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Bacterial infections are commonly found on paper towels and other paper products leading to the potential spread of bacteria and consequent health concerns. The objective of this in vitro study was to introduce antibacterial properties to paper towel surfaces by coating them with selenium nanoparticles. Scanning electron microscopy was used to measure the size and distribution of the selenium coatings on the paper towels. Atomic force microscopy was used to measure the surface roughness of paper towels before and after coated with selenium nanoparticles. The amount of selenium precipitated on the paper towels was measured by atomic absorption spectroscopy. In vitro bacterial studies with Staphylococcus aureus were conducted to assess the effectiveness of the selenium coating at inhibiting bacterial growth. Results showed that the selenium nanoparticles coated on the paper towel surface were well distributed and semispherical about 50nm in diameter. Most importantly, the selenium nanoparticle coated paper towels inhibited S. aureus growth by 90% after 24 hours and 72 hours compared with the uncoated paper towels. Thus, the study showed that nano-selenium coated paper towels may lead to an increased eradication of bacteria to more effectively clean a wide-range of clinical environments, thus, improving health.

Bacterial infections are commonly found on paper towels and other paper products leading to the potential spread of bacteria and consequent health concerns. The objective of this in vitro study was to introduce antibacterial properties to paper towel surfaces by coating them with selenium nanoparticles. Results showed that the selenium nanoparticle coated paper towels inhibited the growth of S. Aureus and P. aeruginosa by 80%∼90% after 72 hours compared with the uncoated paper towels. Thus, the study showed that nano-selenium coated paper towels may lead to an increased eradication of bacteria to more effectively clean a wide-range of clinical environments, thus, improving health.

A novel technique combining both atomic force microscopy (AFM) and scanning electron microscopy (SEM) is used to test the mechanical properties of densely-packed graphene oxide (GO) paper. Individual beams of GO paper with variable widths were prepared using focussed ion beam (FIB) microscopy and tensile tested to failure using the AFM while observing with SEM. A variation in the tensile strength of the GO paper beams up to 64.8 MPa was recorded in the vacuum testing condition. An increase in breaking stress of GO paper with decreasing sample width was determined and proposed as being due to fewer defects present in GO beams of smaller width.

Concentration- and layer-dependent percolation thresholds can be determined for carbon nanotube (CNT) films deposited from aqueous dispersions on paper substrates at both the surface of the deposited film (in-plane) and through the thickness of the paper (thru-plane) using impedance spectroscopy. By analyzing the impedance spectra as a function of the number of layers (solution concentration is constant) or the solution concentration (number of layers is constant), the electrical properties and percolation thresholds for CNT-paper composites can be determined. In-plane measurements show that percolation occurs at 4 layers when 1 mg/mL solution concentration is used. In the thru-plane direction, the films are already percolated at 1 mg/mL concentration, which is confirmed by varying the concentration of the solution used to deposit 1 layer films. A second percolation event happens between 8 and 12 layers due to an increased number of interconnections of CNTs within the paper substrate. The lowest sheet resistance achieved was 100 Ω/□.

The electrode materials for VRFB should possess higher electric conductivity, corrosion resistance and hydrophilic properties in sulfuric acid. The characteristics of the electrode materials affect the stability and the energy efficiency of VRFB. Carbon materials are the best suited for VRFB applications. In this study, the calcined treatment, acid treatment and ozone treatment were used to modify the surface of carbon papers. The redox reaction of [VO]2+/[VO2]+ on the modified carbon papers was evaluated by cyclic voltammetry (CV). The surface compositions of carbon materials were analyzed by X-ray photoelectron spectrometry (XPS). The experimental results reveal that three oxidative methods enhance the redox reaction of [VO]2+/[VO2]+. The calcined treatments and acid treatments also enhanced hydrolysis reaction. The mole ratio of O/C apparently increased, but the binding energy of C1s and O1s were not chemically shifted in the acid treatment. The intensity of binding energy of O1s, between 532 eV and 534 eV, apparently increased in the ozone and calcined treatments. The Ox treated samples were more hydrophilic than the Oz treated samples. In the Ox treated samples, the decrease of Rct value indicates that was contributed from the redox reaction of [VO]2+/[VO2]+ and hydrolysis reaction. It does not completely benefit the energy efficiency of VRFB. The 5 x 5 cm2 modified carbon papers were used as electrode materials in the VRFB. The voltage efficiency, coulomb efficiency and energy efficiency reached 93 %, 90 % and 83 %, respectively, at a current density of 12 mA．cm-2 at 0.8-1.8 V.

