功能化六方BN纳米片/聚乙烯醇复合材料的制备及力学性能

利用三聚氰胺辅助机械球磨剥离六方BN （h-BN），对剥离得到的三聚氰胺功能化h-BN纳米片（f-BNNS）的厚度、形貌及结构进行表征。对f-BNNS/聚乙烯醇（PVA）复合材料进行了研究，考察h-BN的剥离及表面改性对f-BNNS/PVA复合材料力学性能的影响，分析f-BNNS与PVA基体的界面相互作用机制。结果表明：f-BNNS呈现较规则的圆片状，厚度在1~3 nm之间，直径集中在150~400 nm。与h-BN/PVA相比，f-BNNS在PVA基体中显示出更优异的分散效果，填充相同质量分数下，f-BNNS/PVA的屈服强度及模量得到明显的提高。当f-BNNS填充质量分数为5wt%时，屈服强度和弹性模量分别达到175.2 MPa和4.52 GPa，较纯PVA分别增加了45.3%和53.7%。通过f-BNNS和PVA分子结构及断面形貌分析可以推断，f-BNNS表面大量氨基与PVA分子羟基间氢键相互作用有效提升了填料与基体间的界面作用力。

Preparation and mechanical properties of functionalized BN nanoflakes/polyvinyl alcohol composites

Hexagonal boron nitride (h-BN) was exfoliated by ball-milling method with assistance of melamine. The thicknesses, morphologies and structures of as-prepared melamine-functionalized boron nitride nanoflakes (f-BNNS) were characterized. By investigating the f-BNNS-filled polyvinyl alcohol (PVA) composites, the effects of exfoliation of h-BN and f-BNNS on mechanical properties of composites were studied. The mechanism of interface interaction between f-BNNS and PVA matrix was also analyzed. The results show that most of the f-BNNS exhibit regular rounded flake-liked shape with diameters and thicknesses concentrated on the ranges of 1-3 nm and 150-400 nm, respectively. Comparing with h-BN-filled h-BN/PVA composites, f-BNNS can be well dispersed in PVA matrix. In mean time, the yield strength and elastic modulus of f-BNNS/PVA composites are both improved. When the mass fractions of f-BNNS achieves at 5wt%, the yield strength and elastic modulus f-BNNS/PVA composite films are 175.2 MPa and 4.52 GPa, which are 45.3% and 53.7% higher than that of neat PVA, respectively. From the molecular structures of PVA and f-BNNS and the SEM images of fracture surfaces of f-BNNS/PVA composites, the hydrogen-bonding interaction between the amino groups of f-BNNS and the hydroxyl groups of PVA chains effectively enhances the interfacial interaction between f-BNNS and PVA matrix.