Strength Loss in Recycled Fibers and Methods of Restoration

1992 ◽  
Vol 266 ◽  
Author(s):  
James L. Minor ◽  
Rajai H. Atalla
Keyword(s):  
Gas Phase ◽  
Lignin Content ◽  
Strength Loss ◽  
Pulp Fibers ◽  
Recycling Process ◽  
Recycled Paper ◽  
Chemical Pulps ◽  
Mechanical Pulps ◽  
Recycled Fibers ◽  
High Lignin Content

AbstractThe reduced interfiber bonding capability and reduced conformability of recycled fibers compared to virgin wood pulp fibers is caused by the drying phase of the first papermaking cycle. Changes in the fiber result in stiffness. This effect is more pronounced in chemical pulps than in high lignin content mechanical pulps. This chapter describes methods for restoring some or all the interfiber bonding. In an attempt to develop a “dry” newspaper recycling process, the water-intensive repulping and paper-forming steps were replaced with dry-fiberizing, air-forming, gas-phase ozone and ammonia treatments, and pressdrying. The tensile strength of the dry-recycled paper approached that of the original newsprint.

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Jonas Brändström ◽  
Jean-Paul Joseleau ◽  
Alain Cochaux ◽  
Nathalie Giraud-Telme ◽  
Katia Ruel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Significant Proportion ◽  
Pulp Fibers ◽  
Chemical Pulp ◽  
Recycled Pulp ◽  
Transmission Electron ◽  
Large Heterogeneity ◽  
Recycled Fibers ◽  
Packaging Paper

Abstract Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

Quantification of vegetable oil in recycled paper

TAPPI Journal ◽  
2020 ◽  
Vol 19 (9) ◽  
pp. 473-477
Author(s):  
YAO NTIFAFA ◽  
MARIA SZAJDA-LAM ◽  
ASHOK GHOSH ◽  
PETER W. HART
Keyword(s):  
Soybean Oil ◽  
Vegetable Oil ◽  
Oil Content ◽  
Strength Loss ◽  
Gas Chromatography Mass Spectrometry ◽  
Paper Strength ◽  
High Concentration ◽  
Recycled Paper ◽  
Pyrolysis Gas ◽  
Cooking Process

Vegetable soybean oil is commonly used in cooking foods that are packaged in takeaway paper-board containers. Vegetable oil is hydrophobic, and in sufficiently high concentration, could interfere with interfiber bonding and result in paper strength loss. In order to quantify the effect of oil on the resulting paperboard strength, it is necessary to quantify the oil content in paper. A lab method was evaluated to determine the soybean oil content in paper. Handsheets were made with pulps previously treated with different proportions of vegetable oil. Pyrolysis gas chromatography-mass spectrometry (pyGCMS) was used to quantify the amount of oil left in the handsheets. The results revealed a strong correlation between the amount of oil applied to the initial pulp and the amount of oil left in the handsheets. In addition, the effect of vegetable oils on paper strength may be affected by the cooking process. Vegetable oil is known to degrade over time in the presence of oxygen, light, and temperature. The vegetable oil was put in an oven to imitate the oil lifecycle during a typical pizza cooking process. The cooked oil was then left at room temperature and not protected from air (oxygen) or from normal daylight. The heated, then cooled, oil was stored over a period of 13 weeks. During this time, samples of the aged oil were tested as part of a time-based degradation study of the cooked and cooled oil.

