纳米SiO2改性水性聚氨酯的研究进展

详细介绍了共混法、原位聚合法和溶胶凝胶法制备纳米SiO2改性水性聚氨酯的特点,并对水性聚氨酯纳米复合材料的应用以及研究方向作了展望。     

纳米SiO_2/聚甲基丙烯酸甲酯透明复合材料的制备及透光率

首先利用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)对纳米SiO_2进行表面改性(SiO_2-MPS),再通过原位聚合法在SiO_2-MPS表面接枝聚甲基丙烯酸甲酯(PMMA)。采用熔融共混法将未改性和改性SiO_2与PMMA共混制成预分散母料,再分别与PMMA熔融共混制备纳米SiO_2/PMMA透明复合材料。用FTIR、TG和SEM对不同表面处理的纳米SiO_2和纳米SiO_2/PMMA复合材料的结构进行表征,并对其冲击强度、接触角和透光率进行表征。结果表明:SiO_2-MPS/PMMA复合材料中纳米SiO_2与MPS、MPS与PMMA间形成化学键,接枝率分别达到10.01%和22.95%,SiO_2-MPS-PMMA在PMMA中分散性最好,团聚现象明显减少,与纯PMMA相比,SiO_2/PMMA、SiO_2-MPS/PMMA和SiO_2-MPS-PMMA/PMMA复合材料的冲击强度、与水接触角均略有提升,透光率达到90%左右,最高可达94.2%。     

改性纳米SiO_2/环氧-丙烯酸酯水性防腐涂料的研制

通过油酸对纳米二氧化硅(SiO_2)进行改性,将改性纳米SiO_2与环氧树脂和丙烯酸单体充分混合,反应后制得改性纳米SiO_2/环氧-丙烯酸酯乳液。以改性纳米SiO_2/环氧-丙烯酸酯为成膜物质,通过添加颜、填料和多功能助剂,调节改性环氧树脂∶丙烯酸酯的摩尔配比为1∶1,并用0.15%(wt,质量分数)氢氧化钠(NaOH)优化酸碱度,制得一种新型改性纳米SiO_2/环氧-丙烯酸酯水性防腐蚀涂料,涂料的附着力达到1级,耐冲击性达到50cm,铅笔硬度达到2H,并具有贮存稳定性能好、耐候性能和物理机械性能等优异的特性。     

石墨烯/聚氨酯复合材料制备及性能研究进展

近年来,石墨烯改性聚氨酯纳米复合材料因其优异的综合性能而备受关注。在聚氨酯基体中添加石墨烯或其衍生物可显著提升聚氨酯的物理机械、热学、电磁学等性能,满足聚合物复合材料高性能和多功能的特殊要求。首先介绍了石墨烯的功能化改性方法,包括共价键改性和非共价键改性。随后介绍了石墨烯/聚氨酯纳米复合材料的制备工艺,包括原位聚合、溶液共混、熔融共混、水相(胶乳)共混等。综述了石墨烯/聚氨酯纳米复合材料在物理机械性能、导电性能、介电性能、导热性能、气体阻隔性能、阻燃性能、电磁屏蔽性能和防腐蚀性能等方面的最新研究进展。最后,对石墨烯/聚氨酯纳米复合材料面临的挑战和发展前景进行了展望。     

改性纳米二氧化硅增强增韧聚对苯二甲酸丁二醇酯

采用四辛基溴化铵(TOAB)改善纳米二氧化硅颗粒(SiO_2)的分散性,并在SiO_2表面进行聚对苯二甲酸丁二醇酯(pCBT)的接枝改性。以不同含量改性的SiO_2(0.1%~2%(质量分数))与环状聚对苯二甲酸丁二醇酯(CBT)熔融共混,原位聚合制得SiO_2/pCBT纳米复合材料。纳米复合材料的结晶性能和力学性能表征结果表明:随着SiO_2含量的增多,结晶度逐渐提高;与纯pCBT相比,添加1%(质量分数)SiO_2的复合材料的杨氏模量提高了22%,断裂吸收能提高约56%;此外,SiO_2还能显著提高pCBT纳米复合材料的弹性模量和玻璃化转变温度。     

