弹性体和成核剂协同改性聚丙烯研究进展

简述了聚丙烯(PP)成核剂的分类及其增韧改性机理,针对近年来α成核剂/弹性体、β成核剂/弹性体、复配型成核剂/弹性体协同改性PP的研究成果进行了综述,并展望成核剂/弹性体改性PP的研究前景。     

SEBS弹性体在SBS型胶粘剂中的应用

采用在苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)型胶粘剂中引入耐老化性能较好的加氢苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SEBS)热塑性弹性体的方法,以求研制出一种性能优异且其冻融稳定性好的SBS型胶粘剂。结果表明,当SEBS热塑性弹性体的用量占总量的20%~30%时,SBS型胶粘剂各方面性能最优,且其冻融稳定性良好。     

相容剂对弹性体TPU/POE共混体系流变性的影响

我们通过动态频率、应变流变仪研究了添加POE-g-MAH、POE-g-NH2相容剂的TPU/POE共混物三元共混体系在200℃下的动态流变学行为。随POE-g-MAH、POE-g-NH2添加量的增加,共混体系的动态模量G'也显著增加,而且曲线随着频率增大而逐渐靠近。这是因为POE分子链上的酸酐及氨基基团与TPU分子上的氨基甲酸酯发生反应,TPU与POE之间形成的界面区和界面粘结力增加,从而使相态结构的稳定性提高。POE-g-MAH、POE-g-NH2的加入,导致二元共混斜率完全偏离线性关系,极大地提高了POE与TPU的相容能力。     

聚脲弹性体在爆炸防护中的研究进展

从力学性能、防护结构应用研究、吸能机理三个方面综述了聚脲弹性体在爆炸防护中的研究进展。聚脲弹性体的静/动态力学性能优异,断裂伸长率高、应变率效应强,在增强墙体、金属及复合材料等多种防护结构抗冲击性能方面的研究取得了重要进展,获得了一些规律性认识,包括聚脲弹性体在防护结构中的位置、质量比重等因素对抗爆性能的影响以及聚脲弹性体在墙体、金属、复合材料等不同结构中增强抗爆性能的机理。分析认为聚脲弹性体在爆炸防护中具有很大的应用潜力,指出未来需进一步研究聚脲弹性体的本构关系、影响聚脲弹性体抗爆性能的因素、防护结构尺寸效应与聚脲弹性体的微观吸能机理。     

新型碱金属高碘酸盐纳米铝热剂的反应特性

纳米铝热剂向着高能方向发展的一个重要限制因素是在铝热反应过程中缺少大量的气体产物。为了弥补纳米铝热剂产气量不足的缺陷,提高纳米铝热剂的反应活性,通过喷雾干燥法制备了具有核-壳结构的纳米铝热剂Al@KIO₄和Al@NaIO₄。采用扫描电子显微镜、X射线衍射仪、热分析仪、定容燃烧实验、吸湿性实验和威力测试对两种铝热剂的形貌结构、热性能、定容燃烧性能、耐潮湿环境能力和起爆性能进行评估。结果表明,喷雾干燥法制备的Al@KIO₄和Al@NaIO₄纳米铝热剂的形貌规则、纯度高,铝热反应的总放热量分别为1262.12 J?g^-1和1414.7 J?g^-1;两种铝热剂反应过程中的反应起始温度低,反应中伴随大量氧化性气态产物生成;高湿环境中两种铝热剂分别在第6天和第10天达到质量平衡,质量增重约0.64%和0.65%,耐潮湿环境能力良好;96 mg铝热剂作为起爆药装配到8^#工业雷管中能使黑索今完全爆轰,可使5 mm厚的铅板穿孔,穿孔直径几乎到达叠氮化铅的水平。将96 mg的Al@KIO₄、Al@NaIO₄、斯蒂芬酸铅和叠氮化铅分别作为起爆药装填在8^#工业雷管中使黑索今完全爆轰,根据5 mm厚的铅板穿孔直径判断起爆能力为：叠氮化铅＞Al@NaIO₄＞Al@KIO₄＞斯蒂芬酸铅。     

Preparation and characterization of Fe/SiO_2 core/shell nanocomposites

In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.     

Core Cross-Linked Amphiphilic Star-Block Copolymers with (Meth)acrylic Acid Shells Prepared by Atom Transfer Radical Polymerization

Core cross-linked amphiphilic star-block copolymers were prepared by hydrolysis of the outer shell of star-block copolymers prepared using copper mediated atom transfer radical polymerization (ATRP). In an arm-first approach, linear poly(tert-butyl methacrylate) macroinitiators (PtBMA-Cl) were extended with styrene to yield PtBMA-b-PS-Cl and then cross-linked with divinylbenzene (DVB) in order to yield (PtBMA-b-PS)_arms-PDVB_core star-block copolymers. Then, PMAA-b-PS block and (PMAA-PS)_arms-PDVB_core star-block copolymers were obtained by hydrolysis of the PtBMA blocks in both linear and cross-linked copolymers, as confirmed by ¹H NMR analyses. The amphiphilic character of these copolymers was confirmed by solubilisation in water. Several factors affecting the polymer aggregation and solubility such as the length, the composition of the arms and the catalyst used were studied. An acrylate analogue, that is, (PAA-b-PS)_arms-PDVB_core, was also prepared for comparison purposes. Atomic force microscopy (AFM) and differential scanning calorimetry (DSC) were used to elucidate the morphology and the thermal behaviour of the star-block copolymers.     

Preparation and properties of a core-shell styrene-acrylic copolymer modified adhesion mortar using iron tailings as the aggregate

In this paper, the core-shell poly (styrene-hydroxyethyl methacrylate) copolymer was synthesized by emulsifier-free emulsion polymerization. The microstructure of the polymer was characterized by fourier transform infrared spectrum, scanning electron microscope (SEM), and the laser particle size analyzer. Using it as the modifier, iron tailings as the aggregate and eco-cement as the cementing material, a new adhesion mortar was prepared. Results showed that the core-shell cross-linked poly (styrene-hydroxyehyl methacrylate) could substantially improve the modified-mortar’s bond strength compared to the mortar with commercial EVA as the modifier. SEM images of the modified mortar illustrated that the polymer may have three effects: (1) partially obstructing the fine pore network inside of hydrates; (2) filling the large pores; and (3) forming membranes. All these effects improve the mortar’s adhesion properties combinedly.     

热塑性弹性体(TPE)及其在纺织器材上的应用

简要介绍了几种常用TPE的结构、性能、应用特点及其在纺织器材上的应用。