Abstract:

Objective Paper documents, such as old books, archives, and paper-based commemorative items are a rich source of human knowledge and passion. It is challengeable to protect paper documents from moisture, tear and aging. This paper proposes a straightforward and cost-effective approach for paper documents protection by in-situ electrospinning, which directly deposited as-spun nanofibrous membranes onto the paper documents surface.

Method Used mineral water bottles which are transparent and hydrophobic were selected as the raw material (mainly polyethylene terephthalate, rPET) and were dissolved to form solutions with different concentrations. The rPET solution was electrospun into fibers under different spinning parameters, which were directly deposited onto the paper document surface to form a transparent protective membrane using a portable electrospinning device (Fig. 1). The morphology, surface wettability, mechanical properties and UV resistance of the paper documents before and after in-situ electrospinning were analyzed to evaluate the protective effect of the membranes.

Results The optimized spinning parameters were the rPET mass fraction of 8%, spinning distance of 15 cm, spinning time of 10 min, spinning voltage of 15 kV, and solution feeding rate of 10 μL/min. Under these parameters, the prepared rPET fiber membrane was almost transparent without covering the prints on paper (Fig. 2) but would block common dust and mold effectively due to the small membrane pore diameters of about (5.53±0.38) μm (Fig. 3). The as-spun rPET nanofibrous membranes under optimal conditions made the paper's surface hydrophobic with the water contact angle about 135.1° (Fig. 4) to avoid water immersion. It was also found that the deposited rPET fibers could form an interlocking grid structure, increasing the tensile strength in the horizontal and vertical directions by 129.1% and 16.1%. Tear resistance was also improved in both transverse (86%) and longitudinal (161.1%) directions, respectively (Fig. 6). The study also revealed that the as-spun rPET nanofibrous membrane also increased the UV protection factor (UPF) of the paper documents from 16.2 to 71.4 (Fig. 7), reducing UV induced aging.

Conclusion In-situ electrospinning rPET membrane onto paper documents is easy to operate and could achieve a good protection effect. The prepared rPET fiber membrane is transparent, and has small pore size, which could prevent dust while not affecting the appearance of the paper documents. The as-spun rPET membrane could also obviously enhance the mechanical and UV protect properties of the paper documents. These results suggested that in-situ electrospinning rPET onto the paper document forms an useful way for both protection of paper documents and the recycling of water bottles.

Key words: sin-situ electrospinning, recycled polyethylene terephthalate, nanofiber, paper document protection, deposit membrane