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Paper Sheet (paper + sheet)

Distribution by Scientific Domains
Polymers and Materials Science80%

Selected Abstracts

The effect of water-soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheet

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
Arja-Helena Vesterinen
Abstract 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 [source]

Extremum-seeking control of retention for a microparticulate system

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2008
Audrey Favache
Abstract The operation of a paper machine relies on the close monitoring and control of several integrated units to ensure a high quality paper with the required specifications. In this paper, the retention control system in the wet-end of a paper machine is considered. The control objective is to maximize the retention of fines and fibres in the paper sheet to prevent the accumulation of micro particles in the water system. We present an adaptive extremum-seeking scheme for the optimization and control of retention in the wet-end of a paper machine. An adaptive learning technique is introduced to construct an algorithm that drives the system to the optimal retention value. Lyapunov's stability theory is used in the design of the extremum-seeking controller structure and the development of the parameter learning laws. The performance of the technique is illustrated via simulations based on a first-principles dynamic model developed previously for a micro-particulate system. Le bon fonctionnement d'une machine à papier repose sur le suivi et le contrôle étroits de plusieurs unités intégrées afin d'assurer une haute qualité de papier ayant les spécifications requises. Dans cet article, on considère le système de contrôle de rétention dans la partie humide d'une machine à papier. L'objectif du contrôle est de maximiser la rétention des fines et des fibres dans la feuille de papier afin de prévenir l'accumulation de micro-particules dans le système d'eau. On présente un schéma de recherche adaptatif des extrêmes pour l'optimisation et le contrôle de la rétention dans la partie humide d'une machine à papier. Une technique d'apprentissage adaptative est introduite pour construire un algorithme qui amène le système à une valeur de rétention optimale. La théorie de stabilité de Lyapunov est utilisée dans la conception de la structure des contrôleurs de recherche des extrêmes et l'élaboration de lois d'apprentissage des paramètres. La performance de la technique est illustrée par des simulations basées sur un modèle dynamique fondamental mis au point antérieurement pour un système de micro-particules. [source]

The effect of water-soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheet

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
Arja-Helena Vesterinen
Abstract 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 [source]

Poly(ethylene oxide)- block -poly[2-(dimethylamino)ethyl methacrylate] as Strengthening Agent in Paper: Dynamic Mechanical Characterization

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 3 2010
Arja-Helena Vesterinen
Abstract To enhance adhesion properties of PEO on wood fibers, block polymers of PEO and 2-(dimethylamino)ethyl methacrylate were synthesized. The polymers were further modified to obtain strongly cationic species. The resulting polymers were used as additives in paper sheets. Papers were studied by DMA in a controlled-humidity chamber. Addition of the PEO block co-polymers enhanced paper strength. The strength of the paper sheets was highest when polymer with molecular weight of 400,kg,·,mol,1 was used as an additive. Highly cationic block co-polymers increased moduli of paper sheets more than their weakly cationic analogs, which indicated strong interaction with fiber surfaces. Strength of the paper sheets decreased both with increased temperature and humidity. [source]