The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Jeffrey J. Morrell - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of corrugated cardboard biochar as reinforcing fiber on properties, biodegradability and weatherability of wood-plastic composites
Polymer Degradation and Stability, 2019Co-Authors: Xiaoqian Wang, Jeffrey J. Morrell, Farid Sotoudehniakarani, Zhiming Yu, Jed Cappellazzi, Armando G McdonaldAbstract:Abstract Corrugated cardboard (CCB) was pyrolyzed at different temperatures (350, 400 and 450 °C) to produce biochar fibers. The biochar and CCB control fibers were then compounded with high density polyethylene (HDPE) and maleated polyethylene (MAPE) to prepare wood plastic composites (WPC). The effect of different pyrolysis temperature biochars on the WPC's mechanical, thermal and viscoelastic properties, water absorptions, rheological behavior, weatherability and Biodurability performance were evaluated. The CCB composite melts showed higher modulus and viscosity than biochar composites, indicating better melt strength. Compared with CCB composites, an increase of tensile strength (4%) and tensile modulus (30%) could be observed in composites made from CCB 350 °C biochar. In addition, the CCB biochar composite showed lower tan δ and adhesion factor, indicating the strong interfacial interaction between biochar fibers and HDPE. The composite melting temperatures (Tm) were not significantly different. The degree of HDPE crystallinity in the biochar composites decreased relative to the CCB composites, while the thermal properties of the composites improved compared with CCB composites. The CCB composite displayed the highest water absorption (3.9%) and thickness swell (3.8%) after 70 d. The CCB biochar (450 °C) composite experienced the least color change, lightless and carbonyl concentrations due to weathering. Pyrolysis of CCB reduced weight loss in the resulting composites exposed to fungi compared with the CCB composite. Using CCB biochar led to a more biodurable WPC.
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effects of wood fiber esterification on properties weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Armando G Mcdonald, Camille Freitag, Jeffrey J. MorrellAbstract:Abstract Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC.
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Effects of wood fiber esterification on properties, weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Liqing Wei, Camille Freitag, Armando G Mcdonald, Jeffrey J. MorrellAbstract:Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC. © 2013 Elsevier Ltd. All rights reserved.
Bernd Bellmann - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the durability of cellulose fibres in rat lungs
Annals of Occupational Hygiene, 2006Co-Authors: Hartwig Muhle, Heinrich Ernst, Bernd BellmannAbstract:Inhalable cellulose fibres can be released in production processes in the paper industry or during spraying of specially prepared chips of recycled newspapers which are used for thermal insulation of walls in houses. In the latter process, fibre concentrations may amount up to 50 x 10 fibres m~ in building sites (Tiesler and Schnittger, 1992). For the definition of a "critical" fibre the same criteria as for inorganic fibres were used (fibre length > 5 um, fibre diameter 3:1). Milton et al. (1990) instilled cellulose dust intratracheally in hamsters by a single dose of 0.75 mg/100 g body weight. Hamsters were killed after 8 weeks. Lungs of animals showed a significant number of granulomata and thickened interalveolar septae. In a 28-day inhalation study with cellulose in rats, Davis (1993) reported the appearance of alveolitis and granulomata. The test material originated from thermal insulation products. It is an open question, whether cellulose fibres can accumulate in lungs or whether these fibres will show a degradation under physiological conditions. The goal of this investigation was to analyse quantitatively the Biodurability of cellulose fibres in lungs of rats.
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significance of the Biodurability of man made vitreous fibers to risk assessment
Environmental Health Perspectives, 1997Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:It is generally agreed that the Biodurability of man-made vitreous fibers is a major factor for the characterization of potential health effects. As there is currently no standardization of experim...
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Significance of the Biodurability of man-made vitreous fibers to risk assessment.
Environmental health perspectives, 1997Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:It is generally agreed that the Biodurability of man-made vitreous fibers is a major factor for the characterization of potential health effects. As there is currently no standardization of experimental protocols to determine biodurabilty, the results of the clearance assays have not been used up to now for regulatory purposes. Methods used to analyze Biodurability in animal models are short-term inhalational exposure and intratracheal instillation of rat respirable fibers. Both test methods have strengths and limitations for regulatory purposes. We outline recommended procedures for standardized Biodurability assays that can be used to compare different fiber types. In animal experiments, Biodurability is difficult to separate from biopersistence, as mucociliary and macrophage-mediated clearance occur simultaneously with dissolution and disintegration. For intratracheal instillation, a sized rat respirable sample must be used. Precautions should be taken to prevent aggregation of fibers in the lungs. Although from a scientific point of view questions remain about quantifying the influence of fiber length, diameter, dose, and exposure route, consistent data on the Biodurability of vitreous glass fibers are available which may be used for regulatory purposes.