This paper illustrates the use of a high resolution form of rubber stamping, known as microcontact printing (μCP), for patterning plastic active matrix drive circuitry designed for electronic paper. The high resolution (∼1 [.mu]m) of the printed elements, the large area coverage (∼1 sq. ft.) and the good electrical performance of these systems suggest that the methods, materials and processing sequences may be attractive for realistic applications of plastic electronics.

Characterization of paper provides information vital to the preventive care and conservation of vast collections of paper-based materials in museums, libraries, archives and research repositories. Tracing papers, a relatively cheap material used abundantly by folk artists and architects, pose particular problems because of reactivity and instability inherent in their compositions and structures. Previous research published in MRS investigated the aging properties and the impact of conservation treatment on natural, prepared, vellum, and imitation vegetable parchment tracing papers [1, 2]. An additional group, that of genuine vegetable parchment papers, needs particular evaluation with respect to other tracing papers, since they are made by controversial production methods which while considered to be economically advantageous, are environmentally questionable. This technical study characterized three types of genuine vegetable parchment papers, assessing their relative degree of deterioration after aging and their reactivity to solvents commonly used with tracing papers to remove mounts and repairs. The parchment papers were compared optically (fiber, surface, and cross-section morphology; colorimetric, opacity, and gloss properties), chemically (FT-IR, SEM/EDS, and pH), and mechanically (tensile measurements) to provide baseline information on aging properties important to preventive care storage, and relative reactivity important to conservation treatment protocols. The effects of solvents used for conservation treatments (deionized water, ethanol, acetone, toluene, and ammonium hydroxide) were evaluated by comparing relative degrees of reaction (absorption).

Recycling of fiber into structural papers for the corrugated container industry, paper tubes, cartonboard or other paperboard with structural performance needs may require enhancement of properties through changes in the papermaking process. The loss of bonding capability, coupled with a degree of fiber shortening and fiber inflexibility, reduces the utility of recycled fiber and thus their competitiveness with their virgin counterparts. Traditional means for enhancing performance includes addition of starches or other binders, mechanical beating, or heat treatments. Other means for achieving heightened performances are reviewed which include alternative drying technologies, optimal placement of fibers within the paper sheet and forming technologies that provide structural enhancement. KEYWORDS: Fibers. fractionation, swelling, drying methods, fiber bonding. fiber alignment, pulp molding.

For most products, processing recycled paper back into paper will require de-inking and removal of coatings and fillers. Paper to paper recycling will also require sorting the paper waste stream to insure that the stock used contains the type of fiber needed. These problems can be eliminated if the waste paper product stream is used to make fiber based composites. Mixed office waste, packaging materials, paperboard, newspaper, and many other types of paper fiber can be used directly for the production of thermosetting or thermoplastic fiber based composites. High levels of clay used in magazine paper can be tolerated in these composites. This paper will review research in making fiber based composites from several waste paper streams and the properties of these products.

This paper presents a review of micromechanics models that have been used to predict the elastic and strength behavior of paper materials. The models discussed are based on a fiber network model that takes into account the properties of the fibers and the properties of the fiber-to-fiber bond.Elastic models are described for a range of paper density and basis weight ranging from tissue papers to paperboard materials. The effects of fiber curl for low density systems is discussed. Models for predicting both the initial modulus of the paper and the nonlinear elastic behavior for small finite strains is presented. Differences between tensile and compressive straining regimes are addressed.Limit load theory is discussed for predicting the strength of the network. Damage mechanics theory is employed to take into account hypothesized processes of fiber fracture and bond delaminations, and to relate the inelastic network micromechanics to the prediction of the strength of the material.

Studies are presented showing that formation of a sheet of paper from a heterogeneous mix of cellulose fibers and water at the forming section of a paper machine is a three-part process.The studies were carried out using the Weyerhaeuser-developed G/W Drainage/Retention System of following the forming portion of the papermaking process and is a summary of work carried out over a five-year period of time.

