核磁共振氢谱法在聚羧酸减水剂大单体表征中的应用

对常见的4种聚氧乙烯醚大单体进行了核磁共振氢谱法(1HNMR)分析,并以此为依据建立了1HNMR技术快速、准确地检测大单体的方法,实现对聚羧酸减水剂中残留大单体的定性分析。采用该法,确认了各大单体1HNMR的谱峰归属,并根据大单体的特征峰计算其数均分子量大小。同时,利用1HNMR法对聚酯类减水剂的酯化反应中酯化率和双键保留率两个重要指标进行测定。结果表明,该法准确、快速、简便,适用于聚羧酸减水剂中大单体的快速鉴定。     

聚羧酸系减水剂大单体双键保留率碘值法的测定

研究了聚羧酸系减水剂大单体双键值的碘值法测定,论述了溶剂加入量、溴酸钾-溴化钾溶液加入量、静置时间等对测定结果的影响,不同的实验条件会产生不同的结果。通过实验确定了碘值法测定大单体双键值的最适宜操作条件,并对其准确度和精密度进行了测定。     

聚羧酸Y型大单体的合成研究

以甲基烯丙基聚氧乙烯醚(HPEG)和丙三酸(TA)为原料,经酯化反应制得Y型中间体(mY–PEG),以mY–PEG和甲氧基聚乙二醇(MPEG)为原料,经聚合反应制得Y型大单体(Y–PEG),并研究了O₂、阻聚剂和反应时间对Y–PEG双键的保留作用。结果显示：高温环境下,O₂氧化并破坏了Y–PEG的双键;阻聚剂的加入不能完全避免双键被破坏,只能达到一定的保留量;酯化反应中,双键主要在反应2h内被破坏。     

聚羧酸系减水剂大分子单体的无溶剂法制备

以聚乙二醇单甲醚1200(MPEG1200)与丙烯酸(AA)为原料,在无溶剂条件下进行酯化法,成功制备了丙烯酸聚乙二醇单甲醚1200酯(AA-MPEG1200)。经正交实验优选出最佳合成工艺条件如下:酸醇摩尔比为3∶1,催化剂对甲苯磺酸用量为MPEG1200和AA总质量的2%,阻聚剂对苯二酚用量为AA质量的2%,反应时间为7 h,反应温度为125℃。此条件下酯化率达99.72%。此外,对所合成的AA-MPEG1200大单体进行了红外表征。以该大单体合成的聚羧酸减水剂具有良好的分散性和保塑性。     

聚羧酸系减水剂大单体最佳酯化条件的确定

采用聚乙二醇单甲醚(MPEG)和甲基丙烯酸(MAA)为原料,对甲苯磺酸(PTSA)为催化剂,吩噻嗪(PTZ)为阻聚剂,在通氮气赶水的条件下通过酯化反应制备聚羧酸系减水剂大单体聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA).采用单因素试验方法,以酯化率为衡量指标,考察了酸醇物质的量比(n(MAA)∶n(MPEG))、催化剂用量、阻聚剂用量、酯化温度和酯化时间对酯化反应的影响,得出最佳酯化条件:n(MAA)∶n(MPEG)为2.5,催化剂用量为MAA和MPEG总质量的3％,阻聚剂用量为MAA质量的2.5％,酯化温度为120℃,酯化时间为6h,产物酯化率可达95.65％.采用正交试验对上述结论进行了验证,试验结果具有较好的一致性和可行性.大单体的红外分析结果进一步说明酯化效果较好,为目标产物.     

聚羧酸系减水剂中间大分子单体的合成

通过聚乙二醇单甲醚-1200(MPEG1200)与甲基丙烯酸直接酯化合成了甲基丙烯酸聚乙二醇单甲醚-1200酯(MAAPEGME1200)。经正交实验优选出最佳合成工艺条件如下:带水剂甲苯用量为反应物总质量的30%,酸醇摩尔比为3.0∶1,阻聚剂吩噻嗪用量为甲基丙烯酸质量的1.5%,催化剂对甲苯磺酸用量为聚乙二醇单甲醚-1200质量的2.5%,反应温度为125℃,反应时间为9 h。此条件下酯化率达96.72%,双键损失率为3.10%。     

聚羧酸酯类减水剂酯化率的研究

通过核磁共振方法研究了聚羧酸酯类减水剂的酯化工艺。讨论了酯化时间、酸醚比对酯化率的影响,确定最佳酯化工艺:酯化时间9 h、酸醚摩尔比2.5∶1。通过该方法能精确计算物料损失,提高原料利用率,为聚合工艺奠定基础。     

聚羧酸减水剂聚醚大单体的研究进展及展望

聚羧酸系减水剂是一种新型环保的减水剂,是国内外减水剂研究的热点。介绍了聚羧酸系减水剂大单体的种类及特点,围绕聚羧酸减水剂分子结构的可设计性,可通过引入功能化的聚醚单体,开发具有减缩性、低引气性和早强的功能化产品,以满足工程需求。     

国内聚羧酸聚醚大单体生产与市场现状

介绍了国内减水剂的行业发展现状,简述了聚羧酸聚醚大单体的生产工艺概况、产能分布以及市场情况。     

聚羧酸类减水剂中间大分子单体的合成工艺

通过丙烯酸和甲氧基聚乙二醇的酯化,生成了一种具有反应活性的聚羧酸类减水剂中间大分子单体——甲氧基聚乙二醇丙烯酸酯。探讨了各种实验条件对酯化反应的影响,得出了合成甲氧基聚乙二醇丙烯酸酯的最佳工艺条件。     

