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Chemical crosslinking is an established method for improving the wet performance of paper. In the chemical crosslinking process, covalent bonds are formed between cellulosic surfaces. The formed intra- and interfiber bonds increase the paper's wet strength and reduce its water absorptivity. The majority of published studies concern crosslinking treatments with glyoxal, citric acid (CA), or with 1,2,3,4-butanetetracarboxylic acid (BTCA). The most severe disadvantage of the crosslinking treatments with glyoxal, CA, and BTCA is that the formed crosslinks make the fibers and the paper more brittle. This downside effect has largely impeded the utilization of crosslinking in paper and paperboard making. In the present study, handsheets made from Nordic bleached softwood kraft pulp (NBSK) were crosslinked with methylated 1,3-dimethylol-4,5-dihydroxyethylene urea (mDMDHEU), which is commonly used in cotton fabric finishing. Similar to using glyoxal and citric acid, crosslinking with mDMDHEU notably increased the handsheet wet strength and decreased the water absorption. Compared to the use of glyoxal or CA, the crosslinking with mDMDHEU did not make the handsheets that brittle. These results suggest that mDMDHEU could be a more viable crosslinking agent for improving the wet performance of paper products. [ABSTRACT FROM AUTHOR]

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness — an outcome of a CMS layer forming atop the fiber base — which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

There is current interest in replacing petroleum-based additives in consumer paper products with abundantly available, renewable and sustainable biopolymers such as lignin-containing cellulose nanofibers (LCNFs) and cottonseed protein. This research characterized the performance of cottonseed protein isolate with/without LCNFs to increase the dry strength of filter paper. The application of 10% protein solution with 2% LCNFs as an additive improved the elongation at break, tensile strength and modulus of treated paper products compared to the improved performance of cottonseed protein alone. Improvements in tensile modulus and tensile strength were greatest for samples containing larger amounts of lignin and a greater degree of polymerization than for those with less lignin from the same biomass sources. [ABSTRACT FROM AUTHOR]

The overall usefulness of the bursting energy absorption (BEA) was studied for a better analysis of paper strength properties. Additionally, the changes of the BEA during more complex deformations of paper products, e.g., preliminary or simultaneous tensile and burst, were determined. For the purpose of the research, an experimental setup was designed. The results showed that the correlation between BEA and bursting strength was linear, but the proportionality strongly depended on paper grade. Thus, a more accurate method to characterize the bursting resistance (BR) of paper was proposed. The BR parameter is described by the three following parameters: average bursting strength, average bursting energy absorption, and the slope of the fitted linear regression curve (relationship between the bursting energy absorption and the bursting strength). This method revealed new mechanical behaviors of papers related to their preloading. [ABSTRACT FROM AUTHOR]

Background: Through a close reading of the four issues of The Bowater Papers, this article aims to understand the rise of a paper modernity and to reinsert it--as material and infrastructure-- into media studies. Analysis: Producing wood paper is a strain on the landscape and the environment. The Bowater Papers showcases the histories and material possibilities of paper media products. A paper-dependent modernity can be understood as an infrastructural assemblage of harvesting, production, circulation, and consumption. Conclusion and implications: Paper calls for a natural history and geography of media. Thinking about the mediations from tree to paper through the encompassing notion of "xylomedia" is a way of articulating the intersection of the material, environmental, and infrastructural in media studies. Today is still a paper world, one that is also the age of lignin, package, and Amazon. [ABSTRACT FROM AUTHOR]

The current analytical techniques for characterizing printing and graphic arts substrates, particularly those used to date and authenticate provenance, are destructive. This limits the amount of data that can be captured from an individual sample. For samples being evaluated in forensic and archeological investigations, any loss or degradation of the materials is undesirable. Furthermore, it is difficult to produce statistically relevant data for such analytes. We have shown elsewhere that a contactless microwave resonant cavity dielectric spectroscopy technique can discriminate between paper samples made from different plant fiber species based on their lignin content. In this publication, we demonstrate the utility of the contactless resonant cavity dielectric spectroscopy (RCDS) technique in the characterization of naturally and artificially aged paper samples. Based on our experimental results, we suggest that the technique could be used in forensic and archeological investigations of unique paper products. [ABSTRACT FROM AUTHOR]

