High quality 3D printing of low-density polyethylene blends considering the softening effect of polyolefin elastomer

Abstract

Polyethylene (PE) is one of the most widely used thermoplastics in the polyolefin family. Despite its numerous applications in the industry, particularly in packaging, 3D printing with PE has been a significant challenge that has received little attention. The main obstacles to successful 3D printing with PE are high shrinkage, weak adhesion to the print bed, and weak interlayers. This paper addresses this problem by introducing Polyolefin Elastomer (POE) as an additive in the 3D printing process. Three different POE-LDPE compounds with varying LDPE weight percentages (90%, 70%, and 50%) were 3D printed and analyzed for their mechanical and microstructural properties. The POE and LDPE were blended using the melt mixing method, and the resulting POE-LDPE granules were directly used as input for the FDM machine. The 3D-printed samples were then subjected to DMTA, tensile, compression tests, and SEM imaging. The DMTA results showed that the glass transition temperature of all three samples fell within the range of 71°C to 78°C. Increasing the POE content and decreasing the LDPE amount from 90% to 50% led to a decrease in the storage modulus. In terms of the tensile test results, it was observed that reducing the LDPE amount and increasing the POE content had a toughening effect on the samples, improving their formability and elongation from 1566% for POE-90wt% LDPE to 2112% and 2829% for POE-70wt% LDPE and POE-50wt% LDPE respectively. However, the tensile strength decreased with an increase in the POE amount. For POE-90wt% LDPE, the tensile strength was 14.06 MPa, and for POE-90wt% LDPE, it was just below 13.96 MPa. The compression test revealed that the addition of POE weakened the yield strength of the samples. SEM images demonstrated that the printability of the 3D-printed POE-LDPE samples decreased as the LDPE amount decreased and the POE amount increased. The images also revealed single-phase and miscible blends. These findings suggest the potential emergence of a new, affordable, biocompatible, and recyclable raw material for 3D printing.