Font Size: a A A

Preparation And Properties Of Starch/Hydroxypropyl Methyl Cellulose Composite Films

Posted on:2017-04-17Degree:MasterType:Thesis
Country:ChinaCandidate:H L LuFull Text:PDF
GTID:2321330515950731Subject:Food Science
Abstract/Summary:PDF Full Text Request
In order to preopared starch based composite films with excellent properties,the starch/HPMC composite films by solution casting were prepared from high amylose corn starch(HACS)and hydroxypropyl methyl cellulose(HPMC).The effects on the properties of starch/HPMC composite films with different proportion of materials,emulsifiers,degree of modified starch and method of preparation were studied from different aspects through properties of measuring the mechanical,permeability,light-transmittance,heat sealing,combined with scanning electron microscopy(SEM),X-ray diffraction(XRD),fourier transform infrared spectroscopy(FT-IR),dynamic mechanical analysis(DMA).The main results were as follows:(1)The effects of HPMC on the properties of HACS films.FT-IR results showed that interaction of HACS and HPMC were formed after adding HPMC while XRD results show that the crystallinity of composite film can be reduced effectively after adding HPMC and it can inhibited the recrystallization during storage.Through the water soluble indicated that the continuous phase change with the change of proportion of HACS and HPMC.The HACS was the continuous phase with the low proportion of HPMC while the HPMC as the continuous phase when proportion is 60:40.Compared with other proportion when HACS:HPMC was 80:20,the tensile strength increased to 7.5 MPa,a lower water vapor permeability(2.17 × 10-10 g?m?m-2?s-1?Pa-1)and higher contact angle(84.33 °)for composite film.(2)The effects of diferent emulsifiers with different hydrophilic-lipophilic index(HLB)on the properties of HACS/HPMC composite films.XRD analysis indicated that emulsifiers interact with HACS formed V-type crystal after adding it to composite film,then affected the crystallization properties of composite films.When added 2% monoglycerides the mechanical properties of the composite film improved significantly.The tensile strength and elongation at break of composite film were 10.24 MPa and 15.86%,respectively.SEM analysis indicated that chasm of cross-section disappeared and particle aggregation of surface reduced.Compatibility was improved.(3)The effects of esterification on the properties of HACS/HPMC composite films.DMA results indicate that the compatibility can be improved when the HACS was modified with appropriate esterification.The tensile strength and elongation at break of 0.04 acetate starch/HPMC composite film were 11.8 MPa and 26.6%,respectively.The contact angle of composite film was 100 °that was hydrophobic.The cross-section was uniform and the surface was smooth.The change of crystallization peak also indicated that the interaction between starch(DS=0.04)and HPMC was stronger.(4)The effects of film preparation method on the properties of starch/HPMC conposite film.HACS,acetic anhydride,hydroxypropyl crosslinking starch and HPMC all had good film-forming properties.Therefore the properties of blend and three-layer composite films was cpmpared.The results indicated that when starch and HPMC had good compatibility,the difference on the mechanical properties of the two film formation methods was insignificant,but if the compatibility was poor,the properties of the blend film were worse than three layer composite films obviously.Further the transparency of three layer composite films was significantly higher than the blend films.
Keywords/Search Tags:high amylose corn starch, hydroxypropyl methylcellulose, emulsifier, acetic anhydride, blend film, three-layer film
PDF Full Text Request
Related items