During the last years there has been a dramatically increased interest towards both physical and covalent modification of wood fibers. The aim has been both to improve the properties of fibers in existing or dramatically improved fiber products and to prepare fibers for use in new products. The major focus for these new products have been fiber reinforced composites for example for the car industry but based on the inherent properties of the fibers and their cellulose fibrils the product range for modified fibers and fibrils is much, much larger. In order to utilize these properties it is nevertheless important to tailor the surface properties of the fibers and to utilize the properties of the fiber wall. The fibrils have an E-modulus around 130 GPa, a nano-meter sized cross-section and length of more than 1 µm. In water swollen conditions these fibrils are separated whereas they are totally bonded to each other in air dried fibers. These basic facts must be considered when modifying the wood fibers and fibrils either in the fiber wall or in the liberated state. It is also very important that the modification is made all the way from molecular specificity, to the meso-structure scale and to microscopic material properties. In this way the chemical fibers modification can be combined with a supra-molecular structure in the same way animals or plants do to strengthen their bones/shells or their attachment to other materials. The first part of Theme 3 is aimed at modifying fibers/fibrils with either covalent or physical modification strategies in order to tailor their surface for optimized utilization in different types of biocomposites that is developed in Theme 4.
An alternative to utilizing the fibers and fibrils directly from nature is to use the components liberated in Theme 1 and possibly modified in Theme 2 for the preparation of new types of pure nano-fibers with specific properties. There has recently been an increased interest in preparing for example carbon fibers from lignin and to utilize the unique properties of these fibers. It is well known that these fibers have a very high stiffness and are hence interesting for high value added composites. They also have a high electrical conductivity and are therefore interesting in applications where interactive properties are desired. There has also been a revitalized interest in electro-spinning and it has been found that several components that can be extracted from the fiber wall can be used as raw materials in electro-spinning. By modifying the components before electro-spinning it is also possible to prepare fibers with predetermined interactive properties with a sub-micrometer cross-section.
Fibers and fibrous materials
During the last years there has been a dramatically increased interest towards both physical and covalent modification of wood fibers. The aim has been both to improve the properties of fibers in existing or dramatically improved fiber products and to prepare fibers for use in new products. The major focus for these new products have been fiber reinforced composites for example for the car industry but based on the inherent properties of the fibers and their cellulose fibrils the product range for modified fibers and fibrils is much, much larger. In order to utilize these properties it is nevertheless important to tailor the surface properties of the fibers and to utilize the properties of the fiber wall. The fibrils have an E-modulus around 130 GPa, a nano-meter sized cross-section and length of more than 1 µm. In water swollen conditions these fibrils are separated whereas they are totally bonded to each other in air dried fibers. These basic facts must be considered when modifying the wood fibers and fibrils either in the fiber wall or in the liberated state. It is also very important that the modification is made all the way from molecular specificity, to the meso-structure scale and to microscopic material properties. In this way the chemical fibers modification can be combined with a supra-molecular structure in the same way animals or plants do to strengthen their bones/shells or their attachment to other materials. The first part of Theme 3 is aimed at modifying fibers/fibrils with either covalent or physical modification strategies in order to tailor their surface for optimized utilization in different types of biocomposites that is developed in Theme 4.
An alternative to utilizing the fibers and fibrils directly from nature is to use the components liberated in Theme 1 and possibly modified in Theme 2 for the preparation of new types of pure nano-fibers with specific properties. There has recently been an increased interest in preparing for example carbon fibers from lignin and to utilize the unique properties of these fibers. It is well known that these fibers have a very high stiffness and are hence interesting for high value added composites. They also have a high electrical conductivity and are therefore interesting in applications where interactive properties are desired. There has also been a revitalized interest in electro-spinning and it has been found that several components that can be extracted from the fiber wall can be used as raw materials in electro-spinning. By modifying the components before electro-spinning it is also possible to prepare fibers with predetermined interactive properties with a sub-micrometer cross-section.