February 2019 Abstracts

Suitability of Pore Measurement Methods for Characterizing the Hierarchical Pore Structure of Leather

by Xiu He, Ya-nan Wang, Jianfei Zhou, Haobo Wang, Wei Ding and Bi Shi

Pore structure of leather plays an important role in leather-making process as well as in characterization of comprehensive properties of leather. In this study, scanning electron microscopy, mercury intrusion porosimetry (MIP), capillary flow porometry and nitrogen adsorption techniques were used for characterization of the hierarchical pore structure of leather. From the comparison, MIP was found to be more suitable for pore measurement of leather in consideration of its extensive measuring range (from 5.48 nm to 120 μm), high accuracy (measuring both through pores and blind pores in leather) and satisfactory repeatability (with RSD of 3.25% and 1.73% for average pore diameter and porosity, respectively). Then the MIP test conditions were optimized. The appropriate conditions were found to be that a leather sample (approx. 3 cm × 2 cm and 0.6 g) is used for determination with a stem volume around 50%. Blank correction is conducted in the measurement with the maximum pressure of 33000 psia and the equilibration time of 10 s. In general, the characterization of the hierarchical pore structure of leather by MIP is a meaningful aid to explore the relationship between structure and property of leather.

Register Today To Read Entire Article

Studies on the Ethiopian Camel Hides for Their Suitability for Making Leather

by M. Belay, R. Karthikeyan, V. John Sundar and R. Aravindhan

Ethiopia has the largest livestock population in the African countries, providing a strong raw material base for the growing leather and leather products sector. The main source of raw material for the Ethiopian tanning industry comes from sheep, goat and cattle. Since the Ethiopian leather industry is booming, the industry is now looking to exploit the alternative raw materials available in the country. Camel (Camelus dromedarius) is one of the most important livestock in the East African countries. Due to lack of awareness and technology, most of the hides are not utilized fully by the tanners. Hence an attempt has been made in the present study to exploit the camel hides as an alternative source of raw material for the growing Ethiopian leather industry. Histological analysis of the camel hide has been carried out at different stages of processing. Based on the histological understanding, the strategy for making suitable leather from camel hide was established. The raw material has also been characterized for fat, nitrogen and collagen content. The raw material has been converted into finished leather by using suitable tanning methodology and the leathers were utilized for the preparation of different types of end products. Finished leathers have been developed and the physical and chemical properties have also been evaluated. The results obtained from the chemical and physical tests revealed that the raw material is suitable for the manufacture of upper leather.

Register Today To Read Entire Article

Influence of the Chromatographic Conditions of the EN ISO 17226-1 Standard “Determination of formaldehyde content in leather. Part 1. Quantification by HPLC” on the Robustness of the Method

by Albert M. Manich, Sara Cuadros, Agustí Marsal, Maria-Reyes Reyes and Joaquim Font

Given the carcinogenic character of formaldehyde, it should be reliably determined in any substrate. The EN ISO 17226 Standard is the Official Method to quantify formaldehyde in leather using either the chromatographic or the colorimetric methods. In cases of discrepancy between results, according to the ISO Organization, preference should be given to the chromatographic method (EN ISO 17226-1 Standard) instead of the colorimetric one (EN ISO 17226-2 Standard). The EN ISO 17226-1 Standard recommends chromatographic conditions of column, mobile phase composition and flow rate.

The paper studies the influence of changes in flow rate, composition of the mobile phase and separating columns recommended by the EN ISO 17226-1 Standard for the determination of formaldehyde content in leather. It has been made relevant that small variations in the flow rate and differences in mobile phase compositions ranging from 35/65 to 45/55 Water/Acetonitrile does not significantly affect the results of formaldehyde concentration.

As regards the different separating columns, non-significant differences between them were observed. However, considering the effectiveness and the retention time of the separating columns, the solid-core particle (Cortecs®C18) column can be recommended because it has in excess the capacity to separate the formaldehyde peak from that of the residual DNPH reagent in less than 2 minutes which is lower than those of the other columns tested. Consequently, the productivity of the analytical laboratories is improved.

Register Today To Read Entire Article

Analysis of the Processing Histology of Mink Skin

by Meina Zhang, Yao Tian, Yongguang Wang and Zongcai Zhang

Most people around the world regard mink skin as luxurious commodities, since the mink hair is generous and guard hair length is moderate. However, a variety of reasons will attribute to hair loss or orientation phenomenon of upper hair in the processes. The paper studied the processing histology of mink in the processing, which could build a scientific foundation to optimize the process, improve the technical skills and improve product quality. Mink skin samples used in the experiment were taken from soaking, degreasing, bating, pickling, and tanning processes. The photomicrographs were observed by bio-optical microscope. Besides, samples were performed by frozen section method and stained with iron hematoxylin staining method as well as Gill modified hematoxylin staining method. It is found that the hair follicles of the mink were distributed irregularly in the form of compound hair follicles or individual hair follicles. Mink fat glands were very developed. In other words, each hair follicle generally was surrounded by a pair of fat glands. With the increase in degreasing time, the number of fat cells in the fat glands was reduced and the fibers around the hair follicles were initially dispersed. The voids between the collagen fibers became larger and more fully loose after the processes of bating and pickling. In addition, the collagen fiber wove more orderly and closer by tanning. In the case of pickling and bating, most of the hair follicle openings were opened, which could abate the chained force between hair and the follicles and/or the dermal papilla.

Register Today To Read Entire Article