Newsprint Fibers Research Articles

Interfacial contributions in lignocellulosic fiber-reinforced polyurethane composites

Whereas lignocellulosic fibers have received considerable attention as a reinforcing agent in thermoplastic composites, their applicability to reactive polymer systems remains of considerable interest. The hydroxyl-rich nature of natural lignocellulosic fibers suggests that they are particularly useful in thermosetting systems such as polyurethanes. To further this concept, urethane composites were prepared using both unused thermomechanical pulp and recycled newsprint fibers. In formulating the materials, the fibers were considered as a pseudo-reactant, contributing to the network formation. A di-functional and tri-functional poly(propylene oxide)-based polyol were investigated as the synthetic components with a polyol-miscible isocyanate resin serving as a crosslinking agent. The mechanical properties of the composites were found to depend most strongly on the type of fiber, and specifically the accessibility of hydroxy functionality on the fiber. Dynamic mechanical analysis, swelling behavior, and scanning electron micrographs of failure surfaces all provided evidence of a substantial interphase in the composites that directly impacted performance properties. The functionality of the synthetic polyol further distinguished the behavior of the composite materials. Tri-functional polyols generally increased strength and stiffness, regardless of fiber type. The data suggest that synthetic polyol functionality and relative accessibility of the internal polymer structure of the fiber wall are dominant factors in determining the extent of interphase development. Considerable opportunity exists to engineer the properties of this material system given the wide range of natural fibers and synthetic polyols available for formulation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 546–555, 2001

Removal of Inorganic Mercury from Aqueous Solutions by Carbonized Waste Newsprint Fiber

The ability of carbonized waste newsprint fiber to remove Hg(II) from aqueous solutions by physicochemical adsorption was investigated. Defiberized waste newsprint was carbonized in a nitrogen atmosphere at temperatures ranging 600 to 900°C for 3 h. Research parameters included carbonization temperature, initial solution pH, contact time, solution temperature, and initial concentration of Hg(II). The studies showed the adsorbents to be an efficient adsorbent for removing Hg(II) from aqueous solutions. Of the parameters studied, carbonization temperature and initial solution pH were considered to be the most crucial. The amount of Hg(II) adsorbed onto the adsorbent increased with increasing carbonization temperature in the pH range 3 to 9, while it decreased as the temperature increased at pH 11. The extent of the adsorption was also dependent upon the contact time, solution temperature, and initial concentration of Hg(II). The adsorption data were well fitted to both the Freundlich and Langmuir isotherms. Desorption studies imply the occurrence of strong interaction of the Hg(II) species with the active sites on the surface of the adsorbent.

Polystyrene-Newspaper Composites Part I. Degradation of Polymer during Processing

Newsprint reinforced polystyrene was prepared, and the effect of process ing conditions on viscosity (in terms of torque) and molecular weight of polystyrene was studied. Polystyrene was melted in an intensive mixer. The influence of processing tem perature, time, and roller speed was evaluated. Subsequently, newsprint fiber was added to the polymer melt, and the effect of fiber concentration on viscosity and molecular weight of polystyrene was evaluated. A significant decrease in torque and molecular weight was observed when the processing time was longer than 40 minutes. The process ing temperature exhibited discernible effects on torque, specific energy, and degradation of polymer. Torque increased slightly as the roller speed increased from 10 to 20 rpm and then decreased thereafter. However, roller speed appeared to have little effect on polymer properties. Drastic changes in torque, specific energy and polymer degradation were observed with increase of fiber concentration.