Effect of Sanding and Plasma Treatment of 3D-Printed Parts on Bonding to Wood with PVAc Adhesive

Abstract

Additive manufacturing is becoming increasingly important for manufacturing end products, not just prototyping. However, the size of 3D-printed products is limited due to available printer sizes and other technological limitations. For example, making furniture from 3D-printed parts and wooden elements requires adequate adhesive joints. Since materials for 3D printing usually do not bond very well with adhesives designed for woodworking, they require special surface preparation to improve adhesion. In this study, fused deposition modelling (FDM) 3D-printed parts made of polylactic acid (PLA), polylactic acid with wood flour additive (Wood-PLA), and acrylonitrile-butadiene-styrene (ABS) polymers were bonded to wood with polyvinyl acetate (PVAc) adhesive. The surfaces of the samples were bonded as either non-treated, sanded, plasma treated, or sanded and plasma treated to evaluate the effect of each surface preparation on the bondability of the 3D-printed surfaces. Different surface preparations affected the bond shear strength in different ways. The plasma treatment significantly reduced water contact angles on all tested printing materials and increased the bond tensile shear strength of the adhesive used. The increase in bond strength was highest for the surfaces that had been both sanded and plasma treated. The highest increase was found for the ABS material (untreated 0.05 MPa; sanded and plasma treated 4.83 MPa) followed by Wood-PLA (from 0.45 MPa to 3.96 MPa) and PLA (from 0.55 MPa to 3.72 MPa). Analysis with a scanning electron microscope showed the smooth surfaces of the 3D-printed parts, which became rougher with sanding with more protruded particles, but plasma treatment partially melted the surface structures on the thermoplastic polymer surfaces.

Discharge Plasma Treatment as an Efficient Tool for Improved Poly(lactide) Adhesive–Wood Interactions

“…Comparable gains for plasma-treated PLA bonded to wood with a PVAc adhesive (0.55-3.72 MPa) were reported by Kariž at al. [40]. On the other hand, Mandolfino et al [41] observed increases of between 52.5% and 386.6% in lap-shear tests performed on a plasma-treated polypropylene film-epoxy adhesive.…”

Plasma and Polymers: Recent Progress and Trends

“…Among the three treatment regimes, the combination treatment of plasma and sanding produced superior outcomes with respect to improving adhesion strength. Microscopic visualization of thus-treated surfaces showed the development of significant roughness after sanding, with some of this topography lost when the surface was subsequently exposed to plasma-induced ion bombardment [ 91 ].…”

“… ( a , b ) Plasma device used for the surface treatment of 3D-printed samples on a CNC positioning system (top left image) with a gliding arc plasma jet ( a ), and sample for testing the bond shear strength ( b ). Reproduced from Kariž et al (2018) [ 91 ] under conditions of the CC BY license. ( c , d ) Representation of the crack path in ABS-interleaved hybrid composites ( c ) with untreated ABS ( d ) with plasma-treated ABS.…”

“…Given that the improvements in the adhesion performance was similar for atmospheric pressure and low pressure plasma systems, there is a pathway to translate these findings into real-life applications. Figure 10a,b illustrates a plasma device used for the surface treatment of 3D-printed samples on a computerized numerical control (CNC) positioning system with a gliding arc plasma jet, and a sample for the testing of the bond shear strength developed by Kariž et al [91]. 3D printing, or additive manufacturing, enables the production of objects and structures with precise geometric shapes in prototyping and, increasingly, in the industrial scale production of goods.…”

“…These may include roughening through physical means (e.g., sanding), chemical modification and fine etching (e.g., plasma treatment), and a combination of these treatments. When these treatments were applied to fused deposition modeling (FDM) 3Dprinted components fabricated from polylactic acid (PLA), polylactic acid with wood flour additive (Wood-PLA), or acrylonitrile-butadiene-styrene (ABS) polymers, exposure to Figure 10a,b illustrates a plasma device used for the surface treatment of 3D-printed samples on a computerized numerical control (CNC) positioning system with a gliding arc plasma jet, and a sample for the testing of the bond shear strength developed by Kariž et al [91]. 3D printing, or additive manufacturing, enables the production of objects and structures with precise geometric shapes in prototyping and, increasingly, in the industrial scale production of goods.…”