女人爱骚男人爱操B免费视频,中国中老年熟妇性色av,声入人心加长版在线看

Info

Title:: Self-Healing Supramolecular Polyurethane Elastomers Based on Multiple Hydrogen Bonds

Author(s):: He Yufei; You Zhengwei; Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, Research Base of Textile Materials for Flexible Electronics and Biomedical Applications of China Textile Engineering Society,State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201600, China

Keywords:: multiple hydrogen bond; polyurethane; self-healing; supramolecule elastomer; elastomer

Abstract:: Multiple hydrogen bonds are a kind of supramolecular interactions with high bonding strength and dynamic reversibility, which can form physical crosslinking networks in linear polymers to improve the mechanical strength of materials and endow them with good selfhealing ability. Polyurethane with multiple hydrogen bond physical crosslinking structure was synthesized from polytetrahydrofuran, hexamethylene diisocyanate and 2,4-diamino-6hydroxypyrimidine. When the molar ratios of polytetrahydrofuran and chain extender 2,4-diamino-6-hydroxypyrimidine were 7∶3 and 5∶5, supramolecular polyurethane elastomers with mechanical strength and self-healing ability were obtained. The chemical structure and basic properties were characterized by 1H-NMR, IR, gel permeation chromatography, differential scanning calorimetry and rheological test. Comparison of the mechanical and self-healing properties of two groups of elastomers revealed that the different composition altered the physical crosslinking density of multiple hydrogen bonds and the mobility of the molecular chain. When the mole ratio of polytetrahydrofuran and chain extender was 7∶3, material had higher elongation at break (1280%); when the molar ratio was 5∶5, the material had better deformation recovery ability during cyclic stretching, and the stress relaxation was slower; both groups of elastomers showed definite selfhealing ability at 60 ℃.