Marinai Daniele, Borchi Cristiana, Marinai Lorenzo, Defeo Gustavo Adrián, Manariti Antonella, Minei Pierpaolo, Castelvetro Valter, Ciardelli Francesco
Kemas s.r.l., Via Sardegna 2, 56029 Santa Croce sull'Arno, Italy.
CTC Ars Tinctoria s.r.l., Via del Bosco 125, 56029 Santa Croce sull'Arno, Italy.
Polymers (Basel). 2024 Dec 4;16(23):3411. doi: 10.3390/polym16233411.
The elastic response of chromium-tanned leather was successfully improved by treatment with XSBR, a carboxylated styrene-butadiene copolymer. The carboxylic groups pending from a styrene-butadiene rubber (SBR) backbone were found to promote penetration of the aqueous polymer dispersion into the fibrous tanned leather and participated in pH-reversible physical crosslinking by H-bonding. The different penetrations of XSBR or SBR were investigated using a micro-FTIR cross-sectional analysis from the grain (outer) to the flesh (inner) side of 18 wt% elastomer-treated samples, based on the shaved leather weight. In particular, the profile of the diagnostic out-of-plane =C-H bending of butadiene and styrene units was consistent with a more effective penetration of XSBR. The leather with XSBR showed a comparatively lower elastic modulus of 10-15% and roughly a 10% increase in elongation at the break, indicating better flexibility and shape recovery. Also, the leather was characterized by a 15% higher burst strength. These results suggest the better swelling of the ionomeric XSBR in the initial stage of retanning performed at a pH higher than the isoelectric point of the leather when both the tanned leather and the XSBR ionomer had a negative surface charge. The high pH favored the penetration of XSBR due to a poor attractive interaction with the tanned fibrous leather network. Subsequent processing in an acid bath caused further physical crosslinking through hydrogen bonding between XSBR and the leather.
通过用羧化苯乙烯 - 丁二烯共聚物XSBR处理，成功改善了铬鞣革的弹性响应。发现从丁苯橡胶（SBR）主链悬垂的羧基可促进水性聚合物分散体渗透到纤维鞣革中，并通过氢键参与pH可逆的物理交联。基于削匀皮革重量，使用微傅里叶变换红外光谱（micro-FTIR）横截面分析，从18 wt%弹性体处理样品的粒面（外层）到肉面（内层）研究了XSBR或SBR的不同渗透情况。特别是，丁二烯和苯乙烯单元的面外=C-H弯曲诊断谱与XSBR更有效的渗透一致。含有XSBR的皮革显示出相对较低的弹性模量，降低了10 - 15%，断裂伸长率大致增加了10%，表明具有更好的柔韧性和形状恢复能力。此外，该皮革的爆破强度高15%。这些结果表明，当鞣革和XSBR离聚物都具有负表面电荷时，在高于皮革等电点的pH值下进行复鞣初始阶段，离聚体XSBR具有更好的溶胀性。高pH值有利于XSBR的渗透，因为它与鞣制的纤维皮革网络的吸引相互作用较弱。随后在酸浴中处理会通过XSBR与皮革之间的氢键进一步形成物理交联。