This paper presents manufacture and testing of paper boards made from recycled paper pulp. The aim was to create material for creating paper boards which could be used in furniture design with various shapes. The used types of pulp were deinked pulp (DIP) and old corrugated cardboards (OCC). Several test pieces - paper boards were made with different combinations of materials and its mechanical and physical properties were tested. The used glue for each material was urea formaldehyde glue and starch in combination with glucose. The tests which were done were determination of density and density profile (EN 323:2005), moisture content (EN 322:2005), modulus of elasticity in bending and bending strength (EN 310:1993), thickness swelling and water absorption (EN317:2005), internal bond (EN 319:2005) and screw withdrawal resistance (EN 320:2011). The aim was to create material for creating boards which could be used in furniture design with various shapes. The result of this paper shows possible material combinations which could be used for furniture parts. Paper boards will be used for table top of side table in following steps. [ABSTRACT FROM AUTHOR]

A procedure for the rapid simultaneous determination of anthraquinone and bisphenol A in paper and cardboard is proposed based on a combination of extraction with subcritical methanol and subsequent analysis of the extracts by HPLC‒tandem mass spectrometry. The achieved limits of detection are 25 and 250 µg/kg for anthraquinone and bisphenol A, respectively, and fully meet present-day safety requirements for pulp and paper products. The total duration of the analysis, including sample preparation, is not more than 45 min. The sensitivity of anthraquinone determination is 1‒2 orders of magnitude higher than that of the known procedures, including those with the preconcentration of analytes. The results obtained were successfully used to study paper and cardboard samples, in most of which unacceptably high levels of the anthraquinone concentration were found. [ABSTRACT FROM AUTHOR]

Abstract: Previously unreported line patterns visible under ultraviolet light were observed on a proportion of plain white A4 printer/copier paper from different manufacturers. These Ultraviolet Line Patterns (UVLPs) usually appear as stripes down the vertical length of the paper. Typically, the UVLPs were found to “repeat” through the ream in a predictable way, while also changing. It is postulated that the repeating nature of the UVLPs is a result of the way that paper is manufactured. This leads to the ability to sequence the sheets compared to their original source paper. Even in the absence of UVLPs, it is possible to use our observation of the manufacturing process to anticipate the order of several sheets of paper and conclusively associate them, in some cases, by physically fitting their machine cut edges and crossing paper fibers. Such a novel approach to examining questioned documents would be highly useful in forensic casework. [ABSTRACT FROM AUTHOR]

Highlights: [•] No external catalyst is required for citric acid crosslinking of cellulosic fibres. [•] We propose a mechanism for self-catalysed esterification of cellulosic fibres. [•] Crosslinking is facilitated by high curing temperature and citric acid dose. [•] Crosslinking increases linerboard compressive strength at high humidity. [•] Crosslinking extends lifetime of corrugated boxes under cycling high humidity. [ABSTRACT FROM AUTHOR]

The manufacture of low density paper such as tissue and towel utilizes the creping process that consists of adhesively bonding the paper in wet state onto the surface of a smooth drying cylinder and scraping it off with a blade once dried. In this paper, a mechanics of materials description of the creping process is presented. Based upon previous experimental observations, the mechanism of this creping process is proposed as a periodic debonding with a strength-of-materials failure criterion applied and buckling sequence of an elastic thin film. Numerical calculations show results consistent with experimental data and known industrial observations. Crepe wavelength versus creping angle data from experiments can be satisfactorily reproduced by a reasonable set of values for input parameters to the model. Parametric study shows the adhesive shear strength and the sheet stiffness most significantly affect the crepe wavelength and the creping force. The model provides guidance in understanding and optimizing the creping process to produce high quality products. [ABSTRACT FROM AUTHOR]

An investigation was undertaken to establish the concentration in paper products of dehydroabietic (DHA) and abietic (AA) resin acids, present in rosin, which are major toxicants of pulp- and paper-mill effluent. Their migration was studied from paper and paperboard products into various food-simulating solvents and the substitute fatty food simulant Tenax TA (modified polyphenylene oxide). DHA and AA were detected in five of 10 virgin paper products and in all 10 recycled paperboard products for food-contact use at concentrations of 14–500 and 110–1200  µg/g, respectively. In virgin paper products, the highest migration was into 95% ethanol or heptane, with negligible or no migration into other solvents. In recycled paperboard products, migration was highest into 95% ethanol, but was also observed into 20% ethanol, water and heptane. Migration to Tenax TA was also observed and the migration level increased with time. The maximum migration levels of DHA and AA into food simulants were 0.853 and 3.14  µg/g, respectively. The results suggest that, in the worst case, the daily intake of DHA and AA from paper and paperboard products was 50 times lower than the tolerable daily intake of rosin. [ABSTRACT FROM AUTHOR]

