Leather and Shoe Research Association

Palmerston North, New Zealand

Leather and Shoe Research Association

Palmerston North, New Zealand
SEARCH FILTERS
Time filter
Source Type

Edmonds R.L.,Leather and Shoe Research Association | Allsop T.F.,Massey University | Cooper S.M.,Leather and Shoe Research Association | Holmes G.,Leather and Shoe Research Association | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2010

SAXS has been applied to structural determination in leather. The SAXS beamline at the Australian Synchrotron provides 6 orders of magnitude dynamic range, enabling a rich source of structural information from scattering patterns of leather sections. SAXS patterns were recorded for q from 0.004 to 0.223 Å-1. Collagen d spacing varied across ovine leather sections from 63.8 nm in parts of the corium up to 64.6 nm in parts of the grain. The intensity of the collagen peak at q = 0.06 Å-1 varied by 1 order of magnitude across ovine leather sections with the high-intensity region in the corium and the low intensity in the grain. The degree of fiber orientation and the dispersion of the orientation has been quantified in leather. It is shown how the technique provides a wealth of useful information that may be used to characterize and compare leathers, skin, and connective tissue. © 2010 American Chemical Society.


Wells H.C.,Massey University | Holmes G.,Leather and Shoe Research Association | Haverkamp R.G.,Massey University
Journal of the American Leather Chemists Association | Year: 2016

The processing of bovine hides to leather results in a significant proportion of defective leather known as loose leather. It has not previously been possible to recognize hides that may produce loose leather. Hides were processed through to leather with samples retained at the pickle, wet blue and crust leather stages with material that resulted in loose leather compared with that resulting in tight leather, using ultrasonic imaging. The loose precursor is characterized by a lower density of material in the mid grain layer. The looseness is quantified by amplitude differences in ultrasound line scans or cross-sectional area scans between loose leather and tight leather with 2-4 times the amount of low intensity area in loose leather at all three process stages. This enables detection of hides that will result in loose leather and may enable unsuitable hides to be diverted to other process streams to save substantial processing costs.


Basil-Jones M.M.,Massey University | Edmonds R.L.,Leather and Shoe Research Association | Norris G.E.,Massey University | Haverkamp R.G.,Massey University
Journal of Agricultural and Food Chemistry | Year: 2012

The distribution and effect of applied strain on the collagen fibrils that make up leather may have an important bearing on the ultimate strength and other physical properties of the material. While sections of ovine and bovine leather were being subjected to tensile strain up to rupture, synchrotron-based small-angle X-ray scattering (SAXS) spectra were recorded edge-on to the leather at points from the corium to the grain. Measurements of both fibril orientation and collagen d spacing showed that, initially, the fibers reorient under strain, becoming more aligned. As the strain increases (5-10% strain), further fibril reorientation diminishes until, at 37% strain, the d spacing increases by up to 0.56%, indicating that significant tensile forces are being transmitted to individual fibrils. These changes, however, are not uniform through the cross-section of leather and differ between leathers of different strengths. The stresses are taken up more evenly through the leather cross-section in stronger leathers in comparison to weaker leathers, where stresses tended to be concentrated during strain. These observations contribute to our understanding of the internal strains and structural changes that take place in leather under stress. © 2012 American Chemical Society.


Basil-Jones M.M.,Massey University | Edmonds R.L.,Leather and Shoe Research Association | Cooper S.M.,Leather and Shoe Research Association | Kirby N.,Australian Synchrotron | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

Variability of physical properties across hides and skins requires careful consideration when manufacturing goods from leather. Therefore, an understanding of the extent of this variation and its nanostructural basis is useful. Tear strength tests were performed on ovine leather from a grid of 81 positions on skins. Synchrotron small-angle X-ray scattering measurements were made from three positions on the skin, from 26 skins. The X-ray structural measurements are compared with tear strengths of the samples. It is found that the thickness normalized tear strength does not vary greatly between different positions on the skin, in contrast to bovine hides. There is more variation between different skins than within the same skin. The collagen fibril orientation and orientation index, which has previously been shown to be correlated with tear strength, do not vary significantly between the different sampling positions in ovine skins. The collagen fibril orientation varies through the thickness of the skin in a consistent way. The consistency of collagen orientation in ovine leather between different positions on the skin is in marked contrast to bovine hides and informs the use of ovine leather for manufacturing applications. © 2013 American Chemical Society.


