Tuning the mechanical and thermomechanical properties through the combined effect of crosslinking and annealing in poly(lactic acid)/acrylonitrile‐EPDM‐styrene blends

• Published in: Journal of applied polymer science 2024-06, Vol.141 (22), p.n/a
• Main Authors: Luna, Carlos Bruno Barreto, Da Silva Barbosa Ferreira, Eduardo, Do Nascimento, Emanuel Pereira, Da Silva, Adriano Lima, De Albuquerque, Ananda Karoline Camelo, Wellen, Renate Maria Ramos, Araújo, Edcleide Maria
• Format: Article
• Language: English
• Subjects: Annealing; Biodegradable materials; biopolymers and renewable polymers; compatibilization; Crosslinking; Crystallinity; crystallization; Dicumyl peroxide; Elongation; Fourier transforms; Hardness; Heat treatment; Impact modifiers; Impact strength; Infrared spectroscopy; Mechanical properties; Melt flow index; Modulus of elasticity; Polylactic acid; Polymer blends; Styrenes; Terpolymers; Thermal stability; Thermomechanical properties; Torque; X-ray diffraction
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.55446

Acrylonitrile‐EPDM‐styrene (AES) was applied as an impact modifier for poly(lactic acid) (PLA), and the combined effect of dicumyl peroxide (DCP) crosslinking and annealing heat treatment was investigated. Torque rheometry, melt flow index (MFI), mechanical properties (impact, tensile, and Shore D hardness), X‐ray diffraction (XRD), infrared spectroscopy (FTIR), heat deflection temperature (HDT), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were investigated. There was a considerable torque increment and fluidity drop in the PLA/AES/DCP blends caused by the crosslinking process and the formation of PLA‐g‐AES. Consequently, the impact strength and elongation at break properties improved. As an engineering terpolymer, AES was decisive in maintaining high elastic modulus, Shore D hardness, and HDT values. The PLA/AES/DCP (0.8 phr) composition leaned towards a synergism of mechanical properties, gaining 505.6% and 264.8% in impact strength and elongation at break, respectively, compared to neat PLA. FTIR and XRD analysis revealed high crystallinity, with samples presenting large crystals. The higher crystallinity had a deleterious effect on the mechanical properties of the PLA/AES/DCP blends. However, there was a marked improvement in HDT and higher toughness compared to PLA. The results before and after annealing the PLA/AES/DCP (0.8 phr) blend are promising for constructing new semi‐biodegradable materials for additive manufacturing. The crosslinking of the PLA/AES blend with dicumyl peroxide in the molten state formed a tough material, suggesting the formation of PLA‐g‐AES.