共查询到17条相似文献,搜索用时 62 毫秒
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木质素在橡胶中的应用研究进展 总被引:1,自引:0,他引:1
木质素是地球上最丰富的生物材料之一,其基本单元为9-碳苯酚丙烷(香豆醇、松柏醇和芥子醇),这些单元通过不同类型的键连接在一起形成一个多酚类芳香族聚合物。作为造纸工业的主要废弃物,木质素成本低廉,目前主要用作低附加值的燃料,其开发价值还没有得到充分利用。将木质素用于填充改性橡胶既经济又环保,其不仅有补强的效果,还有偶联、抗氧防老、阻燃的作用,可部分代替炭黑。本文将对木质素的改性、橡胶/木质素复合材料的制备方法及研究进展进行综述,并对橡胶/木质素复合材料研究的挑战和机遇进行了展望。 相似文献
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天然大分子木质素在超临界乙醇-甲酸介质中可以有效地降解为酚类化合物.超临界乙醇为木质素提供了理想的反应介质,甲酸热分解原位产生的氢作为木质素裂解自由基封端剂有效促进了降解向小分子转化;过渡金属盐可以催化降解反应.木质素超临界降解机理为自由基反应,在还原状态下氢可以对木质素自由基封端从而得到小分子化合物.木质素理想的超临... 相似文献
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木质素酶及其化学模拟的研究进展 总被引:20,自引:0,他引:20
木质素酶(包括木质素过氧化物酶和锰木质素过氧化物酶)及其模拟物对木质素的催化降解是绿色化学的一个重要研究课题。本文综述了近年来有关木质素酶的分子结构,活性中心结构、催化木质降解机理及模型物的研究进展。 相似文献
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碳中和发展理念的提出使得生物质基催化剂的关注度不断提高,将木质素作为过渡金属催化剂的载体来制备非均相催化剂应用于有机合成领域,可以极大地提高木质素的利用价值.木质素结构中广泛存在的含氧官能团为金属催化剂的负载提供了多种结合位点,通过物理吸附/沉积、离子交换以及与羟基官能团通过静电络合可以有效地捕获金属粒子.首先介绍了木质素的结构,然后介绍了制备非均相催化剂的方法,重点介绍了木质素及其衍生物负载金属催化剂催化点击反应、Glaser反应、Huisgen [3+2]环加成反应、Heck反应、Suzuki反应、Sonogashira反应、Stille偶联反应、迈克尔加成/脱水串联反应、亲电开环反应、Fridel-Crafts型反应及乙烯聚合反应等,并对存在的问题和发展趋势进行了展望. 相似文献
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Kurt Heymann Wolfgang Riedel Günter Woldt 《Angewandte Chemie (International ed. in English)》1970,9(6):425-433
Electroplated plastics combine many advantages of plastics and of metals; they have the low weight and ease of shaping of plastics, together with the luster, hardness, and electrical conductivity of metals. An important part of any process for the electroplating of plastics is a pretreatment to ensure good adhesion of the metal film. Etch activation in the straight-through method requires only six steps for pretreatment. 相似文献
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Helmut Dislich 《Angewandte Chemie (International ed. in English)》1979,18(1):49-59
The Principal material used in optics is glass. Plastics can only gain acceptance in optics if they have properties not encountered with glass or if a desired article can be produced more rationally from a plastic. An example of the first case is provided by UV light guides consisting of a quartz glass core surrounded by a plastic cladding; there is no glass with a sufficiently low refractive index. Examples of the second case are viewfinder optics for camerás and lenses for sunglasses and industrial safety spectacles. 相似文献
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利用磷酸化改性木质素/二氧化硅复合纳米颗粒(PAL/SiO2)作为壁材包埋活性组分异佛尔酮二异氰酸酯(IPDI)制备微胶囊(PAL/SiO2-IPDI). 通过加入少量反应活性更高的聚合多甲基多二异氰酸酯(PMDI), 与水反应形成聚脲, 以增加微胶囊的壁厚. 采用光学显微镜、 扫描电子显微镜(SEM)和激光粒度分析仪(DLS)研究了PAL/SiO2复合纳米粒子掺杂量, 水油比和剪切速率对微胶囊表面形貌、 粒径和壁厚的影响. 结果表明, 所制备的微胶囊呈现规整球形, 壁厚为2.36~3.50 μm, 平均粒径为40.3~201.5 μm. IPDI作为芯材包埋在微胶囊中, 芯材含量约为82.8%. 将制备的PAL/SiO2-IPDI微胶囊添加到环氧树脂中得到自愈合环氧树脂涂层. 其在高盐浓度溶液中的抗侵蚀测试结果显示, 添加质量分数4%的PAL/SiO2-IPDI微胶囊的环氧树脂涂层在划破后能够快速愈合, 显著降低基底的腐蚀电流和腐蚀速率. 纳米压痕实验表明, 环氧涂层的硬度为249.99 MPa, 而添加PAL/SiO2-IPDI微胶囊后硬度增加到302.98 MPa, 弹性模量也有提高. 相似文献