改性纳米TiO2/环氧-聚氨酯水性防腐涂料的研制

以改性纳米TiO_2/环氧-聚氨酯为成膜物质,通过添加颜填料和多功能助剂,制得性能优异的水性防腐蚀涂料。探讨了乳液、玻璃鳞片和氧化铁红用量对涂膜耐蚀性能、附着力和抗冲击力等综合性能的影响。结果表明:当乳液、玻璃鳞片和氧化铁红质量含量分别为40%、30%和22%时,涂膜的耐蚀性能、附着力和抗冲击性能最佳。此外,水性防腐涂料的热稳定性能亦明显改善。     

光固化水性聚氨酯丙烯酸酯涂料制备与性能表征

以异氟尔酮二异氰酸酯、2,2-二羟甲基丙酸、季戊四醇三丙烯酸酯、甘油聚醚为原料,采用3种工艺合成水性紫外光聚氨酯丙烯酸酯(UV-WPUA)预聚物。采用国标要求测定低聚物的表观性能和涂料的基本性能,并分析SiO_2处理、甘油聚醚与2,2-二羟甲基丙酸(DMPA)摩尔比、光引发剂含量和涂料固含量对涂料涂膜硬度的影响。研究结果表明,通过添加改性的纳米SiO_2、调节光引发剂含量和涂料固含量都能提高UV-WPUA涂料涂膜铅笔硬度。当改性纳米SiO_2的质量分数为4%~6%,光引发剂Irgacure2959质量分数为3%,固含量为55%,涂膜铅笔硬度较佳;甘油聚醚与DMPA摩尔比在3∶3~3∶4之间,第一步预封端工艺合成的UV-WPUA涂料涂膜铅笔硬度较佳。     

水性透明隔热涂料的性能研究

以纳米氧化锡锑( ATO)水性浆料和水性聚氨酯(BayhydrolXP2593/1)为原料,采用共混法制备纳米ATO/水性聚氨酯复合涂料.研究了纳米ATO用量及涂膜厚度对涂膜力学、热学和光学性能的影响.结果表明,当w(ATO)/w(PU)=1:15时,所制得的纳米ATO/PU涂层硬度为2H,附着力为1级;涂层可见光平均...     

水性聚氨酯的合成及改性研究

叙述了水性聚氨酯合成的几种方法,包括外乳化法和自乳化法等,同时也介绍了水性聚氨酯改性的几种方法和特点,其中包括用物理共混法和化学接枝法等。其中详细介绍了水性聚氨酯的各种改性技术,如交联改性,聚丙烯酸酯改性,环氧树脂改性,有机硅改性,纳米技术改性,天然产物改性等,并对水性聚氨酯的发展前景进行了展望。     

亲水SiO2改性水性聚氨酯-聚丙烯酸酯的制备及性能

为了提高水性聚氨酯材料的耐热性、耐化学试剂性及力学性能,利用甲基丙烯酸甲酯(MMA)作为聚氨酯预聚合的连续相,同时采用羧酸型以及磺酸型亲水扩链剂,乳化时引入反应性的亲水性纳米二氧化硅(WSiO2),通过无有机溶剂法制备了稳定的耐温水性聚氨酯-聚丙烯酸酯(WPUA)乳液。利用透射电镜、红外光谱、X射线衍射和热重等手段研究了WPUA乳液及其膜的结构和性质。结果表明:随着样品中WSiO2含量的增加,WPUA乳液的平均粒径增大,WPUA膜的光泽度下降,硬度、附着力增加,WPUA薄膜的硬度和附着力增加,拉伸强度值先上升后下降,最佳WSiO2添加量为1%。适量的WSiO2可以改善WPUA材料的耐热行为。当热分解率为50%时,WSiO2改性后WPUA的分解温度比改性前提高了39℃。WSiO2改性使WPUA的力学和耐化学试剂性也得到了改善。     

芳纶纤维表面改性及其对芳纶/橡胶复合材料黏合性能的影响

以原位乳液聚合方法合成水性聚氨酯预聚体（WPUP）包覆纳米ZnO粒子（ZnO@WPUP）,将KOH预处理后的芳纶纤维浸渍在改性ZnO乳液中进行二次处理,进一步与天然橡胶硫化,得到ZnO@WPUP改性芳纶/橡胶复合材料,并通过FTIR、SEM和H抽出实验等测试分析ZnO@WPUP对芳纶/橡胶复合材料黏合性能的影响。结果表明：WPUP能有效提高ZnO分散性,随着WPUP含量增加,ZnO@WPUP在芳纶纤维表面分散更加均匀,纤维表面粗糙度增大,改善了芳纶纤维表面橡胶的黏附量,从而大幅度提高芳纶/橡胶复合材料的黏结强度。     