Characterisation of Drawing Papers for Borko Lazeski’s Cartoons (1951–56)

2018 ◽  
Vol 39 (3) ◽  
pp. 157-183
Author(s):  
Maja Kostadinovska
Keyword(s):  
Raman Spectroscopy ◽  
Chemical Nature ◽  
Lignin Content ◽  
Mural Painting ◽  
Micro Raman Spectroscopy ◽  
Different Types ◽  
Informed Treatment ◽  
Acidic Conditions ◽  
Spot Tests ◽  
High Lignin Content

Abstract This paper presents a study of the drawing papers from Borko Lazeski’s cartoons for a mural painting. The collection is comprised of more than 20 single pieces (170×500 cm) executed in charcoal, pencil, pastel, tempera and ink. The cartoons exhibit different types of damages, such as grease stains, moisture stains, cracks, flaking paint, areas of loss caused by insects and mould stains. The study included spot tests, ATR-FTIR and micro-Raman spectroscopy to characterise the artist’s papers. They were found to be a type of paper composed of partly bleached, neutral sulphite semi-chemical (NSSC) wood pulp originating from coniferous trees (softwood) with the occasional use of abaca fibres. The laboratory tests revealed slightly acidic conditions (pH=5.01–6.52), high lignin content (>5 %) and alum-rosin sizing. Infrared spectroscopy confirmed all findings of the spot tests. Micro-Raman spectroscopy showed the presence of gypsum in the papers. The study addresses conservation issues arising from the chemical nature of the paper support and highlights the need for an extended study in order to be able to make informed treatment choices.

scholarly journals Delignification of Date Palm Fronds using Modified Organosolv Technique

2017 ◽  
Vol 13 (3) ◽  
pp. 1-9
Author(s):  
Yasmeen Salih Mahdi ◽  
Asem Hassan Mohammed ◽  
Alaa Kareem Mohammed
Keyword(s):  
Date Palm ◽  
Lignin Content ◽  
Statistical Experimental Design ◽  
Digestion Time ◽  
Stainless Steel Reactor ◽  
Pre Treatment ◽  
Design Type ◽  
Palm Fronds ◽  
Central Composite ◽  
High Lignin Content

Abstract   In this study, modified organic solvent (organosolv) method was applied to remove high lignin content in the date palm fronds (type Al-Zahdi) which was taken from the Iraqi gardens. In modified organosolv, lignocellulosic material is fractionated into its constituents (lignin, cellulose and hemicellulose). In this process, solvent (organic)-water is brought into contact with the lignocellulosic biomass at high temperature, using stainless steel reactor (digester). Therefor; most of hemicellulose will remove from the biomass, while the solid residue (mainly cellulose) can be used in various industrial fields. Three variables were studied in this process: temperature, ratio of ethanol to water and digestion time. Statistical experimental design type Central Composite Design (CCD) has been used to find a mathematical relationship between the variables and the remaining lignin percent as dependent variable. The results obtained in this study were represented by a polynomial mathematical equation of the second degree.  The results showed that the best digestion time was (80 minutes), which gave the best percent remaining concentration of lignin (3%) at temperature of 185oC and ratio of ethanol: water equal to 50: 50 wt/wt. In order to reduce digesting time, the effect of using different catalysts have been studied such as (NaOH, H2SO4, Ca (OH) 2) at low concentration (0.025, 0.025, 0.05M) respectively. It was found that the best catalyst is sodium hydroxide at concentration (0.025) mol/L which gave the same percent of  lignin 3% but with low digestion time about 30 min. Keywords: Biomass pre-treatment, delignification, lignin, organosolv, date palm fronds.

scholarly journals Potential of Cellulose Microfibers for PHA and PLA Biopolymers Reinforcement

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4653
Author(s):  
Gonzalo Mármol ◽  
Christian Gauss ◽  
Raul Fangueiro
Keyword(s):  
Lignin Content ◽  
Barrier Properties ◽  
Production Costs ◽  
Recycled Paper ◽  
High Fiber ◽  
Kraft Paper ◽  
Layer Composite ◽  
Mechanical And Physical Properties ◽  
Cellulose Microfibers ◽  
Current Production

