聚乙二醇蓄热调温性能及其在功能纺织品上的应用

对聚乙二醇(PEG)的自身交联及其与纤维素纤雏之间的交联反应进行了研究，探讨了交联前后PEG热活性的变化，并对PEG在焙烘交联时的受热稳定性以及分子量对热活性的影响进行了讨论。研究表明，PEG发生交联反应后，热性能参教产生偏移，热活性降低；热活性与分子量有直接关系；过高的焙烘温度将导致PEG氧化降解，热活性下降。在适宜的工艺条件下，纺织品经PEG后整理可获得热活性。     

聚富马酸丁二酯的水热老化行为研究

研究了聚富马酸丁二酯(PBF)的水热老化行为,采用凝胶渗透色谱法(GPC)、力学性能测试,示差扫描量热法(DSC)和全反射红外光谱(ATR-FTIR)研究了老化过程中PBF的分子量、力学性能、热性能和表面化学基团含量的变化.研究结果表明,PBF在30℃下具有良好的耐老化性能.温度对PBF老化行为的影响显著,水热老化温度升至60℃,PBF各项力学性能急剧下降,老化20天后样品在水中断裂并形成碎片,力学性能完全丧失,同时数均分子量下降了50%.80℃水热老化5天,样品即断裂并形成碎片,失去结构的完整性,数均分子量下降了87%.老化过程中碳碳双键的含量未发生明显变化,老化降解的机理是水的增塑、溶胀以及酯键水解,聚合物分子链断裂,分子量下降.     

煤改性聚乙烯塑料的降解性能及其机理探讨

通过对力学性能、红外光谱、粘均分子量及扫描电镜的分析,研究了煤/聚乙烯塑料在室内加速老化实验中的降解性能,并运用降解机理对实验过程进行解析及验证。结果表明,煤降解剂引发的交联和降解反应控制了薄膜的强度,使其柔韧性一直降低,且在整个120h光照过程中,断裂伸长率一直呈下降趋势;72h前是聚合物的氧化诱导期及衰变期,之后进入完全降解期。煤在改性塑料光照过程中引发自由基反应,引入羰基,导致聚乙烯大分子断链降解;共聚物的粘均分子量整体呈降低趋势,说明光照促进聚合物的降解,降解和交联交替控制着反应。煤/聚乙烯的光降解过程遵循链引发、链增长、链终止反应机理,在煤大分子光催化作用下,改变了聚乙烯常规光降解过程,加速了聚乙烯大分子断链和分子量降低。运用煤/聚乙烯塑料降解机理,能够解释样品力学性能变化、化学结构中羰基指数变化、分子量降低及降解过程中的现象和规律。     

热稳定剂对PVC紫外光老化过程中微观结构及宏观性能演变的影响

通过UV-Vis、FTIR、DSC、以及色差、力学性能的测试表征,实时追踪分析了在紫外光老化过程中,含Pb、Sn以及Ca-Zn热稳定剂的PVC体系微观结构和宏观性能的演变过程.结果表明,在相同光老化条件下,PVC/Pb、PVC/Sn和PVC/Ca-Zn体系的微观结构变化规律基本一致,过程中主要的化学反应是,大分子吸收光能后,发生脱HCl生成共轭双键的反应、生成羰基的氧化反应、交联反应和降解反应;不同热稳定剂的作用,主要表现在对于微观结构变化的幅度和动力学过程的影响不同.相应地,3种体系的外观色差和力学性能的变化规律也相似,但色差的变化程度和速度以及老化后力学性能的保持率因所含热稳定剂的不同而不同,其中含Sn体系的颜色稳定性最好,含Pb体系的力学性能保持率最高。     

二维相关红外光谱法及标准线性固态模型对天然橡胶热氧老化机理的研究

对天然橡胶复合材料进行了不同时间下的热氧加速老化实验并分析其老化机理.采用红外测试研究天然橡胶在热氧老化过程中可能的基团变化规律,同时对不同老化时间下的红外结果进行二维相关分析,发现老化产物的生成速率依次为酯过氧化物醚;核磁交联密度测试表明总交联密度(XLD)与网链分子量(Mc)及横向弛豫时间(T2)有很好的对应关系,XLD随着老化时间的增加而增加,即天然橡胶热氧老化过程中交联反应占主导地位;示差扫描量热(DSC)测试发现,随着老化时间的增加,玻璃化转变温度(Tg)升高,玻璃化转变区变宽,表明交联反应占主导地位,与核磁交联密度测试结果一致.通过对天然橡胶进行压缩应力松弛实验,采用修正的标准线性固态模型(SLS模型)进行拟合分析,发现在短时热氧老化过程中,老化以氧化和交联反应为主,与核磁交联密度及DSC实验结果一致.     

