1317 ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version) Fibers and Polymers 2019, Vol.20, No.6, 1317-1322 Preliminary Study on the Adhesion Strength of Electrospun Bi-Layer Membranes by 180 o Peel Test Nor Dalila Nor Affandi * , Fatirah Fadil, and Mohd Iqbal Misnon School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia (Received September 19, 2018; Revised November 30, 2018; Accepted December 9, 2018) Abstract: Three electrospun bi-layer membranes made of nylon 6, polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) were fabricated by electrospinning. The adhesion strength between the interfaces of nanofibres layers is measured by 180 peel tests using a 10 N load cell at 10 mm/min crosshead speed. Electrospun bi-layer membrane of PVDF gave the highest peel strength value of 11 mN/mm compared to PAN and nylon 6 (less than 5 mN/mm). The adhesion strength is attributed to the polymer solidification rate of the respective polymers. Both of bi-layer PAN/PAN and nylon 6/nylon 6 gave lower peel strength values due to rapid polymer solidification thus resulted to a poor adhesion between the layers. Keywords: Adhesion, Polymers, Nanofibres, Bi-layer membranes, Interfaces Introduction The adhesion strength between two or more layered materials is one of the essential physical requirements in technical applications of the product. In electronic applications, it is important to have good adhesion strength as it influences the ability of bonded materials to withstand an aggressive processing stage [1]. The adhesion strength between the layered materials can be measured through tensile, lap joints and peel tests. Peel tests are suitable to assess interface adhesion of microelectronic packaging [1], polymer composites [2-5], adhesive tape [6], sealant [7] etc. The peel test is a simple testing in which measures the force required to separate two surfaces and then used to calculate the energy dissipation. The peel strength depends on variables such as the specimen thickness, peeling speed and peel angle [1]. During manufacture of such filtration comprising electrospun nanofibres materials, it is desirable to measure the adhesion strength between layers of nanofibres or substrates. Recent studies [8-12] have proved that by laminating electrospun nanofibres membrane onto other substrates has improved the substrate performances. Research done by Gibson et al. [8] have found that a thin layer of electropun nanofibres onto a polyurathene foam fabric can enhance the filtration efficiency mainly in air flow resistance and aerosol filtration. Furthermore, a layered of electrospun polypropylene onto a fabric exhibited excellent barrier performances with approximately 90 % against liquid penetration [10]. To improve the performances in filtration and liquid penetration, adequate adhesion strength between the nanofibres membrane and the substrate is necessary for their end applications. Peel tests are suitable to determine adhesion strength for electrospun fibres [9,11]. However, the difficulty in handling electrospun specimens during peel test and the variability of peel test have become a main concern for researchers. Herein, the study will investigate and develop a peel test method suitable for electrospun membranes. Experimental Solution Preparation nylon 6, polyacrylonitrile (PAN) and copolymer polyvinylidene fluoride (PVDF) were dissolved in formic acid, dimethylformamide (DMF) and a mixture of N,N- Dimethylacetamide (DMAc) and acetone, respectively. Details on the solution preparation can be found elsewhere [13]. Membrane Fabrication The respective polymer solutions of PVDF, PAN and nylon 6 were electrospun individually at 20 cm spinneret-to- collector distances with applied voltages of 15-35 kV and constant feed rate of 0.2 ml/h. The electrospinning was carried out at room temperature with relative humidity ranging from 40-60 %. The fabrication of the electrospun bi- layer membranes (shown in Figure 1) involves two steps: 1) Fabrication of bottom layer where, each polymer solution was electrospun on top of an aluminium foil (aluminium 1) for an hour. The electrospun membrane was then dried at room temperature for a day. 2) Fabrication of top layer. In Figure 1, half of the dried electrospun membrane (bottom layer) was covered with an aluminium foil (aluminium 2). The same polymer was extruded and deposited onto the bottom layer for an hour to produce the second layer of electrospun membranes. *Corresponding author: dalila@salam.uitm.edu.my DOI 10.1007/s12221-019-8874-3 Communication