Japanese companies have reinforced bioplastic with fibre from a fast growing plant to make it sufficiently strong and heat resistant to use in electronic devices. The new material is already being used in a mobile phone available on the Japanese market, the NTT DoCoMo FOMA N701iECO.
Biomass-based bioplastics, such as polylactic acid (PLA), which is made from corn, have been hitting the headlines as potential replacements for conventional petroleum-based plastics. However, regular PLA is unsuitable for use in electronic devices as it has insufficient heat resistance and strength.
NEC improved the heat resistance and strength of PLA by adding fibre from kenaf, a fast-growing plant with a high rate of carbon fixation. Then together with textile and polymer company UNITIKA, NEC tested the durability of the new material by making PC components from it.
Other characteristics of the kenaf-reinforced PLA were then enhanced to make it suitable for use in mobile phones. Its moisture resistance was improved by UNITIKA, using another PLA. Adding a flexible biomass material and reinforcing filler developed by NEC increased fall impact durability. The plastic was than made easier to mould using new additives that were jointly developed by NEC and UNITIKA.
The resulting bioplastic has a biomass content of 90 per cent, the highest proportion in a bioplastic currently being used in electronic devices, while meeting the mobile phone casing requirements of fall impact durability, moldability and heat resistance.