层状α-磷酸锆的有机改性及其与聚乳酸复合材料研究

Modification of layered α-zirconium phosphate and its application in poly(lactic acid)/α-zirconium phosphate composites

通过对层状α?磷酸锆进行二次改性,制备具有力学性能改善的聚乳酸复合材料。首先合成一种新型阳离子插层剂十一烷醇三甲基溴化铵(UHTB),并将其用于层状化合物α?磷酸锆(α?ZrP)的改性,制备得到UHTB与α?ZrP杂化物(UHTB?ZrP),然后,利用丙交酯原位聚合对UHTB?ZrP进行表面接枝改性,得到二次改性层状α?MZrP,进而采用溶液浇铸法制备聚乳酸/有机改性α?磷酸锆复合材料(PLA/MZrP)。分别用红外光谱分析仪、激光粒度仪、X射线衍射仪、扫描电镜、透射电镜、旋转流变仪和热重分析仪等对层状α?ZrP的插层过程、微观结构以及PLA/MZrP复合材料的流变性能和热稳定性等进行表征与分析。结果表明:经过一次改性可获得层间距达到1.40 nm的UHTB?ZrP,经两步改性可获得层间距达3.80 nm的MZrP,这种纳米片层能均匀分散在PLA基体中形成纳米复合结构,并使其力学性能、加工性能和热稳定性得到改善。当添加质量分数为1%的MZrP时,PLA/MZrP复合材料的拉伸强度从31.3 MPa提高到53.5 MPa,比纯PLA提高了70.9%,而复数黏度则随着MZrP含量的增加而显著降低。当添加质量分数为3%的MZrP时,在170℃10 Hz时其复数黏度从968.1 Pa·s降低到78.7 Pa·s,比纯PLA降低了91.9%。此外,添加少量的MZrP后,PLA/MZrP复合材料的热稳定性也得到一定的改善。

In this study,1?undecaminium,11?hydroxy?N,N,N?trimethyl?,bromide(UHTB)was synthesized and introduced into the gallery ofα?zirconium phosphate(α?ZrP)as an novel cationic intercalated agent to prepare UHTB?ZrP hybrid compound by intercalation.The as?prepared UHTB?ZrP was further surface modified with DL?lactide by in?situ grafting polymerization to obtain organically modifiedα?zirconium phosphate(MZrP).Then,the biodegradable MZrP/poly(lactic acid)(PLA)composites were prepared by solution casting method.The intercalating process,microstructure,rheological properties and thermal stability of PLA/MZrP composites were investigated by laser particle size analyzer,X?ray diffractometer,scanning electron microscope,transmission electron microscope,rheometer and thermogravimetric analyzer.The results confirmed that UHTB?ZrP with the interlayer spacing of 1.40 nm and MZrP with the interlayer spacing of 3.80 nm were obtained via two?step modification.It was also found that the MZrP?nanosheets were well dispersed in PLA matrix with good compatibility,which could further improve the mechanical properties,processing properties and thermal stability of the resulting composites.The SEM and TEM analysis of MZrP and PLA/MZrP composites also confirmed the formation of layeredα?ZrP.The thickness ofα?ZrP sheets decreased after modification.No obvious separation at the interface between MZrP and PLA matrix such as extracting and stripping at the fracture interface were observed.The tensile strength of MZrP/PLA composites increased with the increase of MZrP content.When the content of MZrP reached 1 wt%,the tensile strength of the PLA/MZrP composite increased from 31.3 MPa to 53.5 MPa,which was higher than that of pure PLA.When the content of MZrP was more than 1 wt%,the tensile strength of PLA/MZrP composites decreased with the increase of MZrP content while the elongation at break decreased slightly for all composite samples.With the addition of MZrP,the complex viscosity of PLA/MZrP composites decreased continuously.When the MZrP content was about 3 wt%,the frequency complex viscosity of the composite decreased from 968.1 Pa·s to 78.7 Pa·s at 170℃and 10 Hz,which was remarkable lower than that of pure PLA.At the same time,the thermal stability of the PLA/MZrP composites was slightly improved.