聚对苯二甲酰对苯二胺纤维的热老化行为与机理研究

在250～400℃空气中对自由状态下对位芳纶进行等温热老化处理,采用万能材料试验机、红外光谱法、广角X射线衍射法、声速法和特性黏数法表征了老化过程中力学性能和结构的变化.结果表明,在老化初期,由于分子链的解取向,强度随时间快速下降;随后的热分解使强度随老化时间继续降低,符合二级反应动力学模型,其热老化表观活化能为32.4kJ/mol.老化样品的强度随温度升高显著下降,但高于350℃时热交联反应变得明显,同时结晶度增大和结晶结构完善,使强度的损失速率减小.老化样品的模量随老化温度的升高而增大,低于350℃时,非晶态分子链的解取向占优,模量较未热老化样品低;升高至350℃时,结晶结构完善占优,表现在第二类晶格畸变参数降低、表观微晶尺寸增大,特别是微晶横向融合使a,b轴方向尺寸显著增大,模量明显高于未老化样品.     

含羧酸稀土光敏剂降解PVC塑料的可降解研究

以羧酸共生稀土作为PVC塑料紫外光氧化降解的光敏剂,采用人工加速老化实验、户外曝晒实验等方法进行降解试验,并用红外光谱,紫外光谱和凝胶色谱等方法对含羧酸共生稀土光敏剂可降解PVC塑料的可降解性能进行了研究。初步探讨了羧酸共生稀土敏化PVC膜光氧化降解的作用机理。结果表明,羧酸共生稀土(如La、Ce、Pr等)对PVC分子的结构具有明显的光敏化降解作用,并具有抑制PVC在光照过程中发生交联的作用。     

含羟酸稀土光敏剂降解PVC塑料的可降解研究

以羧酸共生稀土作为PVC塑料紫外光氧化降解的光敏剂,采用人工加速老化实验、户外曝晒实验等方法进行降解试验,并用红外光谱,紫外光谱和凝胶色谱等方法对含羟酸共生稀土光敏剂可降解PVC塑料的可降解性能进行了研究。初步探讨了羧酸共生稀土敏化PVC膜光氧化降解的作用机理。结果表明,羟酸共生稀土（如La、Ce、Pr等）对PVC分子的结构具有明显的光敏化降解作用,并具有抑制PVC在光照过程中发生交联的作用。     

完全交替结构乙烯-丙烯共聚物的制备与表征

对顺-1,4含量为100%的高顺式聚异戊二烯(HCPI)进行加氢反应,得到了序列结构高度规整的乙烯-丙烯交替共聚物(alt-EP).所用的HCPI有适当的分子量(Mn=41×104)和极窄的分子量分布(Mw/Mn=1.02).HCPI的加氢反应以环烷酸镍和三异丁基铝为催化剂,在60℃和4.0MPa氢压的条件下反应3h,加氢产物的加氢度为100%.GPC测试结果显示所得乙烯-丙烯交替共聚物保持了窄分布的特点,表明HCPI加氢后未发生交联和降解反应;NMR,FTIR和广角X射线衍射测试结果表明此乙烯-丙烯交替共聚物具有高度规整的序列结构,为完全交替结构的乙烯-丙烯共聚物.并通过TGA和DSC对乙烯-丙烯交替共聚物的热性能进行了表征.     

基于TGA-FTIR联用技术研究ABS树脂的热氧降解行为

采用热失重-傅立叶变换红外光谱(TGA-FTIR)联用技术研究了空气气氛下ABS树脂的热稳定性及热氧降解失重情况。研究了ABS在4个不同升温速率下的失重情况;采用TGA-FTIR联用技术对10℃/min等速升温下ABS失重过程的逸出气体进行分析;采用热分解动力学方法分析ABS的热氧降解过程,计算热分解活化能。结果表明,ABS的TGA曲线有两个失重区间:第一区间是ABS的急剧氧化降解过程,活化能(Ea)为191.8~262.8 kJ.mol-1,第二区间是成炭产物的氧化,Ea约为139.7 kJ.mol-1;升温速率越小,ABS热氧降解速率越慢,交联成炭产物越多,有利于抑制ABS的降解;由FTIR测试和Ea变化发现,热氧降解反应为多步复杂反应,初期时氧化反应和氧化断链同时进行,并以氧化断链反应为主,随着分子链上产生的双键增多发生交联反应,失重率大于80%时开始炭化反应,最终交联炭层发生氧化反应生成CO2。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.