The disintegration of recovered paper is the first operation in the preparation of recycled pulp.... more The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%ISV) and from the dissipated energy per volume unit (SS). The %ISV is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 rev/s rotor speed and for different fiber consistency (6, 8, 10, 12, and 14%). The results showed that the values of experimental disintegration kinetic constant, KD, through the analysis of Somerville index, as function of time, increased with the disintegration consistency. Therefore, as consiste...
This study show the results of a self-assessment’s competences in engineering students from two S... more This study show the results of a self-assessment’s competences in engineering students from two Spanish universities, the Polytechnic University of Catalonia (UPC) and the University of Girona (UdG), carried out last year. The objective is to contribute to the discussion by reporting the results of the students' self-assessments. For our research group, it is important to understand the use of self-assessment not to evaluate competence otherwise announcement that describe the behavior of everyday and understandable work activities. It is an efficient method for personal development, to clarify roles and to compromise the objectives of a project. We focus on transversal competence, understanding these as those that explain the difference between a professional and an excellent professional when both have the same training. To carry out this study we have used the Cycloid tool as a part of an ICT platform called Evolute, working with 30 transversal competences that have an important relationship in UPC and UdG. This application evaluates competences trying to make students as if they were project managers. In this case, their project is to pass and finish their Degree. The methodology of this tool starts making 120 questions or affirmations that are linguistically evaluated trying to answer the current level and at the target level. The differences between the two levels indicate the need to develop their skills. The competences are divided in the main group as a personal and social competences. This partition can be divided in other level as a six different groups: self-knowledge, self-management or self-control, cognitive skills, self-motivation, social awareness or empathy and social skills. This study compared the differences between the students of this two universities based on current state, goal state, and creative tension, showing the gap between a student's feeling of the current reality and the goal that they wanted for the future. The analysis of the test results demonstrated the possibility of using this application to evaluate and self-evaluate. The comparison identified commonalities and some significant differences between the two university groupsPostprint (published version
ABSTRACT This work has the aim of study the flexural properties of alpha-grass reinforced starch-... more ABSTRACT This work has the aim of study the flexural properties of alpha-grass reinforced starch-based composites. The composite materials contain alpha-fibers in the range from 5 to 35 wt%. The reinforcing fibers were submitted to an alkali treatment to create a good interphase between the fibers and the matrix. It was observed that a mild 2.5 hours cooking process was enough to create a good interphase, while longer periods rendered lesser improvements. The surface charges of the fibers and the matrix were determined by polyelectrolyte titration, and it was found that after the alkaline treatment both were similar. The composite materials were injection molded and tested under flexural conditions. All the flexural properties of the studies composites increased linearly with the reinforcement contents. The micromechanics of the flexural modulus and strength were studied and compared with that of tensile modulus and strength. It was established that the efficiency factors for the tensile and flexural properties were statistically similar. Three different methods were used to compute the intrinsic flexural strength from the available data. Finally the Weibull theory was used to study the best prediction of the standard deviation of the intrinsic flexural modulus.
Per la importància de l'àrea de les competències en l'educació superior europea i amb l'objectiu ... more Per la importància de l'àrea de les competències en l'educació superior europea i amb l'objectiu d'adaptar-les a la Declaració de Bologna, el nostre grup de treball va decidir fa dos anys testar i avaluar-les, realitzant un estudi a estudiants amb l'objectiu de conèixer més a fons la situació actual d'aquestes competències. Aquest anàlisi és necessari per aconseguir dissenyar una base de competències universitària el més correcte possible.
The objective of this article is double: firstly is to show the standards ISO 9001 and ISO 14001 ... more The objective of this article is double: firstly is to show the standards ISO 9001 and ISO 14001 evolution and secondly evolution and situation in the pulp and paper sector during the last years. We would like to investigate why this decrease and what are the tendencies for the future. The methodology used to elaborate this publication is to study the different ISO's graphs evolution and project them to the future using mathematic logical models to see their tendencies. In other hand, we make a qualitative questionnaire to six pulp and paper companies, trying to obtain common results and to observe the tendency.
