The thermochemical degradation of cork

Pereira, Helena

doi:10.1007/bf00200161

Cited by 56 publications

(39 citation statements)

References 14 publications

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“…This ratio (1/1.7) results from the higher S content of the MWL bamboo since S type phenols are set free easily. Additionally, the residual suberin in MCL, which is well known for its poor heat transfer and thermal stability (Pereira 1992), probably hampers the thermal volatilazation of MCL. Total hydrolysis of MCL could not be performed due to a lack of sufficient material.…”

Section: Analytical Pyrolysis and Analysis Of MCL And Lccmentioning

confidence: 99%

Quantitative Analysis of Cork (Quercus suber L.) and Milled Cork Lignin by FTIR Spectroscopy, Analytical Pyrolysis, and Total Hydrolysis

Marques¹,

Pereira²,

Meier³

et al. 1994

HFSG

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A "milled cork lignin" (MCL) and a lignin-carbohydrate complex (LCC) have been isolated from Quercus suber with respective yields of l .5 % and 0.32 %. Cork and the isolates were characterized by FTIR spectroscopy, elemental analysis, OMe determination, analytical pyroiysis (Py/GC/FID) and acid hydrolysis followed by determination of the monomeric sugars released. Cork contains a lignin-like material in 40% yield. MCL was enriched in this material up to 54%. The non-aromatic part contained suberinic acids and polysaccharides. Both FTIR spectroscopy and pyroiysis revealed the preponderance of guaiacyl-type aromatic rings. Pyroiysis released phenols of which 91 % were guaiacyl-type. The yield of phenol, o-cresol, dimethylphenol, p-hydroxy benzaidehyde was around 10% and that of syringyl-type phenols only l %. Acetic acid, äs one of the thermal degradation products of suberinic acids, was detected in high yields both in cork and in MCL. The ratio of hexosans/pentosans in cork was 1/0.76, in MCL 1/2.6, and in LCC 1/3.4. The problem related to the differentiation between lignin and the aromatic part of suberin is discussed.

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Section: Analytical Pyrolysis and Analysis Of MCL And Lccmentioning

confidence: 99%

Quantitative Analysis of Cork (Quercus suber L.) and Milled Cork Lignin by FTIR Spectroscopy, Analytical Pyrolysis, and Total Hydrolysis

Marques¹,

Pereira²,

Meier³

et al. 1994

HFSG

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“…The most important are: the grinding powder, from granulation or pre-grinding; the cleaning powder, without impurities; the finishing powder from cut and sanding operations or from cork disks and natural stoppers and finally the ''burning powder" that comes from the mixture of these powders [13]. The degradation of cork is strongly dependent on temperature and mass losses become significant at 200°C [14] and the colour start to change to dark brown and at 300°C to black [15]. At lower temperatures 75-85°C, only a phase transition was assigned to the melting of waxes present in cork obtained by DSC that was corroborated by dielectric spectroscopy [16,17].…”

Section: Introductionmentioning

confidence: 99%

Cork based composites using polyolefin’s as matrix: Morphology and mechanical performance

Fernandes¹,

Correlo²,

Chagas³

et al. 2010

Composites Science and Technology

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a b s t r a c tThe cork industry produces high amounts of cork powders resulting from the final stages of cork processing or resulting from existing cork products. Usually these powders are burned and served to boilers in industrial processes. The main goal of this work is to transform this cork sub-product into a highly value composite product. The real value is dependent on the mechanical performance of this product. Thus the mixture between cork and thermoplastics, particularly the improvement of interfacial bonding, is an important topic, which needs to be developed. The interfacial affinity can be greatly increased, applying superficial modification of one of the components, or by the use of coupling agents. In this work, a high amount of cork powder (50 wt.%) from different origins combined with different thermoplastic materials using melt based processes has been examined. Pultrusion was used to produce pellets and compression moulding to obtain boards to determine its properties. Coupling agents based on maleic anhydride (2 wt.%) improved the tensile strength successfully, while the cork powder has an a important role in the stiffness. The morphology of the surface fractures indicated a good dispersion of the cork and a good adhesion between both phases. Thermal properties of the composites disclosed a nucleating effect promoted by cork.

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“…It was also observed that the chemical degradation starts at about 250°C, in air, indicating that cork can be heated up to 250°C without inducing irreversible changes in its composition. Chemical methods [16,17] and scanning electron microscopy [16] were also applied and the results demonstrated that waxes and other soluble components of cork begin to decompose at ca. 150°C and that cork is transformed into ash for temperatures above 450°C.…”

Section: Introductionmentioning

confidence: 99%

Properties of new cork–polymer composites: Advantages and drawbacks as compared with commercially available fibreboard materials

Fernandes

Correlo

Chagas³

et al. 2011

Composite Structures

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Cork powder (50 wt.%) was mixed with polypropylene (PP) or polyethylene (PE) by pultrusion aiming to prepare cork-based composites. In a further step, samples were produced by compression moulding using the compounded composites. Bending strength, impact resistance, hardness, dimensional stability, thermal and acoustic properties of the developed cork-polymer composites (CPC) were determined and compared with commercially available products namely medium density fibreboard (MDF) and high density fibreboard (HDF). It was found that the CPC have good dimensional stability, lower water uptake, a better acoustic insulation performance and similar behaviour in terms of hardness and fire resistance when compared with both MDF and HDF. However, the mechanical strength is inferior comparing with both commercial materials based on fibres. It was also observed that addition of cork improved the flexural modulus, impact resistance and hardness on the developed CPC. Thus, the herein described CPC materials showed important characteristics to be considered as good candidates to be applied in the design of flooring and construction systems.

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The thermochemical degradation of cork

Cited by 56 publications

References 14 publications

Quantitative Analysis of Cork (Quercus suber L.) and Milled Cork Lignin by FTIR Spectroscopy, Analytical Pyrolysis, and Total Hydrolysis

Quantitative Analysis of Cork (Quercus suber L.) and Milled Cork Lignin by FTIR Spectroscopy, Analytical Pyrolysis, and Total Hydrolysis

Cork based composites using polyolefin’s as matrix: Morphology and mechanical performance

Properties of new cork–polymer composites: Advantages and drawbacks as compared with commercially available fibreboard materials

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