稻壳生物炭/醋酸酯淀粉-尿素复合膜的结构和性能

Structure and properties of rice husk biochar/acetate starch-urea starch composite films

采用流延法制备了醋酸酯淀粉(AS)∶尿素(UR)∶稻壳生物炭(RHBC)质量比分别为8∶1∶1、8∶2∶1、8∶4∶1的RHBC/AS-UR复合膜,利用SEM、FTIR、XRD、TGA等测试手段对RHBC/AS-UR复合膜的微观形态和结构性能进行了研究,采用流化床喷雾包膜装置制备了RHBC/AS-UR包膜UR肥并测试了其释放特性。结果表明:RHBC能够均匀的分散于RHBC/AS-UR复合膜中,与UR-AS交联体间形成了“固体桥”的微观结构,结合紧密,同时,RHBC的添加可以提高复合膜的热稳定性。UR的添加可以提高复合膜的延展性能,当UR质量分数为18.2wt%时,RHBC/AS-18.2wt%UR复合膜的力学性能达到最佳,断裂伸长率提高了约500%。UR释放特性试验结果表明,与未包膜UR相比,不同质量比的RHBC/AS-UR包膜UR均能有效降低UR态氮的释放速率,其中,RHBC/AS-18.2wt%UR包膜UR在连续24h浸泡后的总释放率最小(81%),表现出更好的缓慢释放性能。

The rice husk biochar/acetate starch-urea (RHBC/AS-UR) composite films were prepared by casting method with different AS:UR:RHBC mass ratios of 8:1:1, 8:2:1, 8:4:1, respectively. The micromorphology and structure properties of the RHBC/AS-UR composite films were investigated by SEM, FTIR, XRD and TGA. The RHBC/AS-UR composite-coated UR fertilizers were prepared in a spouted fluidized bed coating equipment and its release characteristics were tested. The results show that the rice husk biochar can be uniformly dispersed in the RHBC/AS-UR composite film and has good bonding with AS-UR in a "solid bridge" structure. In the mean time, the thermal stability of RHBC/AS-UR composite films is enhanced by adding RHBC. The adding of UR can improve the ductility of RHBC/AS-UR composite film. When the mass fraction of UR is 18.2wt%, the best mechanical properties of the RHBC/AS-18.2wt%UR composite film can be reached and the elongation at break increases by 500%. Compared to the pure UR granule without and with RHBC/AS-UR coating, the UR coated with different mass ratios of RHBC/AS-UR composite films can effectively reduce the release rate of UR-N. The total release rate of RHBC/AS-18.2wt%UR coated UR is the lowest (only 81%), which exhibits better slow-release property.