Mazda Motor Corp exhibited Premacy Hydrogen RE Hybrid, a hybrid vehicle that runs on a hydrogen rotary engine mated to a motor, at 40th Tokyo Motor Show 2007 as a reference presentation.
With the provision of a motor, the setup compensates for the lack of torque and efficiency in the low-speed range, which are thought to be problems of the hydrogen rotary engine. In addition to the new powertrain, the vehicle features polylactic acid (PLA), a plant-based plastic, used in large quantity.
Specifically, PLA fabric is used for the seat surface, while the lower panel, shift panel, front console and glove box lid of the instrument panel, and the hydrogen tank cover are made of hard PLA. Mazda developed the fabric in collaboration with Teijin Ltd and Teijin Fibers Ltd.
In order to enhance the heat resistance, a stereocomplex PLA was formed by using two optical isomers, poly-L-lactic acid and poly-D-lactic acid. PLA fabric is only required to withstand a temperature of about 80°C when it is used as a material of seat surface.
However, a heat resistance of about 160°C was required because it is subjected to a high temperature during the dyeing process. According to the abrasion test conducted by repeatedly rubbing the fabric while applying a load on it, Mazda's fabric received the Class 4 certification (when rubbed for 1,000 times).
The fabric also has a tension strength 1.5 times higher than the stretching force applied on it when the passenger sit on or stand up from the seat. According to Mazda, this fabric also satisfies the flame resistance specified by the US Federal Motor Vehicle Safety Standards (FMVSS), which is considered to be one of the most severe criteria, said the company.
The hard PLA used for the instrument panel was developed as part of the industry-academia-government collaboration project titled "Consortium R&D Project for Regional Revitalization." The project was sponsored by Japan's Ministry of Economy, Trade and Industry and conducted in Hiroshima, Japan.
The material was obtained by mixing poly-L-lactic acid with a nucleating agent and additive to enhance the heat resistance and shock resistance, respectively. The nucleating agent is a copolymer of starch and poly-D-lactic acid.
The mixture of the nucleating agent and poly-L-lactic acid enhances the deposition speed of stereocomplex PLA. The resultant stereocomplex can be used as a nucleus to promote the crystallization of PLA.
As a result of improved crystallinity, the heat resistance of 100°C or higher was achieved. A copolymer of poly-L-lactic acid and a softening agent is used as the additive to enhance the shock resistance.
Mazda plans to start lease sales of Premacy Hydrogen RE Hybrid in 2008. PLA mentioned above will be used in the cars for lease.