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Biopersistence of man-made vitreous fibres
Annals of Occupational Hygiene, 1995Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:Abstract Methods for the determination of Biodurability of man-made vitreous fibres are reviewed. For mineral wools the first step was the preparation of respirable fibre fractions. Fibres were administered to rats by inhalation or by intratracheal instillation. After serial sacrifice their lungs were digested by low-temperature ashing or by hypochlorite. The total number of fibres per lung and the distributions of length and diameter were analysed by electron microscopy. This resulted in a bivariate distribution of fibres at the various sacrifice dates. If the logarithm of the number of fibres decreased approximately linearly with time after exposure then the elimination kinetics of fibres can be characterized by a half-time. The half-times were compared between various experiments with rats exposed to mineral wool samples. In summary good agreement was found for the elimination of fibres after long-term inhalation and intratraeheal instillation whereas shorter half-times were found after short-term inhalation.
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investigation on the Biodurability of chemically different stone wool fibres
Experimental and Toxicologic Pathology, 1995Co-Authors: Bernd Bellmann, Hartwig Muhle, O Kamstrup, U F DraegerAbstract:Abstract The Biodurability is one of the essential factors for a carcinogenic potential of mineral fibres. The in vivo solubility of commercial fibre products can be influenced by modifications of the chemical composition. Two types of experimental stone wool samples with new chemical composition were compared to a commercial stone wool sample. Sized fractions of these samples with median lengths of 7.1, 9.3 and 6.7 μm, respectively, and median diameters of 0.76, 1.02 and 0.63 μm, respectively, were intratracheally instilled into female Wistar rats with a single dose of 2 mg in 0.3 ml. 5 animals per group were sacrificed after 2 days, 1, 3, 6, 12 and 18 months. After low-temperature ashing of the lungs about 1000 fibres per group and sacrifice date were analysed in SEM for length and diameter. The number of fibres in the total lung was calculated. An analysis of fibre number of different length and diameter fractions was used to estimate whether dissolution, breakage or mechanical clearance is responsible for the elimination of fibres from the lung. Results indicate that the breakage of fibres with length above 20 μm and the dissolution of fibres was faster in the experimental stone wool samples compared to the commercial sample.
Hartwig Muhle - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the durability of cellulose fibres in rat lungs
Annals of Occupational Hygiene, 2006Co-Authors: Hartwig Muhle, Heinrich Ernst, Bernd BellmannAbstract:Inhalable cellulose fibres can be released in production processes in the paper industry or during spraying of specially prepared chips of recycled newspapers which are used for thermal insulation of walls in houses. In the latter process, fibre concentrations may amount up to 50 x 10 fibres m~ in building sites (Tiesler and Schnittger, 1992). For the definition of a "critical" fibre the same criteria as for inorganic fibres were used (fibre length > 5 um, fibre diameter 3:1). Milton et al. (1990) instilled cellulose dust intratracheally in hamsters by a single dose of 0.75 mg/100 g body weight. Hamsters were killed after 8 weeks. Lungs of animals showed a significant number of granulomata and thickened interalveolar septae. In a 28-day inhalation study with cellulose in rats, Davis (1993) reported the appearance of alveolitis and granulomata. The test material originated from thermal insulation products. It is an open question, whether cellulose fibres can accumulate in lungs or whether these fibres will show a degradation under physiological conditions. The goal of this investigation was to analyse quantitatively the Biodurability of cellulose fibres in lungs of rats.
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significance of the Biodurability of man made vitreous fibers to risk assessment
Environmental Health Perspectives, 1997Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:It is generally agreed that the Biodurability of man-made vitreous fibers is a major factor for the characterization of potential health effects. As there is currently no standardization of experim...
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Significance of the Biodurability of man-made vitreous fibers to risk assessment.
Environmental health perspectives, 1997Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:It is generally agreed that the Biodurability of man-made vitreous fibers is a major factor for the characterization of potential health effects. As there is currently no standardization of experimental protocols to determine biodurabilty, the results of the clearance assays have not been used up to now for regulatory purposes. Methods used to analyze Biodurability in animal models are short-term inhalational exposure and intratracheal instillation of rat respirable fibers. Both test methods have strengths and limitations for regulatory purposes. We outline recommended procedures for standardized Biodurability assays that can be used to compare different fiber types. In animal experiments, Biodurability is difficult to separate from biopersistence, as mucociliary and macrophage-mediated clearance occur simultaneously with dissolution and disintegration. For intratracheal instillation, a sized rat respirable sample must be used. Precautions should be taken to prevent aggregation of fibers in the lungs. Although from a scientific point of view questions remain about quantifying the influence of fiber length, diameter, dose, and exposure route, consistent data on the Biodurability of vitreous glass fibers are available which may be used for regulatory purposes.
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Biopersistence of man-made vitreous fibres
Annals of Occupational Hygiene, 1995Co-Authors: Hartwig Muhle, Bernd BellmannAbstract:Abstract Methods for the determination of Biodurability of man-made vitreous fibres are reviewed. For mineral wools the first step was the preparation of respirable fibre fractions. Fibres were administered to rats by inhalation or by intratracheal instillation. After serial sacrifice their lungs were digested by low-temperature ashing or by hypochlorite. The total number of fibres per lung and the distributions of length and diameter were analysed by electron microscopy. This resulted in a bivariate distribution of fibres at the various sacrifice dates. If the logarithm of the number of fibres decreased approximately linearly with time after exposure then the elimination kinetics of fibres can be characterized by a half-time. The half-times were compared between various experiments with rats exposed to mineral wool samples. In summary good agreement was found for the elimination of fibres after long-term inhalation and intratraeheal instillation whereas shorter half-times were found after short-term inhalation.