Este artículo refleja el análisis de competencias personales y sociales a partir del estudio de l... more Este artículo refleja el análisis de competencias personales y sociales a partir del estudio de la tensión creativa en estudiantes de ingeniería, utilizando una aplicación informática denominada Cycloid. El objetivo se centra en comparar la tensión creativa de los estudiantes, actuando éstos como jefes de proyecto, siendo su carrera universitaria el proyecto a coordinar. El proceso consiste en evaluar, mediante encuestas, a un grupo de estudiantes para conocer la situación actual de las competencias utilizando lógica difusa. A partir del auto-conocimiento que brinda la herramienta, los alumnos pueden conocer sus puntos fuertes y débiles y gestionar mejor sus estudios. Los resultados obtenidos demuestran que la tolerancia al estrés y los idiomas son los puntos más débiles. Esta aplicación es útil en el diseño propio de su forma de trabajo que haga el estudiante y así desarrollar estrategias para afrontar con éxito sus estudios.
Packaging consumes around 40% of the total plastic production. One of the most important fields w... more Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclay...
Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The int... more Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The interest in using wastes as fillers or reinforcements for composites has raised recently due to environmental concerns. This study investigates the potential use of BF waste as filler for a high density polyethylene matrix (HDPE). A series of HDPE-BF composites, containing filler concentrations ranging from 20 to 50wt%, were formulated, injection molded and tested. The effect of filler contents on the mechanical properties of the composites were evaluated and discussed. Composites with BF contents up to 30wt% improved the tensile strength and Young’s modulus of the matrix, achieving similar mechanical properties to polypropylene (PP). In the case of flexural strength, it was found to be proportionally enhanced by increasing reinforcement content, maintaining high impact strength. These composites present great opportunities for PP application areas that require higher impact resistance. The...
The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvin... more The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling fa...
In the recent years, there has been a growing interest in eco-friendly composites, based on natur... more In the recent years, there has been a growing interest in eco-friendly composites, based on natural fiber reinforcements. In this work, Alfa fibers were obtained from Alfa grass (Stipa tenacissima) through an intensive cooking with sodium hydroxide and anthraquinone. These fibers, with contents ranging from 20 to 50 wt%, were used to reinforce a high density polyethylene. The composites were prepared in a kinetic mixer and later on tensile tested under standard conditions. The results showed that the tensile strength of the composites increased with the amount of fiber in the composite. Aditionally, a morphology and chemical composition analysis of the fibers surface were carried on, in order to further discuss the micromechanics analysis results. The average orientation factor and intrinsic tensile strength of the fibers were also determined during the micromechanics analysis.
Newspapers have a limited lifespan, and therefore represent a focus of used and disposed paper. W... more Newspapers have a limited lifespan, and therefore represent a focus of used and disposed paper. While these refuses have a considerable value and can be easily recycled, a considerable fraction ends in landfill. The authors show the possibility of adding value to used newspaper and enlarge its value chain. Old newspaper incorporates a high amount of wood fibers able to be used as reinforcement. On the other hand, this material also incorporates inks and other components inherent to newspaper production. In this work, the authors disintegrate old newspaper to recover and individualize wood fibers. A morphological analysis showed that the recovered fibers had aspect ratios higher than 10, revealing, a priori, their strengthening capabilities. Thereupon, these fibers were compounded with polypropylene at different contents, ranging from 20% to 50% w/w. It is well known that wood fibers are hydrophilic, while polyolefin are hydrophobic. This is a drawback to obtaining strong interfaces....
Most of the decisions taken during the early design and development steps of a new product compro... more Most of the decisions taken during the early design and development steps of a new product compromise a large part of its cost, including its environmental footprint and energy consumption. This is of special interest for the automotive industry that has made an effort to increase its sustainability. Adjectives like bio-based, recyclable or biodegradable are commonly used as synonyms of greener; nonetheless, such materials must achieve the requirements of the industry. This paper researches the use of alternative materials instead of glass fiber reinforced polypropylene, a commodity material. The authors propose using a wood fiber reinforced polyamide 11 composite as replacement. The research discussed the mechanical properties of such 2 composites, obtaining values similar to the currently used materials. Moreover, a case study was performed to assess the behavior of the composites when used to manufacture a door car handle. The materials with reinforcement contents ranging from 40 to 60% showed its ability to replace the commodity materials. Furthermore, a preliminary LCA analysis was performed to evaluate the environmental footprint of the researched materials. In was found, that, in terms of energy and carbon footprint, the PA11 composites were penalized by the energy cost of the PA11 monomer production.