Effect of nano-SiO2 modified emulsion sizing on the interfacial adhesion of carbon fibers reinforced composites

The influence of nano-SiO₂ modified epoxy emulsion sizing on the interfacial adhesion properties of carbon fibers reinforced composites was investigated. The interfacial interaction between carbon fibers and the matrix was characterized by X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and three-point short-beam shear testing. The results showed that the amount of hydroxyl groups was slightly increased on the carbon fibers surface after treatment with nano-SiO₂ modified sizing. Compared to the unsized composites, the interlaminar shear strength (ILSS) values for the composites with unmodified sizing and nano-SiO₂ modified sizing were increased by 9% and 14%, respectively. The holes and carbon fibers pullout were not observed in their fracture sections. Surprisingly, the fracture section of the composites with nano-SiO₂ modified sizing was more compact and the fiber debonding was more difficult.     

聚乳酸/纳米SiO2复合纤维的制备及力学性能

首先用硅烷偶联剂(GPS)对纳米SiO2进行接枝改性,利用粒径分析仪、FTIR和沉降实验对改性前后纳米SiO2的粒径大小、结构和溶剂稳定性的变化进行了表征;然后将改性前后的纳米SiO2分别与聚乳酸(PLA)在双螺杆挤出机中熔融混合,利用牵伸卷绕装置制备了PLA/SiO2和PLA/M-SiO2(改性后SiO2)复合纤维。利用视频显微镜和单纱强力仪研究了不同纳米SiO2含量对PLA/SiO2和PLA/M-SiO2复合纤维结构形貌和力学性能的影响,以及不同牵伸倍数对PLA/M-SiO2复合纤维结构形貌和力学性能的影响。结果表明M-SiO2粒径明显减小,且硅烷偶联剂结构中的有机官能团与SiO2表面硅羟基发生反应,减少了其表面Si-OH的量,使得M-SiO2表现出良好的溶剂稳定性和分散性;PLA/M-SiO2复合纤维的力学性能较PLA/SiO2复合纤维得到了明显的改善;当改性纳米SiO2含量为1%时复合纤维强度最好;当牵伸倍数为3时复合纤维强度最好。     

Effect of nano-SiO2 on the performance of poly(MMA/BA/MAA)/EP

In the present work, the dispersive stability of nano-SiO₂ with coupling agent A-174 has been investigated, then in situ nano-SiO₂-MMA/BA/MAA copolymerization has been polymerized. Furthermore, the effects of nano-SiO₂ on performance of poly(MMA/BA/MAA)/EP have been studied, too. The results show that the nano-SiO₂ is soft agglomerate, which diameter is about 2.08 μm. But when it was oscillated by ultrasonic wave with adapt separating agent in low molecule solution, nanometer grade nano-SiO₂ particle could be attained, the average particle diameter is about 45 nm. In addition, the dispersive stability of nano-SiO₂ as treated by A-174 in polymerization system increase. As 3% of nano-SiO₂ treated by 4% of A-174 is added, the shear strength of the thermosetting acrylic-epoxy resin increase about 68%, up to 20.07 MPa, and its heat decomposition temperature increase from 332 °C to 386 °C, furthermore, the excellent water resistance and transparency have been obtained.     

肝素化水性聚氨酯改性医用聚氯乙烯表面的研究

以N 甲基二乙醇胺为扩链剂合成了阳离子水性聚氨酯 (ACPU) ,将其固定在医用聚氯乙烯管内壁并对其进行肝素化。通过全血凝固时间实验证明 ,改性后的医用聚氯乙烯管的抗凝血性明显提高。另外使用红外光谱分析了阳离子水性聚氨酯的结构及其肝素化处理后聚合物结构的变化 ,并考察了MDEA含量对阳离子水性聚氨酯乳液及其涂膜性能的影响。     

Effects of emulsion sizing with nano-SiO<Subscript>2</Subscript> on interfacial properties of carbon fibers/epoxy composites

