| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 92 === Nitrogen plasma caused ion implantation and then carried out surface modification on Poly (ethylene terephthalate)(PET) efficie- ntly. With the increasing of plasma treatment time, water contact angle of treated-PET surface would decrease, finally reached a stable value, 25degree. By X-ray photoelectron spectrometer (XPS) analy- sis, atomic nitrogen content of plasma treated PET by ion implantation and bonding condition can be obtained. Furthermore, the interfacial fracture toughness (Gc) between ( poly styrene–co- maleic anhydride) (PSMA) and plasma treated-PET was had investigated.
Amine groups formed by plasma modification on the PET surface can reacts with styrene maleic anhydride (SMA) in bulk PSMA, forming imide covalent bonds to enhance interfacial fracture toughness between PET/PSMA. In our case, when annealing temperature at 150℃, the PET/PSMA is too strong to cause crack-tip propagated into PET side, the Gc values could be enhanced over 100J/m2 for long plasma treatment time. Otherwise, the diffusion rate of PSMA is too fast at annealing temperature at 160℃, causing a new weak interface occurred, and then crack-tip would propagate into PSMA side, Gc value become lower than condition 150℃. Fracture mechanisms are verified by XPS and SEM analysis of fractured PET and PSMA surface, and the results coincide with our explanation.
In our case, there are two mechanisms of PET/PSMA interface fracture. When areal chain density (Σ) on the interface is lower than 0.05/nm2, the interfacial fracture toughness (Gc) is proportional to Σ2. And at areal chain density larger than 0.05/nm2 region, the interfacial fracture toughness is independent to areal chain density, because the fracture happened in PET side.
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