Properties of Polymer Composites with Cellulose Microfibrils

Polysaccharide elementary fibrils are usually fasciated into microfibrils of from one hundred to a few hundred Angstroms wide. Cellulose microfibrils when subjected to acid treatment dissociate into component elementary fibrils. For pectic acid it was observed that variations in pH could cause a change in the fasciation of the elementary fibrils.Solutions of purified pectic acid and sodium phosphotungtate were adjusted to various pH levels with NaOH or HCl and diluted to give a final concentration of 0.5 and 1% for the polysaccharide and negative stains respectively. Micrographs were made of the samples after drying on a carbon film covered grid. The average number of elementary fibrils was determined by counting the number of elementary fibrils in each fascicle intersected by lines drawn across the micrograph.

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A novel predictive method for filler coflocculation with cellulose microfibrils

TAPPI Journal ◽

10.32964/tj18.11.653 ◽

2019 ◽

Vol 18 (11) ◽

pp. 653-664

Author(s):

IGNACIO DE SAN PIO ◽

KLAS G. JOHANSSON ◽

PAUL KROCHAK

Keyword(s):

Negative Impact ◽

High Strength ◽

Strength Properties ◽

Cellulose Microfibrils ◽

Paper Strength ◽

Flow Loop ◽

Cationic Starch ◽

Reflectance Measurement ◽

Drainage Rate ◽

Complete Study

Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been patented or commercialized, yet a complete study on the behavior of the filler flocs and their effect on retention, drainage, and formation has not been found in literature. This type of research on fillers is often limited by difficulties in simulating high levels of shear at laboratory scale similar to those at mill scale. To address this challenge, a combination of techniques was used to compare preflocculation (i.e., filler is flocculated before addition to the pulp) with coflocculation strategies (i.e., filler is mixed with a binder and flocculated before addition to the pulp). The effect on filler and fiber flocs size was studied in a pilot flow loop using focal beam reflectance measurement (FBRM) and image analysis. Flocs obtained with cationic polyacrylamide (CPAM) and bentonite were shown to have similar shear resistance with both strategies, whereas cationic starch (CS) was clearly more advantageous when coflocculation strategy was used. The effect of flocculation strategy on drainage rate, STFI formation, ash retention, and standard strength properties was measured. Coflocculation of filler with CPAM plus bentonite or CS showed promising results and produced sheets with high strength but had a negative impact on wire dewatering, opening a door for further optimization.

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Increased dryness after pressing and wet web strength by utilizing foam application technology

TAPPI Journal ◽

10.32964/tj15.11.731 ◽

2016 ◽

Vol 15 (11) ◽

pp. 731-738 ◽

Cited By ~ 1

Author(s):

KARITA KINNUNEN-RAUDASKOSKI ◽

KRISTIAN SALMINEN ◽

JANI LEHMONEN ◽

TUOMO HJELT

Keyword(s):

Tensile Strength ◽

Guar Gum ◽

Paper Industry ◽

Reference Sample ◽

Strength Properties ◽

Cellulose Microfibrils ◽

Application Technology ◽

Ethylene Vinyl Alcohol ◽

Wet Pressing ◽

Web Strength

Production cost savings by lowering basis weight has been a trend in papermaking. The strategy has been to decrease the amount of softwood kraft pulp and increase use of fillers and recycled fibers. These changes have a tendency to lower strength properties of both the wet and dry web. To compensate for the strength loss in the paper, a greater quantity of strength additives is often required, either dosed at the wet end or applied to the wet web by spray. In this pilot-scale study, it was shown how strength additives can be effectively applied with foam-based application technology. The technology can simultaneously increase dryness after wet pressing and enhance dry and wet web strength properties. Foam application of polyvinyl alcohol (PVA), ethylene vinyl alcohol (EVOH), carboxymethyl cellulose (CMC), guar gum, starch, and cellulose microfibrils (CMF) increased web dryness after wet pressing up to 5.2%-units compared to the reference sample. The enhanced dewatering with starch, guar gum, and CMF was detected with a bulk increase. Additionally, a significant increase in z-directional tensile strength of dry web and and in-plane tensile strength properties of wet web was obtained. Based on the results, foam application technology can be a very useful technology for several applications in the paper industry.

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