Study On Antibacterial Properties Of Cu-N-TiO₂/Biochar In-situ Modified Polyester And Its Fibers

Polyester(PET)fiber is the largest synthetic fiber today.It has been widely used in the field of textile and industry because it is wrinkle-resistant,sturdy and relatively inexpensive.However,the general PET fabric does not have antibacterial function,and its loose and porous surface is easily attached by external bacteria and microorganisms.It can also be contaminated with human sweat and sebum in the process of wearing,which provides a breeding ground for bacteria.With the advancement of science and technology and the improvement of people's requirements for life quality,the antibacterial modification of PET has become an important direction for new product development.Nano titanium dioxide(TiO₂)is a kind of antibacterial agent with simple synthesis process,low cost,excellent chemical stability,harmless and non-irritating.However,due to its wide band gap,it generally has high antibacterial activity only under ultraviolet light irradiation.In addition,the agglomeration makes its specific surface area small.Its adsorption performance of organic pollutants is poor,which is not conducive to the application in photocatalysis.On the other hand,China is a big country in agricultural production,a large number of waste biomass raw materials are buried and incinerated,which seriously pollutes the environment.It is of great significance to recycle these biomass resources,which is both environmentally friendly and economical.Based on the above problems,nano TiO₂was co-doped in the paper to improve its photocatalytic activity.Further,porous biochar(BC)was prepared with the seed coat of torreya as the carbon source to load doped TiO₂to make the antibacterial composites.The adsorption capacity of biochar is used to enrich bacterial microorganisms on the surface of doped TiO₂,which increases the contact probability between antibacterial agents and microorganisms and enhances the antibacterial effect.Then the antibacterial composite material was introduced to modify PET by in-situ polymerization,and the modified fibers were prepared by melt spinning to explore chips'spinnablity and the properties of fibers.The details are as follows:(1)Cu-N/TiO₂and Cu-N/TiO₂-BC composites were prepared by sol-gel method.The results of X-ray diffraction(XRD)shows that Cu²⁺enters into the TiO₂lattice nicely.With the increase of Cu²⁺doping content,the lattice distortion get more serious,and the grain size get smaller.The UV absorption peak of Cu-N/TiO₂broadens with the increase of Cu²⁺doping content,and the absorption of visible light is enhanced.BC has a specific surface area as high as 931.018m~2/g,and the energy dispersive X-ray spectroscopy(EDX)test shows that BC achieves good loading on Cu-N/TiO₂.With the increase of Cu²⁺doping content,the antibacterial property of doped TiO₂is gradually enhanced.After compounding with BC,the antibacterial activity of Cu-N/TiO₂-BC is further enhanced.When the mass fraction of BC is 10%,Cu-N/TiO₂-BC has the best antibacterial activity.(2)Cu-N/TiO₂-BC(1:0.1)modified PET chips with contents of 0.5wt%,1.0wt%,1.5wt%and2.0wt%were prepared by in-situ polymerization.Cu-N/TiO₂-BC can act as a nucleating agent,which strengthens the crystallization ability and increases the crystallization temperature of modified PET.The grain size of modified PET also becomes uneven,and the melting peak appears split peak phenomenon.The rheological test results show that Cu-N/TiO₂-BC reduces the interaction force between polymer segments,which can promote the motion of the segments.The apparent viscosity of the sample is lower than that of pure PET,but too much powder will increase the steric hindrance in the polymer system,and the apparent viscosity of the sample will rise again.The non-Newtonian index and the structural viscosity index of the sample are similar in the range of 280?-290?,indicating that the melt is relatively stable in this range.(3)Finally,the modified PET chips were melt spun to obtain antibacterial fibers.The mechanical property test shows that with the increase of antibacterial composite powder content,the breaking strength of modified fibers decreased,while the elongation at break increased slightly.When the antibacterial composite powder content exceeds 1.5wt%,the formability of the fibers becomes poor.Modified fibers with a powder content of 0.5wt%and 1.0wt%both achieve a bacteriostatic rate of more than 95%against Staphylococcus aureus.