Search

Poly(L‐lactic acid) (PLLA) with high ductility and transparence is fabricated by a blending tiny amount of polyvinylidene fluoride (PVDF) and reactive comb compatibilizers (RCC). Upon blending, the reaction between terminal carboxyl groups in PLLA and expoxy groups in RCC produces graft copolymer (PLLA‐g‐poly(methyl methacrylate) (PMMA)), which locates at the PVDF/PLLA interface due to the balanced stress on two sides. On the one hand, the PVDF domain size decreases remarkably with the help of compatibilization, accounting for the excellent transparence. On the other hand, the interface is enhanced significantly, resulting in an activated PLLA layer surrounding PVDF domains. The thickness exhibits higher magnitude because of the high molecular weight of grafted PLLA (relative to premade compatibilizers). During uniaxial tension, the activated PLLA layers (in addition to PVDF) can cause effective energy absorption and dissipation in the case of percolation of them, which is the reason for the better ductility. These results provide an efficient strategy to improve the ductility and transparence simultaneously. [ABSTRACT FROM AUTHOR]

Reactive polymer processing is an effective and environmentally-friendly means of preparing new materials based on combining components with various properties. Numerous investigations have been carried out to explore the reaction processes that occur during the melt blending of polymers. However, reactive processing is far from fully understood because it involves a complicated combination of shear and extensional flows as well as high temperatures and pressures. In this work, a two-step compatibilizing strategy (called reactive splicing compatibilization) has been used to compatibilize immiscible Poly(lactic acid) (PLLA)/Poly(butylene adipate- co -terephthalate) (PBAT) blends with two different PBAT molecular weights (termed H-PBAT and L-PBAT, respectively), using styrene- co -glycidyl methacrylate (SG) as the grafting counterpart. Reactive compatibilizers with various architectures were prepared by pre-grafting either PLLA or PBAT (or both) onto the SG main chains. The remaining unreacted epoxide groups of the pregrafted SG underwent in situ reactions to form double grafted copolymers as compatibilizers for the final blends. The reactivity of SG with these polymers was found to decrease in the order of L-PBAT > PLLA > H-PBAT. Reactive compatibilizers having various architectures were applied to PLLA/PBAT blends with compositions ranging from 90/10 to 10/90 (w/w). The most efficient pre-grafted reactive compatibilizer was determined for the blends with certain composition. A higher proportion of H-PBAT had to be pre-grafted onto the SG to achieve the best compatibilization efficiency when increasing the PLLA content in PLLA/H-PBAT blends. In the case of PLLA/L-PBAT blends, PLLA chains had to be pre-grafted onto the SG for the best compatibilization when L-PBAT was the primary component of the blend. These results provide a better understanding of the reactive processing mechanism. Evidently, the dynamic shear applied during melt processing continuously renews the interface between the different phases to provide sites for reactions between the blend components. These reactions are affected by both the reactivity of the components and the contact time, which in turn is determined by the blend composition. The compatibilizers located at the blend interface were found to have very similar symmetrical binary grafted structures for blends with different compositions. Image 1 • A two-step compatibilizing strategy (called reactive splicing compatibilization) has been used to compatibilize the immiscible Poly(lactic acid) (PLLA)/Poly(butylene adipate- co -terephthalate) (PBAT) blends with two different PBAT molecular weights, using styrene-co-glycidyl methacrylate (SG) as the grafting counterpart. • More than 100 compatibilized blends have been prepared and compared the compatibilization effects of the different compatibilizers. • This work demonstrates the locations of the various reactions and the factors affecting the reactive processing. • The work is very important for better understanding the reactive processing, especially the functions of the dynamic shearing, the reactivity and the composition effects. [ABSTRACT FROM AUTHOR]