-
investigation on the Biodurability of chemically different stone wool fibres
Experimental and Toxicologic Pathology, 1995Co-Authors: Bernd Bellmann, Hartwig Muhle, O Kamstrup, U F DraegerAbstract:Abstract The Biodurability is one of the essential factors for a carcinogenic potential of mineral fibres. The in vivo solubility of commercial fibre products can be influenced by modifications of the chemical composition. Two types of experimental stone wool samples with new chemical composition were compared to a commercial stone wool sample. Sized fractions of these samples with median lengths of 7.1, 9.3 and 6.7 μm, respectively, and median diameters of 0.76, 1.02 and 0.63 μm, respectively, were intratracheally instilled into female Wistar rats with a single dose of 2 mg in 0.3 ml. 5 animals per group were sacrificed after 2 days, 1, 3, 6, 12 and 18 months. After low-temperature ashing of the lungs about 1000 fibres per group and sacrifice date were analysed in SEM for length and diameter. The number of fibres in the total lung was calculated. An analysis of fibre number of different length and diameter fractions was used to estimate whether dissolution, breakage or mechanical clearance is responsible for the elimination of fibres from the lung. Results indicate that the breakage of fibres with length above 20 μm and the dissolution of fibres was faster in the experimental stone wool samples compared to the commercial sample.
Armando G Mcdonald - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of corrugated cardboard biochar as reinforcing fiber on properties, biodegradability and weatherability of wood-plastic composites
Polymer Degradation and Stability, 2019Co-Authors: Xiaoqian Wang, Jeffrey J. Morrell, Farid Sotoudehniakarani, Zhiming Yu, Jed Cappellazzi, Armando G McdonaldAbstract:Abstract Corrugated cardboard (CCB) was pyrolyzed at different temperatures (350, 400 and 450 °C) to produce biochar fibers. The biochar and CCB control fibers were then compounded with high density polyethylene (HDPE) and maleated polyethylene (MAPE) to prepare wood plastic composites (WPC). The effect of different pyrolysis temperature biochars on the WPC's mechanical, thermal and viscoelastic properties, water absorptions, rheological behavior, weatherability and Biodurability performance were evaluated. The CCB composite melts showed higher modulus and viscosity than biochar composites, indicating better melt strength. Compared with CCB composites, an increase of tensile strength (4%) and tensile modulus (30%) could be observed in composites made from CCB 350 °C biochar. In addition, the CCB biochar composite showed lower tan δ and adhesion factor, indicating the strong interfacial interaction between biochar fibers and HDPE. The composite melting temperatures (Tm) were not significantly different. The degree of HDPE crystallinity in the biochar composites decreased relative to the CCB composites, while the thermal properties of the composites improved compared with CCB composites. The CCB composite displayed the highest water absorption (3.9%) and thickness swell (3.8%) after 70 d. The CCB biochar (450 °C) composite experienced the least color change, lightless and carbonyl concentrations due to weathering. Pyrolysis of CCB reduced weight loss in the resulting composites exposed to fungi compared with the CCB composite. Using CCB biochar led to a more biodurable WPC.
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effects of wood fiber esterification on properties weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Armando G Mcdonald, Camille Freitag, Jeffrey J. MorrellAbstract:Abstract Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC.
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Effects of wood fiber esterification on properties, weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Liqing Wei, Camille Freitag, Armando G Mcdonald, Jeffrey J. MorrellAbstract:Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC. © 2013 Elsevier Ltd. All rights reserved.
Camille Freitag - One of the best experts on this subject based on the ideXlab platform.
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effects of wood fiber esterification on properties weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Armando G Mcdonald, Camille Freitag, Jeffrey J. MorrellAbstract:Abstract Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC.
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Effects of wood fiber esterification on properties, weatherability and Biodurability of wood plastic composites
Polymer Degradation and Stability, 2013Co-Authors: Liqing Wei, Camille Freitag, Armando G Mcdonald, Jeffrey J. MorrellAbstract:Poplar wood fibers were chemically modified by esterification (acetate, propionate, benzoate) and then compounded with high density polyethylene (HDPE) into wood plastic composites (WPC). The esterified fibers were characterized (spectroscopy, TGA and contact angle) and shown to be more thermally stable and hydrophobic than unmodified fibers. The WPC were characterized for their mechanical and rheological properties, adhesion factor, water resistance, accelerated weathering and Biodurability performance. Color change, surface morphology and extent of oxidation on the surface of weathered WPC were monitored using colorimetry, microscopy and FTIR spectroscopy, respectively. Benzoylated fiber based WPC experienced the least surface crazing and color change due to weathering. Esterification of fibers significantly reduced weight losses in the resulting WPC when it was exposed to brown-rot and white-rot fungi as compared to unmodified fiber WPC. Esterification of wood fibers resulted in more biodurable and photostable WPC. © 2013 Elsevier Ltd. All rights reserved.