The present work shows the suitability of using recovered cardboard boxes for the development of ... more The present work shows the suitability of using recovered cardboard boxes for the development of high-performance papers through the use of cellulose nanofibers (CNF) and sodium carboxymethyl cellulose (CMC-Na). CNF were prepared by enzymatic hydrolysis using bleached kraft hardwood pulp, while a commercial grade of CMC-Na was used. Both were added in bulk together with polyethylenimine (PEI) as wet-end additive to improve pulp drainability. The combination of 3 wt% CNF and 7.5 wt% CMC-Na double the breaking length of paper. In addition, the use of 0.4 wt% of PEI significantly decreased the Schopper - Riegler degree, while mechanical properties remained almost at the same level. It was found that it is possible to recover and even increase the properties of recycled papers, with the added advantage that no structural damages were caused on the fibres, increasing the life span and recyclability of paper products.
Journal of Industrial and Engineering Chemistry, 2017
The aim of this work is to develop high-performance papers from recovered cardboard boxes. To tac... more The aim of this work is to develop high-performance papers from recovered cardboard boxes. To tackle this objective, cardboard boxes were enzymatically refined and subsequently reinforced with CNF. Results revealed that although cardboard boxes are usually used for test-liner paper production, they could be used for high-performance applications. In this sense, stronger papers than common test-liner were produced through the use of harmless techniques for fibers. In terms of circular economy, the proposed combined approach goes further than closing the loop: new markets can be achieved or lighter papers could be used, leading to significant resources savings.
The disintegration of recovered paper is the first operation in the preparation of recycled pulp.... more The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%ISV) and from the dissipated energy per volume unit (SS). The %ISV is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 rev/s rotor speed and for different fiber consistency (6, 8, 10, 12, and 14%). The results showed that the values of experimental disintegration kinetic constant, KD, through the analysis of Somerville index, as function of time, increased with the disintegration consistency. Therefore, as consiste...
This study show the results of a self-assessment’s competences in engineering students from two S... more This study show the results of a self-assessment’s competences in engineering students from two Spanish universities, the Polytechnic University of Catalonia (UPC) and the University of Girona (UdG), carried out last year. The objective is to contribute to the discussion by reporting the results of the students' self-assessments. For our research group, it is important to understand the use of self-assessment not to evaluate competence otherwise announcement that describe the behavior of everyday and understandable work activities. It is an efficient method for personal development, to clarify roles and to compromise the objectives of a project. We focus on transversal competence, understanding these as those that explain the difference between a professional and an excellent professional when both have the same training. To carry out this study we have used the Cycloid tool as a part of an ICT platform called Evolute, working with 30 transversal competences that have an important relationship in UPC and UdG. This application evaluates competences trying to make students as if they were project managers. In this case, their project is to pass and finish their Degree. The methodology of this tool starts making 120 questions or affirmations that are linguistically evaluated trying to answer the current level and at the target level. The differences between the two levels indicate the need to develop their skills. The competences are divided in the main group as a personal and social competences. This partition can be divided in other level as a six different groups: self-knowledge, self-management or self-control, cognitive skills, self-motivation, social awareness or empathy and social skills. This study compared the differences between the students of this two universities based on current state, goal state, and creative tension, showing the gap between a student's feeling of the current reality and the goal that they wanted for the future. The analysis of the test results demonstrated the possibility of using this application to evaluate and self-evaluate. The comparison identified commonalities and some significant differences between the two university groupsPostprint (published version
ABSTRACT This work has the aim of study the flexural properties of alpha-grass reinforced starch-... more ABSTRACT This work has the aim of study the flexural properties of alpha-grass reinforced starch-based composites. The composite materials contain alpha-fibers in the range from 5 to 35 wt%. The reinforcing fibers were submitted to an alkali treatment to create a good interphase between the fibers and the matrix. It was observed that a mild 2.5 hours cooking process was enough to create a good interphase, while longer periods rendered lesser improvements. The surface charges of the fibers and the matrix were determined by polyelectrolyte titration, and it was found that after the alkaline treatment both were similar. The composite materials were injection molded and tested under flexural conditions. All the flexural properties of the studies composites increased linearly with the reinforcement contents. The micromechanics of the flexural modulus and strength were studied and compared with that of tensile modulus and strength. It was established that the efficiency factors for the tensile and flexural properties were statistically similar. Three different methods were used to compute the intrinsic flexural strength from the available data. Finally the Weibull theory was used to study the best prediction of the standard deviation of the intrinsic flexural modulus.
