Abstract

In the present study, a suspension of nanofibrillated cellulose from eucalyptus was spray-dried in order to obtain a powdered material that could be easily transported and stored. The original suspension and the dried material were characterized for their physical, morphological and thermal properties. An increase in crystallinity and reduction in thermal stability were observed after drying. In addition, the fibrils size passed from nano to micro scale The powder obtained was rehydrated and homogenized by two methods: rotor-stator homogenization (5000, 10,000 and 15,000 rpm) and ultrasound (10, 30 and 50% maximum amplitude), during 3 and 5 min, in order to verify the possibility of obtaining a stable reconstituted suspension comparable to the original one. Higher treatment intensities resulted in suspensions with higher viscosity and stability. The suspension homogenized by ultrasound at 50% amplitude for 5 minutes was the most stable one and restored the nano dimensions of the original suspension. Both the original and the reconstituted suspensions showed a shear thinning and “gel-like” behavior. Higher Ultra-Turrax speed and ultrasound amplitude resulted in higher viscoelastic modulus (G′ and G″), although these values were lower than those found in the initial nanocellulose suspension.

Graphic abstract

中文翻译：

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喷雾干燥的纳米原纤化纤维素的表征以及不同的均质化方法对重构悬浮液的稳定性和流变性的影响

摘要

在本研究中，将来自桉树的纳米原纤化纤维素的悬浮液喷雾干燥，以获得易于运输和储存的粉末状材料。对原始悬浮液和干燥的材料进行了物理，形态和热性能表征。干燥后观察到结晶度的增加和热稳定性的降低。此外，原纤维的尺寸从纳米级到微米级。通过三种方法将获得的粉末重新水化和均质化：转子定子均质化（5000、10,000和15,000 rpm）和超声（最大振幅分别为10％，30％和50％） 5分钟，以验证获得与原始悬浮液相当的稳定的再生悬浮液的可能性。较高的处理强度导致悬浮液具有较高的粘度和稳定性。通过超声在50％振幅下均化5分钟的悬浮液是最稳定的悬浮液，并恢复了原始悬浮液的纳米尺寸。原始悬浮液和重组悬浮液均显示出剪切稀化和“凝胶状”行为。较高的Ultra-Turrax速度和超声波振幅会导致较高的粘弹性模量（G'和G''），尽管这些值低于初始纳米纤维素悬浮液中的值。

图形摘要