改性聚氨酯防水材料的流变性能

利用RS150型平板流变仪测试了改性聚氨酯防水材料的表观黏度、粘流活化能、非牛顿指数等流变参数,讨论了剪切速率、剪切应力和温度等对改性聚氨酯防水材料表观黏度的影响。实验结果表明,改性聚氨酯防水涂料的表观黏度随温度的升高而降低;在实验温度范围中,改性聚氨酯防水材料的表观黏度随剪切速率和剪切应力的增大而降低,其非牛顿指数n小于1,并且随着温度升高而增大,表明改性聚氨酯防水材料为假塑性流体;其粘流活化能E0为19.73 kJ/mol。     

原位聚合PA11/GO纳米复合材料的流变性能研究

采用原位聚合法制备了PA11(尼龙11)/GO(GO)纳米复合材料,并采用XLY-Ⅱ型毛细管流变仪研究了共混物的流变特性。结果表明:PA11及其复合材料均为假塑性流体,呈现切力变稀的现象;非牛顿指数n均小于1。随着GO含量的增加,PA11/GO纳米复合材料的表观黏度升高,粘流活化能下降,表明共混材料的表观黏度对温度的敏感性降低,易于加工成型。     

聚乙烯醇缩丁醛/聚乙二醇体系的流变性能

采用美国TA公司的AR2000型应力控制流变仪研究了聚乙烯醇缩丁醛/聚乙二醇(PVB/PEG)体系的流变学性能,研究了温度、PVB质量分数与PEG分子量对PVB/PEG体系的流动曲线和非牛顿指数等流变特性的影响。结果表明PVB/PEG体系存在剪切变稀行为,为假塑性流体;温度升高,表观黏度减小,非牛顿指数增大;PVB质量分数增加,表观黏度增加,非牛顿指数减小;PEG分子量增加,表观黏度增加,非牛顿指数变化很小。在一定的浓度和剪切速率下体系的黏度随温度的变化符合Arrhenius方程式,粘流活化能随剪切速率的增加而减小。     

PP/EPDM-g-MAH/Al(OH)_3/FA复合体系流变性能研究

以毛细管流变仪研究了粉煤灰(FA)改性聚丙烯/三元乙丙橡胶接枝马来酸酐/Al(OH)_3/FA[PP/EPDM-gMAH/Al(OH)_3/FA]阻燃复合体系的流变行为,讨论了复合材料的组成、剪切应力和剪切速率及温度对熔体流变行为、熔体黏度的影响,测定了不同配比的复合材料熔体的非牛顿指数(n)和挤出膨胀比。结果表明:PP/EPDM-g-MAH/Al(OH)_3/FA熔体为假塑性流体,表观黏度随着剪切速率增加而降低。当FA的含量在0%~25%范围内时,共混物的n1,且在5%和20%处有2个极大值点,表观黏度呈先增后减再增的趋势;FA可降低共混熔体的粘流活化能,但适量FA仍可保证温敏性不会降低太大,复合材料的挤出胀大现象随FA增加有所降低。     

乙烯-醋酸乙烯共聚物的流变性能

利用XLY-Ⅱ型毛细管流变仪测试了乙烯-醋酸乙烯共聚物(EVA)的表观黏度、粘流活化能、非牛顿指数等流变参数,讨论了剪切速率、剪切应力和温度等对乙烯-醋酸乙烯共聚物熔体的表观黏度的影响,研究了粘流活化能与剪切速率的变化规律。实验结果表明,乙烯-醋酸乙烯共聚物熔体的表观黏度随温度的升高而降低;粘流活化能ΔE随剪切速率的增大而减小。在实验温度范围内,EVA熔体的表观黏度随剪切速率和剪切应力的增大而降低,其非牛顿指数n小于1,说明EVA熔体为假塑性流体。     

