Heavy metal adsorption ability of a new composite material based on starch strengthened with chemically modified cellulose

Adsorption of heavy metals (Pb, Zn, and Cu) on a new bioadsorbent based on starch reinforced with modified cellulose with toluene‐diisocyanate has been studied using batch‐adsorption technology. The study was carried out in order to find if this bio material, designed for seedling pots manufacture, is able to act like a barrier between soil pollutants and plants. The influence of contact time, pH, adsorbent dose, and salt concentrations was also evaluated. The obtained data were examined using the Langmuir and Freundlich adsorption models. Optimal results were obtained at pH 5.0, temperature of 25°C, contact time of 120 minutes, and an adsorbent dose of 4 mg/mL. Experimental data along with computed Langmuir parameters show that the adsorption process is favorable, and the maximum adsorption capacity of the adsorbent for lead, zinc, and copper was 66.66, 58.82, and 47.61 mg/g, respectively.     

Synthesis and antitussive activity of obtucarbamate A derivatives

Abstract

Obtucarbamate A was purified from Disporum cantoniense with good antitussive property. In present work, a series of obtucarbamate A derivatives were designed and synthesized from obtucarbamate A by microwave method, and their antitussive activity were evaluated. The results showed that the toluene diisocyanate was obtained with a yield of 95.1% using a simple method, 1-methyl-2-pyrrolidinone as solvent, temperature of 190?°C, microwave irradiation at 60?W power for 30?min. All compounds have good antitussive activity, and small steric hindrance unsaturated groups of ester chains and amino groups favor activity. It is the first reported of obtucarbamate A derivatives used as antitussive, and the results provide a basis for the application of obtucarbamate derivatives as new antitussive.     

Synthesis and Properties of Imidazole-Blocked Toluene Diisocyanates

Abstract

Imidazole-, 2-methyl imidazole-, and benzimidazole-blocked toluene diisocyanates (TDI) were prepared and characterized by elemental analysis, IR, and NMR spectroscopy. Simultaneous TGA/DTA results showed that the thermal stability of the adduct decreases in the following order: imidazole-TDI > 2-methylimidazole-TDI > benzimidazole-TDI. Gelation test involving imidazole-blocked adducts and hydroxyl-terminated polybutadiene were also carried out. The cure rate of the adduct increases from the imidazole- to the 2-methylimidazole- and to the benzimidazole-blocked adduct. It is also found that the benzimidazole-blocked adduct shows better solubility in the polyols.     

Influence of Accelerated Weathering on the Properties of Polypropylene/Polylactic Acid/Eucalyptus Wood Composites

In the view of producing environmentally friendly materials without compromising properties, new composites containing polypropylene as a matrix and eucalyptus wood, with or without 15% of polylactic acid, were melt processed. In order to improve compatibility between components, a chemical modification of wood with toluene-2,4-diisocyanate (TDI) was realized and evidenced by changes in FT-IR and XPS spectra. The morphological, mechanical, and thermal characterizations of the obtained composites were evaluated before and after accelerating weathering. The results showed that the material comprising 15% TDI-modified wood, PP, and 15% PLA exhibited the best properties.     

Biodegradable aliphatic thermoplastic polyurethane based on poly(ε‐caprolactone) and L‐lysine diisocyanate

A biodegradable aliphatic thermoplastic polyurethane based on L ‐lysine diisocyanate and 1,4‐butanediol hard block segments, and 2000 g/mol poly(ε‐caprolactone) diol soft block segments was synthesized. The resulting polymer was a tough thermoplastic with ultimate tensile strength of 33 MPa and elongation of 1000%. The polymer displayed classic segmented thermoplastic elastomer morphology with distinct hard block and soft block phases. Thermal and dynamic mechanical analyses determined that the material has a useful service temperature range of around ?40 °C to +40 °C, making it an excellent candidate for low‐temperature elastomer and film applications, and potentially as a material for use in temporary orthopedic implant devices. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2990–3000, 2006     

