Preparation And Performance Of Blended And Composite Packaging Films Based On Nano-antioxidant Assembly

Fat oxidation not only affects food quality,but also relate to food safety.Slow release antioxidant active packaging,which has attracted more and more attention,controles releae rate of antioxidant active substances.For slow release of antioxidant active substances,mesoporous nano-materials usually used as Carrier to form antioxidant active assembly.However,the introduction of the assembly leads to defects in polymer film,which result in a decrease of film’s mechanical and barrier properties.This work executed as following steps:（1）different mesoporous nano-SiO₂ Carriers were prepared to adsorbα-tocopherol（α-TCP）,a natural antioxidant active substance,to form a series ofα-TCP/MCM-41 antioxidant active assembly.（2）Chose a best Assembly add into LDPE to prepare antioxidant active film.LLDPE and POE were introduced as modification to prepare single-layer blended antioxidant active films.（3）Introduced PP layer to prepare a double-layer composite antioxidant film.Studied the microscopic form of the Carriers and load rate of the Assemblys.Films’properties were also detected,which including barrier,mechanical and controlled release properties.The results showed as follows:（1）The mesoporous pore size and pore volume of Carriers increase successively from C12Carrier to C18 Carrier.C14/C16/C18 Carriers show typical two-dimensional characteristics of hexagonal pores,as well as long narrow pores.The C16 Carrier pores has the best microscopic pore structure among Carriers.The Assemblys’insulating effect leads to thermal resistant temperature ofα-TCP,which integrated into Assemblys,increase by 70%when compared with baredα-TCP’s.The C16 Assembly has the highest loading rate forα-TCP,which is 17.37%.Subsequent research used C16 Assembly to prepare antioxidant active films.（2）LDPE used as base material,and LLDPE,POE are introduced respectively as modification to solve the problem caused by the Assembly,which is mechanical performance degradation of films.Totally,10 single-layer films of LDPE,LLDPE-LDPE,and POE-LDPE were prepared.It shows that the addition of LLDPE make melting range of the blend films increased by97.87%when compared to pure LDPE,which is beneficial to films’thermal processing.As compared with LDPE films,the addition of POE increase oxygen permeability by 120%.It means a decrease of the oxygen barrier performance.As compared to pure LDPE film,the mechanical properties of the active films are significantly improved by the additives.Especially the film modified by POE and Assembly,whose tensile strength increase rate is more than 2.5times as other samples’.As compared to the films modified with baredα-TCP,the Assembly reduces the diffusion coefficient ofα-TCP by 45%-47%,which shows the active films have remarkable controlled release property.Films’crystallinity is negatively correlated with release rate of the antioxidant substance,which can be used to control the release behavior of the active film to enhance the controlled release performance.（3）A double-layer composite antioxidant active film was prepared.The LDPE added with the assembly was used as the internal active layer,and the PP layer was introduced as the external barrier layer.Studied its morphological characteristics,barrier,mechanical,and controlled release properties.The double-layer composite antioxidant active film has the best oxygen barrier performance among all films,and the oxygen permeability is about 60%of the the LDPE film.Although the haze is slightly higher than LDPE film,the light transmittance is higher than all other films.The mechanical properties of the double-layer composite antioxidant active film are the best of all films.When compared with the LDPE film,the increase rate of elongation and the increase rate of tensile strength are+67.5%and+86.9%.They are stronger than synergistic enhancement of the single-layer blend active films’.The double-layer composite antioxidant active film has the best slow-release ability of all films,and the diffusion coefficient is 1.1282(10^-9·cm²·s^-1),lower than all other films,about 67%of the control group.In general,the assembly significantly improve the thermal stability of theα-TCP that integrated into Carrier,and the addition of LLDPE increase the melting range of blended films.In terms of barrier performance,the addition of POE reduces the oxygen barrier performance of the film.However,it enhanced with the application of the double-layer composite active film.In terms of mechanical properties:the co-adition of POE and the Assembly have a significant synergistic effect on the mechanical properties（tensile strength,elongation at break）of the films.Moreover,the double-layer composite active film are stronger than all single-layer films.In terms of controlled release performance:assembly,composite active film technology,and film crystallinity all have a significant impact on the active film,which can be used to control the release behavior of active packaging films and enhance the controlled release performance of active packaging.As a result,the prepared materials can be used to regulate active substances’release rate of antioxidant active package.And it shows a good potential for strengthen and toughen package films.