Experiments on laboratory paper sheets have indicated that under certain conditions the elastic modulus is inversely proportional to both the drying shrinkage and dimensional stability. Thus it appears that the elastic response of paper to mechanically and hygroscopically induced stresses is determined by the drying strain or shrinkage of the sheet. It is not clear, however, what effect the geometry of paper network and the properties of papermaking fibers have on the relationship between paper elasticity and drying restraints.We have developed a model for the study of the elastic properties of paper as a function of the drying shrinkage. The model is based on the assumption that there exists a unique relationship between the elastic properties and dried-in compression of fiber. As a consequence, the elastic properties of a fiber depend on its orientation relative to the principal axes of the paper sheet.The qualitative features obtained from the model calculations are consistent with experimental observations and independent of details of the elastic properties of fiber. It is clearly shown that no unique relationship exists between the drying strain and elastic modulus of the paper sheet. However, to a reasonable accuracy certain simple relatioships do exist that appear to be of general validity.

Organic thin-film transistors (OTFTs) are the most promising candidates for flexible electronics owing to their flexible structures, the simplicity of processing large-area devices, and excellent compatibility with flexible substrates. To date, many studies have been reported that have aimed at developing a wide range of plastic electronics such as flexible displays, sensors. In this paper, we discuss our recent work, focusing on OTFT arrays and their application to flexible display. An active-matrix (AM) backplane using a low-temperature cross-linkable olefin-type polymer as the gatedielectric and an air-stable DNTT as the organic semiconductor (OSC) was successfully fabricated on a plastic substrate. The short-channel TFT array exhibited a high hole mobility of over 0.5 cm2/Vs, a low subthreshold slope of 0.31, and excellent environmental and operational stability. A 5-inch flexible OLED display exhibited a high luminescence of over 300 cd/m2 by driving of the DNTT-based OTFTs. Solution-processed OTFTs are also attracting considerable attention owing to both their simple manufacturing process and excellent transistor performance. We present a simple patterning process for a solution-processable OSC that can be used to develop a high-mobility short-channel TFT array. The OSC film was directly patterned on the confined active channel region by a simple lamination coating technique and the resulting TFTs showed a high mobility of up to 1.3 cm2/Vs. In the final section, we report on eco-friendly paper-based organic TFT array. A transparent cellulose nanofibers paper was firstly applied to a flexible substrate for the TFT backplane. A solution-processed TFT on the transparent paper exhibited a high mobility exceeding 1 cm2/Vs, good air stability, and excellent mechanical stability.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), or PEDOT:PSS, and single-walled carbon nanotubes (SWCNTs) were incorporated into an inkjet ink. The combination of PEDOT, a conjugated, conductive polymer, and highly conductive CNTs, yielded a conductive film after printing and curing of the ink. Several paper types were used as substrates for depositing printed patterns of the PEDOT:PSS/SWCNT ink. Wide variability in conductivity was observed for different commercial paper types, ranging from a maximum 0.9 S/cm on Epson® Premium Photo cast-coated glossy paper to 3 × 10-5 S/cm on Epson® Premium Presentation coated cardstock. Increasing the SWCNT content of the ink improved conductivity on a non-permeable cellulose acetate substrate to a point, after which the combined effects of ink filtration and jetting limited the number of nanotubes delivered to the substrate. On permeable paper, the irregularity of the substrate overcame the beneficial effects of SWCNTs as “bridges” between conductive PEDOT regions. Correlations between the substrates’ physical structure and conductivity were established for the printed sheets, with densely coated sheets presenting the highest conductivity, and porous sheets the lowest.

In this paper, we report on a method for fabricating an inexpensive microfluidic platform on parchment paper. Parchment paper was selected for this purpose due to its wide availability for culinary applications and hydrophobic silicone-based surface coating. We were able to selectively modify the surface structure and property (hydrophobic to hydrophilic) using a CO2 laser. The modified surface has highly-porous structure which helps to trap chemical and biological reagents for analysis. The treated surface is stable over time and can be used for aqueous droplet assembly. Finally, we demonstrated the applicability of this platform for performing chemical reaction using luminol-based hemoglobin detection.