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Lignin is potentially a major renewable, nonfossil source of aromatic and cyclohexyl compounds. In this study, we have investigated the abrasive stripping voltammetry of lignin and four lignin model compounds in the room temperature ionic liquids (RTILs) [C4mim][NTf2], [N6,2,2,2][NTf2] and [C4mim][OTf] (where [C4mim]+=1‐butyl‐3‐methylimidazolium, [N6,2,2,2]+=n‐hexyltriethylammonium, [NTf2]?=bis(trifluoromethanesulfonyl)imide and [OTf]? =trifluoromethanesulfonate) on a gold macrodisk and in 0.1 M H2SO4 and 0.1 M NaOH on a boron‐doped diamond (BDD) macroelectrode, with the hope of using the voltammetry to fingerprint the functional groups within the lignin molecule. The use of RTILs on metal electrodes, or either acidic or basic media in combination with BDD electrodes allows solvent systems with wide electrochemical potential windows, useful for studying voltammetry which may be difficult to observe in systems where early breakdown of the solvent occurs. 相似文献
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Markéta Julinová Jan Kupec Jaromír Hoffmann Tomáš Vojtek Peter Bugaj 《Polymer Degradation and Stability》2010,95(2):225-1540
The objective of this work was to study the biodegradation of blow-moulded films of poly(vinyl alcohol) (PVA)/protein hydrolysate (PH) which contain biodegradation inductors of the starch (S) and lignin (LI) types. These increase the biodegradation rate of PVA while preserving or improving the technical and usage properties of blends. The aim of the work was to reach the maximum breakdown rate so that rapid disintegration of PVA could take place at a wastewater treatment plant. The biological material chosen was activated sludge from a municipal wastewater treatment plant. Preparation of the blends required that a plasticiser be used, in this case glycerol (G). This allowed for successful processing but prolonged the lag phase of PVA breakdown as well as reducing its final biodegradation percentage. The influence of G, in this respect, was not affected by incorporating PH. S and LI reduced the influence of the plasticiser but caused a breakdown rate comparable to PVA itself. Contrarily, after adapting biomass to PVA, applying G produced a PVA breakdown rate three times greater, albeit with a lag phase prolonged fivefold. However, due to the duration of breakdown (the period above the retention time of wastewater during activation), this effect was not positive. The addition of PH to the blends mentioned did not exhibit any clear favourable influence. Adding S resulted in a shorter lag phase, in addition to which the degradation rate increased by approximately 1.5 times. Combining LI and S distinctly accelerated the degradation of a blend, although a disadvantage of doing so is an incomplete breakdown of the substrate, which lowers the final biodegradation percentage. Therefore, an eventual compromise was arrived at, this being a blend of PVA/G PH S. Its breakdown time is half that of pure PVA, and the films produced, from a mechanical standpoint, are more convenient. 相似文献
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建立了使用高效液相色谱法检测塑料食品接触材料中双氰胺的分析方法.采用4%乙酸提取样品、色谱柱分离、紫外检测器检测、外标法定量测定双氰胺残留.双氰胺在质量浓度为0.1 ~5.0 mg/L范围内线性良好,相关系数为0.9996.双氰胺的最低仪器检出限为5μg/L,方法的定量下限为0.40mg/kg,样品加标的回收率在94.4% ~ 98.0%之间,相对标准偏差小于1.0%.该方法具有样品处理简单方便、灵敏度高、分析时间短等优点,可以满足塑料食品接触材料中双氰胺残留的测定,并为进出口塑料餐具中双氰胺残留量的检验提供依据. 相似文献