White David E, Kim Hyun Chan, Al-Rawi Mohammad, Yuan Xiaowen, Sojan Tony
School of Engineering, Computer and Mathematical Sciences, Auckland University of Technology, Auckland 1142, New Zealand.
Centre for Engineering and Industrial Design, Waikato Institute of Technology, Hamilton 3240, New Zealand.
Materials (Basel). 2024 Apr 22;17(8):1925. doi: 10.3390/ma17081925.
This pilot investigation identifies the influence that changing the process variables of curing pressure, curing temperature, and mix ratio of a polyurethane/agglomerated cork matrix has on the mechanical properties of energy absorption, Young's modulus of elasticity, and spring stiffness in safety helmets intended for micro-transport riders. The results are compared to expanded polystyrene, a material commonly used in micro-transport helmets. Mechanical testing of the various samples found that, over the range tested, curing pressure had no effect on any of the mechanical properties, while increasing amounts of resin caused a stiffer structure, and increasing curing temperature led to increased energy absorption. Consistent with the elastic modulus findings, all polyurethane/agglomerated cork test samples demonstrated higher median levels of spring stiffness, ranging from 7.1% to 61.9% greater than those found for expanded polystyrene. The sample mixed at a 1.5:1 binder/cork ratio and cured at 40 °C displayed the closest spring stiffness to EPS. While the mechanical properties of the eco-friendly polyurethane/agglomerated cork matrix did not match those of expanded polystyrene, the difference in performance found in this study is promising. Further investigation into process variables could characterise this more ecologically based matrix with equivalent energy-absorbing and structural characteristics, making it equivalent to currently used expanded polystyrene and suitable for use in micro-transport helmets.
这项初步研究确定了改变聚氨酯/团聚软木基质的固化压力、固化温度和混合比例等工艺变量，对微型交通工具骑行者使用的安全头盔的能量吸收、杨氏弹性模量和弹簧刚度等力学性能的影响。将结果与微型交通工具头盔中常用的材料发泡聚苯乙烯进行了比较。对各种样品的力学测试发现，在所测试的范围内，固化压力对任何力学性能均无影响，而树脂用量的增加会导致结构更硬，固化温度的升高会导致能量吸收增加。与弹性模量的研究结果一致，所有聚氨酯/团聚软木测试样品的弹簧刚度中值水平都更高，比发泡聚苯乙烯的中值水平高7.1%至61.9%。以1.5:1的粘合剂/软木比例混合并在40℃固化的样品显示出与发泡聚苯乙烯最接近的弹簧刚度。虽然环保型聚氨酯/团聚软木基质的力学性能与发泡聚苯乙烯不匹配，但本研究中发现的性能差异是有前景的。对工艺变量的进一步研究可以表征这种更具生态基础的基质具有等效的能量吸收和结构特性，使其等同于目前使用的发泡聚苯乙烯，并适合用于微型交通工具头盔。
