亚麻分层纳米纤维素的制备及其增强热电复合材料性能

为从天然亚麻纤维中制备出分层纳米纤维素(即纤维素纳米纤维(CNF)与纤维素纳米晶(CNC)共存),并对其制备方法进行优化完善,提出将亚麻纤维在特定浓度的氢氧化钠溶液中碱化处理后,再进行四甲基哌啶氮氧化物(TEMPO)介导的三元氧化和机械处理的联合处理方法。然后将亚麻CNF与石墨烯复合制备CNF/石墨烯复合薄膜并研究亚麻CNF增强热电复合材料的性能。结果表明:碱化预处理使亚麻纤维直径变细,长度变短,半纤维素被脱除,是生成不同尺寸CNF的重要步骤;随着氢氧化钠用量在0~18%范围内的增加,所得CNF悬浮液的光透过率从3.7%增加到95.1%;CNF/石墨烯复合膜表现出最高功率因子,为8.0×10 ^-3 μW/(m·K ²),表明复合薄膜具有热电性能。

Preparation of flax layered nano-cellulose and properties of its reinforced thermoelectric composites

In order to prepare layered nano-cellulose from natural flax fiber,i.e.coexistence of cellulose nanofiber(CNF)and cellulose nanocrystalline(CNC),and improve the preparation method of CNF from flax fiber,a method of alkaline treatment of flax fiber in a specific concentration of sodium hydroxide solution,followed by tempo mediated ternary oxidation and mechanical treatment,was proposed.The CNF/graphene composite films were prepared by compounding flax CNF with graphene to study the properties of flax CNF reinforced thermoelectric composites.The results show that the diameter and length of flax fiber become smaller and the hemicellulose is removed after alkaline pretreatment,which is an important step towards generation of CNF with different sizes.The optical transmittance of CNF suspension increases from 3.7%to 95.1%with the increase of NaOH concentration in the range of 0-18%,and the highest power factor of CNF/graphene composite film is 8.0×10-3μW/(M·K2),which indicates that the composite film has thermoelectric properties.