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A cellulose paper sheet, chemically modified with azide functions, is described to be a versatile molecular platform for copper-catalyzed 1,3-dipolar cycloaddition with terminal alkynes. This 3-step methodology was carefully optimized at each stage of the process with the support of experimental and physical evidences. Our approach allows the surface coverage of structurally diverse molecular architectures through a covalent grafting with non-hydrolysable chemical linkers. This robust linkage is highlighted with the surface hydrophobization of cellulose paper through the click ligation of cholesterol units as renewable and inexpensive hydrophobic agents. The resulting water-resistant and water-repellent paper-based material shows powerful oleophilicity properties and displays a high contact angle of 139.6°. [ABSTRACT FROM AUTHOR]

The attractive structural and mechanical properties of cellulose substrates (paper, cloth, and thread), including passive fluid transport, biocompatibility, durability, and flexibility, have attracted researchers in the past few decades to explore them as alternative microfluidic platforms. The incorporation of electrochemical (EC) sensing broadened their use for applications such as clinical diagnosis, pharmaceutical chemical analyses, food quality, and environmental monitoring. This article provides a review on the microfluidic devices constructed on paper, cloth, and thread substrates. It begins with an overview on paper-based microfluidic devices, followed by an in-depth review on the various applications of EC detection incorporated on paper-based microfluidic devices reported to date. The review on paper-based microfluidic devices attempts to convey a few perspective directions that cloth- and thread-based microfluidic devices may take in its development. Finally, the research efforts on the development and evaluation, as well as current limitations of cloth- and thread-based microfluidic devices are discussed. Microfluidic devices constructed on paper, cloth, and thread substrates are still at an early development stage (prototype) requiring several improvements in terms of fabrication, analytical techniques, and performance to become mature platforms that can be adapted and commercialized as real world products. However, they hold a promising potential as wearable devices. [ABSTRACT FROM AUTHOR]

Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS C-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites. [ABSTRACT FROM AUTHOR]

In the present work the evolution of physical and mechanical properties of papers and nanopapers is studied. Handsheets made of eucalyptus fibres reinforced with 0, 25, 50, 75 and 100 wt% of nanofibrillated cellulose (NFC) content were fabricated using a Rapid Köthen-like equipment. The obtained papers and nanopapers were physical- and mechanically-characterized. The results showed a significant increase in density and a reduction of porosity in the samples during their transition from paper to nanopaper; besides, nanopapers were more transparent and smoother than normal papers. These physical changes where more evident with increasing amounts of NFC. Regarding mechanical properties, nanopapers with a 100 wt% content of NFC improved their strength and rigidity in 228 and 317 %, respectively, in comparison with normal papers. The evolution of strength and rigidity from paper to nanopaper was linear in relation to the amount of NFC, which means that the ultimate tensile strength was mainly dependant on nanofibril failure. [ABSTRACT FROM AUTHOR]

Hydrophilic paper was rendered with hydrophobic and superhydrophobic property after the treatment with solutions and nanoparticles of cellulose stearoyl ester (CSE), respectively. Cellulose stearoyl ester with a degree of substitution of 2.99 was synthesized from cellulose using stearoyl chloride. By dip-coating paper in CSE solution of at least 3 mg/ml in toluene, paper became hydrophobic with stable water contact angles of more than 120°. After further spray-coating using CSE nanoparticles that were prepared from CSE solution via nanoprecipitation, paper surface became superhydrophobic with water contact angles of larger than 150°. These superhydrophobic surfaces also exhibited self-cleaning character. Furthermore, the superhydrophobic paper surfaces showed a temperature-responsive character and could be turned hydrophobic after a heat-treatment at 70 °C for 5 min. [ABSTRACT FROM AUTHOR]

Background, aim, and scope Packaging uses nearly 40% of all polymers, a substantial share of which is used for sensitive merchandise such as moisture-sensitive food. To find out if bio-based materials are environmentally advantageous for this demanding application, we compared laminated, printed film across the whole life cycle. Materials and methods We compared bio-based materials (paper, polylactic acid, bio-based polyethylene, and a biobased polyester) as well as conventional ones (polypropylene, polyethylene). Data stemmed from13 companies that produce raw materials, films and/or laminates and which co-operated with us in a project commissioned by a large food producer. The functional unit chosen for this study is 1 m2 of packaging film. This is (mostly) laminated, printed film that is delivered on reels to the food industry, where the laminate is cut, sealed and filled. The impact assessment is presented for non-renewable energy use, total energy use, global warming potential, depletion of abiotic resources, photo-oxidant formation, acidification, eutrophication, water use, and land use. Results For Inner Packs that get in direct contact with food and therefore require certain barrier properties, the environmental performance of many laminates is not better than the reference, petrochemical material. However, our study shows that paper/polypropylene laminates perform equally well as the current material (polypropylene) if the material is landfilled, and better if incinerated with energy recovery. For Outer Packs, bio-based polyethylene film shows a particularly low environmental impact. Paper/bio-based polyester laminates also offer significant savings compared with the current material. For Inner as well as Outer Packs, laminates including polylactic acid offer environmental advantages when accounting for wind credits or when assuming a future technology level for polymer or film production. Discussion Increased technology maturity of PLA and cellulose in the film production stage offers significant environmental improvement with respect to global warming potential compared with today's technology. Though large, the uncertainty regarding the degree of degradation of paper, cellulose, PLA and bio-based polyester, is not decisive for the conclusions. Conclusions and recommendations Generally, laminates and films (partly) consisting of bio-based polymers offer opportunities for significantly reducing environmental impacts of food packaging. Large variations in land-use are possible depending on the type of bio-based material that is used. The environmental advantages differ depending on the polymer and the final product (Inner vs. Outer Pack). Lack of experience and investment in converting bio-based polymers into final products and comparatively unfavourable material properties result in lower environmental advantages for some novel bio-based materials than one may expect. However, a) already today, the options with the lowest global warming potential are partly or fully bio-based and b) bio-based materials will benefit more from technological progress than conventional materials, potentially making certain bio-based laminates highly attractive options for the future. Overall, Outer Packs are more promising than Inner Packs when introducing bio-based wrappings to replace the current petrochemical material because a) the opportunities are clearer for this application and b) the product specifications (required barrier properties) are less demanding. Starting with the Outer Packs would also allow bio-based polymer producers and processors to invest and learn, thus offering the opportunity to reduce the environmental impact even further. [ABSTRACT FROM AUTHOR]

Abstract: Books and documents attacked by fungi and insects have already been treated by radiation for disinfestations purposes. However, there is still need to investigate the influence of radiation on the cellulose paper structure. The aim of this research was to study the effects of radiation on paper properties, especially those related to strength and appearance. Paper sheets for this study were prepared in the laboratory, using bleached eucalyptus pulp as raw material. No additives were used to concentrate the attention only on the effects of irradiation on the pure cellulose matrix. The samples were irradiated at IPEN''s 60Co Gammacell irradiator with six radiation doses, from 3 to 15kGy at the dose rate 0.817Gy/s. The properties of paper sheets were tested after irradiation and compared with unirradiated samples according to ISO methods. No significant changes were detected in paper samples irradiated up to 15kGy. [Copyright &y& Elsevier]

Many words have been written regarding alkaline sizing of paper. The learned works often launch directly into cellulose-size reactions. Starch - a carbohydrate with a similar surface chemistry to cellulose - rarely features in the considerations. Yet the contact of size with the starch may be far more intimate and extensive than the contact with cellulose. It is suggested that the reaction of the size with starch is an important and overlooked contribution to our understanding of sizing. [ABSTRACT FROM AUTHOR]