The purpose of this paper was to describe a method of preparing Fe-TiO2 supported on sepiolite fibers with sol-gel method and to discuss the feasibility of photocatalytic degradation of paper-making waste water with chemical oxygen depletion (CODcr) (Potassium dichromate method) as evaluation criterion of catalytic activity. As-fabricated catalysts consisted of TiO2 particles impregnated with iron and dispersed on the sepiolite fibers (S.F.s). The novel Fe-TiO2-sepiolite was characterized by specific surface area and pore size distribution measurements, scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and Fourier transform Infrared spectrometer (FT-IR) etc. The effects of parameters such as the amount of Ti/sepiolite fibers, initial pH, H2O2, Fe-doped, concentration of waste water, etc. were studied in detail. The results indicated that the presence of sepiolite in the support preparation and its role as a matrix over which TiO2 particles were dispersed seem to play an important effect in the migration process of oxygen species through the support vacancies. On the basis of these properties, the most promising carriers to be used in a waste water treatment process were selected.

Wood and paper are ubiquitous in societies around the world and are largely taken for granted as part of traditional industries with no new science to learn. Many of the technologies used in the forest products industry have been gained empirically through experience. The complexities of wood are now yielding to newer tools and we are beginning to see how the mechanical, optical and other physical properties of wood are related to hierarchical structures based on 2 to 10 nm diameter several hundred nm long fibers of nanocrystalline cellulose (NCC). The liberation of these NCC’s is allowing their re-assembly into remarkably strong structures. Examples will be given of the nature of these building blocks and structures assembled from them. Examples will include nanocomposites as well as very high strength “paper”. Paper is another example of a process whereby nanofibrils are released and then re-assembled with the use of “retention, drainage and formation aides” to make substrates we call paper with remarkable strength to weight performance. Other disciplines call this process “self-assembly” and the “aids” as necessary surfactants and additives to control structure and performance. Glossy magazine papers, for example, have approximately 10 micron thick coatings of white minerals and latex binders which are increasingly of nano dimensions. The coatings are assembled in structures to provide optical barrier performance (opacity) as well as controlled ink interaction with the necessary strength to survive printing and handling. These coatings are frequently similar in structure to seashells and, from this knowledge, progress has been made in understanding the mechanisms at play in achieving higher strength coatings. More recently kaolin clays have been introduced with mean crystal thicknesses in the range 20 to 40 nm instead of the usual 100 to 140 nm. These clays show useful strength performance and represent what may be called pragmatic nanoclays. Novel chemistries based on biomimetic learnings are emerging to displace the conventional starch or latex binders. Examples will be given of protocols for moving toward higher strength systems.

An electric insulation resistant coating has been developed by using photo-oxidized silicone oil. The silicone oil was exposed to ultraviolet⊈light in the air; which transformed the organic silicone oil into an inorganic amorphous glass film. Conventional large-area solar panels and smart papers are made of glass or plastic; in addition to being well insulated, waterproof, transparent, and hard, the panels are desirable to be light in weight and flexible. Here, metal foil is dipped into dimethylsiloxane silicone oil, and the silicone oil on the foil surface is irradiated with Xe2 excimer lamplight. Oxygen adsorbed on the sample surface is photo-excited by the irradiation to produce active oxygen. This active oxygen reacts with the silicone oil photo-excited and forms inorganic glass. With the process of the photo-oxidation, the silicone oil is vitrified, being inorganic.

A simple and versatile procedure was developed for synthesizing biomorphic mesoporous Ce1-xZrxO2. Aqueous cerium nitrate and zirconium nitrate solutions, and paper were used as the starting materials. Under the structure-directed effect offered by the active hydroxyl radicals of the cellulose in the paper templates, porous and fibrous structures of paper were replicated by the self-assembly of Ce1-xZrxO2 nanocrystallites after the paper underwent chemical infiltration and calcinations. The product, composing of interwoven network of fibers with diameter ranging from 10 to 20 m, was a replica of the original paper structure only that each fiber was assembled by Ce1-xZrxO2 nanocrystallites with grain size of 3-10 nm. The templating function of cellulose and the mechanism in the formation of nanocrystallites were proposed.

We have demonstrated organic thin-film transistor devices on synthesis paper of polypropylene (PP). All the fabrications are in solution-based processes except electrodes. As a barrier and smoother layer, photosensitive epoxy, 5μm-thich was coated on the paper substrate by using slit die coating. Polyvinyl phenol (PVP) was mixed with poly (melamine-co-formaldehyde) methylated, filmed by spin coating and ultraviolet (UV) cross linked to provide the gate dielectric layer. Using poly (3-hexylthiophene) as an active layer, a high-performance organic transistor with field effect mobility up to 0.006 cm2/ V s and an on/off ratio of 50 can be achieved. For the applications in flexible and disposable electronics, to built organic transistors on a cheap synthesis paper substrate can extremely lower the cost.

