等离子体处理对于聚丙烯胶粘接强度的影响

Effects of Plasma Treatment on Adhesive Bonding Strength of Polypropylene

聚丙烯(PP)是微流控芯片常用的加工材料,但由于PP表面非极性,表面能低,使得PP材料的微流控芯片胶粘接强度较差,难以满足使用要求。等离子体处理是聚合物表面改性常用的一种方法,系统研究了等离子体处理对于PP胶粘接强度的影响。利用光学接触角测量仪和扫描电子显微镜等对比分析了等离子体处理前后PP表面的接触角、自由能和微观形貌的变化,实验发现等离子体处理后PP表面去离子水的接触角由99°减小到了75°,表面自由能由31 m J/m2增大到了49 m J/m2,PP表面由疏水性变为了亲水性,并且表面出现了大量的纳米级凸起和凹坑,从而揭示了等离子体处理对于提高PP胶粘接强度的机理。对等离子体处理的工艺参数进行了优化,利用T剥离强度试验方法对PP的胶粘接强度进行了测试,PP的平均胶粘接强度提高了24%。

Polypropylene(PP) is a popular material for fabricating microfluidic chips. However, the PP surface is non-polar and has a low surface energy, and therefore the adhesive bonding strength of PP microfluidic chips is relatively poor and could not meet the requirement of practical applications. Plasma treatment is a common method of surface modification of polymers. The effects of plasma treatment on adhesive bonding strength of PP were systematically studied. The changes in contact angle, free energy and microscopic morphology of PP surface were analyzed by optical contact angle measuring instrument and scanning electron microscope. It was found that after PP surface was modified by plasma, the contact angle of deionized water on the PP surface was decreased from 99° to 75°, the surface free energy was increased from 31mJ/m~2 to 49mJ/m~2, the PP surface was changed from hydrophobicity to hydrophilicity, and a large number of nanoscale hillocks and pits were formed on the PP surface, which revealed the mechanism of plasma treatment for improving the adhesive bonding strength of PP. The process parameters for plasma treatment were optimized, the adhesive bonding strength of PP was tested by the T-peel strength test method, and the average adhesive bonding strength of PP was increased by 24%.