二氧化矽顆粒階級結構與表面特性對綠色輪胎動態機械性能的影響

Abstract

本研究使用實驗室級之混煉機，混合二氧化矽和橡膠高分子，並探討其階級結構(hierarchical structure)與表面特性(surface texture)對綠色輪胎機械性質的影響。研究內容包括以下六個部分: (1)分析超高、高和中比表面積二氧化矽之粉末性質; (2)比較不同矽烷耦合劑混煉之胎面膠性能，(3)比較並分析二氧化矽表面性質對胎面膠性能之影響，(4)改變二氧化矽添加量，(5)分析低碳材料二氧化矽胎面膠樣品之性能，及(6)使用Gel network model對SAXS圖譜擬合並分析。我們使用新竹同步輻射研究中心(NSRRC-TPS13A1)之生物小角度X光散射(BioSAXS)進行實驗，從散射圖譜中得知二氧化矽粉末之基本顆粒大小(primary particle size)、碎形維度(fractal dimension)、二氧化矽聚集體大小(cluster size)及圍困橡膠尺寸大小(mesh size)等階級結構。我們使用動態機械分析儀(dynamic mechanical analysis)測量胎面膠樣品的機械性質，包括潘恩效應(Payne effect)、濕地抓地力(wet grip)、滾動阻力(rolling resistance)及剛性(stiffness)。磨耗(abrasion)則是使用耐磨耗滾筒進行量測。除此之外，我們也使用熱裂解氣相層析質譜儀(Pyrolysis GC/MS)分析矽烷耦合劑之相對殘餘量。 實驗結果顯示，比表面積與二氧化矽的原始顆粒大小及其碎形結構密切相關，進而影響其在胎面膠中的分散性與機械性質。於高比表面積系列中，S-SiO₂雖與230G-G具相似的碎形維度，但因原始顆粒較小，其BET值最高；而顆粒最大的E-9100因碎形結構較封閉，BET值介於兩者之間。中比表面積系列中，三種二氧化矽顆粒大小相近，但BET值差異則源自碎形維度變化，其中結構較開放的255EG-CO₂具有最高BET值。胎面膠性質方面，聚集體大小與BET值呈反比，聚集體越小，代表分散越佳，通常伴隨較低的滾動阻力與較高的濕地抓地力，但剛性略為下降。不同二氧化矽在各自最適添加量（超高比表面積：S/N/D分別為12/16.2/10.8 phr；高比表面積：G/E分別為9/12 phr；中比表面積：H/C/EG皆為6.4 phr）下，其聚集體尺寸及動態機械性質亦存在差異，其中S-SiO2於最適添加量下具有較佳性能。

This study utilized a laboratory-scale internal mixer to blend silica with rubber polymers, aiming to investigate how the hierarchical structure and surface texture of silica affect the mechanical properties of green tire tread compounds. The research is composed of six main sections: (1) analysis of the powder properties of ultra-high, high, and medium specific surface area silicas; (2) comparison of tread performance with different silane coupling agents; (3) evaluation of the influence of silica surface characteristics on compound performance; (4) investigation of the effects of varying silica loadings; (5) performance analysis of tread compounds incorporating low-carbon silicas; and (6) application of the gel network model to fit SAXS data. Small-angle X-ray scattering (BioSAXS) was conducted at the NSRRC TPS 13A1 beamtime to determine primary particle size, fractal dimension, cluster size, and rubber mesh size. The mechanical properties of tire tread were measured using dynamic mechanical analysis (DMA), including the Payne effect, wet grip, rolling resistance, and stiffness, while abrasion resistance was evaluated using a DIN abrasion tester. The residual content of silane coupling agents was further analyzed by Pyrolysis GC/MS.

Experimental results show that specific surface area is closely related to the primary particle size and fractal structure of silica, which in turn affects dispersion and mechanical performance in rubber compounds. Among the high specific surface area silicas, although S-SiO₂ and 230G-G share similar fractal dimensions, S-SiO₂ possesses a higher BET surface area due to its smaller primary particles. Conversely, E-9100, with the largest particles and lowest fractal dimension, exhibits a BET value between the two. In the medium specific surface area group, all three silicas have comparable particle sizes, yet BET values differ due to variations in fractal dimension, with 255EG-CO₂ having the highest BET value. Generally, a smaller cluster size—associated with a higher BET value—indicates better dispersion, leading to lower rolling resistance and improved wet grip, but with slightly reduced stiffness. Each silica also shows distinct optimal loading levels (ultra-high specific surface area: 12, 16.2, and 10.8 phr for S, N, and D, respectively; high specific surface area: 9 and 12 phr for G and E; medium specific surface area: 6.4 phr for H, C, and EG), under which the best balance between cluster size and mechanical properties was observed. Specifically, S-SiO2 demonstrated superior performance at their respective optimal loadings.