利用超临界CO2流体脱硫再生废丁基橡胶的研究

一方面，我国是橡胶第一消耗大国，2010年我国生胶耗量超过600万吨，橡胶原材料的GDP约为1000亿人民币，橡胶制品加工业的GDP则接近4000亿人民币。尽管如此，我国橡胶进口量很大，     

超临界二氧化碳中再生硫化天然橡胶的影响因素及脱硫效果

以二苯基二硫化物(DD)为脱硫剂,在超临界CO2作用下对硫化天然橡胶(NR)进行了脱硫再生,考察了CO2密度、反应温度和压力以及反应时间等对脱硫作用的影响,并对脱硫降解产物进行了相对分子质量测定和核磁共振表征。结果表明,采用超临界CO2流体为溶剂可以实现对硫化NR的脱硫降解,脱硫降解条件为CO2的密度不小于0.4722g/cm3、反应温度不低于160℃、反应时间不少于90min;溶胶率随降解温度的提高和时间的延长而增大;在降解过程中除了S—S、S—C断裂外还发生了部分主链断裂,降解后橡胶相对分子质量下降;脱硫剂DD能有效打开硫交联键,脱硫降解后再生胶分子中引入了少量的苯环结构。     

两种超临界流体中废旧轮胎橡胶脱硫研究

本文采用超临界二氧化碳和超临界乙醇作为废旧轮胎胎侧胶脱硫的反应溶剂,对比分析了反应温度对两种脱硫过程的影响,并且通过表观反应动力学研究了两个反应过程的差异。结果表明,超临界二氧化碳脱硫过程中,凝胶交联密度会随反应温度的升高逐渐增大,而超临界乙醇中脱硫凝胶交联密度更低。超临界二氧化碳脱硫过程有效反应温度更低,具有更小的反应活化能;超临界乙醇脱硫溶胶分子量更大,凝胶交联密度更小。     

采用转矩流变仪脱硫再生废旧丁基橡胶

采用转矩流变仪对废旧丁基橡胶(IIR)进行脱硫再生,考察脱硫温度以及助剂品种和用量对废旧IIR脱硫产物脱硫程度的影响。结果表明:在200~320℃范围内,温度越高,脱硫产物的脱硫程度越高;引发剂BPO,DCP和AIBN不能提高脱硫产物的脱硫程度;在200℃脱硫温度下,配方为废旧IIR 100,松香3,松焦油10,活化剂4200.8时,脱硫产物的脱硫程度较高。     

废旧丁基橡胶的辐射再生

介绍在高能放射线的辐照下,使废旧丁基橡胶内部结构发生链解聚作用,从而达到再生的机理、工艺过程以及得到再生胶的性能。并建议加速工业化。     

硫化丁基橡胶多段脱硫再生复原新法

技术领域 本文阐述了一种新的硫化丁基橡胶多段脱硫再生复原的方法，依次包括一至七段脱硫，该技术已申请专利。本技术改变了传统脱硫技术中的一次高温脱硫，而采用七段脱硫，得到的丁基再生橡胶比传统工艺加工的丁基再生橡胶拉伸强度平均提高1．5MPa；拉断伸长率平均提高30～50％；门尼粘度值降低3～5。基本上可以达到或超过投料前的指标，是真正意义上的复原丁基橡胶，从而达到高质化橡胶循环利用的目的。     

硫黄硫化的异戊二烯橡胶在超临界二氧化碳中的脱硫作用

本文研究了一种新型的脱硫工艺，该工艺采用脱硫试剂在超临界二氧化碳中使橡胶脱硫。首先，通过控制硫化时间和硫化剂，制备具有不同交联状态的无填料聚异戊二烯橡胶试样(硫化制品)。每一种所用的硫化胶都采用丙酮和氯仿的共沸物通过索氏抽提法除去残余硫化刺。然后在超临界二氧化碳存在下在不同的温度下(140～200℃)脱硫60分钟。制品被分馏成溶胶和凝胶组分，并且测试了溶胶组分的分子量和凝胶组分的交联密度。实验显示，在所用的几种脱硫试剂中，硫醇胺的效果较好；其脱硫产生的溶胶组分的分子量大约为10000，而凝胶组分的交联密度则与初始值相比显著降低。随着二氧化碳压力的增大，溶胶组分的得率相应增大。在超临界液体二氧化碳中，硫化制品的脱硫效果比在常规的气体二氧化碳中更佳。获得溶胶的比率在相当大程度上依赖于硫化胶的交联状态。上述结果说明，在超临界二氧化碳存在的条件下，脱硫试剂穿透了硫化胶并在其内部得到了较好的分散。     

