A kind of semi-aromatic polyamide, poly(dodecamethylene terephthalamide) (PA12T) was synthesized via a three-step reaction of terephthalic acid and 1,12-dodecanediamine. The structure of the prepared PA12T was characterized by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H-NMR). The thermal behaviour of PA12T was determined by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Melting temperature (Tm), glass transition temperature (Tg) and decomposition temperature (Td) of PA12T are 311°C, 144°C and 429°C, respectively. Isothermal crystallization kinetics of PA12T have been investigated in the temperature range of 270-280°C using DSC. The activation energies (ΔE) were determined to be -170.4 kJ/mol for the isothermal crystallization processes by the Arrhenius’ methods.

In this paper, an electromagnetic shell part was studied with the design of die, simulation and the flow control forming (FCF) method. The important technology of FCF was the design of cavity die to control metal flow. The simulation results indicate that pyramidal faces of cavity die exerted a significant influence on qualities of parts. The simulation results also revealed that the effective stresses of the sheet were inhomogeneous and the distributions of the equivalent stress were lamellar with obvious gradients. Experimental results show that steel sheet (08Al) could be formed in one step into intricate shapes at room temperature. This confirmed that FCF is a safe, clean and practical method for the near net forming of parts.