Abstract
Paper cultural heritages are valuable historical records and also abound in cultural resources. Due to its organic property, paper is susceptible to aging, destruction by environmental pollution and human factors. At present, many countries in the world are facing the problem of paper conservation. Coating reinforcement is one of the methods for paper conservation, in which the choice of reinforcing resin is key. A transparent polyurethane, based on epoxycyclohexane (CHO)-tetrahydrofuran (THF) copolyether, was adopted in this study. The ring-opening polymerization for generating the CHO-THF copolyether took place by the reactants CHO and THF, in the catalysis of boron trifluoride diethyl etherate, initiation of glycerol. Characterizations of the synthetic copolyether were conducted by infrared (IR) spectroscopy and proton nuclear magnetic resonance (1HNMR) spectroscopy. The transparent polyurethane was then produced by the CHO-THF copolyether and hexamethylene diisocyanate (HDI) trimer. The influences of different concentrations of polyurethane solution upon the paper tensile strength, elongation, folding endurance, tearing strength, gloss, and brightness were studied. These findings suggest that 10% polyurethane solution is optimal, not only for greatly improving the paper performance, but also for keeping with the principle of “repair as old”. The applied results demonstrate that the polyurethane based on the CHO-THF copolyether has the characteristics of copolyether along with polyurethane, displaying good mechanical properties in paper reinforcement.
Highlights
Paper cultural heritages such as classics, manuscripts, archives, calligraphies, paintings, and letterheads record human history, culture, science, and technology [1,2,3,4]
Main chains of copolyether that contain in general polyurethane are straight, flexible structures lacking rigidity, so it is difficult for polyurethane to possess both excellent mechanical and weathering properties [10,11,12]
The results demonstrate that paper mechanical properties were improved [21]
Summary
Paper cultural heritages such as classics, manuscripts, archives, calligraphies, paintings, and letterheads record human history, culture, science, and technology [1,2,3,4] External factors such as environmental pollution, temperature, light, oxygen, water, and microorganisms, and internal factors such as fiber breakage, acidification cause paper aging and performance degradation [5,6]. Polyurethane, a synthetic polymer material, has good mechanical properties, weatherability, corrosion resistance, and adhesion [8]. Main chains of copolyether that contain in general polyurethane are straight, flexible structures lacking rigidity, so it is difficult for polyurethane to possess both excellent mechanical and weathering properties [10,11,12]. The results demonstrate that paper mechanical properties were improved [21]
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