| The concept of "green economy" is growing in popularity, With the reduction of petroleum resources and the environmental awareness of the people.Theresearch of preparing a new material which is low-carbon and environmentallyfriendly is a general trend to solve our energy resources and environmentalissues.PLLA as a novel biodegradable polymer materials which is expected toreplace oil-based plastics,has become the hotspot of the world today with itsexcellent biodegradable and safe environmental performance.PLLA with highmolecular weight was prepared by melt/chain-extended polycondensation meth-od. The composite nanofibers of wheat protein/PLLA and wheat protein/PVAwere fabricated via electrospinning. Moreover， the composite nanofibers wereinvestigated by Fourier transform infrared (FT-IR), scanning electron microsco-py (SEM) and X-ray diffraction (XRD). The main results are as follows:（1）The following optimal process parameters of melt polymerization ofPLLA were ascertained by single factor and orthogonal experiments: SnCl2usedas catalyst (the dosage was0.6%), reaction temperature was175OC, reactiontime was5h, vacuum condition was about200Pa. Under the conditions, theviscosity-average relative molecular mass of pale PLLA was up to60089.（2）Results of single factor experiment show that the optimal reactioncondition of chain-extended PLLA by TDI were as follows: reactiontemperature was160OC, vacuum condition was about200Pa, reaction time was30min, the dosage of TDI was9%， Under the conditions, the viscosity-averagerelative molecular mass of PLLA was up to84104.（3）The uniform and smooth wheat protein/PLLA composite nanofiberswith average diameter of0.965um could be prepared at the following optimalprocess parameters: the concentration of solution was30%(the solvent wasHFIP)， the weight ratio of wheat protein to PLLA was1:1, the applied voltagewas12kV, and working distance was15cm.（4）The uniform and smooth wheat protein/PVA composite nanofiberswith average diameter of0.280um could be prepared at the following optimalprocess parameters: the concentration of solution was10%， the weight ratio ofPLLA to wheat protein was2:8, the applied voltage was12kV, and working distance was12cm.（5）There exist hydrogen bonds between wheat protein and PLLA (or PVA)in the composite nanofibers. After electrospun, crystallinity of PLLA (or PVA)was destroyed significantly by high voltage in the composite nanofibers. Thedecrease of crystallinity proved that electrospinning effectively improved thecompatibility between wheat protein and PLLA (or PVA) in the compositenanofibers. |
