Improving Impact Properties of Novatein through Polymer Blending and Reactive Extrusion
type: CreativeWork
description: Novatein is a brittle thermoplastic made from protein and requires impact strength modification before it can be used in a wider variety of applications, such as in the agricultural, horticultural and meat processing industries. Polymer blending is often used for improving material properties cost effectively. This study aimed to improve the energy absorbing properties of Novatein through manipulating the morphology of blends and assessing the factors that are important during this process; these were, the choice of polymer, composition, viscosity ratio, interfacial tension and chemical interactions. Novatein was blended with either elastomeric core-shell particles, polyethylene (PE), or biodegradable polybutylene adipate-co-terephthalate (PBAT) using twin-screw extrusion to allow for sufficient mixing and residence time for chemical interactions or reactions to form. Materials were characterized for mechanical (tensile and impact testing), thermal (dynamic mechanical analysis and differential scanning calorimetry) and morphological (microscopy and solvent extraction) properties. The greatest increase in energy absorption occurred in blends containing core-shell particles, but only above a critical particle concentration. This was attributed to good particle dispersion, efficient stress transfer to the particles and a decrease in interparticle distance, allowing the matrix to elongate freely during fracture, forming fibrillar structures. When the particle content was high, the protein secondary structure became more ordered in these fibrils during fracture. It was suggested that the change in protein conformation contributed to the increase in energy absorption, along with matrix yielding. In contrast, in-situ formation of morphologies required for impact strength modification through reactive extrusion of Novatein and modified polyethylene proved difficult due to the viscosity ratio and interfacial tension. In most Novatein/PE blends these factors were not favorabl…
abstract: Novatein is a brittle thermoplastic made from protein and requires impact strength modification before it can be used in a wider variety of applications, such as in the agricultural, horticultural and meat processing industries. Polymer blending is often used for improving material properties cost effectively. This study aimed to improve the energy absorbing properties of Novatein through manipulating the morphology of blends and assessing the factors that are important during this process; these were, the choice of polymer, composition, viscosity ratio, interfacial tension and chemical interactions. Novatein was blended with either elastomeric core-shell particles, polyethylene (PE), or biodegradable polybutylene adipate-co-terephthalate (PBAT) using twin-screw extrusion to allow for sufficient mixing and residence time for chemical interactions or reactions to form. Materials were characterized for mechanical (tensile and impact testing), thermal (dynamic mechanical analysis and differential scanning calorimetry) and morphological (microscopy and solvent extraction) properties. The greatest increase in energy absorption occurred in blends containing core-shell particles, but only above a critical particle concentration. This was attributed to good particle dispersion, efficient stress transfer to the particles and a decrease in interparticle distance, allowing the matrix to elongate freely during fracture, forming fibrillar structures. When the particle content was high, the protein secondary structure became more ordered in these fibrils during fracture. It was suggested that the change in protein conformation contributed to the increase in energy absorption, along with matrix yielding. In contrast, in-situ formation of morphologies required for impact strength modification through reactive extrusion of Novatein and modified polyethylene proved difficult due to the viscosity ratio and interfacial tension. In most Novatein/PE blends these factors were not favorabl…
author: Smith, Matthew J.
keywords: Biopolymer, Novatein, Impact strength, Polymer Blending, Reactive Extrusion
license: https://researchcommons.waikato.ac.nz/bitstreams/77dbdfe3-739f-4ba8-85d4-67901f7bcfea/download
date published: 2018
date modified: 2026-07-24T05:57:33Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato