Related Experiment Video
Updated: Jul 14, 2026

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends
Published on: January 17, 2017
Extrusion foaming of semi-crystalline PLA and PLA/thermoplastic starch blends
Mihaela Mihai1, Michel A Huneault, Basil D Favis
1CREPEC, Chemical Engineering Department, Ecole Polytechnique de Montréal, P.O. Box 6079, Station Centre-Ville, Montréal, Québec, Canada, H3C 3A7.
Abstract:
Low density open-cell foams were obtained from polylactic acid (PLA) and from blends of PLA with thermoplastic starch (TPS) using CO(2) as a blowing agent. Two unexpected features were found. First, a 2D cavitation process in the fractured cell walls was unveiled. Elliptical cavities with dimensions in the 100-300 nm range were aligned perpendicular to large cell cracks clearly exhibiting 2D crazing prior to macroscopic cell rupture. Secondly, a significant crystallization rate increase associated with the CO(2) foaming of PLA was discovered. While the PLA used in this study crystallized very slowly in isothermal crystallization, the PLA foams exhibited up to 15% crystallinity, providing evidence that CO(2) plasticization and the biaxial stretching upon foam expansion provided conditions that could increase the crystallization rate by several orders of magnitude.
Related Concept Videos
Superplasticizers
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
Bioplastics
Classification and Mechanical Properties of Synthetic Polymers
Types of Step-Growth Polymers: Polyesters
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the polymer...
Plasticizers
Plasticizers function by using surface-active agents to create repulsive electrostatic forces between cement particles. This dispersion enhances the concrete's...

