Effect of Different Comonomers Added to Graft Copolymers on the Properties of PLA/PPC/PLA-g-GMA Blends

Abstract

The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged.

The Effect of Functionalized SEBS on the Properties of PP/SEBS Blends

“…By enlarging the regions of 5.1–2.3 ppm and 7.8–7.2 ppm, four signal peaks at 7.73, 7.56, 7.41, and 2.55 ppm appear in the 1 H-NMR spectrum of the SEBS-g-(GMA-co-St) graft copolymer, which are generally attributed to the signal peaks of St. Furthermore, five signal peaks appear at 4.39, 3.87, 2.78, 2.67, 1.85, and 1.53 ppm, which are generally attributed to the signal peaks of GMA [ 55 , 56 , 57 ]. This indicates that GMA has successfully grafted onto the SEBS macromolecular chain under the promotion of St.…”

“…When the Q values of two monomers are close, they are more likely to undergo copolymerization. As shown in Table 4 , the Q and e values of GMA and St are similar [ 56 , 59 , 60 ]. …”

“…This similarity promotes the reaction between GMA and St, thereby driving the progression of the macromolecular free radical copolymerization reaction, which makes GMA more likely to copolymerize with St macromolecular free radicals. Generally speaking, the use of co-graft monomers can significantly enhance the GD and GE of functional monomers on polymers [ 48 , 54 , 56 , 61 , 62 ]. This study used St as a co-graft monomer to graft GMA more efficiently onto SEBS, as St can activate the macromolecular chains of SEBS, providing reactive sites for GMA to graft onto SEBS [ 32 , 33 , 58 , 63 ].…”

On the Production of Poly(Lactic Acid) (PLA) Compounds with Metallic Stearates Based on Zinc, Magnesium and Cobalt. Investigation of Torque Rheometry and Thermal Properties

“…18,19 In addition, PLA has a positive environmental character since its production consumes considerable amounts of carbon dioxide; it is recyclable and compostable. 20,21 From the point of view of technical characteristics, PLA has high tensile strength, high elastic modulus, good transparency, biocompatibility, and good processability, generating potential for applications in packaging and the biomedical area. [22][23][24] Thus, PLA is considered a bioplastic with all the characteristics to replace traditional plastic.…”

Improving the Shear and Tack Strengths of Chlorinated Poly(propylene carbonate) through Chain Extension with Polylactic Acid for Biodegradable Hot Melt Adhesives

“…Although the chlorine modification of PPC has improved some of its properties, there is still a need for improvement in the thermal and mechanical properties of CPPC. To enhance the above performances, several substances have been incorporated, such as polylactic acid (PLA), starch, natural fibers, , and maleic anhydride . One of the advantages of PLA is that it can be sourced from renewable resources, making it an environmentally friendly and fully biodegradable material .…”