Nano-SiO₂ particles were used to modify epoxy emulsion sizing of carbon fibers to improve the interfacial properties of carbon fibers reinforced epoxy composites. The mechanical interfacial strength between fibers and matrix was investigated by the single fiber fragmentation test and the 3-point short beam shear test, respectively. Dynamic contact angle analysis (DCAA), X-ray photoelectron spectrometry (XPS) and atomic force microscopy (AFM) were performed on the carbon fibers with unmodified sizing and nano-SiO₂ modified sizing. The results indicated that modified sizing with nano-SiO₂ slightly increased the surface energy, the hydroxyl functional group and the surface roughness of carbon fibers compared to unmodified sizing, so that the interfacial shear strength (IFSS) of the single fiber composites and the interlaminar shear strength (ILSS) of composites were enhanced. SEM images of fracture sections of composites proved powerfully that the interfacial adhesion between fibers and matrix was improved after nano-SiO₂ modified emulsion sizing treatment.     

pH值对水性聚氨酯及其接枝共聚物分散液形态的影响

以甲苯二异氰酸酯、二元醇、不饱和扩链剂为原料,通过自乳化法合成了阴离子型水性聚氨酯,在微量铜离子存在的情况下,用甲基丙烯酸甲酯对其进行接枝共聚,并用动态激光光散射粒度分析仪对不同pH值下水性聚氨酯及其接枝共聚物的粒径进行了测量,用透射电镜对胶束的粒子形态进行了观察,研究结果表明,在相同pH条件下,聚乙二醇型水性聚氨酯的粒径比聚丙二醇型的粒径大,二者接枝共聚后的聚氨酯水乳液的粒径比接枝前要小。当pH值为强碱性时,水性聚氨酯乳液呈透明溶液状态,pH值为强酸性时,乳液变得不稳定,有沉淀出现。接枝后水性聚氨酯共聚物的乳胶粒子出现微相分离,形成壳-核结构。     

Excellent electrical performance and thermal properties insulation paper based on polyimide porous fiber membrane modified by nano-SiO2

Oil-paper insulation system is an important insulation structure of converter transformer. At present study, polyamic acid introduced was synthesized firstly, then perform electrospinning and thermal imidization to prepare polyimide (PI) porous fiber membrane, and the nano-SiO₂ was introduced into the fiber membrane by in-situ polymerization. FT-IR was used to characterize PI porous fiber membrane chemical structure. Consequently, when the SiO₂ addition amount is 4 wt.%, the breakdown voltage of the SiO₂/PI composite fiber reaches the maximum, which is 74 kV/mm. The dielectric constant and dielectric loss of the composite fiber film are 1.98–0.0013 (10⁷ Hz). It is worth noticing that nano-SiO₂ available in PI significantly improved its electrical performance.

     

Hybrids of silver nanowires and silica nanoparticles as morphology controlled conductive filler applied in flexible conductive nanocomposites

Flexible conductive polymer nanocomposites based on silver nanowires (AgNWs) have been widely studied to develop the next generation of flexible electronics. However, AgNWs tend to aggregate in polymer matrix that usually results in high percolation threshold. In this study, nonconductive silica nanoparticles (nano-SiO₂) were successfully co-assembled on AgNWs to form AgNWs/nano-SiO₂ hybrids and waterborne polyurethane (WPU) conductive nanocomposites filled with the hybrids were prepared. The results show that the resistivity of WPU nanocomposites filled with AgNWs/nano-SiO₂ hybrids decreased about 5000 times and the percolation threshold decreased from 10.6 vol% to 3.6 vol% due to AgNWs distribute more uniformly in WPU with the help of nano-SiO₂. The further study to mechanism of interactions between AgNWs and nano-SiO₂ suggest that the promotion of dispersion is attributed to hydrogen bonding and van der Waals force. The WPU nanocomposites embedded with AgNWs/nano-SiO₂ hybrids present excellent mechanical adhesiveness, flexibility and thermal stability.     

Interfacial enhancement of nano-SiO2/polypropylene composites

The authors proposed an approach for manufacturing nano-SiO₂/polypropylene (PP) composites by in situ reactive processing. The key issue lies in that the nanoparticles were covalently bonded to the matrix polymer via polyurethane (PU) elastomer and PP-g-NH₂. Unlike the previous techniques based on graft polymerization, the present one did not need to pretreat the nanoparticles. Taking the advantages of rubber-type grafting polymer (i.e. PU) and interfacial reactive compatibilization with PP-g-NH₂, a synergetic toughening effect was observed for the PP nanocomposites. Only very low concentrations of nano-SiO₂ (1.5–2.5 vol.%) and PU (<4 vol.%) were sufficient to greatly increase notched impact strength of PP. Meanwhile, tensile properties of the nanocomposites were also slightly enhanced.