The Effects of Chain-Extending Cross-Linkers on the Mechanical and Thermal Properties of Poly(butylene adipate terephthalate)/Poly(lactic acid) Blown Films.

Juliana V C Azevedo,Esther Ramakers-Van Dorp,Berenika Hausnerova,Bernhard Möginger

doi:10.3390/polym13183092

Juliana V C Azevedo, Esther Ramakers-Van Dorp + Show 2 more

Open Access

https://doi.org/10.3390/polym13183092

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Abstract

This study investigates the effects of four multifunctional chain-extending cross-linkers (CECL) on the processability, mechanical performance, and structure of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) blends produced using film blowing technology. The newly developed reference compound (M·VERA® B5029) and the CECL modified blends are characterized with respect to the initial properties and the corresponding properties after aging at 50 °C for 1 and 2 months. The tensile strength, seal strength, and melt volume rate (MVR) are markedly changed after thermal aging, whereas the storage modulus, elongation at the break, and tear resistance remain constant. The degradation of the polymer chains and crosslinking with increased and decreased MVR, respectively, is examined thoroughly with differential scanning calorimetry (DSC), with the results indicating that the CECL-modified blends do not generally endure thermo-oxidation over time. Further, DSC measurements of 25 µm and 100 µm films reveal that film blowing pronouncedly changes the structures of the compounds. These findings are also confirmed by dynamic mechanical analysis, with the conclusion that tris(2,4-di-tert-butylphenyl)phosphite barely affects the glass transition temperature, while with the other changes in CECL are seen. Cross-linking is found for aromatic polycarbodiimide and poly(4,4-dicyclohexylmethanecarbodiimide) CECL after melting of granules and films, although overall the most synergetic effect of the CECL is shown by 1,3-phenylenebisoxazoline.

Highlights

The global plastic waste problems have positively affected the development of biopolymers and other sustainable materials [1,2,3,4] towards the substitution of traditional packaging plastics such as polyethylene and polystyrene with biodegradable starch and biopolyesters [5,6,7]; for more demanding engineering applications, their mechanical properties must be enhanced without compromising their biodegradability
The four chain-extending cross-linkers (CECL) with fractions of 1 wt.% were compounded into the reference Polybutylene adipate terephthalate (PBAT)/polylactic acid (PLA) (REF) compound M·VERA® B5029 [34] from BIO-FED, a branch of AKRO-PLASTIC GmbH, Germany, which is used for packaging and agricultural applications: V1-tris(2,4-di-tert-butylphenyl)phosphite, SongnoxTM 1680 (Songwon Industrial Co, Ulsan, South Korea) [35]; Polymers 2021, 13, 3092
The introduction of CECL modified the properties of the reference PBAT/PLA blend significantly

Summary

Introduction

The global plastic waste problems have positively affected the development of biopolymers and other sustainable materials [1,2,3,4] towards the substitution of traditional packaging plastics such as polyethylene and polystyrene with biodegradable starch and biopolyesters [5,6,7]; for more demanding engineering applications, their mechanical properties must be enhanced without compromising their biodegradability. To accelerate this conversion, the properties of the biomaterials must be enhanced without compromising their biodegradability. In order to increase the mechanical and barrier behaviors, it is often compounded with inorganic fillers such as calcium carbonate and talc [28,29]

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