Strength and Folding Performance of Polypropylene Packaging Samples in Hot Air and High Humidity Condition

摘要

This research was conducted to evaluate the strength and folding performance of polypropylene packaging samples, when exposed to hot air and high humidity condition. Three types of polypropylene samples were chosen, which were flat plastic, plastic with hinges, and plastic film. All of these samples were tested for tensile strength; except plastic with hinges that received additional test to evaluate the folding endurance. American Society for Testing and Materials (ASTM) D638 standard was applied to analyze the mechanical strength of these plastics. This standard was used to determine the value of stress, strain, and Young's modulus. Each sample was exposed to different temperature settings, which were 20°C, 25°C, and 30°C for high humidity condition and 60°C, 65°C, and 70°C for hot air condition. As for the folding endurance test, the hot air temperatures were selected at 60°C, 65°C and 70°C and for the high humidity condition, the range of relative humidity were set at 50%, 55% and 60%. Based on the tensile test results, the values of stress and Young's modulus were higher at higher humidity as compared with the values under hot air condition. However the strain value was the opposite of the stress and Young's modulus, whereby the values started to deceive under high humidity condition, but kept on increasing under hot air condition. In folding endurance test, it was confirmed that the hinge performed better under hot air environment than high humidity. As the relative humidity increases, the average number of folding decreased from 3.00×10~6 to 2.89×10~6 cycles. In the other hand, the value of folding numbers increased from 3.34×10~6 to 3.37×10~6, with increasing temperature. In conclusion, through this performance analysis, the outcomes can be applied to other packaging materials and appliances, which are related to high temperature and high humidity condition.