Isothermal crystallization kinetics and melting behavior of nylon/saponite and nylon/montmorillonite nanocomposites

DSC thermal analysis and X‐ray diffraction have been used to investigate the isothermal crystallization behavior and crystalline structure of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ε‐caprolactam and then exfoliating the layered silicates by subsequent polymerization. The DSC isothermal results reveal that introducing saponite into the nylon structure causes strongly heterogeneous nucleation induced change of the crystal growth process from a two‐dimensional crystal growth to a three dimensional spherulitic growth. But the crystal growth mechanism of nylon/montmorillonite nanocomposites is a mixed two‐dimensional and three‐dimensional spherulitic growth. The activation energy drastically decreases with the presence of 2.5 wt % clay in nylon/clay nanocomposites and then slightly increases with increasing clay content. The result indicates that the addition of clay into nylon induces the heterogeneous nucleation (a lower ΔE) at lower clay content and then reduces the transportation ability of polymer chains during crystallization processes at higher clay content (a higher ΔE). The correlation among crystallization kinetics, melting behavior, and crystalline structure of nylon/clay nanocomposites is also discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2196–2204, 2004     

Preparation and performance of poly(lactic acid)/amidated ammonium citrate intercalated saponite nanocomposites

ABSTRACT

In this article, a novel method, amidation, was used to modify saponite. Amidated ammonium citrate intercalated saponite (Aa-saponite) was synthesized by amidation reaction. The structure of Aa-saponite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), demonstrating that the saponite was successfully amidated. Polylactic acid/amidated ammonium citrate intercalated saponite nanocomposites (PLA/Aa-saponite) were prepared by melt blending. Mechanical tests demonstrated that the addition of Aa-saponite (0.3 wt%) improved the impact strength of PLA. A series of performance analysis results showed that A-saponite improved the comprehensive performance of PLA, such as mechanical, thermal stability, crystallization and rheological properties.     

FCC催化剂新型载体的探索——皂石基复合材料

FCC催化剂的改性主要集中于载体和活性组分,本文旨在合成一种新型复合层柱载体即皂石与微孔分子筛复合结构以改善层柱粘土为载体时稳定性方面的问题。实验结果表明晶化温度为120℃时较适宜;随晶化时间的增长,复合材料的层间距逐渐增大;酸量的变化会影响进入层间的ZSM-5的结构单元的聚集。复合材料的热稳定性和水热稳定性都较皂石有所改善,在催化裂化领域具有较好的应用前景。     

合成皂石为前驱物制备高稳定性含镍介孔分子筛

以无机盐为原料通过控制pH值,用水热法合成含Ni皂石,并以此皂石为前驱物、十六烷基三甲基溴化铵为模板剂,制备含Ni介孔分子筛.用X射线粉末衍射、Fourier变换红外光谱、程序升温还原、透射电子显微镜、比表面积和孔径测定等仪器和方法表征样品的物化性能.结果表明:制得了有序性好的含Ni介孔分子筛,其比表面积为811.2m2/g,平均孔径为3.64nm.所制备的含Ni介孔分子筛经850℃焙烧3h或100℃水热处理10d后仍然具有介孔结构,说明样品具有高的(水)热稳定性.     

新型O2指示剂用于气调包装的研究

利用皂石的反射紫外线作用,在表面活性剂的作用下将亚甲蓝、抗坏血酸引入皂石的层间结构中,从而制成一种新型的氧气指示剂并解决了亚甲蓝易于被光降解的问题,克服了其它变色型氧气指示剂需要避光保存的问题。该氧气指示剂在氧气含量小于0.1%时为红色,当氧气含量上升到0.5%时迅速变为蓝色,具有较灵敏的检测氧气的功能。并且探讨了表面活性剂在氧气指示剂中的作用。     

Synthesis of Titania Pillared Saponite in Aqueous Solution of Acetic Acid

The preparation of TiO₂-pillared saponite was carried out in a CH₃COOH aqueous solution. Titanium ion species to intercalate into the interlayer of saponite were obtained by an addition of Ti(C₃H₇O)₄ to an aqueous solution of CH₃COOH and by subsequent aging of the solution for a prescribed time. Ti⁴⁺-intercalated saponite including organic materials was obtained by ion exchange. After the sample was calcined at 500°C in air, TiO₂-pillared saponite was obtained. The resulting TiO₂-pillared saponite (Ti-Sapo) possessed surface areas in the range 300–400 m²/g and a sharp pore size distribution with the pore radius of 1.2 nm. The basal spacing of the product heated at temperature >250°C was about 2.45 nm. The pillar height of TiO₂ in the Ti-Sapo was estimated to be 1.5 nm.     

含层柱皂石加氢异构裂化催化剂的制备及催化性能

通过水热法合成了酸性、孔径适中的层柱皂石材料,并将其经过机械研磨处理后,作为酸性组分通过挤条成型、浸渍Ni-W非贵金属体系,制得了一种新型的加氢异构裂化催化剂。选用正十六烷为模型化合物,以高压釜作为评价装置,与多产低凝柴油的某工业参比催化剂相比,发现在转化率相近时,制备的加氢异构裂化催化剂的加氢异构性能更好。     

华北某地发现皂石矿

皂石是蒙皂石家族的重要成员,工业应用性能优越,资源相对稀少,矿石经济价值较高。作者在华北地台北缘的侏罗纪火山岩地层中发现一种矿石,经检测证实属皂石。     

Dehydrogenation of ethylbenzene on alumina-pillared Fe-rich saponites

An iron-rich saponite, variety griffithite, from Griffith Park, California, USA, has been pillared with hydroxy-aluminium oligomers, giving rise to very crystalline layered solids with basal spacings of 17.4–17.7 Å and specific surface areas of 233–293 m²/g. The catalytic performance of these pillared solids, and also of the natural griffithite, all after calcination at 773 K, in the dehydrogenation of ethylbenzene was evaluated. The catalytic behaviour strongly depends on the acid properties developed in the solids by the pillaring treatment.     

纳米Fe3O4/皂石复合材料的制备及去除2,4-二氯苯酚的性能研究

本文以水热合成法和共沉淀法制备了纳米Fe₃O₄/皂石复合材料,并用于去除水中2,4-二氯苯酚(2,4-DCP)。采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)、透射电子显微镜(TEM)和X射线荧光光谱(XRF)等表征手段测试了纳米Fe₃O₄/皂石复合材料的物相组成、结构、形貌和元素组成,并考察了纳米Fe₃O₄/皂石复合材料在不同2,4-DCP溶液浓度、反应时间和pH等条件下对2,4-DCP的去除效果。结果表明,在皂石表面原位生长的纳米Fe₃O₄分散较为均匀,有效降低了Fe₃O₄的团聚现象。纳米Fe₃O₄/皂石复合材料在溶液pH值为6时,对2,4-DCP的最大去除量为178.46 mg/g,在反应时间为5 min时,对2,4-DCP去除量达到饱和。纳米Fe₃O₄/皂石复合材料对2,4-DCP的去除动力学符合准二级动力学模型。在此基础上,通过液相质谱联用(LC-MS)检测出2,4-DCP被降解后生成了氯酚等中间产物。本研究成果为水中有机污染物的降解提供了一种新型、环保且高效的环境功能材料。