XXXV IULTCS CONGRESS 2019
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Speed Science

Session chair: Casey, Patricia, T., Dr (Curtiembres Fonseca S.A., Buenos Aires, Argentina); Castell, Joan-Carles, Dr (Stahl Ibérica S.L., Barcelona, Spain)
 
Shortcut: SpSc2
Date: Thursday, 27 June, 2019, 12:05 PM – 12:30 PM
Room: Seminar 1
Session type: Speed Science

Contents

Click on an contribution to preview the abstract content.

12:05 PM SpSc2-01

Sound absorbing nanofibers from tannery solid waste: Trash to treasure (#255)

S. Selvaraj1, R. R. Jonnalagadda1, N. N. Fathima1

1 Central leather research institute, Inorganic and physical chemistry laboratory, chennai, India

Content

Leather processing results in the generation of enormous amount of solid waste. Preparation of value-added materials from leather waste is one of the approaches, which can reduce the pollution burden and also have a significant positive impact on the leather economy. In this present study, we have developed a new method for preparation sound absorption nanofibers from two solid wastes viz., fleshing waste and crust leather waste. The limed fleshing waste and crust leather waste were hydrolysed in both the acid and alkaline conditions. The hydrolysate was blended with the acoustic polymer poly(vinyl alcohol) and electrospun for the preparation of nanofibers. The nanofibers were further placed on the natural sound absorbing materials and their sound absorbing ability was investigated using impedance tube method. The nanofibers were also prepared using layer by layer assembly where the leather hydrolysate- PVA nanofibers sandwiched between polyacrylonitrile nanofiber layers and their properties were studied. The nanofibers were subjected to morphological, thermal and mechanical characterizations. The diameter of the nanofibers were found to be around 100- 200 nm. Hydrolysate- PVA nanofibers showed enhanced thermal stability than the neat PVA nanofibers. The specific surface area of the hydrolysate- PVA nanofibers were found to be 2.97 m2/g. The bilayer material consisting of hydrolysate- PVA with natural fiber coir showed better sound absorption ability when compared to the coir alone. The triple layer material consisting of PAN- hydrolysate PVA- PAN showed better sound absorbing potential when compared to the PAN layer.  Thus, this study paves way for developing a new strategy for managing the leather wastes as “wealth from waste approach”.

 

Take-Away

New approach for leather solid waste management has been developed

The preparation of sound absorbing nanofibers can reduce the pollution load

Keywords: Leather waste, acoustics, nanofibers, hydrolysate
12:08 PM SpSc2-02

Does post tanning chemicals influence sewability of leathers: An approach towards re-instigating the post tanning process (#249)

G. C. Jayakumar1, K. Phebe Aaron2, A. Fathima3, V. Swarna3

1 CSIR-Central Leather Research Institute, Centre for Academic and Research Excellence, Chennai, India
2 CSIR-Central Leather Research Institute, Shoe & Product Design Centre (SPDC), Chennai, India
3 Shoe & Product Design Centre (SPDC), Centre for Human and Organizational Resources Development (CHORD), Chennai, India

Content

Leather is three dimensional matrix possessing unique properties which makes it more comfortable for daily use. Garments made from leathers are a preferred choice owing to their multifaceted properties as compared to textiles in the colder regions. In the present study, an attempt has been made to evaluate the influence of phenolic syntan and synthetic fatliquor on the sewability and physical properties of post tanned leathers. From the experimental results, it is observed that with the increase in offer of phenolic syntan, there is decrease in the softness which reduces the sewability. Optical microscopic images of leathers also show that they are more compact and tight with higher percentage of syntan. Similarly, at higher percentage of fatliquor, sewability property is reduced owing to coating of fatliquors on leathers. The study provides an insight in understanding the optimum usage of post tanning chemicals for better sewing properties without affecting the leather matrix.

Take-Away

1. Understaning co-relation between syntans & fatliquors on sewability

2. Excess fatliquoring might affect the sewability

Keywords: Phenolic syntan, fatliquor, Retanning, Sewability
12:11 PM SpSc2-03

Chemical Safety and Occupational Safety and Health under the banner of REACH, CLP and National Occupational Safety and Health Legislation (#22)

T. Martin1

1 BG RCI, KC GubA, Heidelberg, Baden-Württemberg, Germany

Content

When working with hazardous substances such as those that are put to versatile use in the leather industry, numerous safety regulations must be observed. While the national legislation had previously been foregrounded (e. g. German Ordinance on Hazardous Substances), the number of European regulations concerning occupational safety and health is steadily increasing.

