Property Evaluations of Antibacterial Polypropylene Composites Made of Guanidine Polymers

• Main Authors: LIN, JIAN-HONG, 林建宏
• Other Authors: LU, CHAO-TSANG
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/81139880267341863210

碩士 === 中臺科技大學 === 生物科技暨醫學工程研究所 === 105 === In this study, polypropylene (PP) is used as polymeric substrate, whilst polyhexamethylene guanidine hydrochloride (PHGH) is used an antimicrobial polymer filler. Then, polypropylene grafted maleic anhydride (PP-g-MA) is used a compatilizer in order to improve the compatibility between PP and PHGH. Moreover, dicumyl peroxide (DCP) is used as a crosslinking agent, increasing the bonding between PP and PHGH and improving the physical properties. As a result, PP and PHGH are processed with melt compounding and the hot pressing in order to form composite films. The physical properties of antimicrobial polymer composite films are evaluated using qualitative and quantitative antibacterial assays, tensile test, differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), release assessment, CIELAB, and polarized light microscopy. The test results indicate that PP/PHGH composites have good antibacterial properties. When 10 wt% of PHGH is added, the composites have a 100 % antibacterial efficacy against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The release assessment results show that the composites can efficiently release drug to attain a high antibacterial efficacy due to the fact that PHGH is highly hydrophilic. Based on the results of physical properties, FTIR shows that PHGH is enwrapped in PP substrate in a physical mixing manner. XRD analysis shows that the addition of PHGH has a negative influence on the crystallinity but no influence on crystal form. The polarized light microscopy shows that PHGH serves as the nucleating agent, which contributes to decrease the spherocrystal size. DSC result indicates the influence of the addition of PHGH on the melting temperature and crystallization temperature of PP. The addition of PHGH does not affect the melting temperature or the crystal forms of PP. However, there is a marginal influence of the addition of PHGH on the crystallization temperature, which contributes to the crystal nucleation and the formation of PP. Moreover, increasing the amount of PHGH has a negative influence on the tensile properties, but a positive influence on the rigidity of the composites. According to CIELAB, thermal processing causes the shade of PHGH gradually to change and become yellowish. The more the PHGH, the darker the shade. PP-g-MA or DCP is added to PP to secure the presence of PHGH in the composites so as to improve the antibacterial efficacy of PHGH. The test results show that using PP-g-MA can secure PHGH in the PP substrates, and quantitative antimicrobial assay confirms lower antibacterial activities. The antibacterial effect is inversely proportional to the amount of PP-g-MA. The covalent bond makes a small amount of PHGH dissociate from PP/PHGH/PP-g-MA composites, attaining a long term antibacterial effect but having similar physical properties to those of PP/PHGH composites. CIELAB results show that when PP-g-MA is increased, PHGH is enwrapped in PP substrate, thereby decreasing the change in shades caused by the decreased thermal processing with the thermal energy. Using DCP to secure PHGH in the PP substrate contributes to a good antibacterial effect in both the qualitative and quantitative antibacterial tests. The free radicals of DCP crosslink PHGH to the main molecular chains of PP, allowing the surface of PP-g-PHGH composite abundant with PHGH to completely contact the bacteria, thereby yields extraordinary antibacterial effect. Moreover, using 0.1 DCP helps to improve the physical performances: the tensile properties are significantly improved and close to the original tensile strength of PP. In addition, the crystallization temperature is slightly decreased, which provides a greater range of thermal processing and improves the changes in colors of PHGH. Therefore, there is a greater range in color for applications.