Lewandowska Anna E, Inai Nor H, Ghita Oana R, Eichhorn Stephen J
College of Engineering, Mathematics & Physical Sciences, University of Exeter North Park Road Exeter EX4 4QF UK
Bristol Composites Institute (ACCIS), Department of Aerospace Engineering, University of Bristol Queen's Building, University Walk Bristol BS8 1TR UK
RSC Adv. 2018 Oct 19;8(62):35831-35839. doi: 10.1039/c8ra06674d. eCollection 2018 Oct 15.
Cellulose nanofibers hold much promise for enhancing the mechanical properties of composites owing to their uniquely high stiffness and strength. One major issue limiting this performance however is the dispersion and mixing of cellulose nanofibers within thermoplastic resins. A combination of Raman imaging and chemical analysis has been used to quantify the distribution and mixing of cellulose nanocrystals (CNCs) in a polyethylene-matrix composite. Large area spectral imaging provides information about the effect of a compatibilizer - namely poly(ethylene oxide) (PEO) and maleated polyethylene (MAPE) - on the distribution of CNCs in the thermoplastic matrix. High-resolution images enable quantification of the degree of mixing between the CNCs and HDPE. Lower resolution images, but with greater spatial spread, allow quantification of the distribution of the CNCs. It is shown that the CNCs tend to agglomerate, with little increase in distribution even with the use of the compatibilizer. A shift in the position of characteristic Raman bands indicates the formation of hydrogen bonding between the PEO compatibilizer and the CNCs, which in turn is thought to affect the distribution of aggregates of the reinforcing phase.
由于其独特的高刚度和强度，纤维素纳米纤维在增强复合材料的机械性能方面具有很大潜力。然而，限制这种性能的一个主要问题是纤维素纳米纤维在热塑性树脂中的分散和混合。拉曼成像和化学分析相结合已被用于量化纤维素纳米晶体（CNC）在聚乙烯基复合材料中的分布和混合情况。大面积光谱成像提供了有关增容剂——即聚环氧乙烷（PEO）和马来酸酐接枝聚乙烯（MAPE）——对热塑性基体中CNC分布影响的信息。高分辨率图像能够量化CNC与高密度聚乙烯（HDPE）之间的混合程度。较低分辨率但空间分布更广的图像则可以量化CNC的分布情况。结果表明，CNC倾向于团聚，即使使用增容剂，其分布增加也很少。特征拉曼谱带位置的移动表明PEO增容剂与CNC之间形成了氢键，这反过来又被认为会影响增强相聚集体的分布。
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