The classification and labelling were globally harmonised by GHS. REACH has introduced the first authorisations and restrictions in addition to the already known exposure scenarios with their risk management measures. Today not only considerably more detailed safety datasheets but also REACH and CLP databases from the European Chemicals Agency (ECHA) provide hazardous substances data. However, data on some individual hazardous substances on the market have not been harmonised yet and their evaluation is becoming increasingly more difficult in practice, not to mention the torrent of new substances evaluations, regulation amendments and the corresponding annexes with lists of substances. Mixtures are often used in everyday practice – many of them have already been purchased as mixtures and some of them being prepared in the company. Amendments of source material evaluations are even more difficult to validate in this case.

Due to numerous errors and contradictions the German Ordinance on Hazardous Substances with its technical rules demands a plausibility check and the collection of information concerning hazardous substances, even from open sources.

The approach to a European harmonisation of occupational safety and health in the form of guidelines and regulations is certainly positive. Unfortunately, the different approaches adopted by the member states when it comes to national occupational safety and health causes massive problems –not only with regard to the current issue of evaluating titanium dioxide.

The talk outlines the principles of the European procedures of substance and risk evaluation based on some examples. Additionally, it points out the assistance that is made available to companies in Germany by the statutory accident insurance such as the hazardous material database (GisChem).

Take-Away

REACH and CLP contribute to a more harmonised evaluation of chemicals within the EU by a variety of instruments.

In detail, more complex regulations, constant amendments and revaluations result in considerable uncertainties in practice. Safety datasheets from the suppliers should therefore be subjected to a plausibility check.

In its capacity as the statutory accident insurance in Germany, the occupational accident insurance attempts to support particularly the users of hazardous substances in small and medium-sized enterprises with special offers such as the hazardous materials database (GisChem) in order to improve occupational safety and health.

Keywords: REACH, hazardous substances, clp, Occupational Safety and health
12:14 PM SpSc2-04

Use of different pre-treated chromium leather shavings to produce biogas in continuous scale (#244)

C. S. Gomes1, 2, J. - U. Repke2, M. Meyer1

1 Forschungsinstitut Leder und Kunststoffbahnen (FILK), Freiberg, Saxony, Germany
2 TU Berlin, Dynamik und Betrieb technischer Anlagen, Berlin, Germany

Content

Leather goods are noble and sustainable but leather production may bear a potential for pollution. During leather manufacture high amounts of chromium shavings, wet by-products of the leather industry, are produced worldwide. Due to their chromium content they are disposed in landfill sites worldwide leading to long lasting environmental problems. They are stable towards temperatures of up to 110 °C and enzymatic degradation, preventing anaerobic digestion in a biogas plant. This stability is due to the three-dimensional native structure, typical for collagen, and additional chemical cross-links between the collagen fibers achieved by Cr3+ salts in the tanning step in tanneries. Therefore, hitherto chromium shavings are not utilized industrially to produce biogas.

In order to ease enzymatic degradation, necessary to produce biogas, a previous denaturation of the native structure has to be carried out. Otherwise, the generation of biogas is hindered. In our projects, shavings were pre-treated thermally and mechanically by extrusion and hydrothermal methods. In previous works, we studied intensively the use of these shavings to produce biogas in batch scale and significant improvement was reached when using pre-treated shavings. In this work, a scale-up of the process was performed in a continuous reactor using pre-treated and untreated shavings to examine the feasibility of the considered method. Measuring different parameters along the anaerobic digestion, namely organic matter and volatile fatty acids content, it was possible to show that a higher loading rate can be used when feeding the reactor with pre-treated shavings instead of untreated shavings, which means a more economical process in an industrial scenario.

Take-Away

The use of a pre-treatment improves the biogas production from chromium shavings.