This study presents the research on the chemical analysis and genotoxicity of 28 virgin/recycled paper products in food-contact use. In the chemical analysis, paper products were extracted by reflux with ethanol, and analyzed by gas chromatography/mass spectrometry. 4,4′-bis(dimethylamino)benzophenone (Michler''s ketone: MK), 4,4′-bis(diethylamino)benzophenone (DEAB), 4-(dimethylamino)benzophenone (DMAB) and bisphenol A (BPA) were found characteristically in recycled products. Seventy-five percent of the recycled paper products contained MK (1.7–12 μg/g), 67% contained DEAB (0.64–10 μ g/g), 33% contained DMAB (0.68–0.9 μg/g) and 67% contained BPA (0.19–26 μg/g). Although, BPA was also detected in virgin paper products, the detection levels in the recycled products were ten or more times higher than those in the virgin products. The genotoxicity of paper and paperboard extracts and compounds found in them were investigated by Rec-assay and comet assay. Of the 28 products tested by Rec-assay using Bacillus subtilis, 13 possessed DNA-damaging activity. More recycled than virgin products (75% against 25%) exhibited such activity, which, of the compounds, was observed in BPA, 1,2-benzisothiazoline-3-one (BIT), 2-(thiocyanomethylthio)benzothiazole, 2,4,5,6-tetrachloro-isophthalonitrile, 2,4,6-trichlorophenol (TCP), and pentachlorophenol. The critical toxicant in one virgin paper product was concluded to be BIT. Eight samples with DNA-damaging activity were also tested by comet assay using HL-60 cells; six induced comet cells significantly (five times or higher than the control) without a decrease of viable cells. TCP, BZ, DEAB, and BIT also caused a slight increase in comet cells. In conclusion, we showed that most recycled paper products contain chemicals such as MK, DEAB, DMAB, and BPA, and possess genotoxicity. However, the levels of the chemicals in the recycled products could not explain their genotoxic effects. [Copyright &y& Elsevier]

Background: There has been growing interest in the development of waste-specific decay factors for estimation of greenhouse gas emissions from landfills in national greenhouse gas inventories. Although engineered wood products (EWPs) and paper represent a substantial component of the solid waste stream, there is limited information available on their carbon dynamics in landfills. The objective of this study was to determine the extent of carbon loss for EWPs and paper products commonly used in Australia. Experiments were conducted under laboratory conditions designed to simulate optimal anaerobic biodegradation in a landfill.Results: Methane generation rates over incubations of 307-677 days ranged from zero for medium-density fibreboard (MDF) to 326 mL CH4 g−1 for copy paper. Carbon losses for particleboard and MDF ranged from 0.7 to 1.6%, consistent with previous estimates. Carbon loss for the exterior wall panel product (2.8%) was consistent with the expected value for blackbutt, the main wood type used in its manufacture. Carbon loss for bamboo (11.4%) was significantly higher than for EWPs. Carbon losses for the three types of copy paper tested ranged from 72.4 to 82.5%, and were significantly higher than for cardboard (27.3-43.8%). Cardboard that had been buried in landfill for 20 years had a carbon loss of 27.3%—indicating that environmental conditions in the landfill did not support complete decomposition of the available carbon. Thus carbon losses for paper products as measured in bioreactors clearly overestimate those in actual landfills. Carbon losses, as estimated by gas generation, were on average lower than those derived by mass balance. The low carbon loss for particleboard and MDF is consistent with carbon loss for Australian wood types described in previous studies. A factor for carbon loss for combined EWPs and wood in landfills in Australia of 1.3% and for paper of 48% is proposed.Conclusions: The new suggested combined decay factor for wood and EWPs represents a significant reduction from the current factor used in the Australian greenhouse gas inventory; whereas the suggested decay factor for paper is similar to the current decay factor. Our results improve current understanding of the carbon dynamics of harvested wood products, and allow more refined estimates of methane emissions from landfills. [ABSTRACT FROM AUTHOR]