Accelerated weathering of wood–polypropylene composite containing carbon fillers

Abstract

The effect of freeze-thaw weathering on the tensile properties, and accelerated weathering with xenon-arc light on the color stability and the tensile properties of co-extruded wood–polypropylene composite loaded with different carbon fillers, such as carbon black, graphite, expandable graphite, carbon nanotubes, and carbon fibers is studied. The results showed that carbon fillers prevented the composites from the fading during xenon-arc light weathering. Almost all types of composites showed the reduced tensile properties after the weathering so that during xenon-light treatment, the tensile strength decline for 10–22% and modulus for 9–25%; during freeze-thaw cycling reduction was 3–21% for the strength and 4–20% for the modulus. Scanning electron microscopy analysis revealed deterioration of the polymer surface layer in all xenon-light weathered composites.

Accelerated weathering and decay resistance of heat-treated wood reinforced polypropylene composites

“…As shown by SEM im-ages in Figure 3, various small cracks and deep slits were also observed on the surfaces of the composites with both untreated and heat-treated wood as given in Figure 3c and d, and the pieces of wood in the plastic matrix were observed to come to the surface of the composites (Figure 3a and b). Similar results were obtained after the accelerated or natural weathering in other studies (Turku and Karki, 2016;Selden et al, 2004;Lee et al, 2012). Table 2 shows the decay resistance of the composites with untreated and heat-treated wood.…”

A review of coextruded wood–plastic composites

“…Although it had the same color protection mechanism as graphite, CB could also trap radicals and terminate free-radical chains, which propagated through photooxidation; however, the dark color of the composites introduced by the carbon fillers limited their potential applications. [31] Jin et al [18] investigated the effect of adding blends of ultraviolet absorbers (benzotriazole or hydroxyphenyltriazine) with a hindered amine light stabilizer to the shell of Co-WPCs on the color protection of the Co-WPCs. They concluded that adding light stabilizers into the shell of Co-WPCs was more effective in protecting the composites from discoloration than the bulk addition of light stabilizers into the core-only composites.…”

“…[28,29] In other cases, the addition of 10% fire retardants (aluminum trihydrate, ZB, melamine, graphite, and TiO 2 ) or 3% carbon fillers (CB, graphite, EG, CNTs, and CFs) into the shell of Co-WPCs had a slight protective effect on the surface cracking and mechanical performance decline during weathering, except for the CF-filled Co-WPC whose tensile properties slightly improved. [30,31] Liu et al [24,25] investigated the influence of the nanosilica content and light stabilizers in the shell of Co-WPCs on the weathering performance. The addition of 2% nanosilica or 2% UV-327 demonstrated the best surface cracking prevention and flexural property retention of the Co-WPCs.…”

“…[ 30 ] To investigate the influence of carbon fillers on the weathering performance of Co‐WPCs, CB, graphite, EG, CNTs, and CFs were added to the shells of Co‐WPCs. [ 31 ] All fillers effectively protected the Co‐WPCs from fading, wherein CNTs and graphite had an almost equal color protection effect, and CB had the most significant protective effect. Although it had the same color protection mechanism as graphite, CB could also trap radicals and terminate free‐radical chains, which propagated through photooxidation; however, the dark color of the composites introduced by the carbon fillers limited their potential applications.…”

“…Although it had the same color protection mechanism as graphite, CB could also trap radicals and terminate free‐radical chains, which propagated through photooxidation; however, the dark color of the composites introduced by the carbon fillers limited their potential applications. [ 31 ]…”