异佛尔酮二异氰酸酯自聚产物的~(13)C-NMR研究

研究了用季铵盐N,N,N-三甲基-N-(2-羟基乙基)-氢氧化铵为催化剂时异佛尔酮二异氰酸酯(IPDI)自聚产物的合成,用13C-NMR1、H-NMR、不失真地极化转移增强(DEPT)1、3C-1H异核远程相关(HMBC)实验表征了产物结构.结果表明,自聚产物是三聚异氰酸酯,主要含有三聚体异氰脲基、异氰酸根.一维核磁谱及二维化学位移相关谱分辨出两种羰基,确定了氮上4种不同取代结构的分子链连接情况.对自聚产物的碳谱图进行了全归属.     

甲苯二异氰酸酯生成过程中间副产物结构的确定

在重要有机化工原料甲苯二异氰酸酯的生产过程中经常会产生一些非目标中间体,严重地影响反应进程,确定这些中间副产物的结构对以应机理、改进反应条件具有极其重要的意义,采用核磁共振一振及二维HM－BC技术确定了该反应中的副产物结构,特地用其它分析方法难以确定的其苯环取代的位置进行了准确定位。     

Study of the reaction between 1,5-naphtalene diisocyanate and polycaprolactone in different solvents

The reaction between polycaprolactone and 1,5-naphtalene diisocyanate has been investigated in solvents with different dielectric constants and hydrogen bonding powers (toluene, ethyl acetate, ethyl methyl ketone), and in the same solvents with the addition of a catalytic amount of dimethyl sulfoxide (DMSO). The reaction was considered to proceed over two steps, the reaction of the first NCO group being faster. The course of the reaction was measured by titration of the unreacted NCO groups, ¹H- and ¹³C-NMR spectroscopy, and size exclusion chromatography. By titration only the overall reaction order and reaction rate constants could be determined. DMSO accelerated the reaction in all three solvents, which was explained by the stabilization of the activation complex by DMSO. Both steps of the reaction could be specified by NMR spectroscopy. The ratio between the reaction rate constants for the first and the second step decreased with the increased hydrogen bonding strength of the solvent and with DMSO. By SEC only the reaction of the first NCO group could be determined due to the low resolution for higher molar mass reaction products with a broad distribution. The values obtained for the first step reaction rate constants were in good agreement with NMR values. © 1995 John Wiley & Sons, Inc.     

Studies on the effect of extraction of isophorone diisocyanate-based segmented polyurethanes

Linear segmented polyurethane was synthesised, using isophorone diisocyanate (IPDI), poly(tetramethylene oxide) glycol (PTMG) and 1,4 butanediol, for use in biomedical applications. The chemical stability of this polyurethane in hot methanol during Soxhlet extraction was studied by viscosity measurements, thermal studies, mechanical tests, ultraviolet and infrared spectral studies, and gel permeation chromatography. Hot methanol degrades the polymer at the allophanate linkages, while extracting low molecular weight polyurethane fractions. More urea linkages are formed in the extracted polymer.     

Kinetic Modeling from Early Product Development to Polymerization Process Optimization

Summary: This contribution illustrates how kinetic modeling supports early product development stages under industrial constraints also for smaller scale products. Diisocyanate oligomerization is selected as an example. Data for model parameterization and validation are acquired in kinetic experiments with on-line IR monitoring. Based on these measured data and a proposed reaction scheme for the cyclo-oligomerization of diisocyanates with equal reactivity of both isocyanate groups, two kinetic models differing in level of detail are developed. All experimental trends are described correctly with these kinetic models. A functional group based model is used for parameterization and prediction of conversion profiles. This model version is also applied for assessing working hypotheses on the details of the catalytic cycle and for developing strategies for catalyst and process optimization. A second model takes into account full molecular weight distribution and thus enables prediction of individual oligomer concentrations. Fast assessment of process alternatives is possible with both models.