纳米TiO2LDPE复合材料包膜控释肥残膜的降解特性

将纳米TiO₂与低密度聚乙烯(LDPE)复合形成包膜液,采用喷动流化床包膜设备制备了纳米TiO₂-LDPE复合材料包膜控释肥.在水浸泡法研究控释肥养分释放特征的基础上,对人工加速老化条件下光照不同时间的控释肥残膜进行失重率测定.采用FT-IR、DSC和黏度法等分析了纳米TiO₂对控释肥残膜光催化降解特性的影响,探讨了残膜在光照前后的分子量和羰基指数等的变化规律.结果表明:光催化剂加入后,控释肥的养分释放速率降低且释放期变长;疏水纳米TiO₂对控释肥残膜的降解具有显著的促进作用,当添加的质量分数为1%时,降解性能最好.随着残膜的降解程度增大,残膜中LDPE的羰基指数和结晶度升高,黏均分子量下降.

Degradation behavior of residual films of controlled release fertilizers with nano-TiO2 LDPE composites

Nano-TiO₂ and low density polyethylene (LDPE) were combined to form coating fluids, and nano-TiO₂-LDPE composite-coated controlled release fertilizers were prepared in a spouted fluidized bed coating equipment. Based on the research of their release characteristics via water immersion method, the mass loss rates were measured after different irradiation time by artificial accelerated ageing test. The effects of nano-TiO₂ on photo-degradation behavior of residual films were systematically studied by using FT-IR spectroscopy, DSC and viscosimetry. And changes in molecular mass, carbonyl index and others during degradation were discussed. It is found that under the function of photo-catalyst, the urea release rate of controlled release fertilizer has a certain degree of delay, the release period becomes longer and the degradation of residual film is remarkably promoted by hydrophobic nano-TiO₂. Furthermore, residual film shows the best degradation property when the mass fraction of hydrophobic nano-TiO₂ is 1%. With the increasing of degree of residual film degradation, the carbonyl index and crystallinity of LDPE in residual film increase, and the viscosity-average molecular mass decreases.