Preparation And Research Of High Density Polyethylene Multifunctional Plastic Bottle Cap

At present,the function of the bottle cap on the market is single,and with the increasing demand of consumers for the quality of the inner beverage,it is particularly urgent to develop a new functional bottle cap.In this study,three kinds of materials were used to prepare functional bottle caps and related studies were carried out.The three kinds of materials were antioxidant composite,high barrier composite and bio-based composite.In this study,we prepared new antioxidant active plastic bottle caps by incorporating butylated hydroxyanisole(BHA),or butylated hydroxytoluene(BHT)and 2%(w/w)white masterbatch in high density polyethylene(HDPE).Fourier-transform infrared(FT-IR)spectrometry revealed that the antioxidants and HDPE were uniformly mixed with non-covalent bonding.In addition,the Differential Scanning Calorimetry(DSC)test revealed that the change in melting point and initial extrapolation temperature of the antioxidant active caps was not significant.Sensory evaluation and removal torque tests validated the suitability of the antioxidant active plastic bottle caps in industrial application.The antioxidant activity increased with a greater concentration of BHA and BHT incorporated in both antioxidant active caps(P < 0.05),and with more impact in BHA cap compared to BHT cap in antioxidant activity.Migration experiments for 10 d at 40℃ and 2h at 70℃ showed that active antioxidants in the plastic bottle cap were more easily released into fatty foods and milk products that are highly sensitive to oxidation,and the migration of BHA and BHT was not exceed the maximum amount specified in GB2760-2014(< 200 mg/kg).As such,the antioxidant active plastic bottle caps inhibited oxidation,thereby ensuring higher food quality.In order to improve the gas barrier ability of plastic bottle caps,high barrier HDPE film and bottle caps were prepared using HDPE as substrate,modified montmorillonite(MMT)(0.5%,1% or 2%)as gas barrier,and white masterbatch(2%)as colorant.The effects of different kinds of MMT and their addition amount on the physical properties,gas barrier properties,practical performance,chroma,melting point and other properties of the film and bottle cap were analyzed and compared.The results showed that,compared with the blank film,the tensile strength and elongation at break of all the films after adding MMT were improved to varying degrees,among which the addition of medical-modified MMT and oil-modified MMT increased significantly(P<0.05),while the addition of water-modified MMT had no significant improvement on the mechanical properties of the composites(P>0.05).The addition of MMT can reduce the oxygen transmission coefficient of materials,but the water vapor transmission coefficient of 2% water-based modified MMT is increased,because the water-based modified MMT is better hydrophilic,resulting in a lower barrier to water vapor.Ultraviolet spectrum analysis showed that the blocking effect of visible light was also improved.It was found that the size,opening torque and anti-odor tests of all the test caps were within the qualified range and met the requirements of practical use.In order to develop new biodegradable composite materials to alleviate environmental pollution caused by traditional petroleum-based materials.thermoplastic starch(TPS)as modifier and additive,the composite sheet with TPS content of 0,10%,20%,30% and40% was prepared by melt blending.The influence of TPS content on the physical properties of TPS/HDPE sheet was analyzed and compared.It was found that the addition of TPS reduced the toughness and plasticity of the material and increased the rigidity of the material.When TPS content reached 40%,the tensile strength decreased by 52.3%compared with HDPE,and the elongation at break decreased by 50 times,while the bending strength and bending modulus increased by 100.2% and 70.5% respectively.Infrared spectral analysis showed that a new peak was found at 1200cm-1.DSC analysis showed that the melting temperature of the material decreased from 136.1℃ to132.7℃.When the content of TPS is 40%,the hydrophobicity of composites is the best.The study showed that the introduction of certain amount of TPS could improve the rigidity and hydrophobicity of HDPE,which provided theoretical and technical support for the preparation of high-performance starch-based food contact materials.