MWNT的分散性及其对复合水泥基材料力学性能的影响

Dispersivity of Multi-Walled Carbon Nanotube and Its Effect on the Mechanical Properties of MWNT/Cement Composite

以4种表面活性剂(SAA)(十二烷基硫酸钠(SDS)、曲拉通x100(Tx100)、十六烷基三甲基溴化铵(CTAB)、阿拉伯胶(GA))分别作为多壁纳米碳管(MWNT)分散剂,结合静置及离心分离观察法评价MWNT在水中的分散性;混合浇筑了4组经不同SAA分散、MWNT掺量均为0.21%(相对于水泥质量)的MWNT/水泥基复合材料(MWNT/CCs),同时制备了空白试件(PCP),测试了各组试件的抗折强度σf及抗压强度σc,并观察了用GA分散的MWNT/CC及PCP试样的显微结构.静置3 h后,4种MWNT悬浮液黑度均匀,但在5 000 r/m in离心分离后显示:GA对MWNT分散效果最好,离心90 m in才开始分层;SDS效果最差,离心10 m in就开始分层.相比PCP,用GA分散的MWNT/CC的σf、σc提高幅度最大,分别达31.5%、23.6%,表明MWNT在基体中能较好地发挥纤维拔出和桥联作用;TEM及SEM图也显示MWNT在水及相应水化产物中分布较均匀,MWNT与基体界面结合良好.

Four surfactants （SAA） （sodium dodecyl sulfate （SDS）, Triton x 100 （Tx100）, cetyltrimethyl ammonium bromide （CTAB）, and gum Arabic （GA）） have been used as dispersants to measure the dispersivity of multi-walled carbon nanotube （MWNT） in aqueous media by incubation and centrifugation method. Four groups of MWNT/cement composites （MWNT/CCs） with 0.21% loading （by mass of cement） of MWNT and various SAA dispersions have been east-mixed and the plain cement pastes （PCP） have been fabrieared. Their flexural o-f and compressive strengths σe have been measured, and mierostruetures of MWNT/CC with GA dispersion and PCP samples have been compared. Results show that, after incubation for 3 h, each of the four MWNT suspended solutions had the uniform blackness, yet GA had the best dispersion impact on MWNT as the solution retained stabilization till after 90 min at 5 000 r/min centrifugation, and SDS had the worst effect as the solution remained stable only for 10 rain after centrifugation. Compared with PCP, enhancement of o-f and trc of MWNT/CC with GA dispersion is the maximal, up to 31.5% and 23.6% respectively, which reveals that MWNT has superior fiber pulling-out and bridging effect amongst cement matrix. TEM and SEM images also demonstrate that MWNT is well distributed in aqueous water and cement hydrated products, and there exists good interracial bonding between MWNT and matrix.