Wells H.C.,Massey University | Edmonds R.L.,Leather and Shoe Research Association | Kirby N.,Australian Synchrotron | Hawley A.,Australian Synchrotron | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

The main structural component of leather and skin is type I collagen in the form of strong fibrils. Strength is an important property of leather, and the way in which collagen contributes to the strength is not fully understood. Synchrotron-based small angle X-ray scattering (SAXS) is used to measure the collagen fibril diameter of leather from a range of animals, including sheep and cattle, that had a range of tear strengths. SAXS data were fit to a cylinder model. The collagen fibril diameter and tear strength were found to be correlated in bovine leather (r2 = 0.59; P = 0.009), with stronger leather having thicker fibrils. There was no correlation between orientation index, i.e., fibril alignment, and fibril diameter for this data set. Ovine leather showed no correlation between tear strength and fibril diameter, nor was there a correlation across a selection of other animal leathers. The findings presented here suggest that there may be a different structural motif in skin compared with tendon, particularly ovine skin or leather, in which the diameter of the individual fibrils contributes less to strength than fibril alignment does. © 2013 American Chemical Society.


Basil-Jones M.M.,Massey University | Edmonds R.L.,Leather and Shoe Research Association | Cooper S.M.,Leather and Shoe Research Association | Haverkamp R.G.,Massey University
Journal of Agricultural and Food Chemistry | Year: 2011

There is a large difference in strength between ovine and bovine leather. The structure and arrangement of fibrous collagen in leather and the relationship between collagen structure and leather strength has until now been poorly understood. Synchrotron based SAXS is used to characterize the fibrous collagen structure in a series of ovine and bovine leathers and to relate it to tear strength. SAXS gives quantitative information on the amount of fibrous collagen, the orientation (direction and spread) of the collagen microfibrils, and the d-spacing of the collagen. The amount of collagen varies through the thickness of the leather from the grain to the corium, with a greater concentration of crystalline collagen measured toward the corium side. The orientation index (OI) is correlated strongly with strength in ovine leather and between ovine and bovine leathers. Stronger leather has the fibrils arranged mostly parallel to the plane of the leather surface (high OI), while weaker leather has more out-of-plane fibrils (low OI). With the measurement taken parallel to the animal's backbone, weak (19.9 N/mm) ovine leather has an OI of 0.422 (0.033), stronger (39.5 N/mm) ovine leather has an OI of 0.452 (0.033), and bovine leather with a strength of (61.5 N/mm) has an OI of 0.493 (0.016). The d-spacing profile through leather thickness also varies according to leather strength, with little variation being detected in weak ovine leather (average = 64.3 (0.5) nm), but with strong ovine leather and bovine leather (which is even stronger) exhibiting a dip in d-spacing (from 64.5 nm at the edges dropping to 62 nm in the center). This work provides a clear understanding of a nanostructural characteristic of ovine and bovine leather that leads to differences in strength. © 2011 American Chemical Society.


Sizeland K.H.,Massey University | Wells H.C.,Massey University | Norris G.E.,Massey University | Edmonds R.L.,Leather and Shoe Research Association | And 3 more authors.
Journal of the American Leather Chemists Association | Year: 2015

The physical properties of leather are partly a result of the structure of the leather's network of type I collagen fibrils. To achieve high strength and a soft, supple feel, penetrating oils (usually polyols) are added to leather during manufacture, and this process is known as fat liquoring. The modification of the collagen structure by fat liquoring (with a lanolin-based fat liquor) is investigated using synchrotron-based small angle X-ray scattering. The axial periodicity, or D-spacing, of the collagen changes as a result of fat liquoring. With no fat liquor, the D-spacing is 60.2 nm; spacing increases by 6% to 63.6 nm at 10% fat liquor. Pure lanolin results in a similar increase in D-spacing. We discuss mechanisms for fibril elongation brought about by fat liquoring. The observations of structural changes taking place within collagen fibrils as a result of fat liquoring provides new insight into the nature of fat liquoring and informs future processing developments.


