In Situ Synthesis of Environmentally Friendly Waterborne Polyurethane Extended with Regenerated Cellulose Nanoparticles for Enhanced Mechanical Performances

Abstract

The development of waterborne polyurethane (WPU) has been stimulated as an alternative to solvent-based polyurethanes due to low-VOC alternatives and reduced exposure to solvents. However, their relatively low mechanical performance and degradation have presented challenges in their wide application. Here, we developed environmentally-friendly bio polyol-based WPU nanocomposite dispersions and films, and presented the optimal process conditions for their manufacture. Additionally, the condition was established without using harmful catalysts or ethyl methyl ketone (MEK) during the polymerization. Moreover, regenerated cellulose nanoparticles (RCNs) were employed as natural chain-extenders in order to improve the biodegradability and mechanical performances of the nanocomposite films. The RCNs have a lower crystallinity compared to cellulose nanocrystals (CNCs), allowing them to possess high toughness without interfering with the elastomeric properties of polyurethane. The prepared CWPU/RCNs nanocomposite films exhibited high toughness of 58.8 ± 3 kgf∙mm and elongation at break of 240 ± 20%. In addition, depending on the molar ratio of NCO/OH, the polyurethane particle size is variously controlled from 70 to 230 nm, enabling to fabricate their dispersions with various transmittances. We believe that our findings not only open a meaningful path toward green elastomers with biodegradability but provides the design concept for bio-elastomers in order to develop industrial elastomers with mechanical and thermal properties.

Effects of cellulose micro and nanocrystals on the mechanical, thermal, morphological, and structural properties of rigid polyurethanes

“…However, the high percentage of MCC generally decreased both tensile strength and tensile modulus. This effect was attributed to MCC particle aggregation during solvent casting as determined by Choi et al (2023). As a result, both flexural and tensile results enhanced with the addition of both the fillers, and the effects of CNC on the mechanical properties were higher than that of MCC due to both lower particle size and the higher crystallinity of CNC as presented in dos Santos et al (2017).…”

Exploring the Impact of the Synthesis Variables Involved in the Polyurethane Aerogels-like Materials Design

“…Another parameter to be considered when performing the polymerisation step is the proportion of chain extender added depending on the amount of free isocyanate groups at that time [ 27 , 28 ]. The chain extender compound should be added in a slight excess to promote the reaction with the isocyanate groups.…”

“…The chain extender compound should be added in a slight excess to promote the reaction with the isocyanate groups. However, it is important to avoid adding an excessive amount to prevent degradation over time, which could result in the loss of the distinctive physical and chemical properties that characterize these materials [ 27 ]. This careful balance ensures their suitability for future applications and prevents their wastage [ 29 , 30 ].…”