)为中介溶剂,通过链转移引发完成了油溶性单体苯乙烯与可溶性淀粉间的有效接枝共聚,确定了转化率高、接枝率高、均聚物含量少的最佳反应条件,突破了多年来用相类似化学引发体系引发在苯乙烯与淀粉接枝时转化率低下及均聚物含量高的局限。在上述研究基础上,对反应介质与条件对油溶性烯类单体与可溶性淀粉接枝聚合之接枝参数的影响进行了探讨。     

氯化原位接枝反应制备羟基官能化CPE——结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.     

阳离子淀粉-壳聚糖-丙烯酰胺的接枝共聚研究

以硝酸铈铵为引发剂,合成阳离子淀粉(CS)-壳聚糖(CTS)-丙烯酰胺(AM)接枝共聚物,讨论了反应温度、引发剂浓度、单体用量、反应时间以及壳聚糖用量对接枝共聚反应的影响。结果表明:淀粉中葡萄糖环浓度(cAGU)为0.20 mol/L,mCTS/mCS=1/6,cAM=1.0mol/L,cCe4 =5 mmol/L,反应温度60℃,反应时间3 h时,转化率和接枝效率可分别达到88%和92%以上;转化率随mCTS/mCS增大而增大,接枝效率则随着CTS用量增大降低,CTS的存在使AM均聚的几率增大。     

淀粉-SMAS接枝共聚物的制备及其应用研究

以淀粉、甲基丙烯磺酸钠(SMAS)为主要原料,通过接枝共聚反应,合成了淀粉/甲基丙烯磺酸钠接枝共聚物(St-SMAS)。并进行了制备条件的优选实验,得出最佳条件为:m(淀粉):m(SMAS)=1:1,引发剂浓度为6.7 mmol/L,反应温度为50℃,反应时间为4 h,在上述工艺条件下,淀粉-SMAS接枝共聚物的接枝率为104.0%,接枝效率可达86.7%。红外光谱分析结果表明:St-SMAS接枝共聚物中除含有淀粉本身的特征基团外,还有磺酸基团,说明淀粉与甲基丙烯磺酸钠发生接枝反应。生活污泥脱水实验表明,St-SMAS脱水综合性能优于PAM。     

淀粉与丙烯酰胺的接枝共聚

本文以木薯淀粉为骨架,以丙烯酰胺为单体,进行淀粉—丙烯酰胺接枝共聚的研究。对接枝共聚过程中引发剂浓度、单体浓度、反应温度、反应时间、介质酸浓度及淀粉糊化温度等因素的影响进行了讨论,寻找接枝共聚的最佳反应条件。     

淀粉接枝丙烯酸/醋酸乙烯酯高吸水性树脂的制备

以过硫酸铵为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,淀粉与丙烯酸/醋酸乙烯酯混合单体通过接枝共聚,制备了吸水及耐盐性能均较好的淀粉接枝丙烯酸/醋酸乙烯酯高吸水性树脂(CGAV)。最佳工艺条件为:淀粉10.0 g,m(混合单体)∶m(淀粉)=4∶1,w(引发剂)=0.3%,w(交联剂)=0.05%,于45℃反应2h~3 h。在最佳工艺条件下制得的CGAV吸去离子水率760 g.g-1,吸0.9%NaC l水溶液率68 g.g-1。     

Measurement of thermophysical properties of ammonium salts in the solid and molten states

The thermal conductivity, specific heat capacity and thermal diffusivity of solid and molten ammonium thiocyanate, ammonium formate, ammonium acetate and ammonium nitrate were measured in the temperature range 80–190C, including the solid and liquid phases, by using the AC-heated strip (wire) technique. The results indicate that the thermal conductivities depend on the type of the ammonium salt. It was found that the mechanism of heat transfer is due to phonons in the region below the melting points of the salts, while above this region the main mechanism is due to conduction.     

Pseudohalogenverbindungen. Darstellung und Reaktionsverhalten von Alkyl- und Arylammoniumdicyanamiden, -tricyammethaniden und -dicyanmethanidoaceta-ten [RNH3]X (X  N(CN)2, C(CN)3, C(CN)2C(O)CH3)

Pseudohalogen Compounds. Synthesis and Reactivity of Alkyl- and Arylammonium Dicyanamides, Tricyanmethanides, and Dicyanmethanidoacetates [RNH₃]X (X ? N(CN)₂, C(CN)₃, C(CN)₂C(O)CH₃) The syntheses of alkyl- and arylammonium dicyanamides, tricyanmethanido, and dicyanmethanido-acetates are reported. At higher temperatures the synthesized dicyanamides and tricyanmethanides are reacting to the corresponding cyanoguanidine and to 1,1-diamino-2,2-dicyano-ethene derivatives, respectively. The new compounds are characterized on the basis of their i.r. spectra and elemental analyses.     