氯化丁基橡胶废胶再生方法

由株洲融城新材料应用技术研究所申请的专利(专利号CN 1385461A，公开日期2002—12—18)“氯化丁基橡胶(CIIR)废胶再生方法”，涉及一种橡胶再生处理工艺，即采用传统橡胶生产设备通过分类粗选粉碎、薄通初级再生软化、提炼脱硫再生软化、热炼滤胶和精炼5道工序完成CIIR废胶的再生。两级再生软化过程中分别采用五氯硫酚或二甲苯基硫酚(1～2份)、二乙基二硫代氨基甲酸(0．7～1份)、石油树脂(3份)以及过氧化二异丙苯(0．3～0．5份)、     

超临界二氧化碳流体及其主要应用

综述了超临界流体特性、超临界流体的应用及超临界萃取技术。介绍国内外研究的现状，简述超临界技术的发展方向。     

Complete devulcanization of sulfur‐cured butyl rubber by using supercritical carbon dioxide

Sulfur‐cured butyl rubber was devulcanized completely in supercritical CO₂ by using diphenyl disulfide (DD) as a devulcanizing reagent. The optimum devulcanizing conditions were studied and the sol fraction of the reclaimed rubber obtained was up to 98.5%. The possible devulcanizing mechanism was investigated. Then, the sol component of reclaimed rubber was characterized by gel permeation chromatography, ¹H‐NMR, and differential scanning calorimetry, and the reclaimed rubber was characterized by TGA. Because of the substitution of a large portion of allylic hydrogen by sulfurated functional groups during vulcanization, the signal of the olefinic proton shift. As a result of the numerous decreases in the active crosslinking sites and the remaining DD, reclaimed rubber could not be cured by sulfur. At last, the blends of virgin butyl rubber and different contents of reclaimed rubber were revulcanized and their mechanical properties investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

超临界CO2清洗技术

介绍了超临界CO2清洗的工艺及其应用,分析了超临界CO2清洗在技术、经济及环保方面的特点。     

超临界二氧化碳中丙烯酸乙酯/3-氯丙烯接枝天然橡胶的合成与表征

采用超临界二氧化碳溶胀聚合法,以丙烯酸乙酯（EA）/3-氯丙烯（AC）为单体对天然橡胶进行了接枝改性,合成了接枝共聚物NR-g-(EA/AC)。考察了压力和引发剂用量对接枝聚合反应的影响;对NR-g-( EA/AC)进行了红外光谱、力学性能、耐溶剂性、耐燃性、硬度的测试及接枝效率和接枝率的计算,并与溶液聚合法所得NR-g-( EA/AC)的性能进行了比较。结果发现,在接枝橡胶中成功的引入了—C=O和—Cl基团;接枝橡胶的弹性模量、拉伸强度、硬度、耐燃性和耐溶剂性较天然橡胶的有了显著提高。使用溶液法和超临界二氧化碳溶胀聚合法改性天然胶乳都获得了较高的转化率和接枝率,所得产品的机械力学性能相近,但溶液法所得产品的耐溶剂性能优于后一种方法。由于超临界二氧化碳的绿色溶剂性质,超临界二氧化碳溶胀聚合法有望取代溶液聚合法而发展成一种绿色的接枝改性天然橡胶方法。     

超临界二氧化碳对硅橡胶硫化动力学的影响

采用差示扫描量热法考察了超临界二氧化碳（scCO2）的饱和时间、饱和温度（Ts）、饱和压力（Ps）和过氧化二异丙苯（DCP）用量对甲基乙烯基硅橡胶（MVQ）非等温硫化动力学的影响,并根据Kissinger法计算得到MVQ的硫化表观活化能（Ea）,通过Málek法和?eatak-Berggren自催化模型确定了可用于描述MVQ硫化动力学行为的参数。结果表明,随着DCP用量增加,Ea增大。MVQ在scCO2中饱和12 h后Ea减少至117.0 kJ/mol。当Ts为70 ℃,Ps为20 MPa时Ea分别降至110.6 kJ/mol和109.4 kJ/mol。scCO2饱和前后MVQ的硫化反应级数均约为1,硫化过程均表现出自催化反应的特征。     

Role of supercritical carbon dioxide for selective impregnation of decrosslinking reagent into isoprene rubber vulcanizate

The behavior of supercritical CO₂ (scCO₂)/low molar mass molecule/crosslinked rubber ternary system was investigated in relation to the impregnation of reagent into the isoprene rubber (IR) vulcanizates, which was the first step of new decrosslinking reaction. The diffusion coefficient of decrosslinking reagent, diphenyl disulfide (DD), into the IR network in scCO₂ was 3.2×10⁻¹¹ m²/s. The distribution coefficient (K_c) of DD between the solvent and IR matrix was also determined for scCO₂ and toluene. The K_c for scCO₂ was higher about four orders of magnitude than that for toluene. DD was uniformly dispersed in the crosslinked IR matrix under 10 MPa at 313 K in scCO₂. These phenomena are advantages of use of scCO₂ for the effective decrosslinking reaction of IR vulcanizate.     

