Elsevier

Waste Management

Volume 33, Issue 9, September 2013, Pages 1898-1905
Waste Management

Review
Use of recycled plastics in wood plastic composites – A review

https://doi.org/10.1016/j.wasman.2013.05.017Get rights and content

Highlights

  • A comprehensive review about wood plastic composites made from recycled plastics.

  • Essential properties of waste and recycled plastics which are important in WPCs manufacturing.

  • Effect of recycled plastics on physical and mechanical properties of wood plastic composite.

Abstract

The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs.

Introduction

Recycled and waste thermoplastics are some of the major components of global municipal solid waste (MSW) and they present a promising raw material source for WPCs, especially because of the large volume and low cost of these materials. Table 1 shows that waste plastics account for 11.2% of the annual 84.2 thousands tons of the municipal waste stream generated in Tehran during 2006 (Ashori, 2008) and 12.4% of 250 million tons in the USA during 2010 (EPA, 2011).

As given in Table 2, high density polyethylene (HDPE), low density polyethylene (LDPE/LLDPE), polypropylene (PP), Polyethylene terephthalate (PET), polystyrene (PS) and polyvinyl chloride (PVC) are the primary constituents of plastics in MSW. The blend of the mixed waste plastics can be changed depending on the regional habits and seasons of a year and on the mode of waste collection, also (Chanda and Roy, 2007). Table 2 also shows that only 7.6% of 31 million tons (12.4% of MSW) of generated waste plastics were recycled.

Reutilizing the post-consumed polymeric materials reduces the environmental impact and the consumption of virgin plastics. Most single polymer plastics made from petroleum are relatively easy to recycle. Therefore, with an efficient collection, separation and recycling system, discarded plastics can be recycled into new products with only the addition of energy (Jayaraman and Bhattacharya, 2004).

Products manufactured from waste plastics for use are increasing, including floor carpets, flower vases, waste paper baskets, park benches, picnic tables (DeWeese, 1998) and plastic lumber (Dutta et al., 1994). Also, recycled plastics can be used in wood plastic composites (WPCs), which use will provide an additional market for recycled plastics. Trex, the largest supplier of wood-plastic composite lumber, purchases an average of over 227,000 kg of plastic scrap each day (Principia Partners, 2002). Winandy et al. (2004) listed some wood plastic composite products using recycled plastics, produced commercially in the USA.

Generally in WPC manufacturing, virgin thermoplastic polymers are widely used. The most prevalent polymers are PE, PP, PVC and PS. The waste and recycled plastics have been used for manufacturing WPCs already in 1990s and the use has significantly increased in the developed and developing countries in recent years. This paper presents a detailed review about waste and recycled plastics and the research published on the effect of recycled plastic on the physical and mechanical properties of WPCs.

Section snippets

Properties of waste and recycled plastics

If the recycled plastics are considered as new materials in WPCs production, it is necessary primarily to understand well the elemental and fundamental structure of these materials. By knowing the properties of recycled plastics, the processes for manufacturing WPCs can be well controlled and then the relationship between the properties of recycled plastics and their mechanical aspects can be better understood as well as those of the resulted WPC products.

At the end of the first life cycle of

Use of waste plastic in WPCs

The studies of WPCs based on recycled thermoplastics are limited. Most of the studies have been focused on the use of either a single type of waste plastic (for example, the milk bottle) or a combination of recycled and virgin plastics to produce the WPCs, though some also on using recycled plastic blends. However, the impact of recycled or waste thermoplastics in WPCs is still not fully understood, leaving open research opportunities for the optimization of product properties. There are

Conclusion

It has been shown that recycled thermoplastics have great potential for WPCs manufacturing. Because recycled plastics are probably obtained from various sources, exposed to different storage and reprocessing conditions, they may show different performance depending on their degradation level. The degradation of plastics due to repeated processing cycles and environmental exposure complicates recycling, so focused researches are required. Therefore, the effect of the degradation level of

References (85)

  • J.V. Gulmine et al.

    FTIR characterization of aged XLPE

    Polymer Testing

    (2006)
  • J.V. Gulmine et al.

    Correlations between structure and accelerated artificial ageing of XLPE

    European Polymer Journal

    (2006)
  • H.D. Hoekstra et al.

    UV-exposure of stabilized and non-stabilized HDPE films: physico-chemical characterization

    Polymer Degradation and Stability

    (1995)
  • M. Iring et al.

