Preliminary Study On Tension Properties Of Multi-layer Flexible Packaging Material

This article focuses on rupture of multi-layer flexible packaging material, and it explains crackle growth/propagation by means of damage mechanics and fracture mechanics, based on properties of base material and compounding technique. It works over change on material's stretching under natural environment, simulated ultraviolet radiated condition and soft rot condition respectively, also checks influence of loading rate's change on material's tensile strength. This is favorable to establish new theory of damage mechanics and fracture mechanics about multi-layer flexible packaging material, meanwhile, it offers theoretical basis for compounding technique's development and multi-layer flexible packaging material's improvement.(1)The influence of loading rate on tensile strength's change of the low-density polyethylene film in longitudinal and traverse directions was studied in the paper, and crack growth under different distortion is observed with the help of microscope. Because of molecule structure's difference in longitudinal and traverse directions, traverse tensile strength and tear stretching rate are greater than that in longitudinal direction; low-density polyethylene film enjoys great ductibility, which amortizes material's tensile strength, while, stretching rate has no significant impact on tensile strength or tear rate.(2)Tension properties of multi-layer flexible packaging material(BOPET/AL/LDPE)under different loading rate. Loading rate has some influence on tension, when loading rate is at high speed, no time is left for buffering energy, no time is left for slippage between molecular chain either, so tensile strength remains mild;While loading rate is at low speed, partial energy is consumed, and molecular chain is reorganized, so tensile strengh is comparatively strong.(3)At different loading rates, 4 cutting depths and 5 cutting angles'tear strength of multi-layer flexible packaging materia(lBOPET/AL/LDPE). At a certain cutting angle, smaller cutting angle results in stronger tear strength; when cutting angle is 45°≤α≤90°, as cutting angle increases, tear strength goes stronger; When loading rate is at low speed, followed tear strength is not strong; therefore, loading rate and cutting angle have significant influence on tear strength.(4)Simulated ultraviolet radiated condition's influence on tension of multi-layer flexible packaging material(BOPET/AL/LDPE)at different loading rate. Ultraviolet radiating time has some influence on tension, as radiating time goes, tensile strength decreases correspondingly.(5)Soft rot soil's influence on tension of multi-layer flexible packaging material...