端羧基超支化聚酯增强淀粉/壳聚糖复合膜

Carboxy-terminated hyperbranched polyester reinforced starch/chitosan composite film

为了提高淀粉/壳聚糖复合膜(SC)的机械性能和蒸汽阻隔性能,以端羧基超支化聚酯(HPC)为改性剂,通过溶液浇铸法制备了一系列淀粉/壳聚糖/HPC复合膜[SCH x,x%为HPC含量(以淀粉和壳聚糖干重计,下同)],考察了HPC含量对SCH复合膜性能的影响。采用FTIR、XRD、SEM、DSC、TG对复合膜进行了表征,测试了复合膜的力学性能、热稳定性、水蒸气渗透性、疏水性和蒸汽阻隔性、抗菌性能。结果表明,HPC的加入大体上增加了SC复合膜的平均厚度和密度,在提高拉伸强度的同时保持了断裂伸长率,降低了复合膜的水蒸气渗透性,但对SC的抗菌性能没有明显改变。SCH 2.50力学性能最好,其平均拉伸强度从SC的2.26 MPa增至3.58 MPa,平均断裂伸长率从151.04%降至146.40%。SCH在280~320 nm范围内产生强吸收,强度随HPC含量的增加而提高。SCH复合膜水接触角在106.9°~113.3°之间,整体呈现较强的疏水性。SCH 2.50的水蒸气渗透性从SC的2.855×10^(-9)g·cm/(cm^(2)·h·Pa)降至2.133×10^(-9)g·cm/(cm^(2)·h·Pa)。HPC与淀粉/壳聚糖之间通过氢键和酯化作用形成了均匀致密的内部结构,增加了表面粗糙度,从而提高了SCH的机械性能和蒸汽阻隔性能。

In order to improve the mechanical and vapor barrier properties of starch/chitosan(SC)composite films,a series of starch/chitosan/HPC[SCH x,x%is HPC content(based on the mass of dried starch and chitosan,the same below)]composite films were prepared by solution casting with carboxy-terminated hyperbranched polyester(HPC)as modifier,with the influence of HPC content on its properties analyzed.The SCH composite films obtained were then characterized by FTIR,XRD,SEM,DSC and TG,and further evaluated for their mechanical properties,thermal stability,water vapor permeability,hydrophobicity,vapor barrier properties,as well as antibacterial properties.The results indicated that,with HPC addition,the composite films showed generally an increase in the average thickness and density,improvement in tensile strength reduction in water vapor permeability,while no obvious change in elongation at break as well as the antibacterial property.SCH 2.50 exhibited the best mechanical properties,with the tensile strength increasing from 2.26 MPa to 3.58 MPa and the elongation at break decreasing from 151.04%to 146.40%.SCH displayed strong light absorption in the range of 280~320 nm,with the intensity increasing with the increment in HPC content.The water contact angle of SCH composite films ranged from 106.9°to 113.3°,showing overall strong hydrophobicity.Meanwhile,the water vapor permeability of SCH 2.50 decreased from 2.855×10^(-9) g·cm/(cm^(2)·h·Pa)to 2.133×10^(-9) g·cm/(cm^(2)·h·Pa).HPC and starch/chitosan formed a uniform and dense internal structure through hydrogen bonding and esterification,increased the surface roughness,and thus improved the mechanical properties and vapor barrier properties of SCH.