聚酯-酰胺的水解降解行为

研究了各种条件下聚酯-酰胺的水解降解行为及其与结构之间的关系。结果表明：酯键含量越高，质量损失就越快。聚合物的降解受酸、碱催化。根据SEM观察提出了可能发生的降解机理：表面腐蚀、非晶区腐蚀、晶区破坏到全部降解。     

气氛对尼龙1010热降解的影响

利用ＴＧ和ＤＴＡ研究了尼龙１０１０在Ｎ２气和空气流巾的降解过程和动力学，考察了反应气氛对降解步骤．降解温度、降解率和动力学参数的影响，分析了两者降解机理的可能差别．发现空气中的热氧降解为多步反应，而Ｎ２气中的热降解为一步反应Ｚ降解温度和降解率，Ｎ２气中均高于空气中；表观反应级数Ｎ２气中为１．０，空气中为１．１级．     

微生物降解酚类污染物的研究进展

从降解酚类微生物筛选、影响酚类降解的因素、降解机制和降解动力学等方面综述了微生物降解酚类污染物的研究进展。微生物降解苯酚的代谢途径主要为厌氧途径和好氧途径。好氧条件下,苯酚首先被氧化成邻苯二酚中间态,然后在邻位或者间位发生苯环裂解反应。厌氧条件下,苯酚首先被微生物羧基化,然后发生脱羟基还原反应和开环裂解。微生物降解苯酚的霍尔丹方程模型的参数是多变的,所以微生物降解苯酚的动力学方程没有固定常数。     

瓜尔胶及其衍生物的过硫酸铵氧化降解研究

通过考察90℃,0.5‰过硫酸铵对瓜尔胶、羟丙基瓜尔胶及其羧甲基羟丙基瓜尔胶不同时间的氧化降解反应,发现开始时瓜尔胶主链主要是以糖苷键断裂的降解为主,当降解到一定程度后,才出现糖链上糖环的氧化。瓜尔胶的结构对降解反应有着很大的影响,而且降解速度:羧甲基羟丙基瓜尔胶羟丙基瓜尔胶瓜尔胶。形态观测结果表明氧化降解对微观结构有一定的影响。     

H2O2在苯酚降解过程中的作用研究

H2O2浓度是影响苯酚降解程度的重要因素之一。实验表明，不同浓度的H2O2在苯酚降解过程中所起的主要作用也不相同。在环状有机物的降解过程中，苯酚往往作为副产物出现，因此，苯酚的降解程度也往往影响到这些环状有机物的降解程度。H2O2在光氧化、光催化氧化和光电催化氧化的条件下均能影响苯酚的降解程度。在后两种条件下，H2O2还影响到用作光催化剂的TiO2的活性。     

超临界水中聚乙烯油化的研究

采用125mL间歇式高压釜反应器，在超临界水条件下考察了反应温度、反应时间、水/聚乙烯比和水填充率对聚乙烯降解油化的影响。实验结果表明,聚乙烯在超临界水中迅速降解，油收率可达90%以上；随温度从450℃提高到480℃，油收率从91.4％下降到61.7％，气体收率从1.9％提高到27.7％；在450 ℃反应时间从1 min延长到30 min时，油收率略有下降，油品中C7-11组分所占比例增大一倍。水/聚乙烯比和水填充率的增加在一定程度上对聚乙烯的降解起抑制作用。     

海洋石油降解细菌对石油烃降解效果的气相色谱法分析

用毛细管气相色谱法分析评价海洋石油降解细菌对石油烃的降解效果,结果表明,毛细管气相色谱法能够测定出石油降解细菌对石油烃的降解进程和对正构烷烃的总降解率,以及温度对降解速率的影响。石油降解细菌对正构烷烃有明显的降解作用,混合菌株的降解率明显高于单菌株的降解率;在20℃的条件下,经过21 d后,绝大部分的正烷烃被降解,总的降解率为94.93%。     

纳米氧化锌光催化降解有机染料性能的研究

用自制的纳米ZnO在室外阴天、太阳光照射、室内紫外灯照射等条件下对不同有机染料的降解性能作了系统的研究。结果表明纳米ZnO在太阳光照射条件下对弱碱性有机染料溶液的降解效果较好。本文还比较了自制纳米ZnO与纳米TiO2对有机染料的降解性能，结果表明ZnO的降解效果优于TiO2。     

四甲基氢氧化铵降解苯酐固化双酚A型环氧树脂的研究

将四甲基氢氧化铵(TMAH)降解聚酯的方法移植用于降解苯酐(PA)固化双酚A型环氧树脂(DGEBA),降解生成的邻苯二甲酸二甲酯(DMP)可被气相色谱―质谱(GC-MS)快速检测到,同时通过内标法考察了TMAH用量对降解率的影响,结果表明TMAH降解苯酐固化环氧树脂效率较高,甲酯化率在95%以上。此项研究为剖析毫克级酸酐固化环氧树脂中的固化剂提供了一种快速且有效的方法。     

