聚氨酯废弃物的化学降解机理

根据降解剂的种类 ,聚氨酯废弃物的化学回收方法可以分为醇解法、胺解法、醇胺法、磷酸酯法、水解法、碱解法、氨解法、热解法、氢解法等等。本文主要介绍了前四种方法的降解机理     

头孢氨苄降解产物荧光性质的研究及分析应用

详细研究了头孢氯苄在酸，碱介质中的降解反应，建立了酸，碱降解的荧光分析法，线性范围是０．５０－１００ｎｇ／ｍＬ（酸降解）和２．０－７０ｎｇ／ｍＬ（碱降解）。从精密度和准确度看，酸降解优于碱降解的荧光分析，将酸降解荧光分析应用于血清和尿样中头氨苄的测定，结果良好。     

Degradation of polypropylene impact-copolymer during processing

The effect of processing on molecular structure and properties of polypropylene impact-copolymer (ICPP) was investigated. It was confirmed that multiple extrusions induced changes in molecular weight resulting in increased MFI and decreased long-term thermooxidation stability. In terms of mechanical properties only impact strength well reflected the processing history. Tensile and flexural properties remained almost unchanged. The sizes of rubbery domains observed by SEM exhibited only minimum changes. The results of SSA and TREF techniques provided further data helping to elucidate the phenomena in rubbery phase. Based on indirect indications one could conclude that while typical polypropylene degradation resulting in chain backbone cleavage took place in the PP homopolymer phase, the rubbery phase containing EPR and PE homopolymer underwent a certain extent of crosslinking.     

Degradation of Acetophenone in Water by Pulsed Corona Discharges

Degradation of acetophenone in dilute aqueous solution has been studied using pulsed corona discharges in water. Higher conversions of acetophenone were obtained with the addition of oxygen or ozone than with the addition of nitrogen and without the addition of any gas. Intermediates of acetophenone degradation, as determined by gas chromatography–mass spectroscopies (GC–MS), were phenethyl alcohol, toluene, and 2-acetylphenol. In addition, the degradation reaction pathways of acetophenone in water are discussed.     

四元Mg0.9Ti0.1Ni0.9X0.1(X=Mn,Zn,Co,Fe)系列合金的制备及性能研究

用机械合金化法合成了Mg0.9Ti0.1Ni0.9X0.1(X=Mn,Zn,Co,Fe)系列合金.X射线衍射(XRD)结构分析表明,用X部分替代Ni后,促进了Mg0.9Ti0.1Ni合金的非晶化过程.用Co和Fe部分替代Ni提高了合金的放电容量,但却降低了合金的循环稳定性.用Zn和Mn部分替代Ni提高了合金电极的循环寿命,尤其是Mg0.9Ti0.1Ni0.9Zn0.1合金电极经10个充放电循环后,其放电容量仍可达到313.8mA.h/g.对添加Co后的合金进行p-c-T测试发现,Mg0.9Ti0.1Ni0.9Co0.1合金的吸放氢容量明显比Mg0.9Ti0.1Ni合金高,这与电化学所测到的结果一致.     

高分子共混物中Friedel-Crafts烷基化反应原位增容与催化降解机理

采用GPC方法对共混组分的分子量、接枝率和降解度等数据进行分析, 发现AlCl₃催化剂对PS/POE共混物的作用表现在原位增容和催化降解两个方面. 结合Friedel-Crafts烷基化反应的特点细化反应过程, 发现PS/POE共混物在AlCl₃作用下发生接枝反应时, 有大量碳正离子出现, 而碳正离子周围的电子重排会导致分子链断裂, 从而引起共混组分出现大幅度降解. PS/POE/AlCl₃共混物中原位接枝与催化降解是一对竞争性反应, 同时存在, 并相互竞争.     

Screening structure-property correlations and device performance of Ir(III) complexes in multi-layer PhOLEDs

The structure-property correlations of a set of heteroleptic red- and green-emitting Ir(III) complexes with different temperature sensitivities and charge trapping capabilities are described, revealing superb performance in multi-layer phosphorescent organic light-emitting diodes (PhOLEDs) expressed by very high maximum luminous efficiencies up to 36.8 cd A(-1). Using 2-phenylpyridine and with 2-(naphthalen-1-yl)pyridine as the C^N ligand, the resulting red emitting complex featured a maximum luminous efficiency of 10.8 cd A(-1); one of the most excellent device performances within this class of red Ir(III) emitters.     

