PBS基生物降解材料的研究进展

PBS(聚丁二酸丁二醇酯 )是一种具有良好生物降解性的聚酯塑料。本文简述了PBS的基本特性、降解机理和制备方法 ,对各种PBS基生物降解材料的特性进行了分析 ,介绍了PBS基生物降解材料的研究进展     

聚(丙烯酸钠-4-乙烯基吡啶)的生物降解性和功能性研究

用自由基共聚法制备了一系列可生物降解的功能聚合物聚(丙烯酸钠-4-乙烯基吡啶)[P(SA-co-4VP)],研究了其组成和分子量与生物降解性、资合性及分散性间的关系.结果表明:聚合物中小乙烯基吡啶含量越大,P(SA-co-4VP)的生物降解越显著.分子是一定时,少量的个乙烯基吡啶引入聚丙烯酸钠主链是增强聚合物生物降解性和保持原有功能特性的有效途径.     

生物降解高分子/笼型倍半硅氧烷纳米复合材料的制备、结晶行为与性能研究进展

由于相对较高的价格、较慢的结晶速率、较弱的力学性能、较差的热稳定性、较窄的加工窗口和较慢的生物降解速率等自身的弱点,生物降解高分子材料并未如通用高分子材料一样得到广泛应用,制备以生物降解高分子为基体的纳米复合材料是有效的改性方法之一。本文结合作者近年来在生物降解高分子改性领域中的工作,对以笼型倍半硅氧烷(POSS)作为纳米填料改性左旋聚乳酸(PLLA)和聚ε-己内酯(PCL)的研究进行简单综述,POSS可有效提高PLLA和PCL基体的结晶速率和力学性能,并促进了聚合物基体的水解过程。     

聚琥珀酸丁二酯的辐射交联和它的热变形行为

近年来 ,塑料废弃物污染环境的问题日趋严重 .对于环境的关心 ,已经使越来越多的科研人员对于研究环境友好化合物的发展产生了极大的兴趣 .发达国家先后制订了限制或禁止某些场合使用非降解性塑料 ,因此 ,多种可生物降解性塑料已经发展起来 .目前已经商业化的可生物降解性聚合物主要有脂肪族聚酯、聚醚、聚乙烯醇和聚多糖 .其中 ,利用化学合成法开发的可生物降解性聚合物是非常重要的 .脂肪族聚酯 ,例如聚乳酸(ＰＬＡ) .聚乙二酸 (ＰＧＡ)等被广泛地用于药物的载体[1] ,聚 (ε 己内酯 ) (ＰＣＬ)也已经被用作生产生物降解性薄膜 .脂肪族聚酯…     

生物降解脂肪族不饱和聚酯碳酸酯 2.生物降解

土埋法显示脂肪族不饱和聚酯碳酸酯(AUPEC)有良好的生物降解活性,单位面积失重(WPA)为其生物降解性能的较好指标,土埋三个月,AUPEC的WPA可达55mg·cm~(-2),失重达0.15质量分数,此外,实验表明生物降解主要在ALPEC的表面进行,聚合物的特性粘数、链结构、玻璃化转变温度及热分解温度不随聚合物的降解失重而变化。     

可生物降解抗污材料

研究和开发抗生物污染材料,降低蛋白质的非特异性吸附和微生物的附着生长,不仅可以大大提高仪器的灵敏度,降低植入材料在愈合过程中的副作用,如炎症和血栓等,还可以节省很多航海时所需的能源和动力。目前抗污染材料多为亲水性的聚乙烯醇、聚(N-乙烯基吡咯烷酮)、聚(2-口恶唑啉)、聚乙二醇和两性离子聚合物。虽然这些材料抗污染能力强,但是分子链大多为聚丙烯酸酯或聚丙烯酰胺,不具有可生物降解性。可生物降解抗污材料可通过将抗污功能分子引入到可生物降解的基质分子(如脂肪族聚酯、聚碳酸酯、聚多肽和多糖等)中得到。本文综述了可生物降解抗污材料的研究进展,首先介绍了生物污染的危害,抗生物污染材料的分类、特征和存在的问题。重点综述了可生物降解抗污材料的研究现状,从亲水性聚合物(如聚乙二醇、两性离子聚合物)和抗污剂具体阐述了可降解抗污材料的抗污机理、合成、结构和性能,并对可生物降解抗污材料的未来发展进行了展望。     