壳聚糖的酶法降解

用壳聚糖酶降解壳聚糖,探讨了壳聚糖降解过程中温度、pH值、底物浓度和金属离子对酶促反应的影响。结果表明:酶促反应进行到5 h左右时,即可得到聚合度小于10的壳寡糖。该酶促反应的最适温度为50℃,最适pH=5.5;最适底物浓度为0.02 g/mL;金属离子Ca2+和Mg2+对酶降解有一定的促进作用,而Zn2+、Cu2+对酶降解有较强的抑制作用。该酶促反应符合米氏动力学方程,米氏常数Km=7.80 g/L,最大反应速率Vmax=7.72 g/(min.L)。     

油田污水中聚丙烯酰胺(HPAM)的降解机理研究

随着聚合物驱油技术在我国油田的大面积推广,含聚丙烯酰胺污水的产量在逐年增加 .聚丙烯酰胺在为油田生产提高原油采收率的同时,也大幅度增加了混合液的粘度和乳化性 ,使油水分离难度加大,造成采出水含油量严重超标.含聚丙烯酰胺污水具有粘度高、油水分离难度大、可生化性差等特点,对环境的负面影响也越来越明显.因此,亟待解决的问题便是部分水解聚丙烯酰胺的降解.本文综述了聚丙烯酰胺化学、生物降解机理,总结了降解聚丙烯酰胺的典型的微生物种群,阐述了生物方法的优势,为油田含聚丙烯酰胺污水的处理研究提供参考.     

In vitro release of protein from poly(butylcyanoacrylate) nanocapsules with an aqueous core

Factors influencing the in vitro release of bovine serum albumin (BSA) from poly(butylcyanoacrylate) (PBCA) nanocapsules, such as the pH value, BSA loading, the polymeric nanocapsule walls and protein molecular weight, were investigated in detail. The BSA release rate was affected by the degradation rate of the polymeric wall and protein loading. For low molecular weight proteins, the initial burst release was faster than that of high molecular weigh proteins and got to equilibrium quickly. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis results showed that BSA encapsulated within PBCA nanocapsules did not suffer covalent aggregation or fragmentation during the initial days of in vitro incubation. For nanocapsules prepared by interfacial polymerization in water-in-oil microemulsions, these findings were useful as a foundation for the development of nanocapsules with desired properties.     

Effect of carbon dioxide on rheological properties and structure of polyacrylamide solutions

The effect of CO₂ on rheological properties and structure of polyacrylamide solutions was studied as a function of pressure, treating time, polymer type and presence of inorganic electrolytes and natural formation rocks. It was found that the serious deterioration of the solution viscosity can be attributed mostly to the change of the solution structure, while the actual molecular degradation plays negligible role in the process. The phenomena are explained by modification of the dissociation equilibrium of poly-electrolytes in presence of high hydrogen ion concentration. The experimental results may contribute significantly to elaboration of new stabilization concepts in special enhanced oil recovery technologies based on joint application of carbon dioxide and polymers.     

大孔聚丙烯酰胺树脂的Hofmann降解反应(Ⅱ)

在不同的条件下进行了大孔聚丙烯酸胺树脂的Hofmann降解反应,得到大孔聚乙烯胺树脂,并对产物作了对比及讨论.     

High photocatalytic degradation activity of polyethylene containing polyacrylamide grafted TiO2

A novel photocatalytic polyacrylamide grafted TiO₂ (PAM-g-TiO₂) nanocomposite was prepared and embedded into a low density polyethylene (LDPE) plastic. Photocatalytic degradation of the LDPE/PAM-g-TiO₂ composite film was carried out under ambient conditions under ultraviolet light irradiation. The properties of composite film were compared with those of the pure LDPE film by measuring the changes in weight loss, carbonyl index, molecular weight, tensile strength and elongation at break. PAM-g-TiO₂ embedded LDPE showed highly enhanced photocatalytic degradation. Irradiating the LDPE/PAM-g-TiO₂ composite film for 520 h under UV light reduced its weight by 39.85% and average molecular weight (M_w) by 94.60%, while that of pure LDPE film was only 1.03% and 69.59%, respectively. The addition of PAM-g-TiO₂ brought about the good dispersion of TiO₂ in LDPE matrix and improved the hydrophilicity of composite film, which were able to facilitate the degradation of LDPE. The photocatalytic degradation mechanism of the films is briefly discussed.     

