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Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

Abstract: The influence of operational variables in the pulping of vine shoots by use of ethylene glycol [viz. temperature (155–185°C), cooking time (30–90min) and ethylene glycol concentration (50–70% v/v)] on the properties of the resulting pulp (viz. yield, kappa number and viscosity) and paper sheets (breaking length, stretch, burst index, tear index and brightness) was studied. A central composite factorial design was used in conjunction with the software ANFIS Edit Matlab 6.5 to develop fuzzy neural model that reproduced the experimental results of the dependent variables with errors less than 5%. The model is therefore effective with a view to simulating the ethylene glycol pulping process. [Copyright &y& Elsevier]

The article focuses on a study which developed a rheological model to predict the tensile creep behavior of paper under a uniaxial stress. The rheological model examined creep strain based on stress, time and efficiency factor. Study authors claim that their model can be used to predict the creep behavior of paper over a range of bonding levels, induced by mechanical changes in bonded area or chemical modification of specific bond strength.

Abstract: This paper considers calcined paper sludge as an alternative source of metakaolin, an established supplementary cementitious material. Calcination of the sludge generated in the recycling of newsprint paper at 700 °C yields a product with pozzolanic properties. The effects of this recycled metakaolin on the rheology and conduction calorimetry of cement pastes have been studied and compared to the effects of commercial metakaolin. The effects are similar and the results show that calcined paper sludge has the potential to be used as a supplementary cementitious material. This offers a route for utilising this waste material, as an alternative to the increased environmental burden associated with the production of metakaolin from natural kaolinite resources. [Copyright &y& Elsevier]

Abstract: Antimicrobial papers were prepared by coating paper with soy protein isolate (SPI) solution as inclusion matrix of carvacrol, an antimicrobial agent. Addition of carvacrol (30% w/w of SPI) to SPI solution (10% w/v) prepared at 25°C induced soy protein aggregates and viscosity decrease. Heat treatment (50, 70, 90°C) of SPI solutions and carvacrol addition improved homogeneity reduced particles size and increased viscosity of solutions. The aggregated structure of SPI in the presence of carvacrol at 25°C may play the role of a trapping structure leading to low carvacrol losses during coating and drying process of paper (9.6% against 37% after heat treatment at 90°C) and to lower release rates specially the first three days (0.04g/m2/day and 0.31g/m2/day when SPI coating solutions were prepared at 25 and 90°C, respectively). Regardless of the heat treatments received by the SPI solutions, residual carvacrol quantities in the coated papers after 50 days ranged between 0.6 and 0.7g/m2. [Copyright &y& Elsevier]

Abstract: Agitated pulp chests act as low-pass filters attenuating high-frequency variability and thus complimenting the action of control loops which attenuate slow disturbances. Dynamic tests made on industrial and scale-model chests show that non-ideal flows, including short-circuiting, recirculation, and dead zones, are common and significantly reduce the ability of the chest to attenuate fluctuations. In this paper, we explore the effect of suspension yield stress on the extent of non-ideal flow and upset attenuation by conducting dynamic tests using two different pulp suspensions: a long-fibred softwood pulp and a shorter-fibred hardwood pulp. Dynamic tests were also made as a function of the fibre mass concentration, with the yield stress used to characterize the dynamic behaviour observed in mixing. It was found that while the yield stress plays a significant role determining the mixing of pulp suspensions, the dynamic behaviour of pulp mixing could not be fully described by yield stress alone. Tests show that when the surface of the cavern created by the impeller approaches the pulp outlet, which was located on the impeller wall, the percentage of short-circuiting approached zero. [Copyright &y& Elsevier]