柴油结构特点的核磁共振波谱法研究

采用硅胶色谱和尿素络合法分离柴油，得到正构烷烃，异构烷烃，芳烃，胶质和沥青质。并利用１＾ＨＮＭＲ谱对其中正构烷烃和异构烷烃组分进行定性定量分析，计算出二者的支化度。结果表明，异构烷烃具有单个支链的结构特征。     

Nuclear Magnetic Resonance Spectroscopy: A Versatile Tool for Qualitative and Quantitative Analysis of an Emulsifier Mixture of Soybean Oil

Finding a fast, reliable, and reproducible approach for an accurate analysis of complex lipid mixtures of emulsifiers is crucial for the food and beverages, pharmaceuticals, personal care products, cosmetics, and agrochemicals industries. In the current study, a comprehensive qualitative and quantitative nuclear magnetic resonance (NMR) spectroscopy analysis of a high monoester mixture of soybean oil (HMMS) was conducted using ¹H, ¹³C, and ³¹P NMR of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane (CTDP) derivatives. The HMMS was produced by enzymatic alcoholysis of soybean oil and 1.2-propanediol in a supercritical CO₂ system. Compositional distribution analysis, quantified by aliphatic carbons with ¹³C NMR, showed that HMMS is composed of more unsaturated fatty acids, comprised of polyunsaturated fatty acids (PUFA) (60 ± 1.1%) and monounsaturated fatty acids (MUFA) (22 ± 0.8%), than saturated fatty acids (18 ± 0.9%). The ³¹P NMR quantification of HMMS demonstrated that, out of the total amount of monoacylglycerols (MAG), they are composed of 21 ± 2.9% of 2-MAG and 4 ± 0.3% of 1-MAG. Among the three techniques, ³¹P NMR spectroscopy proved to be a practical methodology with high reproducibility for the precise detection and quantification of partially esterified glycerols and free fatty acids in complex lipid mixtures.     

从核磁共振谱分析橡胶助剂对轮胎环保合规性的影响

在研究欧盟REACH法规附件XVⅡ和其指定的核磁共振检测技术的基础上,通过大量的检测实例,阐述除填充油以外的其他橡胶助剂对轮胎环保合规性的影响情况,为国内企业应对欧盟环保法规提供参考。     

Rapid and Simple Identification and Quantification of Components in Detergent Formulations by Nuclear Magnetic Resonance Spectroscopy

A rapid, inexpensive, and simple high-resolution NMR spectroscopic method is outlined for determining the content of surfactants and other low-molecular-weight organic compounds in detergent formulations. With simple sample preparation, quantitative results can be obtained from an internal standard and/or the method can be used as a fingerprint analysis of the surfactant composition. The NMR sample is prepared by suspending the detergent sample in deuterated acetic acid and thus dissolving surfactants and other organic compounds. Any content of carbonate will be liberated as CO₂, whereas other inorganic materials are removed by centrifugation. From one-dimensional ¹H and two-dimensional HSQC NMR spectra, the surfactant components and low-molecular-weight organic compounds can be identified from reference spectra. Intensities of signature signals in the one-dimensional ¹H NMR spectrum are used for quantification by comparing with an internal standard. Furthermore, it is demonstrated how ³¹P NMR can be used to identify and quantify phosphonate-type chelators.     

Multidimensional Proton Nuclear Magnetic Resonance Relaxation Morphological and Chemical Spectrum Graphics for Monitoring and Characterization of Polyunsaturated Fatty-Acid Oxidation

Polyunsaturated fatty acids (PUFA) are components of many commercial products such as edible oils, foods, cosmetics, medication, and in biological systems such as phospholipids of cellular membranes. Although PUFA aggregates are important functional components, they are also related to system degradation, because PUFA are susceptible to oxidation via their multiple double bonds and allylic carbons. Current technologies are not effective in characterizing the morphological and chemical structural domains of saturated, monounsaturated fatty acids (MUFA) and PUFA materials, or how the morphological structures of fatty acids, at the mesomolecular, nanomolecular, and molecular levels, affect their oxidation mechanisms. In this article, the ¹H low-field (LF) NMR energy relaxation time technology is proposed as a tool to analyze PUFA oils undergoing thermal oxidation. This technology generates two-dimensional (2D) chemical and morphological spectra using a primal-dual interior method for the convex objectives (PDCO) optimization solver for computational processing of the energy relaxation time signals T₁ (spin–lattice) and T₂ (spin–spin). The 2D graphical maps of T₁ vs. T₂ generated for butter, rapeseed oil, soybean oil, and linseed oil show that the different degrees of unsaturation of fatty-acid oils affect their chemical and morphological domains, which influences their oxidative propensity. The technology of the ¹H LF-NMR energy relaxation time proved to be an effective tool to characterize and monitor PUFA oxidation.     

Proton Nuclear Magnetic Resonance-Based Method for the Quantification of Epoxidized Methyl Oleate

Epoxidized methyl esters (EMO) with their high oxirane ring reactivity, acts as a raw material in the synthesis of various industrial chemicals including polymers, stabilizers, plasticizers, glycols, polyols, carbonyl compounds, biolubricants etc. EMO has been generally quantified by the gas chromatography (GC) and high-performance liquid chromatography (HPLC) techniques. Taking into the account of the limitations of these techniques, two qHNMR-based equations have been proposed for the quantification of EMO in the mixture of EMO and methylesters (MO). The validity of the proposed method was determined using standard mixtures of MO and EMO having different molar concentrations. The developed equations have been applied on the samples of EMO prepared from oleic acid in two-step process viz., esterification followed by epoxidation. The qHNMR-based EMO quantification showed acceptable agreement with the results obtained from HPLC analysis.