Mechanically adaptive nanocomposites with cellulose nanocrystals: Strain-field mapping with digital image correlation.

Strain-transfer plays a key role in overall modulus of mechanically adaptive nanomaterials. Herein, mechanically adaptive nanocomposites were prepared via introducing cellulose nanocrystal (CNC) percolating network into poly butyl methacrylate (PBMA) with polyethylene glycol (PEG) as a stabilizer. The prepared PBMA/CNC nanocomposites were soaked in deionized water at 23 °C and 37 °C for one week to investigate their mechanically adaption. The interactions between PEG, CNC, and PBMA were assessed by Fourier Transform infrared, X-ray diffraction, and X-ray photoelectron spectroscopy. Incorporation of PEG to CNC and PBMA/CNC nanocomposites on the morphological and thermal properties was also investigated. The mechanical adaption of PBMA/CNC nanocomposites after switching dry-to-wet state and surrounding temperature (soaked in deionized water at 23 °C and 37 °C for one week, respectively) was evaluated by mechanical testing. Meantime, digital image correlation (DIC) was firstly used to study strain transfer mechanism in mechanical adaption which was carried out in real-time synchronized with mechanical measurement. It indicated that PEG improved the dispersion of CNC in PBMA/CNC nanocomposite and its thermal properties. Furthermore, CNC with PEG modification bridged PBMA during crack propagation and promoted the stress and stain transfer in PBMA/CNC nanocomposites according to DIC analysis.