Comparison of nanocrystalline cellulose dispersion versus surface nucleation in poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) crystallization
Comparison of nanocrystalline cellulose dispersion versus surface nucleation in poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) crystallization
复制标题
DOI：
10.1002/pls2.10011
复制
发表时间：
2020-09
期刊：
影响因子：
--
通讯作者：
H. Haham;Mo-Yuan Shen;S. Billington;C. Frank
中科院分区：
文献类型：
--
作者：
H. Haham;Mo-Yuan Shen;S. Billington;C. Frank
纳米结晶纤维素（NCC）是一种已知的晶体成核剂，用于改善聚（3-羟基丁酸酯-共-3-羟基戊酸酯）（PHBV）的热性能。由于NCC在PHBV中的聚集对复合材料性能和可加工性产生负面影响，因此在等温和非等温条件下在低浓度（<1%）下检查NCC晶体成核有效性。采用溶剂交换法将NCC分散在PHBV溶液中，然后浇铸成膜。我们发现，NCC是一种有效的成核剂，其量低至0.25%，导致PHBV结晶速率增加50%以上。然而，增加到1%NCC导致PHBV聚集，与较低的NCC浓度相比，NCC变得不那么有效。为了改善NCC的分散性，我们将醋酸纤维素（CA）或硬脂酸（SA）加入到浇铸溶液中，预期CA或SA将优先吸附在NCC上。通过这样的预处理，分散性确实得到改善，但NCC作为PHBV成核剂变得不太有效。该工作显示了使用低NCC浓度（<0.5%）促进PHBV结晶的优点，但是在添加CA和SA时缺乏改进的成核支持了NCC表面可及性的重要性。
Nanocrystalline cellulose (NCC), which is a known crystal nucleating agent, is utilized to improve poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) thermal properties. Since NCC aggregation in PHBV negatively affects composite properties and processability, NCC crystal nucleation effectiveness was examined at low concentrations (<1%) under isothermal and nonisothermal conditions. NCC was dispersed in PHBV solutions using a solvent exchange method and then cast into films. We found that NCC was an effective nucleating agent in amounts as low as 0.25%, resulting in an increase in PHBV crystallization rate by more than 50%. However, increasing to 1% NCC resulted in aggregation in PHBV, with the NCC becoming less effective compared to lower NCC concentrations. In an attempt to improve NCC dispersion, we added cellulose acetate (CA) or stearic acid (SA) to the casting solution, anticipating that CA or SA would preferentially adsorb on the NCC. With such pretreatment, dispersion was indeed improved but NCC became less effective as a PHBV nucleating agent. This work shows the advantage of using low NCC concentrations (<0.5%) for promoting PHBV crystallization, but the lack of improved nucleation upon addition of CA and SA supports the importance of NCC surface accessibility.