Cellulose nanocrystals (CNC) have attracted the attention of many engineering fields and offered excellent mechanical and physical properties as polymer reinforcement. However, their application in composite products with high material demand is complex due to the current production costs. This work explores the use of cellulose microfibers (MF) obtained by a straightforward water dispersion of kraft paper to reinforce polyhydroxyalkanoate (PHA) and polylactic acid (PLA) films. To assess the influence of this type of filler material on the properties of biopolymers, films were cast and reinforced at different scales, with both CNC and MF separately, to compare their effectiveness. Regarding mechanical properties, CNC has a better reinforcing effect on the tensile strength of PLA samples, though up to 20 wt.% of MF may also lead to stronger PLA films. Moreover, PHA films reinforced with MF are 23% stronger than neat PHA samples. This gain in strength is accompanied by an increment of the stiffness of the material. Additionally, the addition of MF leads to an increase in the crystallinity of PHA that can be controlled by heat treatment followed by quenching. This change in the crystallinity of PHA affects the hygroscopicity of PHA samples, allowing the modification of the water barrier properties according to the required features. The addition of MF to both types of polymers also increases the surface roughness of the films, which may contribute to obtaining better interlaminar bonding in multi-layer composite applications. Due to the partial lignin content in MF from kraft paper, samples reinforced with MF present a UV blocking effect. Therefore, MF from kraft paper may be explored as a way to introduce high fiber concentrations (up to 20 wt.%) from other sources of recycled paper into biocomposite manufacturing with economic and technical benefits.

Oak contribution to litter nutrient dynamics in an Appalachian forest receiving elevated nitrogen and dolomite

2009 ◽  
Vol 39 (5) ◽  
pp. 936-944 ◽  
Author(s):  
K.B. Piatek ◽  
P. Munasinghe ◽  
W.T. Peterjohn ◽  
M.B. Adams ◽  
J.R. Cumming
Keyword(s):  
Atmospheric Deposition ◽  
Nutrient Dynamics ◽  
Lignin Content ◽  
Nutrient Fluxes ◽  
Mixed Species ◽  
N Dynamics ◽  
P Flux ◽  
P Immobilization ◽  
High Lignin Content ◽  
N Flux

Ecosystem nitrogen (N), phosphorus (P), and calcium (Ca) fluxes are affected by inputs of atmospheric N. Oak litter may additionally affect these fluxes because of its high-lignin content. We analyzed nutrient dynamics in ambient mixed-species litter in an aggrading hardwood stand at the Fernow Experimental Forest in West Virginia. We separated oak from the mix for analysis (oak) and compared it with total litter (all species) to understand how oak affects nutrient fluxes in the litter layer. The study was conducted under ambient atmospheric deposition, under elevated atmospheric deposition, and under elevated deposition plus mitigation with dolomite. N flux between litterfall and 12 months later indicated a net loss in all-species litter of up to 7.3 kg N·ha–1 and a retention of up to 0.6 kg N·ha–1 in oak. P flux included losses in all species in ambient and in dolomite treatments of up to 0.19 kg P·ha–1 and gains of up to 0.12 kg P·ha–1 in oak in all treatments. Oak mineralized Ca at an average across treatments of 4.6 kg Ca·ha–1 compared with 16 kg Ca·ha–1 in all species, with half of that when trees were dormant. Percent immobilization and release over initial litter were greater in oak than in all species, but nutrient fluxes were lower in oak than in all species because of low oak litter mass. Elevated deposition lowered N and increased P immobilization. Dolomite appeared to affect early N dynamics only. With an increase in litterfall mass when forests mature, these effects are also likely to increase.