Stability assessment of FDA-approved ramucirumab monoclonal antibody; validated SE-HPLC method for degradation pattern evaluation

Ramucirumab (RAMU) is a recently US Food and Drug Administration-approved monoclonal antibody that is included in various anticancer protocols. It has a structural complexity and high degradation risk that have a significant effect on its safety and effectiveness. The major aim of this work was to assess the degradation pattern of RAMU based on physicochemical characterization. Mechanical agitation, repeated freeze–thaw cycles, pH and temperature were the selected stress conditions to which RAMU samples were subjected. The SE-HPLC method was applied and validated to monitor the RAMU monomer along with its aggregates and/or fragments. The purity of the separated peaks together with system suitability parameters were determined through the calculation of percentage purity and percentage drop in RAMU concentration. The results were interpreted by correlating them with those of dynamic light scattering and reducing and non-reducing sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Samples incubated at pH 2.0–10.0 and 37°C for up to 4 weeks were analysed, recording detection of reversed phase (RP) aggregates and low molecular weight peptide fragments. Similarly, samples under short-term storage conditions of 4 weeks at different temperatures (−20, 2–8, 25, 37 and 50°C) showed low molecular weight peptide fragments but to a lesser extent. These results highlight the alarming effect on RAMU multidose vial efficacy and safety.     

金属阳离子对聚丙烯酰胺溶液黏度的影响及其降黏机理研究

聚丙烯酰胺(HPAM)是油田常用的驱油聚合物,用油田污水配制HPAM溶液易导致其黏度明显降低,影响驱油效果。依据埕东油田污水实测的各种金属阳离子含量来配制HPAM溶液,测得各金属阳离子对其黏度影响由大到小的顺序为:Na⁺>Fe²⁺>Ca²⁺>K⁺>Mg²⁺;通过红外光谱和扫描电镜分析金属阳离子导致HPAM溶液降黏的机理,Na⁺、K⁺、Ca²⁺、Mg²⁺主要是通过与HPAM链上的羧酸根阴离子静电引力相互作用,降低HPAM分子表面原有的电荷密度,造成分子链卷曲,同时减弱了极性基团的溶剂化能力,释放大量的"束缚水",从而使黏度显著降低;Fe²⁺离子主要是与水中溶解氧共同作用,引发自由基反应,导致HPAM骨架水解断裂,致使黏度显著降低。     

Degradation of Polyacrylamide and Its Derivatives in Aqueous Solutions

General features of degradation of polyacrylamide and its anionic and cationic derivatives under the action of radical degradative agents are considered. The molecular weight of these polymers can be controlled by varying the structure and concentration of the degradative agent and salt additions, the concentration, molecular weight, and composition of the initial (co)polymer, and the process temperature and time.     

高分子量聚L-乳酸热降解回收L-丙交酯*

本文综述了高分子量聚L-乳酸(Poly(L-lactide), PLLA)经热降解直接回收L-丙交酯的研究进展。纯PLLA的热降解为无规反应,经添加金属类催化剂后,PLLA则可获得以L-丙交酯为主的热降解产物。本文介绍了聚乳酸热降解的反应机理,详细阐述了添加的金属催化剂的种类,及其催化PLLA热降解生成L-丙交酯及发生消旋化作用的机理。经PLLA热降解直接回收L-丙交酯技术的研究,可缩短PLLA再循环使用周期,既降低生产成本,又充分利用资源,达到促进发展循环经济的目的。     

Synthesis and cleavage of core‐labile poly(alkyl methacrylate) star polymers

Core‐cleavable star polymers were synthesized by the coupling of living anionic poly(alkyl methacrylate) arms with either dicumyl alcohol dimethacrylate (DCDMA) or 2,5‐dimethyl‐2,5‐hexanediol dimethacrylate (DHDMA). This synthetic methodology led to the formation of star polymers that exhibited high molecular weights and relatively narrow molecular weight distributions. The labile tertiary alkyl esters in the DCDMA and DHDMA star polymer cores were readily hydrolyzed under acidic conditions. High‐molecular‐weight star polymer cleavage led to well‐defined arm polymers with lower molecular weights. Hydrolysis was confirmed via ¹H NMR spectroscopy and gel permeation chromatography. Thermogravimetric analysis (TGA) of the star polymers demonstrated that the DCDMA and DHDMA star polymer cores also thermally degraded in the absence of acid catalysts at 185 and 220 °C, respectively, and the core‐cleavage temperatures were independent of the arm polymer composition. The difference in the core‐degradation temperatures was attributed to the increased reactivity of the DCDMA‐derived cores. TGA/mass spectrometry detected the evolution of the diene byproduct of the core degradation and confirmed the proposed degradation mechanism. The DCDMA monomer exhibited a higher degradation rate than DHDMA under identical reaction conditions because of the additional resonance stabilization of the liberated byproduct, which made it a more responsive cleavable coupling monomer than DHDMA. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3083–3093, 2003