Shape Memory Assisted Self-healing Behavior of Biobased NR/PCL Blends

• Main Authors: Huang, Yu-Han, 黃玉涵
• Other Authors: Lai, Sun-Mou
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/k8sdjd

碩士 === 國立宜蘭大學 === 化學工程與材料工程學系碩士班 === 107 === This study focused on the processing and preparation of intelligent environmentally friendly elastic materials with self-healing effects. Self-healing ability depends on the depth of crack, temperature, and grafting percentage. The materials we used in this study are natural rubber (NR) and poly(ε-caprolactone) (PCL). In this study, we have modified the PCL and grafted acrylic acid (AA) onto PCL. After grafting PCL, it was mixed with NR. Benzoyl peroxide (BPO) and dicumyl peroxide (DCP) were used as the initiator of grafting reaction and crosslinking agents, respectively. Among them, the reason for the graft reaction that it is desirable to form hydrogen bonding by AA to enhance the self-healing effect by the attraction of hydrogen bonds. Because the material we used in this study has a shape memory effect, it is hoped that the shape memory effect can help the crack on the sample to close together, and then the mobility of molecules chain of the material can diffuse between the crack surface to achieve a higher healing effect. And this mechanism can be called shape memory assisted self-healing (SMASH). In addition, we add multi-walled carbon nanotubes (MWCNTs) into blends, and hope to have a multi-stimulus response mechanism. After adding MWCNTs, the blends can absorb near-infrared (NIR) light and convert it into thermal energy. In the dynamic mechanical analysis test, (D) NR had a low storage modulus at 25 oC, only 1.8 MPa, while (D) PCL had a storage modulus of 672.1 MPa. So it can improve the disadvantage of (D) NR with the addition of PCL. In the mechanical properties tests, the results showed that the (D) NR/PCL-g-2AA and (D) NR/PCL-g-4AA blends systems had a slight increase in Young's modulus compared with (D) NR/PCL blends. It was suggested that (D) NR/PCL-g-2AA and (D) NR/PCL-g-4AA blends had more hydrogen bondings to form physical crosslinking networks through the grafting reaction. In the shape memory tests, it can be seen that NR/PCL blends had excellent shape memory effects with the fixity ratio and recovery ratio of all samples are above 91 %. In the self-healing tests, the depth of the crack and the healing temperature directly affected the self-healing effect. All the samples heated at 80 °C were better than 60 °C. By grafting AA to generate the hydrogen bond. It can effectively improve the healing efficiency. Under the condition of 50% depth crack and 80 oC healing temperature for the (40/60) blend, the efficiency of (D) NR/PCL (40/60) increased from 28.5 % to 56.8 % by grafting 2 phr AA, and to 62.8% by grafting 4 phr AA. Due to the excellent shape memory effects of all the samples, it can helpe to heal by SMASH mechanism. The efficiency of NR/PCL-g-4AA (40/60) has increased from 62.8 % to 79.9 %.