Effects of various atmospheres and some metal oxide additives on the thermal decomposition on ammonium chromate

The thermal decomposition of ammonium chromate (AC) in dynamic air, CO₂ and N₂ and in static atmospheres and in the presence of MoO₃, V₂O₅, Fe₂O₃, CuO, MnO₂ and Nd₂O₃ additives was studied by means of TG, DTA, IR spectroscopy and electrical conductivity measurements. It was found that AC decomposes in four stages, forming unstable intermediates which produce Cr₂O₃ as a final product. The presence of the different atmospheres and the oxide additives affected the decompositions of these intermediates and the oxidation state of the chromium ions. Finally, the mechanisms associated with the different decomposition stages are discussed.     

二甲基烯丙基苄基氯化铵的合成及表征

用氯化苄与二甲基烯丙基胺为原料合成了二甲基烯丙基苄基氯化铵,研究了光照、温度、原料配比、反应时间和溶剂等因素对反应产率的影响,确立了最佳反应条件,并对产物的结构进行了表征.     

磷酸铵与多聚磷酸铵插层可膨胀石墨的制备

Expandable graphite intercalated by ammonium phosphate (AP) or ammonium polyphosphate (APP) was prepared by direct intercalation and two-step method, respectively. The products from two-step method show higher expansion volume, more weight increase and more weight loss after expansion, suggesting that the two-step method is a favorable method for preparation of APP intercalated EG. XRD provides convincing evidence for successful formation of APP-EG by showing strong diffraction peak at much lower 2θ angle. Scanning electron microscopy (SEM) with energy dispersive X-ray Spectroscopy (EDS) gives more evidence for intercalation of APP in the graphite layers.     

Indirect Determination of CTMAB with Sodium Chloride and Ammonium Thiocyanate by Floatation and Separation of Zinc

Cetyl-trimethylammoniumbromide(CTMAB)isaveryusefulcationicsurfactant,sothestudyondeterminationofCTMABassumesgreatimportance.AsmallamountofCTMABisgenerallydeterminedbyspectrophotometrybasingCTMABcombineswithtriazidetoformcoloredbinaryion-associationcomplex1-3.However,thosemethodsofdeterminationofCTMABhavedisadvantagesofsmalllinearrange,needofspecialreagent,determinationinbaseenvironment,etc.Inthispaper,indirectdeterminationofCTMABwithNaClandNH4SCNbyfloatationandseparationofZn(II…     

An eco-friendly oxidative bromination of alkanones by an aqueous grinding technique

Abstract

α-Bromoalkanones have been synthesized by reacting alkanones with ammonium bromide and ammonium persulfate in high yields using an aqueous grinding technique.     

Thermal Analysis for Control of the Properties of Mineral Fertilizers

The development of equipment for thermal analysis has opened up new areas for applications in science, industrial practice and environment studies. On the basis of the literature and information from equipment producers, the directions for the use of thermal analysis in research and practice are classified. Special attention is paid to the possibilities of controlling environmental pollution, and the stability and other properties of intermediate and final industrial products. It is stressed that DSC and DTA systems can be successfully applied to determine enthalpy changes in raw materials and products as control tests for their application. The advantages of coupled thermal systems for complex studies and the control of raw materials, products and wastes are described. This revised version was published online in August 2006 with corrections to the Cover Date.     

Separation and determination of quaternary ammonium compounds by high-performance liquid chromatography with a hydrophilic polymer column and conductometric detection

An HPLC method has been developed for separation and determination of long alkyl chain quaternary ammonium compounds. A column packed with a hydrophilic polymer packing, Shodex Asahipak GF-310 HQ, and a water–acetonitrile mixture containing 4,4′-bipyridyl and hydrochloric acid were used to depress hydrophobic adsorption of the quaternary ammonium compounds and increase the sensitivity of the conductometric detection with a micromembrane suppressor. Dodecyltrimethylammonium, cetyltrimethylammonium, tetradecyldimethylbenzylammonium and stearyltrimethylammonium ions can be completely separated from one another and quantified at 0.1 nmol level.     

Determination of quaternary alkylammonium compounds by capillary zone electrophoresis and indirect UV detection as a real alternative to ion chromatography with suppressed conductivity detection

A capillary electrophoretic (CE) method for the determination of residual mid-chain alkyltrimethylammonium compounds in the pharmaceutical product Welchol™ (an alkylated, crosslinked polyallylamine) was developed, validated and compared with the existing ion chromatographic (IC) method with suppressed conductivity detection. Excellent reproducibilities of migration times (RSD<0.5% within a series of 55 sample injections) and relative peak areas (RSD<2%) make the method suitable for quality control as a real alternative to IC. Limits of quantification of 0.01% w/w of each impurity in the active substance were achieved. Buffer systems for indirect UV detection based on creatinine as visualization reagent with different inorganic and organic acids (phosphoric, sulfuric, formic, acetic, oxalic and citric acid) and their effect on selectivity to ten quaternary ammonium compounds were studied. Selectivity changes were observed for the di- and trivalent analytes depending on the buffer applied. Also, the influence of acetonitrile, methanol, 1,4-dioxane and tetrahydrofuran on selectivity was investigated. In addition, CE–MS experiments were carried out in order to identify several impurities in the product.