title: High strength of hemicelluloses based hydrogels by freeze/thaw technique.
abstract: Novel hydrogels were prepared from hemicelluloses, polyvinyl alcohol (PVA), and chitin nanowhiskers through 0, 1, 3, 5, 7, and 9 times of freeze/thaw cycle. These hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), swelling property, and compressive strength. The repeated freeze/thaw cycles induced physically crosslinked chains packing among these polymers, and a phase separation caused by the hydrogen bonds. Larger pores led to a high swelling degree, whereas the formation of compact structure after multiple freeze/thaw cycles resulted in high mechanical strength and thermal stability. The highest compressive strength of these hydrogels was achieved by the 9 times of freeze/thaw cycles with compressive stress of 10.5 MPa. This work provides a remarkable way for the preparation of hydrogels with good mechanical properties by physical method.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Guan
authors.forename: Jing
authors.initials: J
authors.lastname: Bian
authors.forename: Feng
authors.initials: F
authors.lastname: Peng
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Zhang
authors.forename: Run-Cang
authors.initials: RC
authors.lastname: Sun
mesh_terms: D002686:Chitin / Q000737:chemistry; D019245:Compressive Strength; D005615:Freezing; D020100:Hydrogels; D011134:Polysaccharides / Q000737:chemistry*; D011142:Polyvinyl Alcohol / Q000737:chemistry
chemical_list: D020100:Hydrogels; D011134:Polysaccharides; D002686:Chitin; C007916:hemicellulose; D011142:Polyvinyl Alcohol
keywords: Chitin nanowhiskers; Freeze/thaw cycle; Hemicelluloses; Hydrogel; Polyvinyl alcohol