PC/HBPS共混物的流变性能

通过熔融共混法制备了PC/HBPS共混物,研究了其流变特性。结果表明,此共混物属于假塑性流体,随着HBPS含量的增加,非牛顿指数增加;随着剪切速率的增加,表观黏度下降,但下降趋势较缓慢;随着温度的增加,表观黏度下降,但下降趋势很快;共混物的粘流活化能都比纯PC的粘流活化能高;随着HBPS含量的增加,表观黏度下降。     

聚碳酸酯/甲基丙烯酸甲酯-丁二烯-苯乙烯共混物的流变性能

利用双螺杆挤出机制备了聚碳酸酯/甲基丙烯酸甲酯-丁二烯-苯乙烯共混物(PC/MBS),研究了温度和MBS含量对PC/MBS共混物主要流变性能参数的影响。结果表明,MBS能有效改善PC的加工性能。共混物表观黏度随温度升高而降低。当MBS质量分数低于15%时,随着MBS含量的增加,共混物的表观黏度和粘流活化能降低,同时非牛顿指数增加。MBS质量分数为15%时,共混体系流变性能最好。继续增加MBS含量,流变性能变差。     

表面改性对聚丙烯/纳米氢氧化镁复合材料性能的影响

研究了表面处理剂(钛酸酯和硅烷偶联剂)对聚丙烯/纳米氢氧化镁(MH)阻燃复合材料性能的影响。通过高压毛细管流变仪、LO I、力学测试、DSC和SEM对PP/纳米MH复合体系的结构与性能进行了研究。结果表明,所选偶联剂能有效地降低复合体系的表观黏度,改善体系的流动性。未改性的纳米MH对PP基体有异相成核作用;而表面改性剂能削弱填料对基体的异相成核作用。改性后的纳米MH粒子以独立形式均匀分散在基体中,PP与纳米MH界面的粘接力得到了加强,复合材料的拉伸性能和冲击强度有较大幅度的提高,阻燃性能也得到了改善。     

氢氧化镁的改性及其填充聚丙烯复合材料的燃烧性能和结晶行为的研究

研究了硅烷改性剂对氢氧化镁(MH)的表面改性和其填充聚丙烯(PP)复合材料的阻燃性能和结晶行为.用FTIR、XRD和SEM对改性前后MH的结构和形貌进行了分析.结果表明,硅烷处理剂包覆在MH粉体的表面,有效地降低MH粉体的表面能,提高了MH在干态下的分散性.DSC、POM和LOI对PP/MH复合材料的结晶行为和燃烧性能进行了研究.结果表明,未改性的MH对PP有异相成核作用,使结晶峰温度升高;而表面改性剂削弱了填料的异相成核作用.POM结果暗示了MH粒子在基体中的分散性对PP球晶的晶粒形貌和晶粒尺寸起着十分重要的作用.改性后的MH能进一步提高复合材料的LOI.     

聚乙烯醇水溶液的剪切流变行为

研究了不同浓度和分子量的聚乙烯醇(PVA)水溶液的流变性能。讨论了剪切速率和温度对PVA水溶液的表观黏度、非牛顿指数和粘流活化能的影响。实验结果表明,随剪切速率增加,不同浓度和聚合度样品间黏度的差别降低,所有PVA水溶液均显示剪切变稀行为。随PVA浓度提高,溶液的非牛顿指数是先增大后降低。同时发现剪切速率的变化影响PVA水溶液黏度的温度依赖性。     

Dispersion,thermal and mechanical properties of polypropylene/magnesium hydroxide nanocomposites compatibilized by SEBS-g-MA

Isotactic polypropylene (PP)/nano-magnesium hydroxide (nano-MH) composites with 10 wt.% maleic anhydride grafted styrene–ethylene-butylene–styrene tri-block copolymer (SEBS-g-MA) as a compatilizer were prepared by melt extrusion compounding and injection molding. The effects of SEBS-g-MA on dispersion of nano-MHs in PP matrix and interfacial adhesion were studied in order to prepare highly filled PP/MH nanocomposites. The results showed that SEBS-g-MA improved both dispersion of nano-MHs and interfacial adhesion in PP/MH nanocomposites with up to 40 wt.% nano-MHs. The elastic moduli of PP/SEBS-g-MA /MH nanocomposites increased marginally and tensile yield strengths were almost invariant with nano-MH loading. Significant impact toughening of these ternary nanocomposites was, however, achieved due to the cavitation of SEBS-g-MA/MH particles and expansion of voids as well as plastic deformation of the PP matrix.     

