Effect of proteins on the structure of crosslinking junctions and mechanical properties of vulcanized natural rubber

IF 5 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing Pub Date : 2025-03-27 DOI:10.1016/j.polymertesting.2025.108782

Masaki Yamano , Takayuki Saito , Yoshimasa Yamamoto , Seiichi Kawahara

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Abstract

Primary structure of vulcanized natural rubber was quantitatively analyzed by rubber state NMR spectroscopy to investigate a relationship between structure, strain-induced crystallization and mechanical properties of the rubber. The vulcanized natural rubber was prepared from deproteinized natural rubber (DPNR) and natural rubber, which were compounded with sulfur, ZnO, stearic acid, and N-tert-butyl-2-benzothiazole sulfenamide (TBBS), at temperatures of 110, 130, 150, and 170 °C under pressure of 15 MPa for optimal vulcanization time, t₉₀. The vulcanized rubbers were characterized by rubber-state NMR spectroscopy, swelling method, and wide angle X-ray diffraction measurement. Carbon-sulfur bonds of the vulcanized rubbers were quantitatively compared with crosslink density, and abnormal groups such as trans-1,4 isoprene units were analyzed as a side reaction product. Contents of carbon-sulfur bonds and trans-1,4 isoprene units of the vulcanized rubbers increased as the vulcanization temperature rose; that is, a sequence length of cis-1,4 isoprene units was shortened with the temperature. Accordingly, the strain-induced crystallization was suppressed and the mechanical properties were reduced as the vulcanization temperature rose. The strain-induced crystallinity and tensile strength of the vulcanized DPNR were higher than those of the corresponding vulcanized natural rubber while the crosslink density and cis-1,4 isoprene unit content of the vulcanized DPNR were lower.

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蛋白质对硫化天然橡胶交联结结构及力学性能的影响

采用橡胶状态核磁共振光谱法定量分析了硫化天然橡胶的一级结构，探讨了橡胶的结构、应变结晶与力学性能之间的关系。以脱蛋白天然橡胶（DPNR）和天然橡胶为原料，分别与硫、ZnO、硬脂酸和n -叔丁基-2-苯并噻唑磺酰胺（TBBS）进行复配，在温度为110、130、150和170℃、压力为15 MPa的条件下，获得了最佳的硫化时间t90。通过橡胶态核磁共振光谱、膨胀法和广角x射线衍射测量对硫化橡胶进行了表征。用交联密度定量比较了硫化橡胶的碳硫键，并分析了副反应产物反式-1,4异戊二烯单元等异常基团。随着硫化温度的升高，硫化橡胶的碳硫键和反式-1,4异戊二烯单元的含量增加；即顺式-1,4异戊二烯单元的序列长度随着温度的升高而缩短。因此，随着硫化温度的升高，应变诱导结晶受到抑制，力学性能下降。硫化DPNR的应变诱导结晶度和抗拉强度高于相应的硫化天然橡胶，而交联密度和顺式-1,4异戊二烯单位含量较低。

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来源期刊

Polymer Testing 工程技术-材料科学：表征与测试

CiteScore

10.70

自引率

5.90%

发文量

328

审稿时长

44 days

期刊介绍： Polymer Testing focuses on the testing, analysis and characterization of polymer materials, including both synthetic and natural or biobased polymers. Novel testing methods and the testing of novel polymeric materials in bulk, solution and dispersion is covered. In addition, we welcome the submission of the testing of polymeric materials for a wide range of applications and industrial products as well as nanoscale characterization. The scope includes but is not limited to the following main topics: Novel testing methods and Chemical analysis • mechanical, thermal, electrical, chemical, imaging, spectroscopy, scattering and rheology Physical properties and behaviour of novel polymer systems • nanoscale properties, morphology, transport properties Degradation and recycling of polymeric materials when combined with novel testing or characterization methods • degradation, biodegradation, ageing and fire retardancy Modelling and Simulation work will be only considered when it is linked to new or previously published experimental results.