Wells H.,Massey University | Holmes G.,Leather and Shoe Research Association | Haverkamp R.G.,Massey University
XXXIII IULTCS Congress | Year: 2015

Looseness is defect that affects the quality of a significant proportion of leather, particularly bovine leather. This defect causes a wrinkled appearance on the leather surface and results in a significant reduction in the leathers value. The structural mechanism and causes of looseness in leather are not well understood; therefore this study aims to gain a better understanding of this. We have used small angle X-ray scattering, ultrasonic imaging, electron microscopy and tensile testing to characterize and compare the structures of loose and tight bovine leather. Loose leather appears to have more highly aligned collagen fibrils, resulting in less overlapping of fibrils and weaker connections between the layers in leather. Loose leather has a looser fibre packing arrangement, with larger gaps in between fibre bundles, particularly in grain-corium boundary region. We are able to see this characteristic loose region using in-situ ultrasonic imaging and electron microscopy. We have used a range of techniques to gain a better understanding of the physical basis of looseness. This knowledge will be useful for further studies into the cause and prevention of looseness from developing during leather production.


Edmonds R.L.,Leather and Shoe Research Association
XXXIII IULTCS Congress | Year: 2015

In this work, a mathematical model of leather fibre reorientation during strain was developed in order to improve understanding of the stress strain processes occurring at fibre level within the bulk of a fibrous sheet. The model consisted of parameters including, fibre density, fibre diameter, fibre angle, fibre arc length, fibre chord length, and D-spacing spring constant. A number of different mechanisms for the reorientation and strain of individual fibres were examined and compared to real data. After a number of refinements, a mechanistic model that fit the data was found as follows. In the model, the sheet of leather was assumed to be composed of discrete fibres fixed in space at each end with a defined initial angle between those ends and a corresponding chord length and separate arc length between the two ends. During strain, the fibres are stretched in a way that takes up slack in the fibre arc length until it equals the chord length then the taught-straight fibre reorients towards the direction of strain, and finally fibres stretch with an associated shift in the measured d-spacing. Model predictions were compared to real measured changes in fibre reorientation and strain during bulk strain and found to fit the data well. The mechanism for reorientation and fibre strain developed in this work can now assist in the development of statistical mechanistic models that describe bulk properties of leather, such as tear strength, based on the properties of the intrinsic fibres.


PubMed | Leather and Shoe Research Association and Massey University
Type: | Journal: Journal of chromatography. A | Year: 2016

We have developed a novel chromatographic analytical method for the simultaneous quantitation of collagen crosslinks. Seven non-derivatised crosslinks could be separated on a Cogent Diamond Hydride HPLC column using either isocratic or gradient conditions then detected by mass spectrometry. The total run time was less than 10min which is significantly shorter than that previously reported. This is the first method in which histidinohydroxylysinonorleucine (HHL) and histidinohydroxymero-desmosine (HHMD) were separated and identified by mass spectrometry without the need for pre- or post-column derivatization. The CVs of the retention times of all seven crosslinks were less than 1% and the limit of detection (LOD) and the limits of quantitation (LOQ) were 0.07-0.13pmol/L and 0.20-0.38pmol/L, respectively. This novel method was used for the routine analysis and quantitation of crosslinks in different animal skins in which potential new collagen crosslinks were identified that are as yet undocumented.

Loading Leather and Shoe Research Association collaborators
Loading Leather and Shoe Research Association collaborators