Compatibilizing Effects of Maleated Poly(lactic acid) (PLA) on Properties of PLA/Soy Protein Composites

Abstract

Poly(lactic acid) (PLA)/soy protein concentrate (SPC) composites were prepared using a twin-screw extruder. Extra amounts of water and glycerol were added to SPC prior to compounding with PLA to ensure that SPC behaved like a thermoplastic during subsequent mixing. Free radical grafting of maleic anhydride (MA) onto PLA was performed by reactive extrusion, and PLA-g-MA was used as a compatibilizer in the composites. The effects of compatibilizer concentration and degree of functionality on the tensile, morphological, and thermal properties of PLA/SPC composites were studied. The tensile strength of the composites containing 4 phr compatibilizer increased by 19% compared to that of the uncompatibilized one. Also, the presence of compatibilizer resulted in finer domain sizes of SPC and a lower damping peak, both of which suggested that good interfacial adhesion between the two phases was achieved. Differential scanning calorimetry analysis indicated that SPC induced and accelerated cold crystallization of PLA.

The morphology, rheological, and mechanical properties of wood flour/starch/poly(lactic acid) blends

“…With the decrease of the starch/WF ratio, the E 0 first increased significantly then showed a tendency to be a constant value. 40 With the decrease of the starch/ WF ratio, the width of the damping peak became slightly broader, indicating the gradual increased restriction of the segment motion caused by the larger WF. This result tended to weaken the compatibility of the multiphase system, and reduced the mechanical strength of the blends.…”

Modification of interfacial adhesion with a functionalized polymer in PLA/wood composites

“…Zhou [41] and Avella [46] observed a shoulder at 1850 cm -1 on the FTIR spectra of modified PLA and assigned it to the anhydride group of MA. Based on their results they claimed successful grafting.…”

“…The preparation of MAPLA has been done in two different ways. Carlson et al [40] as well as Zhu et al [41] grafted maleic anhydride to PLA with peroxide initiation in the melt, in an extruder. Plackett [42], on the other hand, modified the polymer in solution with a different peroxide and the same approach was followed by Wu [43] as well.…”

Effect of the montmorillonite intercalant and anhydride maleic grafting on polylactic acid structure and properties

“…These compatibilizers are largely used to improve the interface adhesion between two polymers, polymer/fibers, polymer/starch… (Zhang and Sun, 2004;Nabar et al, 2005;Nyambo et al, 2011;Zhu et al, 2012). One classical way is to graft maleic anhydride (MA) onto the polymer chains.…”