PAA对PLA流变性能和热性能的影响

通过熔融共混法制备了一系列的PLA/PAA共混物,考察了PLA/PAA共混体系的流变行为和热性能(结晶行为和热降解行为).FTIR测试结果证实PLA与PAA分子链之间形成了氢键网络.动态剪切流变测试和DSC测试均表明共混体系的流变行为和冷结晶行为会随着PAA含量的改变而改变,这可能是由于PLA与PAA的氢键作用受到PAA含量的影响.另外,DSC测试证实共混体系中的氢键网络还会受到试样热历史的影响.当PAA含量较低(低于5 wt%)时,PLA/PAA共混体系中PAA与PLA熔体两相的相分离不严重,使得PAA与PLA分子链能够较大限度地接触而形成较强的氢键作用,因而可以明显减缓增塑作用对黏度降低的影响.

EFFECT OF POLY(ACRYLIC ACID) ON THE RHEOLOGICAL AND THERMAL PROPERTIES OF POLY(LACTIC ACID)

Poly(lactic acid)/poly(acrylic acid) blends(PLA/PAA) were prepared by melt blending.The hydrogen-bonding between PLA and PAA was analyzed by Fourier transform infrared spectroscopy(FTIR).The rheological properties,thermal behaviors and the stability of PLA/PAA blends were also investigated by dynamical rheological test,differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The FTIR results indicated that the hydrogen-bonding interaction was existed in PLA/PAA blends between the oxygen atom of carbonyl(—C-O) on PLA and the hydrogen atom of carboxyl acid groups(—COOH) on PAA.The rheological behaviors and cold-crystallization behaviors of PLA/PAA blends were changed with the contents of PAA,because the formation of the hydrogen-bonding in PLA/PAA blends was influenced by the contents of PAA.Meanwhile,the hydrogen-bonding networks were also affected by the heating history that the blends underwent.When the content of PAA was lower than 5 wt%,PLA and PAA was partially miscible,which was favorable to the formation of hydrogen-bonding networks between PAA and PLA chains.And the formed hydrogen-bonding networks can partially decrease the effect of plastification of PAA on the viscosity of the blends.However,when the content of PAA was greater than 5 wt%,the phase separation of melt PAA and PLA became serious,which counteracted the formation of hydrogen-bonding.