How are Bioplastics used in the Automotive Industry?

The automotive industry has experienced significant changes over recent years.  Vehicle population has grown strongly, exceeding population growth, and vehicle ownership per capita has been rising.  As ownership rises, concerns have been raised about cost, sustainability, and environmental impact.  This has led to innovations within the automotive industry in order to address these concerns.  From one point of view, fuel specifications are changing to reduce pollutants and noxious gases expelled into the atmosphere.  From another, the materials the vehicle itself is made from are being challenged.  Reduction of a vehicles weight, or lightweighting, can reduce the amount of fuel required and goes some way toward addressing environmental concerns.

The significant increase in the proportion of polymers used in motor vehicle construction combined with increased vehicle manufacture has boosted demand for automotive polymers. The general trend for polymer demand into the automotive industry has displayed ongoing growth in China and the United States, as illustrated below.

Although the consumption volume of bio-based plastics in vehicles is small, it has been growing in the past decade.  Fuel economy standards, lightweighting, new regulations for controlling greenhouse gas emissions, sustainability, safety, public appeal, and style are some of the factors that have encouraged the automotive industry to develop bio-based plastic materials and biocomposites for cars. It has been estimated that about 15 percent of the world’s bioplastics market find home in the automotive industry, with growth expected to continue close to the double digits.

While the most common automotive components made from bioplastics are for interior applications, uses in exterior and under-the-hood applications have emerged as automotive manufacturers become more accustomed to working with bioplastics.  New plastics and renewable sources are being investigated for the development of automobile components that can substitute current materials. In general, automobile producers seek bioplastics that can provide similar performance, product quality, and safety in automobile parts made from conventional plastics.

Some of the bioplastics used in automobiles include polyurethanes, polyamides, and polyesters:

• Polyols produced from renewable sources are most commonly produced from vegetable oils such as soybean oil, rapeseed oil, and castor oil. Automobile manufacturers (such as Ford and General Motors) use soy-based polyurethanes to manufacture seats, headrests, tire gaskets, and headliners.
• Polyamides (PAs) are recognized as the first and one of the most important classes of engineering plastics discovered. There are several routes that lead to the bio-based monomer production used in the manufacture of polyamides.  These include amino acids (e.g., 11-aminoundecanoic acid) and diacids (e.g., sebacic acid).  Automobile manufacturers (such as Hundai-Kia and Toyota) use castor-based polyamides to manufacture seats frames and radiator end tanks.
• Polytrimethylene terephthalate (PTT) is an aromatic polyester produced from 1,3-propanediol (1,3-PDO) and terephthalic acid (PTA) via polycondensation. 1,3-PDO is commercially produced from a one-step fermentation process from corn-sugar. Automobile manufacturers (such as Nissan and Toyota) use PTT to manufacture floor mats, panels, and sun visors.
• Polylactic acid (PLA) is an aliphatic polyester with no aromatic ring structure. Produced from the fermentation of sugar derived from sugar beet, sugarcane, or corn, PLA has recently gained more acceptance as eco-friendly material.  The car components made of PLA are efficiently recovered from end-of-life vehicles (ELV) at low cost and possibly in obtaining higher purity recycled lactic acid monomer. Automobile manufacturers (such as Ford and Mazda) use PLA to manufacture floor mats, tires, and consoles.

A comparison of production costs of key bioplastics in the United States, China, Brazil, and Western Europe illustrates that there is a wide range of costs associated with using bio-based polymers which primarily depend on the renewable resource (e.g., castor oil, soybean, or sugar) used.  Hence, feedstock pricing of the renewable resource is the key to the competitiveness of the bioplastics against conventional petroleum-based routes.

While the production of bioplastics have reached a maturity level suitable for use in the manufacture of automobile parts, they still face many challenges against conventional plastics such as improvements in characteristics and subsequent processing, constant and reliable feedstock supplies, and better economies of scale.

Nexant has just completed a Biorenewable Insights report titled “Bioplastics in Automotive.” The purpose of this study is to assess the technical, commercial, and economic aspects of bioplastics used in the automotive industry. Several commercial technologies are provided for key plastics used in exterior and interior functions, under the hood parts, and chassis components. The study also compares cost of production estimates for the key bioplastics.

The Author

Marisabel Dolan – Senior Consultant, Nexant

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