头孢噻肟钠的降解及其产物伏安行为的研究

头孢噻肟钠在ＮａＯＨ溶液中降解后，于０．１ｍｏｌ／ＬＮａＯＨ中得一灵敏的吸附伏安原峰，Ｅｐ＝－０．７８Ｖ（νｓＡｇ／ＡｇＣｌ），ｉｐ与头孢噻肟钠浓度在１．０×１０＾－＾９－１．０×１０＾－＾８，１．０×１０＾－＾８－１．０×１０＾－＾７，１．０×１０＾－＾７－１．０×１０＾－＾６ｍｏｌ／Ｌ范围内呈线性关系，检出限为５．０×１０＾－＾１＾０ｍｏｌ／Ｌ。用多种电化学手段研究其降解产物的伏安行为，测定了     

The Degradation of Poly(ethylene terephthalate)

The penetration of new markets by polyester fibers has emphasized the need for increased stability of the polyester toward a variety of degradative reactions. Extensive studies of the nature of the thermal, hydrolytic, oxidative, and radiation-induced degradation reactions have been reported. The interpretation of kinetic investigations and the identification of the reaction products have been facilitated by using suitable esters as model compounds in place of the polymeric species.     

Degradation of chitosan with self-resonating cavitation

For the degradation of chitosan, a novel physical method of self-resonating cavitation with strong cavitation effects was investigated in this paper. The effects of initial concentration, pH, temperature, inlet pressure and cavitation time on the degradation efficiency of chitosan were evaluated. It was found that the degradation efficiency was positively correlated with temperature and cavitation time, but was negatively correlated with the solution concentration. The degradation efficiency was maximized at pH of 4.4 and inlet pressure of 0.4 MPa. Under the experimental conditions, the intrinsic viscosity of chitosan solution was reduced by 92.2%, which was twice as high as the degradation efficiency where a Venturi tube cavitator was used. The viscosity-average molecular weights of initial and degraded chitosan were 651 and 104 kD, respectively. The deacetylation degree of chitosan slightly decreased from 89.34% to 88.05%. Structures and polydispersity of initial and degraded chitosan were measured by Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance hydrogen spectroscopy (¹H NMR), X-ray diffraction (XRD) and gel permeation chromatography (GPC). The results showed that the degradation process did not change the natural structure of chitosan. XRD peaks of the original chitosan were observed at 2θ of 9.59° and 20.00°, and the one at 2θ of 20.00° was obviously weakened after the degradation process, which indicated that the crystallinity of chitosan decreased significantly after the degradation. The polydispersity index of chitosan samples decreased from 3.17 to 2.75, indicating that the molecular-weight distribution of products after the degradation was more concentrated. The results proved that self-resonating cavitation prompted the degradation of chitosan and could reduce the polydispersity of the products for the production of oligochitosan with homogeneous molecular weights.     

Forced Degradation of Flavonol Glycosides Extraced from Ginkgo biloba

The degradation of flavonol glycosides extracted from Ginkgo biloba was performed under different conditions and the degraded products were determined by reversed-phase high performance liquid chromatography (RP-HPLC) method. Four stress conditions including acid(0.1 mol/L HCl), base(0.1 mol/L NaOH), temperature (70 ℃) and oxidation(0.03% H₂O₂, volume fraction) were used for the forced degradation studies. The pH stabilities of the flavonol glycosides were determined in phosphate buffers of varying pH values from 4.5 to 7.4. The degradation rate constants and half-life of three Ginkgo flavonol aglycones(quercetin, kaempferol and isorhamnetin) which represent Ginkgo flavonol glycosides were calculated in forced degradation and pH-stability studies of them. The results indicate that the three substances were more stable when incubated under acid condition and showed pH-dependent stability. The degradation was observed to follow first-order kinetics in all degradation studies. The stability results could provide important bases on development, preparation and storage of products of Ginkgo biloba extract and should be significantly considered during the further formulation development.     

Degradation of polyhydroxyalkanoates in eutrophic reservoir

During the summers of 1999-2001 the dynamics of polyhydroxyalkanoate degradation in a small recreational eutrophic reservoir was studied experimentally. It has been shown that biodegradation of polyhydroxyalkanoates in the environment is determined by the structure and physicochemical properties of the polymer and by local weather conditions, which influence the state of the aquatic ecosystem. Species (clones) of bacteria able to utilize polyhydroxyalkanoates in the reservoir were identified using molecular phylogenetic analysis of 16S rRNA genes.     

