Surface Modification of Polypropylene Non-woven Substrates by Padding with Antistatic Agents for Deposition of Polyvinyl Alcohol Nanofiber Webs by Electrospinning

Abstract

In recent years, the electrospinning process has become one of the most interesting processes to obtain nanofiber webs with interesting properties for uses in a wide variety of industrial sectors such as filtration, chemical barriers, medical devices, etc., as a consequence of the relatively high surface-to-volume ratio. Among the wide variety of polymers, polyvinyl alcohol (PVA) offers good advantages since it is water-soluble and this fact enables easy processing by electrospinning. There are many variables and parameters to be considered in order to optimize PVA nanofiber webs: some of them are related to the polymer solution, some others are related to the process, and some of them are related to the collector substrate. In this work a study on the effects of two different surface pre-treatments on a nonwoven polypropylene substrate as a collector of PVA nanofiber webs has been carried out. In particular, a chemical treatment with anionic antistatics and a physical treatment with lowpressure plasma have been investigated. The effects of these pre-treatments on morphology of PVA nanofiber webs have been evaluated by scanning electron microscopy. Results show that surface resistivity is one of the main parameters influencing the web formation as well as the nature of the electric charge achieved by the pre-treatment. The plasma treatment promotes changes in surface resistivity but it is not enough for good web deposition. Chemical pre-treatment (padding) with anionic antistatic leads to a decrease in surface resistivity up to values in the 1 × 10 9 -1 × 10 11 Ω which is enough for good nanofiber deposition.

Chemical treatments for improving adhesion between electrospun nanofibers and fabrics

“…Unfortunately, textiles being dielectric materials can interfere with electrospinning process. 11,16 On the other hand, nanofibers have to be stuck to the substrate with an adequate strength. The enhancement of adhesion between nanofiber layers and textile substrates promoted by plasma treatments has been recently investigated.…”

“…Despite the huge scientific knowledge developed in the field about nanofiber formation within an electric field, some issues have to be faced for reaching real industrial applications, namely increase of nanofiber throughput, continuous collection of nanofiber layers and adhesion of electrospun nanofibers to substrates. For applications such as clothing, filtration, and protective devices electrospun nanofibers have to be deposited on a substrate (usually a textile material such as woven or non‐woven fabrics). The substrate has the function to give mechanical properties allowing further processing, such as pleating in filter production or sewing in protective clothing.…”

“…The most simple way to deposit nanofibers on a substrate is to place the substrate between the jet source and the collector. Unfortunately, textiles being dielectric materials can interfere with electrospinning process . On the other hand, nanofibers have to be stuck to the substrate with an adequate strength.…”

Characterization of melt spinnability of ethylene vinyl alcohol copolymers

“…The spinnability of a polymer is typically influenced by (1) its chemical and thermal stability under spinning conditions, (2) ability to form continuous fluid or semisolid fibers and (3) ease of transformation into a solid polymer. 16–21 In addition, the rheological properties of EVOH, such as its apparent viscosity, shear stress, shear rate, non-Newtonian flow index and others, also affect its fiber formation. The chemical and thermal stability of EVOH depends mainly on its chemical composition.…”

Obtención de velos de nanofibras de alcohol de polivinilo (PVA) sobre substratos textiles, con aplicaciones como absorbentes acústicos

“…En el caso que nos ocupa (NS-Lab), el electrodo colector es el electrodo con signo negativo, por lo que un acabado antiestático catiónico sobre el substrato colector, no va a permitir la formación de los velos de nanofibras de PVA. [177] -Paralelamente se extrae la conclusión de que las propiedades hidrofílicas o hidrofóbicas del substrato, no van a interferir en la formación del velo de nanofibras de PVA, aunque en principio se pensaba que sí. Si el acabado antiestático es el adecuado, este tipo de propiedades superficiales no van a interferir.…”