Exploring the impact of cellulose nanocrystals and annealing treatment on the interlayer bond strength of polylactic acid 3D printed composites

Abstract

AbstractThe extrusion‐based 3D printing process offers advantages, such as high precision, low cost, high speed, simplicity, and the ability to deposit multiple materials simultaneously. However, using 3D printing composite materials with orthogonal anisotropy can limit the interlayer bonding strength of printed parts. In this study, the interlayer tensile strength of 3D‐printed polylactic acid (PLA) was affected by adding 0.5 wt% cellulose nanocrystals (CNC) and 1.2 wt% di‐cumyl peroxide (DCP) to PLA, and annealing at low temperature (373 K, 1 h). The effects of annealing and CNC were determined by mechanical testing, scanning electron microscopy, differential scanning calorimetry, expansion testing, rheological testing, and x‐ray diffraction analysis. After annealing, the interlayer gap increased due to crystal shrinkage, leading to a 25.9% decrease in tensile strength. However, the addition of CNC and DCP significantly improved the flow properties of the sample, resulting in better interlayer bonding and a 52.7% increase in tensile strength.