    The thermo-oxidative degradation of polyolefins-Part 10. Correlation between the formation of carboxyl groups and scission in the oxidation of polyethylene in the melt phase

    Polymer Degradation and Stability

    (1980)
  • K. Jayaraman et al.

    Mechanical performance of wood fibre–waste plastic composite materials

    Resources, Conservation and Recycling

    (2004)
  • K. Jayaraman et al.

    Harakeke (phormium tenax) fibre–waste plastics blend composites processed by screwless extrusion

    Composites: Part B

    (2009)
  • D.P. Kamdem et al.

    Properties of wood plastic composites made of recycled HDPE and wood flour from CCA-treated wood removed from service

    Composites: Part A

    (2004)
  • F.P. La Mantia et al.

    Recycling of degraded polyethylene: blends with nylon 6

    Polymer Degradation and Stability

    (1992)
  • Y. Lei et al.

    Preparation and properties of recycled HDPE/natural fiber composites

    Composites: Part A

    (2007)
  • C. Meran et al.

    Examination of the possibility of recycling and utilizing recycled polyethylene and polypropylene

    Materials and Design

    (2008)
  • C. Sadrmohaghegh et al.

    Effect of reprocessing on polymers: Part II-Polypropylene

    Polymer Degradation and Stability

    (1981)
  • R. Satoto et al.

    Weathering of high-density polyethylene in different latitudes

    Polymer Degradation and Stability

    (1997)
  • S.E. Selke et al.

    Wood Fibre/Polyolefin Composites

    Composites: Part A

    (2004)
  • N.M. Stark et al.

    Surface chemistry changes of weathered HDPE/wood flour composites studied by XPS and FTIR spectroscopy

    Polymer Degradation and Stability

    (2004)
  • A. Tidjani

    Comparison of formation of oxidation products during photo-oxidation of linear low density polyethylene under different natural and accelerated weathering conditions

    Polymer Degradation and Stability

    (2000)
  • A. Valadez-Gonzalez et al.

    Mineral filler influence on the photo-oxidation of high density polyethylene: I. Accelerated UV chamber exposure test

    Polymer Degradation and Stability

    (1999)
  • W.R. Waldman et al.

    Thermo-mechanical degradation of polypropylene, low-density polyethylene and their 1:l blend

    Polymer Degradation and Stability

    (1998)
  • M. Abdouss et al.

    Effects of compatibilization of oxidized polypropylene on PP blends of PP/PA6 and PP/talc

    Journal of Applied Polymer Science

    (2004)
  • D.S. Achilias et al.

    Recycling techniques of polyolefin’s from plastic wastes

    Global NEST Journal

    (2008)
  • K.B. Adhikary et al.

    Long-term moisture absorption and thickness swelling behavior of recycled thermoplastics reinforced with Pinus radiata sawdust

    Chemical Engineering Journal

    (2007)
  • A. Ashori

    Municipal solid waste as a source of lignocellulosic fiber and plastic for composite industries

    Polymer–Plastics Technology and Engineering

    (2008)
  • A.F. Avila

    Modeling recycled polymeric matrix composites: a social environmental solution

    Polymer–Plastics Technology and Engineering

    (2001)
  • Bahrami, M., 2012. Effect of oxidized polypropylene (OPP) as compatibilizer on physical and mechanical properties of...
  • Baquero, I., Moreno, N., Ichazo, M., Sabino, A. M., 2002. Thermal and mechanical studies of recycled HDPE, PP and PET...
  • T. Bremner et al.

    Melt flow index values and molecular weight distributions of commercial thermoplastics

    Journal of Applied Polymer Science

    (1990)
  • M. Chanda et al.

    Plastics Technology Handbook

    (2007)
  • J.D. Cho et al.

    Surface modification of polypropylene sheets by UV-radiation grafting polymerization

    Journal of Applied Polymer Science

    (2006)
  • Ciesielska, D., 1998. A study on properties and structure of recycled polystyrene, Society of Plastics Engineers, ANTEC...
  • C. Clemons

    Raw materials for wood–polymer composites

  • V. Dang et al.

    Preparation of grafted copolymers via oxidized polypropylene

    Journal of Applied Polymer Science

    (2007)
  • A. DeWeese

    New uses for old plastic

    World Wastes

    (1998)
  • Dutta, P.K., McDevitt, C.F., Manikonda S.G., 1994. Applications of recycled plastics for roadside safety hardware. in:...
  • Cited by (0)

    View full text