Electronic systems that offer elastic mechanical responses to high strain deformations are of growing interest, due to their ability to enable new electrical, optical and biomedical devices and other applications whose requirements are impossible to satisfy with conventional wafer-based technologies or even with those that offer simple bendability. This talk describes materials and mechanical design strategies for classes of electronic circuits that offer extremely high flexibility and stretchability over large area, enabling them to accommodate even demanding deformation modes, such as twisting and linear stretching to ‘rubber-band’ levels of strain over 100%. The use of printed single crystalline silicon nanomaterials for the semiconductor provides performance in flexible and stretchable complementary metal-oxide-semiconductor (CMOS) integrated circuits approaching that of conventional devices with comparable feature sizes formed on silicon wafers. Comprehensive theoretical studies of the mechanics reveal the way in which the structural designs enable these extreme mechanical properties without fracturing the intrinsically brittle active materials or even inducing significant changes in their electrical properties. The results, as demonstrated through electrical measurements of arrays of transistors, CMOS inverters, ring oscillators and differential amplifiers, suggest a valuable route to high performance stretchable electronics that can be integrated with nearly arbitrary substrates. We show examples ranging from plastic and rubber, to vinyl, leather and paper, with capability for large area coverage.

A new technique in microscopy is demonstrated in which the domain of Atomic Force Microscopy (AFM) is extended to optical spectroscopy at the nanometer scale. Molecular resonance of feature sizes down to the single molecular level were detected and imaged purely by mechanical detection of the force gradient between the interaction of the optically driven object molecular dipole and its mirror image in a Platinum coated scanning probe tip. We provide full experimental details including a basic theory for this new technique. The microscopy and spectroscopy technique is extendable to frequencies ranging from radio to infrared and the ultra violet.

1-Phenyl-3-naphthyl-5-((dimethylamino)phenyl)-2-pyrazoline with different diameters of 40 - 190 nm were prepared by the reprecipitation method and polymerized with poly(methyl methacrylate-co-ethylene glycol dimethacrylate) using cationic surfactants for full color electronic paper, which is expected to substitute for the future display. The electronic ink particles of pyrazoline organic nanoparticles polymerized by poly(methylmethacrylate-co-ethylene glycol dimethacrylate) were prepared and monodispersed successfully in aqueous alcohol medium. The size of mono-dispersed electronic ink particles is from 160 to 550 nm. The ink particle size was found to decrease with increasing concentration of the surfactant. The effect of surfactant was significant. The appropriate additions of surfactants result in an increase in electrophoretic mobility. The electrophoretic mobility of the resulting electronic inks was −7.5 to −3.6 × 10−5 cm2/ V·s in the presence of surfactants.

An organic light emitting device (OLED) has been successfully fabricated on a thin paper-like polyimide substrate (about 10 μm-thick), which is sandwiched between silicone oxide and silicone nitride films. The emission characteristics of the OLEDs, which consist of diamine derivative (α-NPD) and 8-hydroxyquinoline aluminum (Alq3), are similar to those fabricated on a conventional glass substrate. Since the substrates and the OLEDs are very thin like a paper, the devices can be applicable for paper-like displays.

