Search

Vanillin was used as sustainable source for phthalonitrile monomer synthesis, and allyl/propargyl ether moieties were introduced to improve the processability at the minimal cost of thermal properties. The synthesis route was optimized to minimize side-reactions and simplify post-processing, and the monomers were obtained in high purity and good yields. The curing behavior, mechanism, and processability of the monomers were studied, and the thermal properties of cured polymers were evaluated. Of the two monomers, the allyl ether-containing one exhibited a wide processing window of 185 °C, and was mainly cured into phthalocyanine and linear aliphatic structures through self-catalytic curing process. Also, the glass transition temperature was higher than 500 °C. In contrast, the propargyl ether-containing monomer could only be partially cured, and heat resistance was found to be compromised. Compared with traditional petroleum-based phthalonitrile resins, the bio-based monomers could be cured without the addition of catalysts, and improvement in processability was achieved at no cost of thermal performances.

Low melting phthalonitrile monomers containing allyl and/or methoxyl groups were designed, synthesized and characterized. In order to evaluate their potential application in phthalonitrile resins, these monomers were blended with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-(4-aminophenoxy)phthalonitrile, then cured into polymers. Curing mechanisms of different prepolymers were proposed and compared, and processability, thermal and mechanical properties were characterized. The introduction of methoxyl units was found to postpone the curing, and thermal properties were slightly compromised. On the contrary, the usage of allyl was beneficial to both processability and thermal properties. More importantly, the impact strength for allyl-containing polymers could be as high as 13.63 kJ m−2, indicating such resin could be applied as high temperature structural composite matrices.

The piezoelectric actuator has high-speed response in comparison with the electro-magnetic actuator. However, it is not easy to achieve both high-speed and high-precision response by feedforward control only because the piezoelectric element has nonlinear properties such as the hysteresis effect. Thus, feedback control is required to achieve good performance. In this paper, we develop a new control design method to achieve both high-speed and high-precision response for piezoelectric actuators using the discrete-time H ∞ control method and the two-degree-of-freedom control scheme. The effectiveness of our proposed method has been shown by the simulation and experimental results. The most important contribution of our study is that our method can be directly applied to commercial machines.

This paper is concerned with a study of the high performance realization of electronic engrave technology. Using actual piezo actuator for ultra-high speed electronic engrave machine, we designed several control systems to realize a good performance, after the system identification and modeling. The designed control strategies consist of (i) LQI servo control, (ii) Two-degree-of-freedom control system, (iii) Sliding mode control with observer, (iv) Sliding mode control with output feedback. Incidentally, we also find out the compulational speed limit of DSP system via the experiments. We realized the good performance using the two-degree-of-freedom control and the sliding mode control with observer. The most important contribution of this study is that the experimental results can be directly used to commercial machine.