改性淀粉材料生物降解性分析体系的建立及应用

测定了热塑性淀粉(TPS)和热塑性双醛淀粉(TPDAS)在堆肥条件下的生物降解能力。根据ISO 14855建立了一套新的测试体系并且验证了这个体系测定高分子材料生物降解性能的可行性。对热塑性淀粉材料生物降解性的测试结果发现化学改性对于淀粉的降解速率和降解速度都有很大的影响。在可控堆肥条件下TPS比TPDAS降解的要快。TPDAS的降解速度和最终的生物降解百分率和双醛淀粉(DAS)的氧化度有密切的关系。文中讨论了存在这种关系的可能原因。有不同降解速率的TPS和TPDAS的降解过程呈现出三个阶段,即迟滞阶段。降解阶段和平稳阶段。     

准噶尔盆地陆梁油田部分原油生物降解程度与重排藿烷的相互关系

1原油的分类 原油生物降解现象在准噶尔盆地普遍存在,在陆梁油田部分原油中,还普遍存在新藿烷系列和重排藿烷系列.据最新研究成果表明,陆梁油田原油来自同一油源,我们本次研究准噶尔盆地陆梁油田部分原油以同一油源为前提.     

PLA,PPC和PHBV共混物的热性能、力学性能和生物降解性能研究

将聚乳酸(PLA)、聚碳酸酯(PPC)及β-羟基丁酸酯与β-羟基戊酸酯共聚物(PHBV)以溶液浇注法制备了各种不同比例的共混膜(60/20/20,40/20/40,40/40/20,20/60/20,20/40/40,20/20/60)。采用示差扫描量热分析(DSC)和热重分析(TG)研究了共混物的热性能,采用万能材料试验机研究了共混物的力学性能,通过土壤悬浊拟环境降解实验和扫描电子显微镜(SEM)研究了共混材料的环境生物降解性能。结果显示,该三元共混体系是部分相容的体系,PLA增加了材料的强度,PPC增加了材料的断裂伸长,PHBV则提高了材料的环境生物降解速率,三者优势互补,是一种有应用前景的生物降解共混体系。     

偶氮染料分子的电子结构与生物降解活性(Ⅰ)——电荷分布对偶氮键还原裂解的影响

用量子化学MNDO方法计算了不同结构类型的偶氮染料分子的电子结构.与厌氧活性污泥对偶氮双键生物降解实验结果对照分析后发现,分子电子结构中,电荷分布的对称性对偶氮键生物降解活性有重要影响.并通过LUMO_lp(具有反应部位氮原子孤电子对特征的最低空轨道)及分子偶极矩阐述了电子结构与生物降解活性的关系.     

Effect of temperature on friction and wear behaviors of polyimide (PI)‐based solid–liquid lubricating materials

The tribological properties of polyimide (PI) under four oils (including two perfluoropolyether oils and two silicon oils) lubricated conditions were comparatively investigated at room temperature in vacuum and Fomblin M30 and chlorine‐containing silicon oil were selected to study the friction and wear behaviors of PI‐based solid–liquid lubricants against steel at different temperatures in vacuum. Significant improvement in tribological performance of PI was found under oil‐lubricated conditions. The friction coefficient increased as the test temperature decreased for the mobility of liquid lubricant was limited at lower temperatures, while the wear rate exhibited distinct rule. Besides, no tribochemical reaction was detected at the contact surface of PI and chlorine‐containing silicon oil. However, the –CF₃ and fluorinated C? O groups were detected on the worn tracks of PI/Fomblin M30 by X‐ray photoelectron spectroscopy, which indicated that tribochemical reaction happened to PI and Fomblin M30 under high temperature as well as the simulation of friction heat. Copyright © 2015 John Wiley & Sons, Ltd.     

Über das Phasenverhalten ternärer Systeme des Typs H2O-Öl-Nichtionisches Tensid

This paper deals with the change of the phase diagram of ternary systems of the type H₂O-oil-nonionic surfactant with temperature, in particular, with the question regarding the reasons for the separation of such mixtures into three phases. It is shown that the phase behavior is mainly determined by the interplay between the lower miscibility gap between oil and surfactant with the upper miscibility gap between H₂O and surfactant. From systematic investigations with dodecane, octane, cyclohexane and toluene as oils with ?simple“ alkylpolyethyleneglycolethers C_iE_j as surfactants, ten qualitative rules are derived concerning the dependence of the position and the width of the three-phase temperature interval on the hydrophobicity of the oil and the amphiphilicity of the surfactant. The rules permit the choice of the appropriate surfactant for application in chemical engineering. Finally, the phase behavior with mixtures of oils and mixtures of surfactants, resp., is studied.     

