Effect of Atmospheric Pressure Plasma Treatment on the Lap-Shear Strength of Adhesive-Bonded Sheet Molding Compound Joints

Atmospheric pressure plasma treatment(APPT)technology was used herein to treat sheet molding compound(SMC)substrates to increase the lap-shear strength of adhesive-bondedSMCjoints.Further,the mechanisms behind the lap-shear strength improvements in APPT-treated adhesive-bonded SMC joints were explored.A maximum lap-shear strength about three times that of the as-received SMC joints was achieved when the APPT distance was set to 20 mm.The surface roughness,which exhibited little benefit to the lap-shear strength,was determined to not be the primary reason for the increase in lap-shear strength.Specifically,X-ray photoelectron spectra revealed that an increased amount of O-containing groups(i.e.,C–O–H,C–O–C,H–O–C=O or R–O–C=O)following APPT contributed to the improved lap-shear strength.In addition,the surface free energy increased significantly after APPT,which improved the lap-shear strength of the adhesive-bonded SMC joints.Compared to the change of surface morphology,the changes in both the surface chemical property and surface free energy played larger roles in increasing the lap-shear strength of APPT-treated SMC joints.

等离子体处理对于聚丙烯胶粘接强度的影响

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%。

利用等离子体处理提高胶版纸表面强度的实验研究

表面强度是胶版纸最重要的印刷运行性能。在实验室利用低温等离子体对纸张进行表面处理后再表面施胶的研究发现，纸张经等离子体处理后，表面施胶效果得到改善，纸张表面强度显著提高。从表面化学的角度，通过对处理后纸张表面自由能和接触角变化的考察，对表面强度提高的原因进行了分析。

离子渗氮对Cr12MoV表面CrNiTiN镀层耐磨性和表面能的影响

在经过离子渗氮(PN)处理的冷作模具钢Cr12MoV基体上,采用闭合场非平衡磁控溅射离子镀法制备CrNiTiN镀层,与未渗氮的试样进行了膜/基结合力、耐磨性和表面能的对比。研究表明,CrNiTiN膜层具有较低的表面能,但是膜层和基体的结合力较差。Cr12MoV钢经离子氮化后,CrNiTiN膜层与氮化层间结合紧密,提高了膜与基体的承载能力;离子氮化处理使膜层的摩擦系数和磨损率明显降低;离子氮化会提高CrNiTiN膜层总表面能,但不会影响表面的抗粘性能。