Copolymerization And Compound Modification Of Novel Bio-Based Poly (Neopentyl Glycol Furandicarboxylate)

Polyester is one of the most versatile polymers and has been widely applied in plastics,fibers,elastomers,coatings,plasticizers,etc.The monomers of polyester are mainly derived from petrochemical products,so the large-scale use of polyester makes environmental and resource problems increasingly serious.Due to the huge pressure of petrochemical products on the environment,the biomass industry has developed rapidly.At present,many scholars have focused on the research and development of bio-based polyesters.Poly（neopentyl glycol furandicarboxylate）（PNF）is a new member of bio-based furan polyesters.With the aromatic rings,PNF has a high glass transition temperature,excellent thermal stability,and excellent mechanical properties.However,PNF exhibits brittleness,poor toughness,and weak crystallization ability,which must limit the practical application of PNF.In view of the inherent defects of PNF polyester,related modification studies were carried out in this dissertation.On one hand,long aliphatic segments were introduced into the PNF main chain to further improve the thermomechanical properties.On the other hand,MWCNTs were introduced into the PNF matrix by an in-situ polymerization to promote the crystallization performance of PNF,hoping to further expand the potential application of PNF.1.Poly（neopentyl glycol furandicarboxylate-co-adipate）copolyestersA series of poly（neopentyl glycol furandicarboxylate-co-adipate）（PNFAs）copolyesters were synthesized by a melt polycondensation from dimethyl-2,5-furandicarboxylate（DMFD）,neopentyl glycol（NPG）,and adipic acid（AA）.The composition,thermal properties,and crystallization behavior were invesitigated in detail.Thermogravimetric analysis results showed the introduction of neopentyl glycol adipate（NA）segments would reduce the thermal stability of polyesters,but the decomposition temperature at 5%weight loss of all copolyesters were still above 360 ℃,which revealed a good thermal stability of PNFAs.The DSC studies proved that the T_gand T_mof PNFAs decreased significantly with the increase of NA content.The introduction of NA did not change the crystal structure of PNFAs,while reduced copolyesters’crystallinity and crystallization rate.Furthermore,the introduction of flexible NA segments realized the transition of polyesters from hard to soft;especially,the elongation at break of PNFA30,a copolymer containing 30 mol%of NA,was as high as 749.9%.2.Poly（neopentyl glycol furandicarboxylate）/multi-walled carbon nanotubes compositesPNF/MWCNTs composites containing 0.2 and 0.5 wt%MWCNTs were prepared by an in-situ melt polycondensation.Scanning electron microscopy results show that the MWCNTs were uniformly dispersed in the PNF matrix.With the introduction of MWCNTs,the thermal stability of the PNF/MWCNTs composite was slightly improved.MWCNTs significantly enhanced the crystallization of PNF under isothermal and non-isothermal crystallization conditions as heterogeneous nucleating agents.Only 0.5 wt%of MWCNTs significantly increased the melt crystallization temperature from132.9 ℃ for PNF to 141.2 ℃ for the composite and reduced the crystallization half-time(t_0.5)from 3.1 min for pure PNF at 165 ℃ to 1.9 min for the composite.Furthermore,MWCNTs did not alter the crystal structure of PNF.In brief,the above studies showed that the introduction of long aliphatic segments into PNF main chain may adjust the thermomechanical properties of PNF in a wide range and expand the potential application of PNF.At the same time,the introduction of MWCNTs could greatly improve the crystallization properties of PNF and have a positive impact on the processing of PNF materials.