私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

Links
Contact Info.
  • Address:杭州市浙大路38號浙大玉泉校區第十教學大樓(石化大樓)4111室
  • Zip:310027
  • Tel:0571-87952631
  • Fax:0571-87951612
  • Email:wulinbo@zju.edu.cn
Current Location :> Home > News > Text
An article entitled "Biobased poly(butylene 2,5-furandicarboxylate) and poly(butylene adipate-co-butylene 2,5-furandicarboxylate)s: From synthesis using highly purified 2,5-furandicarboxylic acid to thermo-mechanical properties" published in Polymer (2014)
   To synthesize high quality (co)polyesters derived from 2,5-furandicarboxylic acid (FA), an acetic acid refluxing/pH-swing method was proposed to purify FA. 2-Carboxyl furfural and other impurities were removed completely from FA with this method. Using highly purified FA, biobased polyester poly(butylene furnadicarboxylate) (PBF) and aliphatic-aromatic copolyesters poly(butylene adipate-co-butylene 2,5-furandicarboxy-late)s (PBAFs) were synthesized via melt (co)polycondensation. The (co)polyesters were characterized with GPC, FTIR, 1H NMR, DSC and TGA, and their tensile mechanical properties were also assessed. The copolyesters possess random chain structure, monomer feed ratio-controlled copolymer composition and excellent thermal stability (Td,5% > 340 oC) in full composition range. Both BA-rich and BF-rich PBAFs are crystalline polymers. The crystallizability decreases with composition, up to nearly amorphous at moderate ?BF (40-60%). PBAFs with ?BF no more than 50% exhibit obvious high-elastic deformation and rebound resilience, and possess tensile properties (E 18-160 MPa, sb 9-17 MPa, eb 370-910%) comparable to poly(butylene adipate). PBAFs with higher ?BF behave like nonrigid plastics with low tensile moduli (42-110 MPa), moderate strength (30-42 MPa) and high elongation at break (310-470%). In comparison, PBF is a strong and tough thermoplastic having balanced mechanical properties, namely, much higher tensile modulus (1.9 GPa) and strength (56 MPa) and high elongation at break (260%). It seems necessary and effective to use highly purified FA for synthesizing high performance FA-derived (co)polyesters.