Acylation of glucose catalysed by lipases in supercritical carbon dioxide

The acylation of glucose with lauric acid in a reaction catalysed by two Candida lipases and a Mucor miehei lipase in supercritical carbon dioxide (SCCO₂) was investigated. A linear dependence of the reaction rate on enzyme concentration was observed. Studies on the effect of temperature on enzyme activity showed that Candida antarctica lipase remains stable at temperatures as high as 70°C. Non-immobilised Candida rugosa lipase was found to have a temperature optimum at 60°C. The acylation reaction rate depended on the initial water activity of both substrates and enzyme; the optimum was 0·75 for Candida antarctica lipase, 0·53 for Candida rugosa lipase, and between 0·3 and 0·5 for Mucor miehei lipase. Candida rugosa lipase was most active at a molar ratio of sugar: acyl donor of 1: 3, while the optimum ratio was found to increase to 1: 6 when the reaction was catalysed by Candida antarctica and Mucor miehei lipases. © 1998 SCI     

超临界二氧化碳技术的应用进展

超临界流体(SCF)因其具有很多优异特性而广泛应用于各个领域。主要介绍了超临界二氧化碳流体技术在萃取、制备超细颗粒材料、化学反应、酶催化、高分子科学、化学分析以及精密仪器清洗几个领域中的应用进展。     

Quality of wheat germ oil extracted by liquid and supercritical carbon dioxide

The extraction of wheat germ oil by liquid and supercritical CO₂ is described from the point of view of both operative method and pretreatment of raw material. The best conditions for wheat germ oil extraction are: pressure, 150 bar; temperature, 40°C; and solvent flow rate, 1.5 L/min at standard temperature and pressure. The yields and fatty acid compositions obtained are very similar to those resulting from the conventional extraction process using hexane as solvent (8.0 wt%), although a higher-quality oil is obtained by using CO₂ as solvent (free fatty acids, 12.4%; tocopherol content, 416.7 mg tocopherol/g wheat germ oil). These factors lead to the conclusion that the extraction process using CO₂ could be economically competitive with the conventional process, since it considerably simplifies the oil refinement stages and completely eliminates the solvent distillation stage, which are the most costly processing steps in terms of energy consumption.     

Impregnation of silk sericin into polyester fibers using supercritical carbon dioxide

Silk sericin was impregnated into polyester fabric using supercritical carbon dioxide (SCCO₂) to overcome polyester hydrophobicity. The effects of sericin molecular weight, pH of sericin, solution and cosolvent types on sericin impregnation were investigated. Enzyme‐hydrolyzed, acid‐, based‐hydrolyzed sericin in SCCO₂, and a 30 kDa sericin in SCCO₂ modified with cosolvents such as water, methanol, 1‐propanol, and acetone; and a modifier: sodium hydroxide solution were used in this work. Impregnation of sericin in polyester was indicated by Fourier transform infrared spectrophotometry (FTIR) and dyeing with acid dye. Degradation of polyester fibers during SCCO₂ process was indicated by scanning electron microscopy (SEM). Methylene blue dyeing was used to realize carboxyl group in polyester. The results showed no impregnation of sericin into polyester by using SCCO₂ modified with cosolvents. However, sericin was impregnated into modified surface polyester since hydrophilic groups such as carboxyl and hydroxyl groups were regenerated by alkaline hydrolysis. Samples impregnated with hydrolyzed sericin showed high color strength of Supranolechtbordeaux B acid dye. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars

This work evaluates the hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars in a single‐step process. The effects of temperature, pressure, despressurization rate, moisture content and reaction time on the amount of fermentable sugars released were assessed. Results obtained showed the feasibility of adopting the present procedure since it produced about 287 g of fermentable sugars per kg of dry bagasse, which corresponds to 60% yield on the basis of total cellulose. Such a result is very attractive from an industrial viewpoint because there is no use of toxic solvent, solvent removal is completed (no residues), and the method has very low water consumption since the process is a solid–gas reaction. © 2012 Society of Chemical Industry