Per la importància de l'àrea de les competències en l'educació superior europea i amb l'objectiu ... more Per la importància de l'àrea de les competències en l'educació superior europea i amb l'objectiu d'adaptar-les a la Declaració de Bologna, el nostre grup de treball va decidir fa dos anys testar i avaluar-les, realitzant un estudi a estudiants amb l'objectiu de conèixer més a fons la situació actual d'aquestes competències. Aquest anàlisi és necessari per aconseguir dissenyar una base de competències universitària el més correcte possible.
The objective of this article is double: firstly is to show the standards ISO 9001 and ISO 14001 ... more The objective of this article is double: firstly is to show the standards ISO 9001 and ISO 14001 evolution and secondly evolution and situation in the pulp and paper sector during the last years. We would like to investigate why this decrease and what are the tendencies for the future. The methodology used to elaborate this publication is to study the different ISO's graphs evolution and project them to the future using mathematic logical models to see their tendencies. In other hand, we make a qualitative questionnaire to six pulp and paper companies, trying to obtain common results and to observe the tendency.
Este artículo refleja el análisis de competencias personales y sociales a partir del estudio de l... more Este artículo refleja el análisis de competencias personales y sociales a partir del estudio de la tensión creativa en estudiantes de ingeniería, utilizando una aplicación informática denominada Cycloid. El objetivo se centra en comparar la tensión creativa de los estudiantes, actuando éstos como jefes de proyecto, siendo su carrera universitaria el proyecto a coordinar. El proceso consiste en evaluar, mediante encuestas, a un grupo de estudiantes para conocer la situación actual de las competencias utilizando lógica difusa. A partir del auto-conocimiento que brinda la herramienta, los alumnos pueden conocer sus puntos fuertes y débiles y gestionar mejor sus estudios. Los resultados obtenidos demuestran que la tolerancia al estrés y los idiomas son los puntos más débiles. Esta aplicación es útil en el diseño propio de su forma de trabajo que haga el estudiante y así desarrollar estrategias para afrontar con éxito sus estudios.
Packaging consumes around 40% of the total plastic production. One of the most important fields w... more Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclay...
Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The int... more Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The interest in using wastes as fillers or reinforcements for composites has raised recently due to environmental concerns. This study investigates the potential use of BF waste as filler for a high density polyethylene matrix (HDPE). A series of HDPE-BF composites, containing filler concentrations ranging from 20 to 50wt%, were formulated, injection molded and tested. The effect of filler contents on the mechanical properties of the composites were evaluated and discussed. Composites with BF contents up to 30wt% improved the tensile strength and Young’s modulus of the matrix, achieving similar mechanical properties to polypropylene (PP). In the case of flexural strength, it was found to be proportionally enhanced by increasing reinforcement content, maintaining high impact strength. These composites present great opportunities for PP application areas that require higher impact resistance. The...
The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvin... more The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling fa...
