| Aluminum-plastic composite packaging materials were extensively used in many kinds of packaging. However, the aluminum film was inevitably wrinkled during the process of product loading, sealing, packing and transportation. Most companies only focus on the initial oxygen and water vapor tests of the aluminum-plastic composite packaging materials, while ignoring the minor defects like cracks of the materials. And the defects will have effect on the barrier properties of the materials and on the shelf-life of the products. This thesis will study these defects and find their impacts on the barrier property of packaging. The paper includes five parts:(1) Research into classification of the small defects and reasons of the aluminum-plastic packaging materials. According to the degrees of damage to the minor defect, the minor defect can be divided into these kinds: crease defects, pinhole defects, perforate defects, and sealing defects. Besides, summarize the reasons of the phenomenon, and finally put forward several measures to avoid the minor defects.(2) Experimental study of the crease defects on the barrier property of packaging. Simulate the effect of folding creases on the water vapor permeability and oxygen permeability through the experiments. Obtain the empirical models of the effect of the folding length and folding times on the barrier property. Find that pairs of folding times on the barrier effect is limited, and mainly for folding length of the right barrier impact, but totally speaking, the crease defect has the least impact on the barrier property of the materials.(3) Theoretical and experimental research of the pinhole defects on the barrier effects of the packaging. First, according to the Fick diffusion theory and the theory of multi-layer composite material, simplify the impact of cracks on the barrier part of the permeability into internal and external defects, non-defective part was provided by the three-tier materials, co-established the rift area and theoretical model of ventilation volume, then validate crack area on the impact of the amount of ventilation through the experiments. And found that experimental measure was significantly higher than the theoretical measure. Some views of the outcome was put forward.(4) The theoretical and experimental of the micropore effects of on the packaging barrier research. First, based on micro-Fick diffusion law, a theoretical model about the micropore volume and the air permeability was established, and got the correction factor of the water vapor permeability and oxygen permeability of the PET12μm/AL12μm / PE75μm through experiments, and found that it had a good degree of matching value in the theoretical prediction and experimental measurement. In addition, the chosen representative of several liquid products were measured by their density, viscosity, surface tension and other physical properties, and then established a theoretical model and calculated the critical pressure under the different size micro-leakage and conducted a validation of their theory.(5) Experimental study of all the small defects on the barrier property of packaging. Gelbo flex and folding tests were used to evaluate the effect of small defects such as cracks and pinholes on barrier properties of aluminum-polymer packaging films such as aluminum or metalized polymer films. The results showed that barrier properties of all kinds of films deteriorated gradually as the number of flexing or folding cycles increased; the barrier properties of aluminum-polymer films deteriorated more quickly than polymer films; metalized polyester is the most susceptible to the defects; and the thickness of aluminum also influence the severity to the defects.
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