Through a series of experiments the mechanical properties of paper are explored. Hydrogen bonding is fundamental to the performance of paper and its disruption results in distinctive stress-strain behavior. Stress-strain curves were generated from which tensile strength, Young's modulus, percent stretch, and work (tensile energy absorption) were obtained. It was found that the contribution of the fiber to the mechanical properties of paper is primarily elastic. Fibers are many times stronger than paper. Only fibers which have been severely deteriorated show measurable changes in stress-strain behavior. Fiber deterioration results in characteristically different stress-strain behavior than that which results from disruption of interfiber bonding. Water immersion results in the disruption of interfiber bonds in paper, leaving only 2–3% of dry tensile strength. Interfiber bonds make a profound contribution to the mechanical properties of the paper. Aqueous treatment is shown to be a radical treatment, altering the original dried-in properties of the sheet. The release of structural bonds and dried-in strains during wetting and the subsequent reformation of interfiber bonds during drying are shown to be independent of water purity, be it ultrapure water, tap water, or water containing washing aids such as Ca(OH)2, NaOH, CaCO3 or Na2CO3. The effects of immersion in organic solvents was explored. Solvents have effects on mechanical properties which are approximately proportional to the degree of swelling caused by the solvent. Water, the liquid which caused the greatest swelling of the liquids evaluated, is shown to be the most disruptive liquid followed by methanol and acetone; toluene caused virtually no change. To explore the behavior of interfiber bonds paper was taken through a solvent exchange process. A sample was immersed in water and then taken through separate ethanol and acetone immersions to toluene, and dried. The result was a sheet with little bonding and decreases in all mechanical properties. To explore the surface tension and capillary action effects of water, the solvent-exchanged sheet was re-immersed in water. Upon drying, interfiber bonding was reintroduced which resulted in the regain of mechanical properties lost. p]A paradigm for the mechanical behavior of paper is developed. Fibers contribute elastic behavior and interfiber bonds are a principal source of plastic behavior.

Through a series of experiments the mechanical properties of paper are explored. Hydrogen bonding is fundamental to the performance of paper and its disruption results in distinctive stress-strain behavior. Stress-strain curves were generated from which tensile strength, Young's modulus, percent stretch, and work (tensile energy absorption) were obtained.It was found that the contribution of the fiber to the mechanical properties of paper is primarily elastic. Fibers are many times stronger than paper. Only fibers which have been severely deteriorated show measurable changes in stress-strain behavior. Fiber deterioration results in characteristically different stress-strain behavior than that which results from disruption of interfiber bonding.Water immersion results in the disruption of interfiber bonds in paper, leaving only 2-3% of dry tensile strength. Interfiber bonds make a profound contribution to the mechanical properties of the paper. Aqueous treatment is shown to be a radical treatment, altering the original dried-in properties of the sheet. The release of structural bonds and dried-in strains during wetting and the subsequent reformation of interfiber bonds during drying are shown to be independent of water purity, be it ultrapure water, tap water, or water containing washing aids such as Ca(OH)2, NaOH, CaCO3 or Na2CO3.The effects of immersion in organic solvents was explored. Solvents have effects on mechanical properties which are approximately proportional to the degree of swelling caused by the solvent. Water, the liquid which caused the greatest swelling of the liquids evaluated, is shown to be the most disruptive liquid followed by methanol and acetone; toluene caused virtually no change.To explore the behavior of interfiber bonds paper was taken through a solvent exchange process. A sample was immersed in water and then taken through separate ethanol and acetone immersions to toluene, and dried. The result was a sheet with little bonding and decreases in all mechanical properties. To explore the surface tension and capillary action effects of water, the solvent-exchanged sheet was re-immersed in water. Upon drying, interfiber bonding was reintroduced which resulted in the regain of mechanical properties lost.A paradigm for the mechanical behavior of paper is developed. Fibers contribute elastic behavior and interfiber bonds are a principal source of plastic behavior.

The development of an adhesive that is a hybrid between a pressure sensitive adhesive and a heat seal adhesive is described. The goal of this project, which is a joint collaboration between the Museum of Modern Art and the Polymer Research Institute, is to develop a preservation quality adhesive for application to RC print photographs. RC prints are clad in polyethylene, a low surface energy (LSE) polymer that requires special consideration when devising an adhesive to adhere to it. In arriving at a formula for this purpose research has focused on a combination of hydrocarbon-based polymers and low molecular weight oligomers. In addition, this work addresses other aspects such as activation conditions and joint design, factors critical to developing an adhesive that has the potential to satisfy the stringent criteria of a material acceptable to conservation applications.

Paper and paper composites are utilized in applications where they are subjected to multiaxial stress states and changing environmental conditions. Such materials exhibit nonlinear anisotropic material behavior which is time dependent and affected adversely by slight changes in moisture content and temperature. At present, lack of adequate theoretical models often hampers the design and development of structurally optimized paper products. Therefore, it has been common practice in the pulp and paper industry to use trial and error, and empirical approaches. Accurate continuum models for the mechanical behavior of paper and paper composites are needed to guide the paper product design process.In this work, a limited review of the existing methods for modeling the mechanical response of paper and paper composites is given. At first, a brief overview of the goals of current modeling techniques based on hydrogen bond, fiber network, and continuum approaches is presented. The governing equations and capabilities of current continuum models are then discussed in greater detail. Theories which include linear elastic (generalized Hooke's Law), nonlinear elastic (hyperelastic), linear viscoelastic, nonlinear viscoelastic, and inelastic constitutive relations are addressed. Finally, applications of existing continuum theories to the analysis of paper materials in structural configurations are presented. After these discussions, the limitations of the available continuum models are assessed and future research needs are suggested.

