Preparation And Properties Of Low Density Polyethylene Antibacterial Functional Materials Filled With CA - MMT Nanoparticles

Low-density polyethylene (LDPE) is the most commonly used thermoplastics in a daily life, was widely used in plastic sheeting, fruits plastic wrap, packaging materials, and construction materials. In recent years, LDPE is also used in biomedical field, such as intravenous fluids, catheters. However, because the LDPE surface does not exist any polar groups, leading to low surface energy, chemical inertness and poor wettability and so on. Therefore, many problems encountered in practical applications. For example, it is difficult to print the ordinary ink on the inert surface of LDPE package. It is easy to form a moist environment due to the respiration of fruits or vegetables and breed and reproduce of bacteria, because of the poor wetting respiration. Breeding and reproduction of bacteria will cause a threat to human health, especially, the medical materials such as intravenous infusion sets, catheters are bacterial infection, which will seriously threat the health of patients, and even cause death. Thus, it is particularly important to prepare a long-term and safety LDPE antibacterial nanocomposite by adding antibacterial nano-particles into LDPE.In this paper, CA as a traditional anti-inflammatory/antimicrobial agent was select to intercalate into the interlayer of MMT by solution intercalation method and prepare the CA-MMT antibacterial nano-filler. Then, LDPE was melt blended with MMT, CA and CA-MMT in a HAAKE torque rheometer system to obtain different LDPE composite masterbatch. Lastly, masterbatch was pressed into thin slices on the vulcanizing machine and the structure and properties of slices were studied.The structure of powders and nano-composites were characterized by XRD. As can be seen from the XRD patterns, compared with natural MMT, the interlayer spacing of CA-MMT nano-particle increases from1.291nm to1.560nm. This demonstrates that CA has successfully intercalated into the MMT interlayer. In addition, the FT-IR characterization of the nano-particles also shows that CA has successfully intercalated into the MMT interlayer. The XRD patterns of LDPE/MMT nanocomposites appear a d001diffraction peaks at20=6.060, corresponding to the layer spacing is1.475nm, slightly increased compared with the pure MMT. This manifestated LDPE molecular chains have intercalated into the interlayer of MMT. However, the d001diffraction peak disappeared in LDPE/CA-MMT nanocomposite, which demonstrates the MMT Lamellae have exfoliated and the exfoliated composite is obtained. TGA was employed to investigate the thermal stability of the nano-particles and composites. It is found that the CA intercalation into the MMT interlayer can effectively improve the thermal stability of organic antimicrobial agent. The LDPE/CA-MMT just begins to decompose at420℃, compared to the LDPE/CA have severe decomposed at200℃.The tensile tests showed that adding MMT can play the role of reinforcement in composites, thereby increasing the tensile strength and Young’s modulus of the systems。 However, CA was added to play a plasticizer role, which increases the elongation at break and decreases the tensile strength and Young’s modulus of composites. The rheological tests found, compared with those of LDPE blank, G’, G", k*and tanθ of LDPE/MMT is almost unchanged. But LDPE/CA-MMT significantly increases and LDPE/CA is significantly reduced. This is due to modify MMT with CA can promote the exfoliation of CA-MMT and plasticizing effect of the CA.In this research, we assess the antibacterial effect of nanocomposites on E. coli by bacterial adhesion test and contact film method. It can be found from the SEM images of bacterial adhesion, the bacterial adhesion on the surface of LDPE/MMT nanocomposite is more than the LDPE blank, because of the MMT existence. However, the bacterial adhesion on the surface of LDPE/CA and LDPE/CA-MMT nanocomposites significantly less than the LDPE blank, and the LDPE/CA-MMT have minimal bacterial adhesion. This demonstrates that LDPE/CA-MMT nanocomposite has the best antibacterial properties. In addition, the results of contact film test show that the antibacterial rate for LDPE/CA-MMT is99.2%, is higher than93.3%of LDPE/CA. This is basically consistent with the results of the bacterial adhesion.In addition, this paper also studies the isothermal and non-isothermal crystallization kinetics of composite materials by DSC to analyze the impact of nano-filler on the crystallization process and morphology of the composites. The study found that the addition of MMT induces the heterogeneous nucleation of LDPE/MMT composite and the presence of CA causes the crystalline rearrangement of LDPE/CA composite. Furthermore, we believe that the crystallization behavior of LDPE/CA-MMT can be attributed to the synergies of MMT and CA.