Japanese engineering plastics suppliers are turning to foaming as a process to realize further lightweighting in automotive and other transportation applications. Kaneka, for example, recently introduced developments in the foaming of polycarbonate alloys and now, fellow Japanese company says it has been successful in chemical foaming of its Glamide polyamide (PA) and Vylopet polyethylene terephthalate (PET) engineering resins.

30% and 50% glass fiber reinforced grades of Glamide, for example, can be foamed to increase part thickness from 1.5 mm in solid form to 2.5 mm after foaming, thereby improving load-bearing characteristics (stress versus strain properties). Lightweighting of 30-50% is reportedly achievable. In addition to chemical foaming, the materials can also be foamed using the Mucell process. Uniform, micro-sized cells also reportedly deliver enhanced thermal insulation properties.

Toyobo has also developed Glamide and Vylopet grades for metal replacement applications. Grade JF-30G, for example is a 30% glass fiber reinforced PA grade that exhibits a good balance of Charpy impact strength and flexural modulus (ca. 30 kJ/m² versus ca. 28 GPa). Toyobo adds that energy is absorbed in both the impact and vertical directions. Flowability is also reported to be good, at around 140 mm for a 1-mm-thick sample when injection pressure is approximately 133 MPa.

In a real world application of the grade, Yamaha Motor has adopted grade JF-30G for the bottom cowl top of an outboard motor, thereby slashing part weight from around 12.3 kg in for the previous aluminum die-cast component to just 4.6 kg for the glass fiber reinforced PA grade.

High heat resistance PA is also on the agenda at Toyobo. The company’s HR Series Vyloamide grades, for example, maintain 95% of their tensile strength at 200 deg C after 2000 hours. This compares with 75% for competing high heat resistance materials according to Toyobo. Chemical resistance is also reportedly superior to PA 6T and traditional PA 66 materials. Target applications include under-the-hood cooling systems. Vyloamide is based on the bio feedstock castor oil.

Toyobo also offers HR Series grades in its Glamide PA 6 and 66 line-ups with heat resistances of 200 deg C and oil resistance to boot. Calcium chloride and long-life coolant-resistant grades are also available.

Toyobo has also developed a new polyester-based elastomer grade with enhanced long-term heat resistance. The ester-carbonate copolymer grade, dubbed Pelprene C-type, boasts continuous use heat resistance of 175 deg C as well as superior oil resistance according to Toyobo, making it a viable thermoplastic alternative to acrylic rubber, which is commonly used in automotive transmissions and hoses.

Available in Shore hardness of 50D and 60D, the material can be applied in applications that come into contact with fuels, lubricants, and brake fluid. Weight change in the oil immersion test using IRM903 reference oil is reportedly superior to that of nitrile, chloroprene and silicone rubbers, and on a par with acrylic rubber.