Isolation and characterization of microcrystalline cellulose from oil palm biomass residue.

In this work, we successfully isolated microcrystalline cellulose (MCC) from oil palm empty fruit bunch (OPEFB) fiber-total chlorine free (TCF) pulp using acid hydrolysis method. TCF pulp bleaching carried out using an oxygen-ozone-hydrogen peroxide bleaching sequence. Fourier transform infrared (FT-IR) spectroscopy indicates that acid hydrolysis does not affect the chemical structure of the cellulosic fragments. The morphology of the hydrolyzed MCC was investigated using scanning electron microscopy (SEM), showing a compact structure and a rough surface. Furthermore, atomic force microscopy (AFM) image of the surface indicates the presence of spherical features. X-ray diffraction (XRD) shows that the MCC produced is a cellulose-I polymorph, with 87% crystallinity. The MCC obtained from OPEFB-pulp is shown to have a good thermal stability. The potential for a range of applications such as green nano biocomposites reinforced with this form of MCC and pharmaceutical tableting material is discussed.

Relationships between specific surface area and pore size in electrospun polymer fibre networks.

From consideration of the extent of contact between fibres in electrospun polymer networks, we provide theory relating the specific surface area of the network to the characteristic dimensions of interfibre voids. We show that these properties are strongly influenced by the cross-sectional morphologies of fibres. Whereas porosity has a strong influence on pore dimensions, in the range of porosities typically obtained in real networks, its influence on specific surface area is weak. By considering reference geometries of collapsed ribbons and fibres with circular cross sections, we demonstrate that at a given network porosity, fibre parameters that increase the specific surface area reduce the characteristic dimensions of voids. The implications of the theory, mainly in the context of cell proliferation on electrospun polymer scaffolds, are discussed; the theory has relevance also to future applications of these materials in composites.

Tensile and shear properties of fingernails as a function of a changing humidity environment.

The mechanical properties of fingernails are important because of their impact in preventing damage and in maintaining their appearance. In particular, knowing the effect of local environmental conditions can tell us how they might best be protected. In order to better understand this, tensile tests were carried out to characterise the properties of fingernails at different relative humidities. Cyclic tests were also conducted to investigate the ability of the structure to recover deformation at different moisture contents. Torsional tests were performed to determine the shear modulus of the keratinous matrix material which binds together the fibrous components of the fingernails. This enabled an analysis of how the material may resist bending, torsion and permanent deformation in a natural environment. In particular, it is shown that at low relative humidity the nails are more brittle, and at high moisture contents they are more flexible. Increasing relative humidity lowers torsional stiffness much more than tensile stiffness, suggesting that moisture plasticises the matrix rather than affecting the fibres. The twist to bend ratio is minimised at 55% RH, close to the natural condition of nails which should minimise susceptibility to torsional damage due to plasticisation and a disruption of the matrix material binding the keratin fibres.