Study On The Influences Of Topological Ionic Liquid Oligomer On The Aggregation Structures And Mechanism Of Interfacial Controlling Of PLA/PCL Blends

In this work, linear PEG oligomer contained imidazolium ionic liquid moiety (LIL)/Poly(lactic acid)(PLA) and Tri-arm star-shaped PEG oligomer contained imidazolium ionic liquid moiety (TSIL)/Poly(lactic acid)(PLA) samples were prepared, respectively, by blending method in this work. We investaged the synergetic effects of PEG arm and ionic liquid moiety contained in the tri-arm shaped PEG oligomer on the crystalline behavior of PLA. During the ivestagation, both isothermal and non-isothermal crystallization progress were investagated using differential scanning calorimetry (DSC). And crystallization kinetic parameters of the two kinds of blends, such as relative crystallinity (Xt), crystallization half time (f1/2), and Avrami exponents (n) were determined by Avrami and Mo Method. In this work, poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL) blends were also prepared by melting blending method. The phase behavior of the blends was investigated by SEM and rheometer. The prepared diblock copolymer PEG-6-PCL and mPEG-b-PCL(IL) were adopted to modify poly(lactic acid) (PLA) and poly(ε-caprolactone)(PCL) by melt blending.From the results, we can see that:(1) Both of the LIL and TSIL can accelerate the crystallization progress of PLA, but the results of TSIL was worse than that of LIL as the branching structure. The incorporation of both the LIL and TSIL would inhibit the nucleation of PLLA and accelerate the growth rate of the spherulites;(2) From the results we also can make sure the kinetics equation proposed by Mo can describe the crystallization process well;(3) For the incompatible PCL/PLA blend, three typical immiscible morphologies, spherical droplet, fibrous and co-continuous structures can be observed at various compositions. The phase inversion is close to the PLA weight of 60wt%;(4) The influences of both PEG-b-PCL and PEG-b-PCL(IL) on the mechanical properties of PLA/PCL blends were investigated. The results are as follows.Because the PEG-b-PCL and PEG-b-PCL(IL) containing both of PEG segment and PCL segment, the chains of molecules can tangle more easily at the interface of PLA/PCL blends;(5) As the weight content of PEG-b-PCL or PEG-b-PCL(IL) increased, they would form micel, the results became worse. The addition of PEG-b-PCL played an important role on the mechanical properties of PLA/PCL blends. It can improve the elongation at break of the blends significantly without decreasing the modulus and the tensile strength.