Synthesis and tribological investigation of 4-vinyl guaiacol–based thioether derivatives as multifunctional additives and their interactions with the tribo surface using quantum chemical calculations

Novel 4-vinyl guaiacol based thioether derivatives were synthesized in a three-step reaction procedure by thiol-ene coupling as the key step. The synthesized compounds were characterised by spectroscopic techniques and evaluated for their tribological and antioxidant properties in two different base oils namely epoxy2-ethylhexyl esters of karanja fatty acids (EKE) and dioctyl sebacate (DOS). It was found that the synthesized products were exhibited superior antioxidant performance compared to butylated hydroxytoluene (BHT). All the three synthesized additives were improved the tribological properties of the base oil EKE and DOS. Dithio derivative at 0.75 wt% reduced the wear scar diameter by 36% and at 1 wt% improved the weld point by 33% of base oil EKE. Surface and elemental analysis result suggests that in the tribochemical process the synthesized thioether derivatives decompose and form an effective tribofilms on interacting surfaces. X-ray Photoelectron Spectroscopy (XPS) of the surface lubricated with base oil containing DMFD was evidence for the formation of tribofilm with FeS, FeSO₄ and Fe₂O₃. The antiwear behaviour of the additives was well correlated with quantum chemical calculations. Overall the dithio derivative is more effective as antiwear, extreme pressure and antioxidant bio lubricant additive than other thioether derivatives.     

Synthesis of ricinoleate anion based ionic liquids and their application as green lubricating oil additives

Ricinoleate anion based ionic liquids (ILs) were synthesized from four different nitrogen containing cationic counterparts such as tetrabutylammonium, tetrapropylammonium, cetyltrimethylammonium, imidazolium. Tribological performance of synthesized ILs were evaluated using four ball tribo tester by blending with two lubricant base oils namely epoxy2-ethylhexyl esters of karanja fatty acids (EKE) and dioctyl sebacate (DOS). Antiwear behaviour was explored by varying different factors including concentration, applied load and rotation speed. It was found that the synthesized ILs in base oil significantly reduced the wear scar diameter by 17–25% at 0.8 wt% and a remarkable reduction in wear scar diameter was observed for all the tested applied load (40 to 80 kg) and rotation speed (1200 to 1742 rpm). Further, the load carrying capacity of base oil was improved by 25–43% at 1.25 wt% of IL dosage. The imidazolium cation containing IL outperform tribological performance among all the ILs being studied. The morphology of worn surface after the wear tests and deposition of elementals on the worn surface lubricated with neat base oil and IL blended base oil was studied by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX).     

The hydrophobicity of silicone-based oils and surfactants and their use in reactive microemulsions

In this work, for the first time, the Hydrophilic-Lipophilic Difference (HLD) framework for microemulsion formulation has been applied to silicone oils and silicone alkyl polyether surfactants. Based on the HLD equations and recently introduced mixing rules, we have quantified the hydrophobicity of the oils according to the equivalent alkane carbon number (EACN). We have found that, in a reference system containing sodium dihexyl sulfosuccinate (SDHS) as the surfactant, 0.65 centistoke (cSt) and 3.0 cSt silicone oils behave like n-dodecane and n-pentadecane, respectively. Silicone alkyl polyether surfactants were found to have characteristic curvatures ranging 3.4-18.9, exceeding that of most non-ionic surfactants. The introduction of methacrylic acid (MAA) and hydroxyethyl methacrylate (HEMA) to the aqueous phase caused a significant negative shift in HLD, indicative of an aqueous phase that is less hydrophilic than pure water. The more hydrophobic surfactants (largest positive curvatures) were used in order to compensate for this effect. These findings have led to the formulation of bicontinuous microemulsions (μEs) containing silicone oil, silicone alkyl polyether and reactive monomers in aqueous solution. Ternary phase diagrams of these systems revealed the potential for silicone-containing polymer composites with bicontinuous morphologies. These findings have also helped to explain the phase behavior of formulations previously reported in literature, and could help in providing a systematic, consistent approach to future silicone oil based microemulsion formulation.     

