PMID- 31991599 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20200928 IS - 2073-4360 (Electronic) IS - 2073-4360 (Linking) VI - 12 IP - 2 DP - 2020 Jan 24 TI - Flexural Creep Behavior of High-Density Polyethylene Lumber and Wood Plastic Composite Lumber Made from Thermally Modified Wood. LID - 10.3390/polym12020262 [doi] LID - 262 AB - The use of wood plastic composite lumber as a structural member material in marine applications is challenging due to the tendency of wood plastic composites (WPCs) to creep and absorb water. A novel patent-pending WPC formulation that combines a thermally modified wood flour (as a cellulosic material) and a high strength styrenic copolymer (high impact polystyrene and styrene maleic anhydride) have been developed with advantageous viscoelastic properties (low initial creep compliance and creep rate) compared with the conventional WPCs. In this study, the creep behavior of the WPC and high-density polyethylene (HDPE) lumber in flexure was characterized and compared. Three sample groupings of WPC and HDPE lumber were subjected to three levels of creep stress; 7.5, 15, and 30% of the ultimate flexural strength (Fb) for a duration of 180 days. Because of the relatively low initial creep compliance of the WPC specimens (five times less) compared with the initial creep compliance of HDPE specimens, the creep deformation of HDPE specimens was six times higher than the creep deformation of WPC specimens at the 30% creep stress level. A Power Law model predicted that the strain (3%) to failure in the HDPE lumber would occur in 1.5 years at 30% Fb flexural stress while the predicted strain (1%) failure for the WPC lumber would occur in 150 years. The findings of this study suggest using the WPC lumber in structural application to replace the HDPE lumber in flexure attributable to the low time-dependent deformation when the applied stress value is withing the linear region of the stress-strain relationship. FAU - Alrubaie, Murtada Abass A AU - Alrubaie MAA AUID- ORCID: 0000-0002-6989-348X AD - Department of Civil and Environmental Engineering, Advanced Structures and Composites Center, University of Maine, Orono, ME 04469, USA. FAU - Lopez-Anido, Roberto A AU - Lopez-Anido RA AUID- ORCID: 0000-0001-8702-0642 AD - Department of Civil and Environmental Engineering, Advanced Structures and Composites Center, University of Maine, Orono, ME 04469, USA. FAU - Gardner, Douglas J AU - Gardner DJ AD - School of Forest Resources, Advanced Structures and Composites Center, University of Maine, Orono, ME 04469, USA. LA - eng PT - Journal Article DEP - 20200124 PL - Switzerland TA - Polymers (Basel) JT - Polymers JID - 101545357 PMC - PMC7077215 OTO - NOTNLM OT - HDPE OT - WPC OT - composite OT - creep OT - flexure OT - modeling OT - power law OT - thermoplastic OT - viscoelasticity OT - wood COIS- The authors declare no conflicts of interest. EDAT- 2020/01/30 06:00 MHDA- 2020/01/30 06:01 PMCR- 2020/01/24 CRDT- 2020/01/30 06:00 PHST- 2019/11/26 00:00 [received] PHST- 2020/01/07 00:00 [revised] PHST- 2020/01/09 00:00 [accepted] PHST- 2020/01/30 06:00 [entrez] PHST- 2020/01/30 06:00 [pubmed] PHST- 2020/01/30 06:01 [medline] PHST- 2020/01/24 00:00 [pmc-release] AID - polym12020262 [pii] AID - polymers-12-00262 [pii] AID - 10.3390/polym12020262 [doi] PST - epublish SO - Polymers (Basel). 2020 Jan 24;12(2):262. doi: 10.3390/polym12020262.