Increasing the surface energy of nonwoven fabrics by exposure to a one atmosphere uniform glow discharge plasma (OAUGDP)

Summary form only given, as follows. A technique for generating active species with the one atmosphere uniform glow discharge plasma (OAUGDP) has been developed and used to increase the surface energy, wettability, and wickability of nonwoven fabrics. The OAUGDP is a non-thermal plasma with the classical characteristics of a low pressure DC normal glow discharge that operates in air (and other gases) at atmospheric pressure. No vacuum system or batch processing is necessary, and a wide range of applications to fabrics and polymeric webs can be accommodated in a parallel plate plasma reactor. This technology is simple, produces many effects that can be obtained in no other way, generates minimal pollutants or unwanted by-products, and is suitable for online treatment of webs, films, and fabrics. Early exposures of nonwoven fabrics to the OAUGDP required minutes to produce relatively small increases of surface energy. These durations appeared too long for commercial application to fast-moving webs. Recent improvements in OAUGDP power density, plasma quality, and impedance matching of the power supply to the parallel plate plasma reactor have made it possible to raise the surface energy of a variety of polymeric webs (PP, PET, PE, etc.) to levels in the range of 60 to 70 dynes/cm with one second of exposure. In most cases these high surface energies were not durable, and fell off to 50 dynes/cm after periods of weeks to months. We report the exposure of nonwoven fabrics made of PP and PET at the UT Textiles and Nonwovens Development Center (TANDEC) to an impedance matched parallel plate OAUGDP for durations ranging from one second to several tens of seconds. Data is reported on the surface energy, wettability, and wickability as functions of time of exposure, and of the aging effect after exposure.