尿素缓释膜材料——机械活化醋酸酯淀粉的制备及其膜性能

Preparation of mechanically activated starch acetate of ester-film material for carbamide controlled release and its film performance

为了有效提高淀粉基质尿素缓释膜的性能,对机械活化1.0 h的木薯淀粉(MAS)进行酯化改性,制备了机械活化醋酸酯淀粉(MASA)、机械活化醋酸酯淀粉/聚乙烯醇的生物降解塑料膜(MASA/PVA)及MASA/PVA包膜尿素。用傅立叶红外光谱仪(FTIR)、扫描电镜(SEM)、差示扫描量热仪(DSC)分别对MASA的结构、形貌、热稳定性等进行测试,并与用不同取代度制备的原木薯醋酸酯淀粉/聚乙烯醇生物降解塑料膜(SA/PVA)进行比较。结果表明,机械活化淀粉经酯化改性后,结构和形貌都有很大的改变,热性能提高;MASA/PVA的性能均比SA/PVA好,以机械活化醋酸酯淀粉(取代度为0.2)原料制备的MASA/PVA浸水前的拉伸强度为3.23 MPa,断裂伸长率206.68%,24 h吸水率为115.96%,在20 d内生物降解率为36.46%。MASA/PVA包膜尿素淋溶9次后尿素总溶出率为45.69%,比SA/PVA包膜尿素降低18.12%,比普通尿素降低51.49%。用MASA/PVA包膜尿素对尿素态氮有明显的缓释作用。

In order to improve the properties of starch-based films for carbamide controlled release, the mechanically ac-tivated starch acetate （MASA） was synthesized from mechanically activated cassava starch （MAS）. The biodegradable mechani-cally activated starch acetate polyvinyl alcohol（MASA/PVA） films were produced. Fourier transform infrared spectrogram （FT-IR）, scanning electron microscopy （SEM） and differential scanning calorimetry （DSC）, the microstructure, particle shape and thermal property of MASA were studied. And the film performances were compared with those made of starch acetate （SA） with variacs degrees of substitution（DS）. The results revealed that the microstructure and particle shape changed greatly and thermal property of MASA increased. The properties of MASA/PVA were better than those of SA/PVA. The tensile strength of the MA-SA/PVA with MASA （ DS = 0. 2 ） was 3. 23 MPa, the breaking elongation was 206. 68% before soaking in water, the absorption of water was 115. 96% after 24 h, and the rate of biodegradation was 36. 46% in the soil after 20 d. The to-tal urea stripping rate of MASA /PVA coated urea reached 45. 69% after 9 times leaching, 18. 12 percent and 51. 49 per-cent lower than urea and coated that with SA/PVA, respec-tively. Coating film made of MASA/PVA had remarkable controlling effects on urea nitrogen release.