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Electrosterically stabilized nanocrystalline cellulose (ENCC) was modified in three ways: (1) the hydroxyl groups on C2 and C3 of glucose repeat units of ENCC were converted to aldehyde groups by periodate oxidation to various extents; (2) the carboxyl groups in the sodium form on ENCC were converted to the acid form by treating them with an acid-type ion-exchange resin; and (3) ENCC was cross-linked in two different ways by employing adipic dihydrazide as a cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide as a carboxyl-activating agent. Films were prepared from these modified ENCC suspensions by vacuum filtration. The effects of these three modifications on the properties of films were investigated by a variety of techniques, including UV-visible spectroscopy, a tensile test, thermogravimetric analysis (TGA), the water vapor transmission rate (WVTR), and contact angle (CA) studies. On the basis of the results from UV spectra, the transmittance of these films was as high as 87%, which shows them to be highly transparent. The tensile strength of these films was increased with increasing aldehyde content. From TGA and WVTR experiments, cross-linked films showed much higher thermal stability and lower water permeability. Furthermore, although the original cellulose is hydrophilic, these films also exhibited a certain hydrophobic behavior. Films treated by trichloromethylsilane become superhydrophobic. The unique characteristics of these transparent films are very promising for potential applications in flexible packaging and other high-technology products.

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Cellulose nanofibrils (CNF) are steadily gaining attention since this material is a renewable alternative to artificial polymers. Moreover, waste products from cellulose-based industries (e.g. paper mills) or from agriculture can be used as raw material for CNF isolation. However, the up-scaling from the laboratory to the industry can only be achieved if the energy costs are low enough to compete against low-price petroleum derivatives. The objective of this work is to present an energy-related study of the direct fibrillation of cellulose-based materials using a grinding process. Two waste materials, namely wheat straw and recycled newspaper, have been investigated as starting materials, together with bleached wood pulp for comparison purposes. The mechanical properties and specific surface areas of the resulting fibrillated materials are then presented and systematically compared with each other. The properties of the bleached wood-pulp fibres exhibited the highest values that were reached already at low energy inputs. The different properties of CNF isolated out the waste materials could reach values close to their maxima for energy inputs as low as about 5 kWh/kg compared to the ca. 10 kWh/kg needed with high pressure homogenization.

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Several lignin (L)-based novolac-type phenolic prepolymers with two phenol (P) substitution degrees have been synthesized using three L from different origin (kraft pine L, soda/anthraquinone (AQ) flax L, and sulfonated kraft softwood L). These lignophenolic (LPF) resins have been characterized by means of free P and formaldehyde (F) analysis, viscosity, chemical structure (FTIR), and thermal behavior (DSC). Temperature at which curing reaction begins (DSC), hardening time at several curing temperatures (rheology) and volumetric changes (PVT) have also been determined for the curing process with 10 wt % hexamethylenetetraamine (HMTA). All the results have been compared to those obtained for a commercial novolac. Depending on the L type employed a homogeneous material with lower curing onset temperature and gelation time than reference PF can be obtained even at high P substitution level (45 wt %).

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