Surface modification of magnesium hydroxide and its application in flame retardant polypropylene composites

In this article, titanate and zinc stearate modified superfine magnesium hydroxide [Mg(OH)₂] was filled into polypropylene (PP) as a flame retardant (FR). The structure and morphologies of untreated and treated Mg(OH)₂ particles were characterized by Fourier transform infrared (FTIR), wide-angle X-ray diffraction (WAXD), and scanning electron microscope (SEM). PP/Mg(OH)₂ (1:1) composites were also prepared in co-rotating twin-screw extruder, and the effects of treatment agents on the rheological behavior, mechanical properties, and flame retardancy of PP/Mg(OH)₂ composites were studied. The results from FTIR and WAXD show that treatment agents are adsorbed onto the surface of Mg(OH)₂ particles. The complex viscosity (η*) values of the composites decrease with the addition of various treatment agents. Surface treatment agent could significantly improve tensile and impact strength of PP/Mg(OH)₂ composites due to its enhanced interfacial adhesion between Mg(OH)₂ particles and the PP matrix. According to limiting oxygen index (LOI), titanate treated magnesium hydroxide (MH) greatly enhanced flame retardancy of PP/Mg(OH)₂ composites.     

改性氢氧化镁的制备及在PA66中的阻燃应用

以氯化镁、氢氧化钠、尿素和硬脂酸钠为原料,采用沉淀法制备出改性氢氧化镁(MH)粉末材料。结果表明,制备的MH为无规则的、粒径为30～120nm的,且至少有一维是纳米结构的片状材料。在应用方面,采用熔融挤出法制备了多组不同配方的尼龙66(PA66)复合材料。研究发现,MH单独使用时阻燃效率低,将它与微胶囊红磷(MRP)复配使用后能有效地提高材料的阻燃性能。当x(PA66)∶x(MRP)∶x(MH)=100(phr)∶10(phr)∶8(phr)时,MRP/MH/PA66复合材料的垂直燃烧为V-0级,LOI能达到32%。此外,还探讨了可能的阻燃机理,并通过TG、TG-MS等手段研究了材料的热氧稳定性及热氧分解气态产物。     

Synergistic catalysis effects of lanthanum oxide in polypropylene/magnesium hydroxide flame retarded system

Lanthanum oxide (La₂O₃) was incorporated as a catalytic synergist to enhance the flame retardancy of the environmental friendly halogen free inorganic compound magnesium hydroxide (MH), the main flame retardant, filled in the flammable polymer polypropylene (PP) matrix. It was found that the addition of an appropriate loading of La₂O₃ could remarkably improve the flame retardancy of MH filled PP FR composite. The significant enhancement in the flame retardancy was attributed to the greatly improved quality of the condensed phase charred layers deposited on the surface of the formed magnesium oxide (MgO) particles through participation of PP macromolecular chains themselves in the char formation reaction under the catalytic action of La₂O₃. It was believed that the char formation reaction involved with the PP macromolecular chains is composed of two processes related to the catalytic role of La₂O₃, i.e. catalytic oxidation hydrogenation and catalytic partial oxidation.     