Keywords: Biogas production; Continuous process; Chromium shavings; Extrusion; Hydrothermal treatment
12:17 PM SpSc2-05

Keratin derived from tannery cattle hair waste used for the preparation of waterborne polyurethane (#113)

J. Liu1, F. F. Zhang1, Z. C. Liu1, H. Li1, X. S. Li1

1 Qilu University of Technology (Shandong Academy of Sciences), School of Light Industry and Engineering, Jinan, China

Content

Polyurethane (PU) has excellent performance because of its special structure, but it has defects in hygienic property and natural degradation. On the other hand, in recent years, hair-saving unhairing process replace the conventional sulfide hair-destroying process and become an indispensable process in the production of cattle leather. However, the subsequent problem is that a large number of abandoned cattle hair, which poses a serious threat to the environment. Although the quantity and property of hair derived from different raw hides are different, they are essentially composed of α keratin.
Keratin belongs to natural macromolecule compounds, and its molecular structure has a large number of peptide bonds and hydrophilic groups, which can make up for the shortage of polyurethane materials. In this study, keratin was prepared from tannery cattle hair waste. The keratin, isocyanate, polyol and other raw materials were used as the raw materials to prepare polyurethane materials with excellent comprehensive properties by chemical bonding. 
Moreover, polytetrahydrofuran ether (PTMEG) was reacted with 4.4-dicyclohexylmethane diisocyanate (HMDI) to form prepolymer. Then, dihydroxymethylpropionic acid (DMPA), neopentane diol (NPG) and trimethylolpropane (TMP) were used to extend the chain. Finally, neutralization and emulsification were carried out. Keratin was added in the emulsification process and then keratin modified waterborne polyurethane was prepared. The effects of keratin on the structure and properties of waterborne polyurethane were also investigated.
The experiment results indicated that the addition of keratin does not affect the transparency and thermal stability of the PU film, and the hydrophilicity of the modified PU film was enhanced and the water vapor permeability becomes better. The DMA test showed that the mechanical properties of the modified PU film with a certain amount of keratin added (≤0.1 wt.%) were significantly improved. The yellowing resistance test showed that the addition of a proper amount of keratin can effectively increase the degree of cross-linking of the PU and increase its stability to light, but the addition of an excessive amount of protein (≥0.2 wt.%) would result in a decrease in the yellowing resistance of the PU film.

 

Take-Away

  1. The cattle hair keratin modified waterborne polyurethane emulsion is stable and uniform. What's more, the modified PU film is flexible and transparent.
  2. Keratin modification has little effect on the thermal stability of waterborne polyurethane. The addition of appropriate keratin (< 0.1 wt.%) can significantly improve the crosslinking degree and light stability of PU, but the excessive addition of keratin will decrease of yellowing resistance of PU.
  3. The water vapor permeability of PU film increased with the increase of keratin content. The contact angle test showed that the surface hydrophilicity of modified PU decreased with the increase of keratin content. The tensile strength and elongation at break of modified PU film also increased, too.
Appearance of cattle hair keratin modified waterborne polyurethane
Yellowing resistance of keratin modified polyurethane
Keywords: waterborne polyurethane ; modification ; cattle hair; keratin
12:20 PM SpSc2-06

Closed loop systems for liming and tanning hides and skins at large and cottage-scale (#57)

R. P. Daniels1, R. P. Daniels1

1 Greentech, Northampton, United Kingdom

Content

To reduce the environmental impact of tanneries at source for all types of leather, a series of investigations started at laboratory, then large pilot scale, to rationalise liming and tanning processes. This included the elimination of washes at the end of these processes, with retention of residual processing floats at maximum concentration as a chemical resource for reuse in subsequent processing.

Adopted by four tanneries manufacturing more than 70,000 hides per week to the chromium tanned state, analysis detailing the equalisation of ions and solubles within these closed-loops was possible, and the subsequent release mechanisms.

Large scale wet blue units specifically built to match the technology are now in the final stages of construction. From foundation level these differ from normal design, also uses of equipment, management of discharges, and plant operation. Low-impact chemical processing is locked into the fabric of these new tanneries.

The technology has also spread to large scale nappa sheepskin production.  And at cottage scale, thirty small tanneries in a tanning cluster processing sheep, goat, and bovine leathers to the wet blue are already changed their processing to meet a policy of no chromium discharges from their tanning areas by June 2019.

The aims of low-impact manufacture, where the use of active chemicals is complete, quality fully maintained, and waste minimised are being met. This new approach to leather making offers considerable benefits at both large and small scale for wet blue manufacture.

Take-Away

  • Closed loop systems for liming and tanning are highly effective in leather manufacture.
  • Hight quality leathers can result fron this technology.
  • There are considerable savings in chemical use and minimisation of waste water treatment
Keywords: Rationalised - recycling - liming – tanning