Rheological investigation and modeling of healing properties during extrusion‐based 3D printing of poly(lactic‐acid)

Dear fellow iMechanicians,

Here is our recent paper that studies and models the rheological behavior of PLA deposited by 3D printing and allows to highlight the important process parameters than enable a full healing of the interface between printed layers.

Abstract

The focus of the present paper is the rheological study of poly(D,L-lactic-acid) (PDLLA) towards a modeling of their heal- ing properties during 3D direct pellet printing extrusion (DPPE). The viscoelastic properties of PDLLA and the filament temperature during deposition are first characterized. The influence of DPPE processing conditions is investigated in terms of temperature, time, and printing speed. For this, we propose a modeling of the process-induced interphase thickness between two deposited layers considering the non-isothermal polymer relaxation and accounting for the contribution of entanglement rate through the Convective constraint release model. Hence, taking into account the induced chain orienta- tion and mobility coming from filament deposition, this model quantifies the degree of healing between 3D-printed layers. Eventually, the proposed model is validated by comparing the theoretically calculated degree of healing with experimental tensile properties and lap shear results.

https://doi.org/10.1007/s00397-022-01377-6