Properties of wood composite plastics made from predominant Low Density Polyethylene (LDPE) plastics and their degradability in nature

PLoS One. 2020 Aug 3;15(8):e0236406. doi: 10.1371/journal.pone.0236406. eCollection 2020.

Abstract

To address concerns over plastics in the global environment, this project produced three wood plastics composites (WPCs) which could divert plastics from the waste stream into new materials. The three materials made had a ratio of 85%:15%, 90%:10%, and 95%:5% low density polyethylene (LDPE) to wood powder and were produced using the dissolution method. Physical and mechanical properties of each WPC were evaluated according to Japanese Industrial Standard (JIS) A 5908:2003. Their degradation in nature was evaluated through a graveyard test and assay test conducted in Coptotermes curvignathus termites. Results showed that density, moisture content, thickness swelling and water absorption of the WPCs fulfilled the JIS standard. The mechanical properties of these composites also met the JIS standard, particularly their modulus of elasticity (MOE). Modulus of rupture (MOR) and internal bonding (IB) showed in lower values, depending on the proportion of wood filler they contained. Discoloration of the WPCs was observed after burial in the soil with spectra alteration of attenuated transmission reflectance (ATR) in the band of 500-1000 cm-1 which could be assigned to detach the interphase between wood and plastics. As termite bait, the WPCs decreased in weight, even though the mass loss was comparatively small. Micro Confocal Raman Imaging Spectrometer revealed that termite guts from insects feeding on WPCs contained small amounts of LDPE. This indicated termite can consume plastics in the form of WPCs. Thus WPCs made predominantly of plastics can be degraded in nature. While producing WPCs can assist in decreasing plastics litter in the environment, the eventual fate of the LDPE in termites is still unknown.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biodegradable Plastics / chemical synthesis
  • Biodegradable Plastics / chemistry*
  • Elasticity*
  • Humans
  • Polyethylene / chemical synthesis
  • Polyethylene / chemistry*
  • Recycling
  • Water / chemistry
  • Wood / chemistry*

Substances

  • Biodegradable Plastics
  • Water
  • Polyethylene

Grants and funding

AN thanks to Universitas Sumatera Utara (USU) for funding this research under scheme of Penelitian Terapan TALENTA-USU year of 2018, contract number 2590/UN5.1.R/PPM/2018 date of March 16, 2018. FKS is employed by and receives salary from PT.Horiba Indonesia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.