Blends of Poly (Butylene Adipate-Co-Terephthalate) and Thermoplastic Whey Protein Isolate: A Compatibilization Study

Abstract

This work assesses the in uence of the plasticizer polyethylene glycol (PEG) on the compatibilization of poly(butylene adipate-co-terephthalate) (PBAT) and thermoplastic whey protein isolate (WPIT) blends. To prepare the blends, WPI was denatured at 90 o C, in the presence of PEG, to become a thermoplastic material. Dried WPIT was later mechanically blended with PBAT using a torque rheometer at 160 o C and 80 rpm. Two blends were prepared: 90% of PBAT/10% of WPIT (90_10) and 70% of PBAT/30% of WPIT (70_30). Scanning electron microscopy (SEM) analyses showed a homogenous blend morphology and good interaction between the dispersed phase and the matrix. Atomic force microscopy-based infrared spectroscopy (AFM-IR) showed PBAT and WPIT bands in all studied regions of both blends, which suggests that these materials presented partial miscibility. The viscosity ratio of the PBAT/WPIT system was less than 3.5 in the high shear rate region in complex viscosity curves, which indicates that droplet break-up of WPIT may occur by the drop brillation mechanism. The addition of WPIT reduced the degree of crystallinity of PBAT in the blends in comparison to pristine PBAT as shown by X-ray diffraction (XRD).Mechanical tests showed that blend tensile strength and elongation at break decreased with the addition of WPIT. Elastic modulus of the blends increased compared to pristine PBAT. Barrier properties were also evaluated showing that the oxygen permeability coe cient reduced by 20% for the blend with 30% of WPIT and vapor water permeability increased with the addition of WPIT.

Producing Blends of Polybutylene Adipate Terephthalate and Blood Meal That Are Safe to Render

“…Bio-based materials manufactured from renewable polymers such as soy protein, starch, or gluten offer the opportunity to reduce plastic pollution and resource depletion [ 2 , 3 ]. However, renewable thermoplastics, such as those from proteins, typically have relatively high glass transition temperatures (T g ), leading to difficulties in processing [ 4 ]. To improve the mechanical properties and processability of protein-based thermoplastics, native proteins are typically denatured with heat and additives (such as urea, sodium dodecyl sulphate, and sodium sulphite) are included to facilitate protein unfolding.…”

“…PBAT is a random copolymer, which means that it cannot crystallise significantly and thus, has a relatively wide melting point, low elastic modulus, and stiffness, but has relatively high flexibility and toughness, making it ideal for improving the toughness of polymer blends. Because of these properties, PBAT is often blended with protein-based thermoplastics (e.g., thermoplastic whey [ 4 , 8 ], soy [ 9 , 10 , 11 , 12 ], zein [ 13 ], sodium caseinate [ 14 ], and blood meal [ 15 , 16 ]), and a compatibiliser is typically included in these blends to aid in interfacial adhesion. Common compatibilisers are maleic anhydride-grafted PBAT [ 10 , 11 ], poly-2-ethyl-2-oxazoline (PEOX), pMDI [ 17 ], itaconic anhydride-grafted PBAT [ 16 ], poly(ethylene glycol) diglycidyl ether) [ 13 ], and glycidyl methacrylate-grafted PBAT.…”

“…in the presence or absence of water. The plasticiser aids in the rearrangement of polymer chains, leading to the formation of a homogenous blend [ 4 , 11 , 19 ].…”

“…Novatein ® is a newly developed material made from blood meal, a by-product of the red meat processing industry with high protein content [ 17 ]. Novatein ® is a biodegradable, thermoplastic protein but it becomes brittle over time due to loss of plasticiser; however, this can be mitigated by blending with other polymers [ 16 ], similar to many other protein-based materials [ 4 , 18 , 22 ]. Novatein ® is best suited for agricultural and horticultural applications, but it lacks the durability required for hygeine control products in red meat processing.…”

Intention to Purchase Milk Packaged in Biodegradable Packaging: Evidence from Italian Consumers

“…From a circular economy prospective, a promising feasible solution to increase the sustainability of the dairy supply chain could be the use of the whey, an organic waste, for the production of innovative biopolymers such as poly(butylene-co-adipate terephthalate) (PBAT), polyhydroxyalkanoates (PHA), polylactic acid (PLA), and polyvinyl acetate (PVA) for food packaging applications [ 14 , 19 , 20 , 21 ]. These polymers are completely bio-based, biodegradable and their barrier properties are comparable to the conventional petroleum-derived alternatives [ 22 ].…”