Drying of foam-formed mats from virgin pine fibers

Timofeev, Oleg; Jetsu, Petri; Kiiskinen, Harri; Keränen, Janne

doi:10.1080/07373937.2015.1103254

Cited by 24 publications

(21 citation statements)

References 18 publications

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“…We can define a "drying time" [Timofeev et al, 2016]. Impingement drying is well suited to the fibrous samples due to the porosity of both the structure and the gauze it is formed on.…”

Section: Drying Processmentioning

confidence: 99%

“…The technique consists of blowing hot air through the sample, which is then recirculated back to an air drier where the moisture is extracted. The benefit of this technique is that it can evenly and rapidly dry the samples, unlike oven drying, which usually dries the outermost part of the samples first [Timofeev et al, 2016]. We will address the possible decrease in drying times of our samples in future work.…”

Section: Drying Processmentioning

confidence: 99%

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Properties of lightweight fibrous structures made by a novel foam forming technique

et al. 2019

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We describe a novel method for the production of lightweight fibrous structures of densities as low as 8.8 kg.m −3. The method is based on the use of liquid foam as a carrier medium for dispersed Kraft fibres. Different to the process of foam forming, where the quick removal of the foam results in the formation of thin fibrous sheets, our samples are allowed to slowly drain and dry until all foam has disappeared. This procedure results in bulk samples whose height (up to 25 mm) and density are controlled by initial fibre concentration and liquid fraction of the foam. Above a minimum density, the compression modulus of elasticity of the samples increases linearly with density. Furthermore, we show compressive strength of the structures being controlled via the initial liquid fraction of the foam, making this an important process parameter for the fabrication of such structures.

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“…We can define a "drying time" [Timofeev et al, 2016]. Impingement drying is well suited to the fibrous samples due to the porosity of both the structure and the gauze it is formed on.…”

Section: Drying Processmentioning

confidence: 99%

Section: Drying Processmentioning

confidence: 99%

Properties of lightweight fibrous structures made by a novel foam forming technique

et al. 2019

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“…10,11 A dispersion is firstly obtained by stirring the particles in water for air incorporation in the presence of surfactants, followed by foam draining and drying. 12,13 During draining, the water excess is usually removed by gravity, balancing opposing forces, such as capillary pressure, gravity, and mechanical pressure. The residual humidity that remains after liquid flow can be dried under heating using ovens, air impingement, microwave or infrared radiation.…”

Section: Introductionmentioning

confidence: 99%

“…The residual humidity that remains after liquid flow can be dried under heating using ovens, air impingement, microwave or infrared radiation. 13 These methods are scalable and can be continuous, so that cellulose foams emerge as interesting green substitutes for polymeric foams derived from fossil fuels. However, dealing with wet foams is not a simple task, as these systems are thermodynamically unstable and many factors must be carefully controlled to slow down processes such as draining, coalescence and Ostwald ripening, 14 in order to keep the system metastable until liquid removal.…”

Section: Introductionmentioning

confidence: 99%

Simple Preparation of Cellulosic Lightweight Materials from Eucalyptus Pulp

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2018

ACS Sustainable Chem. Eng.

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Cellulosic foams and aerogels are tridimensional materials prepared from cellulose fibers and nanostructures that display interesting properties, such as extremely low density, high fluid permeability, sound and heat insulation. Currently, the most common techniques to obtain such porous matrices are gel or foam forming, followed by freeze-drying or critical point drying, which are energy and time-consuming processes for solvent removal. In this work, we present a new methodology to produce cellulosic lightweight materials from eucalyptus pulp, using cellulose fibers partially hydrolyzed with sulfuric acid. This method is based on a drying step easily performed at mild temperatures around 60°C in a convection oven and eliminates the need of more sophisticated drying techniques. In addition, the procedure does not require the use of surfactants or special foam forming equipment. Micro-CT and FESEM analysis showed the formation of a porous and lightweight material (density as low as 0.15 g/cm³), where the fibers are randomly assembled in a 3D-network with a few contact points. Mechanical testing reveled that foams of hydrolyzed fibers have great performance under compressive strain, with high mechanical energy absorption (ca. 360 kJ/m³). This purely cellulosic material is suitable for the incorporation of particles or functional groups aiming a wide range of final applications.

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“…Lately, the technology has been intensely studied in the preparation of sheet structures (Radvan and Gatward 1972;Lehmonen et al 2013) and bulk materials (Madani et al 2014;Alimadadi and Uesaka 2016) made from wood fibers, especially for filtering (Heydarifard et al 2016) and insulating applications (Poranen et al 2013;Pöhler et al 2016). Forming and subsequent water removal and drying methods have a profound effect on the sheet structure (Timofeev et al 2016;Haffner et al 2017). Foam-formed fiber networks can have a much lower density (Madani et al 2014), improved and tailored pore size distribution (Al-Qararah et al 2015a), and more diverse fiber orientation (Alimadadi and Uesaka 2016) compared with similar water-formed materials.…”

Section: Introductionmentioning

confidence: 99%

Improving Compression Recovery of Foam-formed Fiber Materials

et al. 2018

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Foam technology enables the preparation of new fiber-based materials with reduced density and improved mechanical performances. By utilizing multi-scale structural features of the formed fiber network, it is possible to enhance the elasticity of lightweight cellulose materials under compressive loads. Sufficient strength is achieved by optimally combining fibers and fines of different length-scales. Elasticity is improved by adding polymers that accumulate at fiber joints, which help the network structure to recover after compression. This concept was demonstrated using natural rubber as the polymer additive. For a model network of viscose fibers and wood fines, the immediate elastic recovery after 70% compression varied from 60% to 80% from the initial thickness. This was followed by creep recovery, which reached 86% to 88% recovery within a few seconds in cross-linked samples. After 18 h, the creep recovery in those samples was almost complete at up to 97%. A similar improvement was seen for low-density materials formed with chemi-thermomechanical fibers. The formed structure and elastic properties were sensitive not only to the raw materials, but also to the elastomer stiffness and foam properties. The improved strain recovery makes the developed cellulose materials suitable for various applications, such as padding for furniture, panels, mattresses, and insulation materials.

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Drying of foam-formed mats from virgin pine fibers

Cited by 24 publications

References 18 publications

Properties of lightweight fibrous structures made by a novel foam forming technique

Properties of lightweight fibrous structures made by a novel foam forming technique

Simple Preparation of Cellulosic Lightweight Materials from Eucalyptus Pulp

Improving Compression Recovery of Foam-formed Fiber Materials

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