Plasma Induced Degradation of Azobenzene in Water

The degradation of azobenzene (AO) by a gaseous plasma is reported. The plasma was generated in a localized zone between an electrolytic solution and a tip of an anode in contact with the surface of solution by means of contact glow discharge electrolysis. There is an optimum pH for the degradation of AO. Iron (II) had a remarkable catalytic action on it. Furthermore, the degradation followed the first‐order kinetic law. Some of the intermediate products of the degradation process were detected by HPLC.     

阿维菌素在柑桔和土壤中的消解动态研究

利用高效液相色谱法,建立了阿维菌素在柑桔和土壤中的残留分析方法.研究了阿维菌素在柑桔和土壤中的残留消解动态,对影响残留分析方法的主要参数进行了优化.柑桔和土壤样品分别用乙腈和二氯甲烷提取,弗罗里硅土柱净化,高效液相色谱仪可变波长紫外检测器检测,外标法定量.结果表明,该方法在柑桔和土壤中的最低检测浓度均为0.01 mg/...     

多金属氧酸盐光催化降解有机污染物研究进展

光催化作为一种高级氧化技术在有机污染物的降解方面得到广泛研究。本文概述了多金属氧酸盐光催化降解有机卤化物、染料、农药等有机污染物的研究进展,介绍了多金属氧酸盐与半导体氧化物、层状双氢氧化物、分子筛与介孔材料、离子交换树脂形成的复合材料,以及与半导体氧化物、聚乙烯醇等形成的复合膜材料的相关研究。     

聚合物太阳能电池的降解与稳定性研究

近几年,聚合物太阳能电池的光电转化效率进展迅速,由5%提升至目前的11%以上,应用前景及商业化生产备受关注,但其稳定性问题一直是一个重要的限制因素。无机太阳能电池,如硅电池使用寿命长达25年,而聚合物太阳能电池因其易受氧气、水甚至光的作用而发生降解,使用寿命仅几千小时,且由于其复杂的多层结构、各层不同的降解机制以及加工方法多样,所以仍无法弄清其降解机理。本文概述了对聚合物太阳能电池的稳定性和降解过程的认识,分析讨论了活性层材料的光稳定性、本体异质结器件的反型结构、相分离的影响以及卷对卷加工(R2R)方法所产生的特殊稳定性等问题。     

超声协同纳米TiO2光催化降解水中苯酚机理的研究

本文考察了声光催化技术降解水中苯酚的降解效率,测定了超声波联合光催化降解苯酚的主要中间产物,初步探讨了声光催化降解苯酚的反应机理。实验结果表明：超声波与光催化之间存在协同效应;光催化与声光催化降解苯酚的反应历程和产物基本一致。这两个反应的中间产物都是苯醌、邻苯二酚和对苯二酚;最终产物是水和二氧化碳。     

两类不同阳极电氧化过程中的失活现象及氧化机制

利用电化学测试技术分析了两类不同阳极在电氧化降解对氯苯酚过程中的失活现象及氧化机制. 结果表明, 对氯苯酚在“I”类阳极Pt和“II”类阳极含氟树酯(polytetrafluoroethylene, PTFE)的β-PbO2 (PTFE-β-PbO2)上可发生直接氧化反应, 且两者的电催化活性均会在短时间内失活. 高电位电解能使失活的PTFE-β-PbO2和Pt得到再生, 但Pt电极需要更高的电解电位. 常见有机溶剂(如丙酮、四氢呋喃、二甲基亚砜)的浸洗可以再生失活的Pt电极, 但不能再生PTFE-β-PbO2电极. 对于“I”类阳极Pt, 当阳极电位大于2.0 V时, 除对氯苯酚的直接氧化反应外, 晶格氧的氧化作用成为整个降解过程的主导因素; 而对“II”类阳极PTFE-β-PbO2, 当阳极电位大于1.8 V时, 除直接氧化反应外, 羟基自由基的降解反应成为对氯苯酚去除的主要原因.     

Degradation of polyamide 11 in rotational moulding

The degradation of polyamide 11 (PA 11) was studied in samples rotationally moulded using a range of processing temperatures. The chemical changes occurring in the moulded material were assessed using FTIR, UV-vis spectroscopy, ¹H NMR spectroscopy, gas chromatography, rheometry and microscopy. The results showed that the degradation is complex and depends on the location of the material in the moulding. At the internal surface, the degradation is predominantly thermo-oxidative leading to the formation of carbon dioxide, carboxylic acids and conjugated unsaturated oligo-enimines (UV-vis-active chromophores). Away from the internal surface, the dominant process is through the recombination of broken chains and/or post-condensation reactions that increase the molecular weight without the formation of UV-vis-active chromophores. A degradation mechanism is proposed for PA 11 in rotational moulding.