Recycling Bleach Technologies

1992 ◽  
Vol 266 ◽  
Author(s):  
James L. Minor
Keyword(s):  
Heavy Metals ◽  
Metal Content ◽  
Chelating Agents ◽  
Lignin Content ◽  
Sulfinic Acid ◽  
Factors Associated ◽  
Organic Chromophores ◽  
Environmental Attributes ◽  
Effective Removal ◽  
Recycled Fibers

AbstractWhen faced with bleaching recycled fibers, the technologist must consider the usual factors associated with the bleaching of virgin fibers plus additional factors introduced by recycling. The lignin content of the furnish and the products to be made determine whether delignifying or lignin-preserving agents are to be used. Factors introduced by recycling include mixed lignin contents, dyes, residual ink particles and carrier chemicals, contaminants, color reversion, and hornification (which affects accessibility of chromophores to bleaching reagents). In addition, the technologist must be concerned with the environmental impact of the bleaching operation.Dithionite and formamidine sulfinic acid are effective lignin-preserving reductive bleaching agents for recycled fibers. Hydrogen peroxide is an effective lignin-preserving oxidative agent, but heavy metals and enzymes catalyze its decomposition. Chelating agents have an important role in decreasing metal content. For some delignification and effective removal of organic chromophores, oxygen and ozone show promise. Research on the use of oxygen-based oxidative bleaching agents is intense because of their favorable environmental attributes.

scholarly journals Precipitate obtained following membrane separation of hydrothermally pretreated rice straw liquid revealed by 2D NMR to have high lignin content

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Kengo Sasaki ◽  
Mami Okamoto ◽  
Tomokazu Shirai ◽  
Yota Tsuge ◽  
Hiroshi Teramura ◽  
...  
Keyword(s):  
Rice Straw ◽  
Membrane Separation ◽  
Lignin Content ◽  
2D Nmr ◽  
High Lignin Content

scholarly journals Producing Direct Food Packaging Using Deinked Office Paper Grades—Deinkability and Food Contact Suitability Evaluation

2021 ◽  
Vol 13 (22) ◽  
pp. 12550
Author(s):  
Sonja Jamnicki Hanzer ◽  
Branka Lozo ◽  
Lidija Barušić
Keyword(s):  
Food Safety ◽  
Food Packaging ◽  
Wood Fiber ◽  
Safety Evaluation ◽  
Recycled Paper ◽  
Safety Issues ◽  
Food Contact ◽  
Primary Aromatic Amines ◽  
Recycled Fibers ◽  
Office Paper

Paper recycling is the most eco-efficient waste management option, since the use of recycled fibers reduces the need for virgin wood fiber and lowers energy consumption, and hence has a positive effect on the environment. The use of recycled paper is by far the highest in the packaging industry. In food packaging production, recycled paper is often favored over paper and board made from virgin fibers. However, due to the possible hazardous chemicals that can be found in recycled paper, there is a dilemma of how to overcome food safety issues while making food packaging more circular. The objective of the study was to determine if deinked office paper grades could be used as an alternative fiber source in the production of food packaging white top linerboards. For that purpose, three different types of digitally printed papers were submitted to a chemical deinking flotation in laboratory conditions, and the handsheets formed after each recycling trial were tested on the suitability for direct food contact. Evaluation of deinkability for each group of recycled prints was performed, as well. Deinkability was evaluated by calculating the flotation yield, pulp’s brightness and whiteness increase, ink elimination factor, determination of residual ink area, as well as ash content elimination. Food safety evaluation was performed by determining the content of heavy metals (Cd, Pb, Hg, and Cr VI), primary aromatic amines, diisopropylnaphthalenes (DIPN), phthalates, and polychlorinated biphenyls (PCB) from aqueous or organic solvent extracts of recycled paper pulp. The fastness of the fluorescent whitening agents was determined, as well. Of all evaluated deinking flotation efficiency parameters, only flotation yield and ash reduction by flotation were positively assessed. High content of residual ink particles detected after the flotation stage indicates that the flotation was not a successful method for the elimination of disintegrated ink particles, which was also confirmed by deficient results of ink elimination measurements and whiteness increase. Flotation proved to be the least efficient in the recycling of inkjet prints, where the lowest ink elimination, whiteness, and brightness values were achieved. As far as food safety assessment of deinked pulp is concerned, all tested deinked handsheets were found suitable to be used in direct contact with foods.

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