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The development of paper-based flexible electronic devices can reduce the use of traditional petroleum-based polymer substrates, thereby reducing environmental pollution. However, paper substrates tend to absorb moisture, which would degrade the performance of electronic devices. Polytetrafluoroethylene (PTFE) films were proposed as coatings for the paper substrate to improve the hydrophobic performance of the paper, thereby enhancing the stability of paper-based device. Hydrophobic PTFE films were deposited on both sides of the paper substrate using electron beam evaporation, which block the paper substrate from absorbing moisture. The zinc oxide (ZnO) film was sputtered onto the paper substrate and fabricated into ultraviolet photodetectors (UVPD). Numerical simulations show that the introduction of PTFE films can greatly reduce the stress from 3.21 × 109 N m−2 to 3.50 × 107 N m−2 in the ZnO epitaxial layer on the paper substrate. The stability and detectivity of the UVPD with PTFE coatings are greatly improved compared to that without PTFE coatings, providing a promising avenue for fabricating stable, superior, and sustainable paper-based electronic devices. [ABSTRACT FROM AUTHOR]

The cellulose–water system was traced down by the in situ transmission FTIR spectroscopy upon water desorption/sorption cycles at various conditions (dry air, humid air, water vapour) and temperatures. The results provide the information on the changes of the hydrogen bonds network during water desorption from paper and the changes in water sorption capacity of paper in the cycles. [ABSTRACT FROM AUTHOR]

We report on the use of elemental composition, determined by energy dispersive X-ray fluorescence (EDXRF), to identify different types of paper. The concentrations of S, Cl, K, Ca, Ti, Mn, Fe, Co, Cu, Zn, As, Br, Rb, Sr, Ba and Pb were determined in papers from 1555, 1575, 1724, 1748, 1779, 1782, 1787, 1806, 1861, 1919, 1941 and 2005. A preliminary analysis was made with the use of a dendrogram. The Euclidian distances evidenced a big fluctuation in the elemental composition on most recent papers. The dendrogram also allowed us to catalogue the analysed samples into ten types of paper. Calcium, Cu, Fe, Zn and Sr were the only elements found in all paper samples. However the content of each element was different in every paper type. Calcium is the predominant element in all paper types. Applying Spearman coefficients correlations to these papers for Ca, Cu, Fe, Zn and Sr, we found moderate negative correlations between Ca-Cu. Positive correlations were also found between Fe-Cu, though not very strong. High levels of the toxic elements, Co, Ni, As and Pb were present in papers from 1779 and 1787. From this work it becomes clear that the number of elements in modern papers is lower than in older ones. [ABSTRACT FROM AUTHOR]

Cleaning of paper objects represents one of the most complex cases of laser ablation, since low volumes of dispersed material phases are evaporated while a sensitive and fragile fibrous organic matrix has to be preserved. Conventional chemical and mechanical cleaning methods suffer from the common phenomenon that the foreign matter is diluted into the substrate rather than removed. The application of a laser beam allows highly localized and optically specific interaction. However, the occurrence of extreme temperatures and light intensities may cause irreversible alteration of the paper matrix. Further, incomplete removal and/or chemical conversion of contaminations may result in insufficient cleaning or affect the ageing behaviour. Laser treatments were performed by Q-switched Nd:YAG lasers at three wavelengths (355 nm, 532 nm, and 1064 nm). Papers contaminated with inks and adhesive-tape remnants served as model samples. Multispectral imaging and colorimetric results served to quantify and systematize the results. [ABSTRACT FROM AUTHOR]

Paper is one of the most important materials in cultural heritage given its extensive use as the data carrier for religious, artistic and scientific records. For both aesthetic and conservation reasons, cleaning of these materials is often needed. Current paper cleaning methods using conventional means are not always sufficient, e.g. for the local cleaning of paper in the vicinity of sensitive media. In this respect a ns-pulse laser provides a valuable tool for solving difficult cleaning problems. The influence of various laser wavelengths (355 nm, 532 nm, and 1064 nm) and the ageing status of modern paper test systems were studied. Colorimetric measurements, the determination of the average molecular mass of cellulose, and chemiluminescence analysis proved to be useful for the characterization of the laser-treated paper. Treatment with green laser light at λ=532 nm below the paper ablation threshold fluence gave the most promising results on pure papers, with no discolouration and no other visible alteration, nor detectable chemical changes. [ABSTRACT FROM AUTHOR]

Effect of silver nanoparticles on MMA/HEMA behavior in enhancing and restoring the lost chemical bonds of paper was estimated in the current study through the study of mechanical strengths (tensile and elongation), infrared spectrum and environmental microscopic examination. The results of tensile strength and elongation rate showed the effectiveness of nanoparticles in supporting paper properties under the influence of accelerated aging via the bond at 1630 cm−1 that is responsible for the bonds of silver ions and cellulose. Simultaneously, the micrographs showed that the type of fiber walls impacted the effectiveness of the copolymer where the completely pure cellulose cells absorbed the copolymer, while the presence of lignin reduced the absorption which helped create interface cross-links between fibers via the adsorbed copolymer on the surface. [ABSTRACT FROM AUTHOR]