Processing and characterization of bio‐based poly (hydroxyalkanoate)/poly(amide) blends: Improved flexibility and impact resistance of PHA‐based plastics

Abstract

One of the most significant limitations to widespread industrial implementation of emerging bioplastics such as poly(lactic acid) and poly(hydroxyalkanoate) (PHA) is that they do not match the flexibility and impact resistance of petroleum-based plastics like poly(propylene) or high-density poly(ethylene). The basic goal of this research is to identify alternative, affordable, sustainable, biodegradable materials that can replace petroleum-based polymers in a wide range of industrial applications, with an emphasis on providing a solution for increasing the flexibility of PHA to a level that makes it a superior material for bioplastic nursery-crop containers. A series of bio-based PHA/poly(amide) (PA) blends with different concentrations were mechanically melt processed using a twin-screw extruder and evaluated for physical characteristics. The effects of blending on viscoelastic properties were investigated using small-amplitude oscillatory shear flow experiments to model the physical character as a function of blend composition and angular frequency. The mechanical, thermal, and morphological properties of the blends were investigated using dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and tensile tests. The complex viscosity of the blends increased significantly with increasing concentration of PHA and reached a maximum value for 80 wt % PHA blend. In addition, the tensile strength of the blends increased markedly as the content of PHA increased. For blends containing PA at >50 wt %, samples failed only after a very large elongation (up to 465%) without significant decrease in tensile strength. The particle size significantly increased and the blends became more brittle with increasing concentration of PHA. In addition, the concentration of the PA had a substantial effect on the glass relaxation temperature of the resulting blends. Our results demonstrate that the thermomechanical and rheological properties of PHA/PA blends can be tailored for specific applications, and that blends of PHA/PA can fulfill the mechanical properties required for flexible, impact-resistant bio-based nursery-crop containers.

An overview of biodegradable packaging in food industry

“… The complex viscosity and elastic share modulus of the blend increased with increasing PHA content. DMA, DSC, TGA, SEM Yang et al (2015) PCL PCL/PLA The stiffness of the blend decreased with increase in PCL. The blend exhibited good toughness balance and the impact strength of the material increased with increased elongation at break.…”

Biodegradability of Polyolefin-Based Compositions: Effect of Natural Rubber

“…and Brevibacillus spp . produce proteases involved in the degradation of various polymers [ 28 , 29 , 30 , 31 ]. Molds often contain laccase, which catalyzes the reactions of aromatic and nonaromatic compounds during oxidation.…”

Towards High-performance Materials Based on Carbohydrate-Derived Polyamide Blends

“…Another abundant class of biopolymers are aliphatic polyesters, such as PLA and poly(hydroxyalkanoate) (PHA), although they suffer from brittleness [41]. While blending with polyamides, for example, has proved to be an effective way to overcome the brittleness of PLA [42,43,44] and PHB [45], no reports are known on the improvement of the mechanical properties of another class of brittle biopolymers—namely, GalX-containing polyamides.…”