The synthesis of 2‐hydroxy‐N‐[2‐(2‐hydroxy‐propionylamino)‐ethyl]propionamide (“aliphatic amidediol”) is described. Aliphatic amidediol and glycerol were used as a novel mixed plasticizer for corn starch to prepare thermoplastic starch. Fourier transform infrared (FT‐IR) spectroscopy proved that the mixture of aliphatic amidediol and glycerol could form more stable and strong hydrogen bonds with starch molecules than glycerol alone. By scanning electron microscopy (SEM) and X‐ray diffraction (XRD) it was proven that native starch granules and crystalline structures were broken and starch was plasticized. Tensile testing revealed that TPS plasticized by aliphatic amidediol and glycerol (AGPTPS) showed a better mechanical properties than TPS plasticized by glycerol (GPTPS). Furthermore, the water resistance of AGPTPS was better than that of GPTPS. In addition, dynamic mechanical thermal analysis (DMTA) showed that both storage modulus and glass transition temperature (Tg) of AGPTPS were higher than those of GPTPS. 相似文献
The fatigue property of riveted lap joint is greatly related to the riveting-induced residual stress, especially the stress distribution on the faying surface. However, an accurate study of the residual stress characteristics in the riveted sheet could be very difficult. In this paper, both numerical and experimental investigations were carried out on the stress/strain characteristics in riveted aircraft lap joints. A special specimen was designed for the test of strain variations on the faying surface of the sheet by microstrain gages. For the numerical simulation, the rivet squeezing process was analyzed using the explicit dynamic finite element (FE) method, whilst a general static FE analysis was employed for the elastic springback after the squeeze force was removed. A comparison of the strain variations between the experimental results and FE simulations shows a general good agreement, although there may be some difference for points measured near the hole surface. The FE analysis reveals that both compressive and tensile residual stresses could be introduced in the riveted sheet. Massive compressive residual stress can be created in the near-surface layer of the hole. However, the stress level is not always increased with increasing the squeeze force, and so is the improvement of fatigue life observed. Further study is still necessary to account for the fatigue life decreasing effect caused by a high squeeze force.