Improvement of the resistance to oxidation of the ecological greases by the additives

This article presents the results of research aimed at improving the oxidation stability of the ecological greases addressed toward application in machines working in the food industry. In order to improve the functional properties of grease, additives that modify the thermal stability have been added. Then, the influence of the additive on the grease resistance to the oxidation was examined. The results of tests of lubricants containing different types of additives are presented. The thermal examinations of the greases were carried out with the use of scanning differential calorimetry techniques. The lubricated properties of greases were investigated with the use of a four-ball tribotester. Based on the results, the relationships between the kind of additive, the resistance to oxidation and the lubricated properties of the grease were analysed, and the relationships between thermal and antiwear properties of grease were identified. Based on the results of this research, a new formulation of grease was proposed, which meets both the ecological needs and the working conditions in the food industry.     

Modeling solubilization of oil mixtures in anionic microemulsions II. Mixtures of polar and non-polar oils

Polar/amphiphilic oils, called lipophilic linkers, are sometimes added to oil-water-ionic surfactant microemulsions in order to increase the solubilization of hydrophobic oils. The solubilization increase has been well documented for a number of systems. However, mathematical models to calculate the solubilization increase have been proposed only for optimum microemulsions (i.e., middle phase microemulsions solubilizing equal volumes of oil and water). In this paper we propose a model, which predicts solubilization enhancement for non-optimum microemulsion systems as well. The model is an extension of the net-average curvature model of microemulsion. The net-average curvature model is combined with a surface activity model to account for the increased palisade layer solubilization due to the presence of the polar/amphiphilic oil component. New non-linear mixing rules are also incorporated to account for the optimum salinity and the characteristic length variation of the anionic surfactant microemulsion as a function of the lipophilic linker concentration. The model predicts the effect of the lipophilic linker and the electrolyte concentration on the oil solubilization in accordance with the experimental results.     

GC-MS法鉴别食用油和餐饮业中废弃油脂的研究

用气相色谱 质谱联用(GC MS)方法对7种餐饮业中废弃油脂(简称废油脂)和5种合格成品食用油(简称食用油)中所有脂肪酸进行分析。研究发现,废油脂中部分不饱和脂肪酸受到氧化,使脂肪酸相对不饱和度(U R)值明显小于同种类食用油中的脂肪酸相对不饱和度(U R)值,其脂肪酸的质量分数分布与同种类的食用油中脂肪酸的质量分数分布有很大的区别,以及绝大部分废油脂中存在较大量矿物油。研究表明,脂肪酸相对不饱和度(U R)值和脂肪酸的质量分数分布可以鉴别废油脂。     

Analysis of essential oils from Voacanga africana seeds at different hydrodistillation extraction stages: chemical composition,antioxidant activity and antimicrobial activity

In this study, essential oils from Voacanga africana seeds at different extraction stages were investigated. In the chemical composition analysis, 27 compounds representing 86.69–95.03% of the total essential oils were identified and quantified. The main constituents in essential oils were terpenoids, alcohols and fatty acids accounting for 15.03–24.36%, 21.57–34.43% and 33.06–57.37%, respectively. Moreover, the analysis also revealed that essential oils from different extraction stages possessed different chemical compositions. In the antioxidant evaluation, all analysed oils showed similar antioxidant behaviours, and the concentrations of essential oils providing 50% inhibition of DPPH-scavenging activity (IC₅₀) were about 25 mg/mL. In the antimicrobial experiments, essential oils from different extraction stages exhibited different antimicrobial activities. The antimicrobial activity of oils was affected by extraction stages. By controlling extraction stages, it is promising to obtain essential oils with desired antimicrobial activities.     

A rapid screening technique for vegetable oil identity by sub-ambient DSC

Vegetable oils are widely used in the food industry. Labeling requirements have alerted the consuming public to the presence of vegetable oils and to the wide variety of oils used. Vegetable oils are selected commercially for their physical properties, price and availability, and many ingredient labels contain the ‘and/or’ clause reflecting the interchangeability of food grade vegetable oils.A ‘fingerprinting’ method has been developed utilizing the characteristic sub-ambient liquid—solid and solid—solid transitions of vegetable oils. The DSC was used in the temperature range 320 to 220 K. The cooling curves and their first derivatives were recorded for a pattern recognition library of pure vegetable oils, mixtures of oils, and oils present in standard cookie dough. This pattern library will serve as the basis for rapid verification of identity for vegetable oils, mixtures of oils and oils in commercially prepared food products.