Chlorinated butyl rubber/two-step modified montmorillonite nanocomposites: Mechanical and damping properties

Montmorillonite (MMT) was modified by ultrasound and castor oil quaternary ammonium salt intercalation method to prepare a new type of organic montmorillonite (OMMT). The surface structure, particle morphology, interlayer distance, and thermal behavior of the samples obtained were characterized. The modified OMMT was then added to chlorinated butyl rubber (CIIR) by mechanical blending, and a composite material with excellent damping properties was obtained. The mechanical experiment results of CIIR nanocomposites showed that the addition of OMMT improved their tensile strength, hardness, and stress relaxation rate. Compared with pure CIIR, when the content of OMMT was 5 phr (part per hundred of rubber), the tensile strength of the nanocomposite was increased by 677% and the elongation at break was also increased by 105.4%. The enhancement of this performance was mainly due to the dispersion of the nanosheets in CIIR rubber and the chemical interaction between the organoclay and the polymer matrix, which was confirmed by morphology and spectral analysis. OMMT also endowed a positive effect on the damping properties of CIIR nanocomposites. After adding 5 phr of OMMT, the nanocomposite owned the best damping performance, and the damping factor, tanδ_max, was 37.9% higher than that of pure CIIR. Therefore, the good damping and mechanical properties of these CIIR nanocomposites provided some novel and promising methods for preparing high-damping rubber in a wide temperature range.     

蒙脱土改性聚甲基丙烯酸甲酯复合材料的硫酸腐蚀行为

对乳液聚合法制备出的聚甲基丙烯酸甲酯/蒙脱土(PMMA/MMT)复合材料在硫酸介质中的腐蚀情况进行了研究,探讨了蒙脱土含量、硫酸浓度以及腐蚀时间对腐蚀速率的影响。结果表明,硫酸浓度较低且腐蚀时间较短时,含有2%~3%蒙脱土的复合材料的腐蚀速率比PMMA明显降低;PMMA及其复合材料的腐蚀速率随腐蚀时间的延长而下降,随硫酸浓度的增加而上升;硫酸浓度越高或腐蚀时间越长,复合材料中蒙脱土的片层阻隔作用越不明显。     

蒙脱石粘土／水分散体系中颗粒的性质

在实验测定了蒙脱石粘土／水分散体系中颗粒的比表面积，ζ电位及颗粒粒度的分布的基础上，研究了粘土颗粒在分散体系中的聚焦状态，颗粒结构以及颗粒的表面性质，为研究粘土分散体系的稳定与聚深以及体系性质提供参考。     

Surface-coating montmorillonite nanoclay by water-soluble proteins extracted from hominy feed

Montmorillonite (MMT) nanoclay was surface-coated by water-soluble proteins precipitated from hominy feed extract at pH 6.0, 5.5, and 4.3 to modify its native structure. Surface-coating was performed at 60 °C, pH 2.0–10.0, and MMT:protein mass ratios from 49:1 to 2:1, followed by lyophilizing the triple-washed precipitate for characterization. Proteins precipitated at pH 5.5 were the most effective in creating intercalated and/or exfoliated MMT structures that were also impacted by the protein level and pH during coating. At pH 2.0, X-ray diffraction peaks of pristine MMT were no longer observed at an MMT:protein mass ratio of 4:1 or lower, while different degrees of intercalation were achieved at other pH conditions. The adsorption of proteins on MMT at all studied pH conditions was confirmed by FTIR, analysis of adsorbed proteins, and zeta-potential. These results suggest that interactions involved in coating MMT include coulombic and non-coulombic forces.