Blar i NTNU Open på forfatter "Gregersen, Øyvind Weiby"
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Cellulose nanocrystal/PVA nanocomposite membranes for CO2/CH4 separation at high pressure
Jahan, Zaib; Niazi, Muhammad Bilal Khan; Hagg, May-Britt; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2018)Biogas can be used as an alternative energy source in place of conventional fossil fuels. However, for this to happen, it is necessary to optimize biogas production as well as improve the biogas quality. Crystalline ... -
Cellulose Nanofibrils as Paper Additive and Coating Material: Properties, Distribution and Interaction Effects
Ottesen, Vegar (Doctoral theses at NTNU;2018:115, Doctoral thesis, 2018)Cellulose is well-known as the most common bio-polymer on earth. In the cell wall of most plants, it is organized in nanoscopic structures with interesting properties for a wide range of applications, among them as an ... -
Coatability of cellulose nanofibril suspensions: Role of rheology and water retention
Kumar, Vinay; Ottesen, Vegar; Syverud, Kristin; Gregersen, Øyvind Weiby; Toivakka, Martti (Journal article; Peer reviewed, 2017)Cellulose nanofibril (CNF) suspensions are not easily coatable because of their excessively high viscosity and yield stress, even at low solids concentrations. In addition, CNF suspensions vary widely in their properties ... -
Decoupling the effect of membrane thickness and CNC concentration in PVA based nanocomposite membranes for CO2/CH4 separation
Jahan, Zaib; Niazi, Muhammad Bilal Khan; Hagg, May-Britt; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2018)The effect of the viscosity of the casting suspension on membrane morphology and thickness has been investigated for polyvinyl alcohol (PVA)/crystalline nanocellulose (CNC) nanocomposite membranes used for CO2/CH4 separation. ... -
Development of novel nanocomposite membranes and facilitated transport membranes for CO2 capture
Helberg, Ragne Marie Lilleby (Doctoral theses at NTNU;2019:381, Doctoral thesis, 2019)The implementation of Carbon Capture and Storage (CCS) is a critical action to reduce the CO2 emissions from power production and industrial sources and thereby reach the 2 °C target of the Paris Agreement. There are several ... -
Development of Structural Characterization Methods for Polyvinyl Alcohol (PVA)/Nanocellulose Composite Membranes
Riis, Henrik (Master thesis, 2016)Structural characterization of polyvinyl alcohol (PVA)/nanocellulose films by scanning electron microscopy (SEM) generally only provides an qualitative estimate of how well the nanocellulose is distributed, and is not ... -
FIB/SEM Characterization of Paper Materials
Roede, Erik Dobloug (Master thesis, 2016)3D microscopy is of interest for structural characterization of paper materials to study the use of cellulose nanofibrils as a paper additive. Focused ion beam (FIB) tomography is a promising microscopy technique for this ... -
Fundamental properties of nanocelluloses, and teir application in membranes for CO2 Separation
Torstensen, Jonathan Økland (Doctoral theses at NTNU;2019:146, Doctoral thesis, 2019) -
Mechanical and Thermal Properties of Carboxymethyl fibers (CMF)/PVA based nanocomposite membranes
Niazi, Muhammad Bilal Khan; Jahan, Zaib; Arooj, Ahmed; Uzair, Bushra; Mukhtar, Ahmad; Gregersen, Øyvind Weiby (Peer reviewed; Journal article, 2020)Carboxymethyl fibers (CMF) of cellulose are renewable biopolymer and have shown strong reinforcing properties when added to a compatible polymer matrix. The objective of this study was to investigate the effect of CMF on ... -
Mechanical properties of cellulose nanofibril films: effects of crystallinity and its modification by treatment with liquid anhydrous ammonia
Ottesen, Vegar; Larsson, Per Tomas; Chinga-Carrasco, Gary; Syverud, Kristin; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2019)The influence of cellulose crystallinity on mechanical properties of cellulose nano-fibrils (CNF) was investigated. Degree of crystallinity (DoC) was modified using liquid anhydrous ammonia. Such treatment changes crystal ... -