In the past, many attempts have been made to determine the degree of polymerization (DP) of cellulose in ligneous pulps or papers. Frequently, the methods employed caused severe depolymerization of the cellulose.The present paper provides a detailed procedure of DP determination of cellulose for both lignin-free and ligneous papers. The proposed method is based on viscosity measurements of cadoxen solutions of cellulose. Prior to dissolution in cadoxen, ligneous samples are partially delignified by a modified chlorite method, under conditions preventing any substantial depolymerization of cellulose. Results of preliminary experiments carried out on groundwood newsprint papers provide strong evidence of reliability of DP values so determined.

Electron Spin Resonance spectroscopy has been used to carry out a systematic investigation of the paramagnetic impurities present in antique and modern paper. Up to eleven different paramagnetic centres, which include different transition ions (Fe3+, Mn2+, Cu2+), organic free radicals, and paramagnetic point defects have been detected, in concentrations ranging from few ppm to several hundreds. Experiments performed on new and deteriorated samples strongly indicate that some of these impurities participate directly or are produced during the aging and degradation processes. They can be used as quality indicators or probes for quantitative monitoring of the degradation of paper.

Currently, there is considerable interest in producing patterned metallic structures with reduced dimensions for use in technologies such as ultra large scale integration (ULSI) device fabrication, nanoelectromechanical systems (NEMS), and arrayed nanosensors, without sacrificing throughput or cost effectiveness. Research in our laboratory has focused on the preparation of precious metal thin films on semiconductor substrates via electroless deposition. This method provides for the facile interfacing of metal nanoparticles with a group (IV) and III-IV compound semiconductor surfaces. Morphologically complex films composed of gold, platinum, and palladium nanoparticles have been prepared as a result of the immersion of germanium and gallium arsenide substrates into dilute, aqueous solutions of tetrachloraurate (III), tetrachloroplatinate (II), and tetrachloropalladate (II), respectively. Continuous metallic films form spontaneously under ambient conditions, in the absence of a fluoride source or an externally applied current. This facile electroless deposition methodology provides an alternative to complex and expensive vacuum methods of metallization, yet allows for the preparation of both thin and thick nanostructured films with control over surface morphology and deposition rate. Furthermore, precious metal films prepared in this way exhibit excellent adhesion to the underlying semiconductor substrate. The resultant films were characterized utilizing scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and scanning probe microscopy (SPM). In order to apply this novel metallization method toward the development of useful technologies, patterning utilizing photolithography, microcontact printing (μCP), and scanning probe nanolithography (SPN) has been demonstrated.

We follow the accumulation of microscopic damage ahead the crack tip in paper. The fiber debonding process varies even within each specimen because of large variation in fiber and bond properties. In general, stiff and weakly bonded fibers tend to debond as a rigid body while ductile or well bonded fibers pull out gradually in a process that propagates from the crack line to the fiber ends. Particularly in the latter case the network ruptures coherently rather than through debonding of single fibers. Experimental analysis and simulations show that fracture energy correlates closely with the size of the fracture process zone (FPZ) irrespective the nature of the debonding process. Only the cases of low bonding and stiff fibers seem to make an exception in that FPZ can grow in size without a corresponding increase in fracture energy.

Microwave multiport sensors have been shown to provide some unique capabilities to achieve real-time testing of products conveyed at high speed. In many applications, quantitative measurements of physical quantities such as moisture content, density, etc… are required, either to guarantee reliable production or to optimally control a fabrication/transformation process. In this paper, different ways of extracting such physical quantities from microwave measurements performed by multiport sensors are presented. Model approaches are used, based on polynomial expansions of the physical quantities to be measured as a function of the microwave amplitude and phase data. Calibration procedures have been investigated for both paper and wood material samples. Comparisons between in-situ, microwave and conventional, measurements are analysed.