Core-shell magnesium hydroxide/polystyrene hybrid nanoparticles prepared by ultrasonic wave-assisted in-situ copolymerization

In this paper, vinylated magnesium hydroxide (MH) nanosheets were prepared with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and pristine MH nanosheets, then the MH/polystyrene (PS) hybrid nanoparticles were prepared by ultrasonic wave-assisted in-situ copolymerization of vinylated MH nanosheets and styrene (St). The morphology, thermal stability and chemical structure of the final products were investigated in detail with transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR). The TEM and FTIR results showed that the uniformly-dispersed core-shell structure of MH/PS nanocomposites with MH-cores and PS-shell was formed. TGA indicated that the covalent interaction between PS and MH improved the thermal stability of PS. A possible formation mechanism of the MH/PS core-shell nanocomposites was also proposed.     

表面改性剂对聚丙烯/氢氧化镁复合材料燃烧性能和热稳定性及结晶行为的影响

研究了硅油对聚丙烯(PP)/氢氧化镁(MH)复合材料性能的影响。通过极限氧指数(LOI)、热失重分析仪(TGA)、差示扫描量热仪(DSC)和偏光显微镜(POM)对PP及阻燃PP的性能进行了研究。结果表明,阻燃PP比纯PP有较高的残留量,热稳定性得到改善。其LOI达到难燃塑料的要求,有良好的阻燃性。未经改性的MH对PP基体有异相成核作用,使结晶峰温度向高温方向偏移,而硅油削弱填料对PP基体的异相成核作用。POM分析表明,MH粒子在基体中的分散性对PP的晶粒形貌和尺寸起着十分重要的作用。     

Improving the flame retardance of hydrophobic silica aerogels through a facile post-doping of magnesium hydroxide

A facile post-doping of magnesium hydroxide (MH) is proposed to improve the flame retardancy of hydrophobic silica aerogels (SA). The lower tap density (0.12 g/cm³) and thermal conductivity (26 mW/m/K) are still maintained at the largest MH content of 20%. Meanwhile, the gross calorific value of the SA/MH is reduced by 15% and the thermal stability is improved to over ~545 °C. The SA/MH pyrolysis process can be divided into four stages, while the hydrophobic SA is a two-stage pyrolysis process. Furthermore, the improved flame retardancy of SA/MH is mainly attributed to the thermal decomposition of MH, the pyrolysis products (MgO, SiO₂ and H₂O) and the reaction between MgO and SiO₂. The research outcomes demonstrate the validity of using MH as dopant to improve the flame retardancy of hydrophobic SA by a facile post-doping, which is beneficial to the expansion of hydrophobic SA in their practical thermal insulation application.     

碱式硫酸镁形貌对碱式硫酸镁/聚丙烯复合材料力学性能的影响

以三种不同形貌的碱式硫酸镁(颗粒状(MOS_P)、晶须状(MOS_W)和扇形(MOS_S))为填料、月桂酸(LA)为改性剂、聚丙烯(PP)为树脂基体,通过熔融共混法制备了系列MOS/PP复合材料。SEM结果显示,改性后的MOS_P和MOS_W在基体中分散均匀,但与基体PP的相容性依然较差;MOS_S/PP样品中同时存在着尺寸较大且形貌复杂的MOS_S和部分分散的MOS_W,界面缺陷更加明显。广角X-射线衍射(WXRD)结果表明,三种MOS均能诱导β-晶型PP的产生,与月桂酸的加入无关,其中MOS_P诱导效果更明显。力学性能测试结果表明,三种形貌MOS的加入稍降低了基体的屈服强度,一方面是MOS与基体相容性差,另一方面归结于β-晶型PP生成;相比之下,MOS_W加入能较好地保持PP基体的屈服强度和拉伸断裂韧性,且明显增强基体的模量,主要归因于MOSW较大的长径比;MOS_P对基体的增韧效果更为明显,一方面是由于MOS_P诱导生成β-晶型PP的效果强于MOSW和MOS_S,另一方面则可能是由于MOS_P较大的比表面积附着了较多的脂肪酸盐,其增塑效果更强。