超声对不同粒径二氧化硅改性热塑性木薯淀粉的影响

Effect of ultrasound on thermoplastic cassava starch modified by silica with different particle sizes

通过熔融共混模压法制得了热塑性木薯淀粉(TPS)/SiO_(2)复合材料。采用DSC、偏光(PLM)、水接触角、TG、SEM、FTIR、XRD考察了超声作用下不同粒径(0.02、0.2、23μm)SiO_(2)对热塑性木薯淀粉的回生熔融焓、回生速率、回生指数及球晶形态结构、水接触角、热稳定性的影响。结果表明,超声作用使TPS/SiO_(2)复合材料的熔融焓增加、回生速率提高、回生指数降低,且添加粒径0.02μm SiO_(2)制得TPS/SiO_(2)复合材料的回生速率提升幅度最大;超声作用使TPS/SiO_(2)复合材料球晶变得明显、水接触角提高;超声作用使复合材料的水分容易挥发,甘油与淀粉的结合能力增强,淀粉的分子结构稳定性增加;超声作用使SiO_(2)粒子在基体中聚集减少、分散更好;复合材料的回生程度增加,双螺旋结构减少;复合材料呈现出A+V晶型,超声作用后,复合材料V晶型增加、A晶型减少。

Thermoplastic cassava starch(TPS)/SiO_(2)composites were prepared by melt blending and molding methods.The effects of SiO_(2)with different particle sizes(0.02,0.2,23μm)on the retrogradation melting enthalpy,retrogradation rate,retrogradation index,spherulite morphology,water contact angle and thermal stability of thermoplastic cassava starch under ultrasonic treatment were studied by DSC,polarization(PLM),water contact angle,TG,SEM,FTIR and XRD.The results indicated that ultrasonic treatment led to the increment of enthalpy retrogradation,enhancement of the retrogradation rate,and reduction of the retrogradation index.The retrogradation rate of the TPS/SiO_(2)composites with 0.02μm SiO_(2)added increased the most.Ultrasonic treatment made the spherulite of TPS/SiO_(2)composites become more obvious,the water contact angle increase,the moisture in the composite easier to volatilize,the bonding between glycerol and starch enhance,and the molecular structure stability of starch increase.Furthermore,ultrasonic treatment made the SiO_(2)particles aggregate less and disperse better in the matrix,the degree of retrogradation increase,while the degree of the double helix structure decrease.The composites was presented in the form of A+V type crystal,with the V type crystal increased and the A type crystal reduced after ultrasonic treatment.