High-efficiency chrome tanning using pre-treatments: synchrotron SAXS and DSC study

Authors: Yi Zhang (Leather and Shoe Research Association of New Zealand) , Jenna K. Buchanan (Leather and Shoe Research Association of New Zealand) , Geoff Holmes (Leather and Shoe Research Association of New Zealand) , Sujay Prabakar (Leather and Shoe Research Association of New Zealand)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: XXXV IULTCS Congress 2019
Peer Reviewed: No

State: Published (Approved)
Published: June 2019

Abstract: Pre-treatments are widely used during tanning processes as to improve the performance of the main tannage. Synchrotron small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to study four common types of pre-treatments, viz. monodentate complexing agent (sodium formate, SF), chelating agent (disodium phthalate, DSP), covalent cross-linker (glutaraldehyde, GA) and nanoclay (sodium montmorillonite, MMT) about their effects on chromium-collagen cross-linking reaction during tanning. Based on the results, the performance of chromium-collagen cross-linking with and without pre-treatments was presented considering five aspects: cross-linking, the level of hydration, hydrothermal stability, uniformity through leather cross-section and the uptake of chrome. Comparing to the original ThruBlu chrome tanning, at the same chrome offers, leather pre-treated using SF, DSP and MMT showed improved hydrothermal stability, uniformity and the level of hydration, while GA showed decreased hydration. All of the pre-treatments reduce surface fixation by decreasing the reactivity of chromium with collagen. Changes in the reaction performance can influence the properties of the leather products as well as the efficiency of the leather manufacturing processes. Insights into the structural changes of collagen during tanning with varied reaction conditions can guide the design of novel, benign tanning processes to reduce environmental impact. Take-Away: 1. Uniformity of the hydrothermal stability through leather cross-section were improved by all of the studied pre-treatments. 2. Reactivity of chromium to cross-link with collagen was reduced as a result of the complexing, covalent cross-linking, or preferential adsorption. 3. Complexing agents and nanoclay pre-treatments tend to retain collagen bound water, while covalent cross-linker causing decrease in the level of hydration of collagen.

Journal Keywords: collagen structure; pre-treatment; chrome tanning; SAXS; DSC

Subject Areas: Materials

Instruments: I22-Small angle scattering & Diffraction

Added On: 08/08/2019 14:13

Discipline Tags:

Materials Science

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)