In the recent years, there has been a growing interest in eco-friendly composites, based on natur... more In the recent years, there has been a growing interest in eco-friendly composites, based on natural fiber reinforcements. In this work, Alfa fibers were obtained from Alfa grass (Stipa tenacissima) through an intensive cooking with sodium hydroxide and anthraquinone. These fibers, with contents ranging from 20 to 50 wt%, were used to reinforce a high density polyethylene. The composites were prepared in a kinetic mixer and later on tensile tested under standard conditions. The results showed that the tensile strength of the composites increased with the amount of fiber in the composite. Aditionally, a morphology and chemical composition analysis of the fibers surface were carried on, in order to further discuss the micromechanics analysis results. The average orientation factor and intrinsic tensile strength of the fibers were also determined during the micromechanics analysis.
Newspapers have a limited lifespan, and therefore represent a focus of used and disposed paper. W... more Newspapers have a limited lifespan, and therefore represent a focus of used and disposed paper. While these refuses have a considerable value and can be easily recycled, a considerable fraction ends in landfill. The authors show the possibility of adding value to used newspaper and enlarge its value chain. Old newspaper incorporates a high amount of wood fibers able to be used as reinforcement. On the other hand, this material also incorporates inks and other components inherent to newspaper production. In this work, the authors disintegrate old newspaper to recover and individualize wood fibers. A morphological analysis showed that the recovered fibers had aspect ratios higher than 10, revealing, a priori, their strengthening capabilities. Thereupon, these fibers were compounded with polypropylene at different contents, ranging from 20% to 50% w/w. It is well known that wood fibers are hydrophilic, while polyolefin are hydrophobic. This is a drawback to obtaining strong interfaces....
Most of the decisions taken during the early design and development steps of a new product compro... more Most of the decisions taken during the early design and development steps of a new product compromise a large part of its cost, including its environmental footprint and energy consumption. This is of special interest for the automotive industry that has made an effort to increase its sustainability. Adjectives like bio-based, recyclable or biodegradable are commonly used as synonyms of greener; nonetheless, such materials must achieve the requirements of the industry. This paper researches the use of alternative materials instead of glass fiber reinforced polypropylene, a commodity material. The authors propose using a wood fiber reinforced polyamide 11 composite as replacement. The research discussed the mechanical properties of such 2 composites, obtaining values similar to the currently used materials. Moreover, a case study was performed to assess the behavior of the composites when used to manufacture a door car handle. The materials with reinforcement contents ranging from 40 to 60% showed its ability to replace the commodity materials. Furthermore, a preliminary LCA analysis was performed to evaluate the environmental footprint of the researched materials. In was found, that, in terms of energy and carbon footprint, the PA11 composites were penalized by the energy cost of the PA11 monomer production.
The present work shows the suitability of using recovered cardboard boxes for the development of ... more The present work shows the suitability of using recovered cardboard boxes for the development of high-performance papers through the use of cellulose nanofibers (CNF) and sodium carboxymethyl cellulose (CMC-Na). CNF were prepared by enzymatic hydrolysis using bleached kraft hardwood pulp, while a commercial grade of CMC-Na was used. Both were added in bulk together with polyethylenimine (PEI) as wet-end additive to improve pulp drainability. The combination of 3 wt% CNF and 7.5 wt% CMC-Na double the breaking length of paper. In addition, the use of 0.4 wt% of PEI significantly decreased the Schopper - Riegler degree, while mechanical properties remained almost at the same level. It was found that it is possible to recover and even increase the properties of recycled papers, with the added advantage that no structural damages were caused on the fibres, increasing the life span and recyclability of paper products.
Journal of Industrial and Engineering Chemistry, 2017
The aim of this work is to develop high-performance papers from recovered cardboard boxes. To tac... more The aim of this work is to develop high-performance papers from recovered cardboard boxes. To tackle this objective, cardboard boxes were enzymatically refined and subsequently reinforced with CNF. Results revealed that although cardboard boxes are usually used for test-liner paper production, they could be used for high-performance applications. In this sense, stronger papers than common test-liner were produced through the use of harmless techniques for fibers. In terms of circular economy, the proposed combined approach goes further than closing the loop: new markets can be achieved or lighter papers could be used, leading to significant resources savings.
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