Mechanical, thermal and swelling properties of cellulose nanocrystals/PVA nanocomposites membranes
Jahan, Zaib; Niazi, Muhammad Bilal Khan; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2018)Cellulose nanocrystals (CNC) have strong reinforcing properties when incorporated in a compatible polymer matrix. The study was conducted to investigate the effect of addition of different proportions of CNC on the mechanical, ... -
Mixing of cellulose nanofibrils and individual furnish components: Effects on paper properties and structure
Ottesen, Vegar; Syverud, Kristin; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2016)Thermo-mechanical pulp (TMP) handsheets with different fractions of cellulose nano fibrils (CNF) and ground calcium carbonate (GCC) were made. CNF and retention chemicals were added in three different ways; to GCC, to long ... -
Nanocomposite Membranes containing Bio-nanofibers and Mimic Enzyme for Biogas upgrading
Jahan, Zaib (Doctoral theses at NTNU;2018:64, Doctoral thesis, 2018)CO2 is the most dominating anthropogenic greenhouse gas. Combustion of fossil fuels, to meet energy demands is one of the major sources of CO2 emission. Release of CO2 from burning fossil fuel and cement industry has ... -
Nanocomposite membranes with high-charge and size-screened phosphorylated nanocellulose fibrils for CO2 separation
Helberg, Ragne M Lilleby; Torstensen, Jonathan Økland; Dai, Zhongde; Janakiram, Saravanan; Chinga-Carrasco, Gary; Gregersen, Øyvind Weiby; Syverud, Kristin; Deng, Liyuan (Peer reviewed; Journal article, 2020)In this study, cellulose nanofibrils (CNF) of high charge (H-P-CNF) and screened size (H-P-CNF-S) were fabricated by increasing the charge of phosphorylated cellulose nanofibrils (P-CNFs) during the pre-treatment step of ... -
Porous filters of nanofibrillated cellulose
Sandberg, Linn Ingunn C. (Master thesis, 2011)Filters for air purification are predominantly produced of synthetic and non-biodegradable materials. In this work, a range of various air filters have been prepared from 100% pure cellulosic material, with the goal to ... -
Preparation of cellulose nanofibrils for imaging purposes: comparison of liquid cryogens for rapid vitrification
Torstensen, Jonathan Ø; Johnsen, Per-Olav; Riis, Henrik; Spontak, Richard J; Deng, Liyuan; Gregersen, Øyvind Weiby; Syverud, Kristin (Journal article; Peer reviewed, 2018)Artifact-free imaging of cellulose nanofibrils (CNFs) from aqueous nanocellulose suspensions is nontrivial due to frequent irreversible agglomeration and structure damage during the course of sample preparation, especially ... -
PVA/nanocellulose nanocomposite membranes for CO2 separation from flue gas
Torstensen, Jonathan Økland; Helberg, Ragne M Lilleby; Deng, Liyuan; Gregersen, Øyvind Weiby; Syverud, Kristin (Peer reviewed; Journal article, 2019)In this paper, we explore the use of nanocelluloses as an additive to poly (vinyl alcohol) (PVA) nanocomposite membranes for CO2/N2 mixed-gas separation. Our findings are that several types of nanocellulose can be used to ... -
Relation between fibre flexibility and cross-sectional properties
Rusu, Marius; Mörseburg, Kathrin; Gregersen, Øyvind Weiby; Yamakawa, Asuka; Liukkonen, Sari (Journal article; Peer reviewed, 2011)The correlation between the fibre flexibility and cross-sectional area moment of inertia of thermomechanical pulp fibres was investigated. The main effects of refining were found to be internal fibrillation, external ... -
Some factors affecting the grades of technology students
Gregersen, Øyvind Weiby; Kløkstad, Geir Øivind; Hervik, Sigbjørn; Plesser, Hans Ekkehard; Pettersen, Ivar (Journal article; Peer reviewed, 2017)In this study factors that affect the grades of Norwegian technology students have been investigated. The total data set contained 355.706 individual exams from 63 different engineering master programs during the 2010 to ... -
Swelling and Free-Volume Characteristics of TEMPO-Oxidized Cellulose Nanofibril Films
Torstensen, Jonathan Ø; Liu, Ming; Jin, Soo-Ah; Deng, Liyuan; Hawari, Ayman I.; Syverud, Kristin; Spontak, Richard J.; Gregersen, Øyvind Weiby (Journal article; Peer reviewed, 2018)