The relationship between morphology development and mechanical properties in thermoplastic protein blends

Abstract

Novatein thermoplastic protein was blended with modified polyethylene (containing either epoxy, carboxylic acid functionalities partially neutralised to produce zinc carboxylate salts, or maleic anhydride functionalities) to alter blend morphology and to manipulate thermal and mechanical properties. Up to 40 pph Novatein polyethylene (PE) was blended with Novatein by extrusion and injection moulding. Using zinc ionomer resulted in optimal properties and was compatible with a finely dispersed morphology at high content; high interfacial tension (σ) and a viscosity ratio (λ) of ~1 was observed. Unmodified blends and those containing epoxy functionalities showed co-continuity at low PE content. Whilst co-continuity appeared to increase impact resistance, other mechanical properties decreased due to lack of phase interaction. Maleic anhydride-grafted-polyethylene blends showed a finely dispersed PE phase, yet was less compatible. Zinc ionomer was deemed to be the most appropriate for modification of mechanical properties in Novatein. K E Y W O R D Sbiopolymers, blends, morphology, thermoplastic protein How to cite this article: Smith MJ, Verbeek CJR. The relationship between morphology development and mechanical properties in thermoplastic protein blends.

Structural changes and energy absorption mechanisms during fracture of thermoplastic protein blends using synchrotron FTIR

“…Hence, importance has been placed on modifying Novatein using elastomeric, low T g second phase inclusions. This has proven to be successful by incorporating modified PE or core‐shell particles, however composition affects the level of improvement . For all PE blends, the inclusion of 40 pph Novatein produced the best energy absorbing properties .…”

“…In the case of Novatein/PE blends, granules of Novatein Crude and PE were tumble mixed in a ziplock bag before extrusion . Novatein/core‐shell particle blends were produced from Novatein IR3020 and Paraloid EXL 2314 which was incorporated during the Novatein production stage .…”

“…The injection molding grade of Novatein shows high tensile strength and modulus but has low strain at break and impact strength . In comparison, increased plasticizer and protein denaturant content brings about better energy absorbing properties in Novatein, but a reduction in strength and modulus are observed .…”

“…Impact modification of Novatein has been achieved in a number of ways; nano‐scale core‐shell particles with an elastomeric core and rigid shell were shown to improve the unnotched impact strength by an order of magnitude . Similarly, reactively blending high contents (∼40 wt%) of modified polyethylene (PE) with Novatein, doubled the elongation at break and increased impact strength by ∼350%, while decreasing tensile strength by less than 25% . Whether these changes in energy absorption could be correlated to changes in protein structure, or if morphology effects were the sole reason for the improved properties, is still unknown.…”

Manipulating morphology in thermoplastic protein/polyester blends for improved impact strength

“…It has low energy absorbing properties but can be improved to some extent through reactive polymer blending [1] or particulate reinforcement. It has low energy absorbing properties but can be improved to some extent through reactive polymer blending [1] or particulate reinforcement.…”