Bending Capacity and Rotational Stiffness of Glued and Detachable Corner Joints in PMMA/ATH Solid-Surface Composites

Quantitative data on the bending capacity and rotational stiffness of corner joints made from acrylic solid-surface PMMA/ATH composites are limited, despite their widespread use in furniture and interior components. The study provides comparative bending moment and rotational-stiffness benchmarks for 18 PMMA/ATH corner-joint series, using a stiffness-evaluation procedure tailored to corner-joint testing. L-type joints produced from two commercial PMMA/ATH materials (Kerrock and Corian) at 6- and 12-mm thickness were manufactured in 18 configurations, including glued butt, 45° mitre, reinforced mitre, rebate, groove variants, and detachable Minifix eccentric and Lamello Clamex connectors. Specimens were tested under arm-compression bending and maximum bending moment (Mmax), and joint rotational stiffness was derived. The best-glued solution was the 12 mm Kerrock 45° mitre with Mmax 186.21 N·m, whereas the strongest 6 mm joint reached 40 N·m. Reinforcing the 12 mm Kerrock mitre joint increased stiffness to 9521 N·m/rad but did not increase bending capacity relative to the non-reinforced mitre. Detachable joints formed a clearly distinct low-rigidity class with bending moments of 2.22–3.89 N·m and stiffness below 194 N·m/rad. Overall, thickness and joint geometry dominate both strength and stiffness, and the tested detachable connectors should be reserved for applications requiring disassembly rather than for load-bearing corners.