Malaysian Journal of Analytical Sciences Vol 26 No 2 (2022): 176 - 190

 

 

 

 

COMPARATIVE STUDY ON VISCOSITIES, STRESS RELAXATION, CURING AND MECHANICAL PROPERTIES OF SEPIOLITE AND SILICA FILLED NATURAL RUBBER COMPOSITES

 

(Kajian Perbandingan Mengenai Kelikatan, Kelonggaran Tekanan, Penyembuhan dan Sifat Mekanikal Komposit Getah Asli dengan Sepiolit dan Silika)

 

Nabil Hayeemasae^1,2, Ajaman Adair³, Abdulhakim Masa^2,4*

 

¹Department of Rubber Technology and Polymer Science, Faculty of Science and Technology

²Research Unit of Advanced Elastomeric Materials for BCG Economy, Faculty of Science and Technology
Prince of Songkla University, Pattani Campus, 94000 Pattani, Thailand

³Department of Cosmetic Science and Beauty, Faculty of Science Technology and Agriculture,
Yala Rajabhat University, 95000 Yala, Thailand

⁴Rubber Engineering & Technology Program,

 International College, Prince of Songkla University,
90110 Hat Yai, Songkhla, Thailand

 

*Corresponding author:  abdulhakim.m@psu.ac.th

 

 

Received:  1 November 2021; Accepted: 3 February 2022; Published:  28 April 2022

 

 

Abstract

In the present study, natural rubber composites filled with sepiolite and silica were prepared. The effects of the two fillers by loading (1–10 phr) on viscosities, stress relaxation, curing, and mechanical properties of the composites were investigated. Viscosity of rubber usually increased with filler loading about 7–22% with sepiolite and about 3–37% with silica, depending on filler content. Smaller rate of stress relaxation was found with sepiolite filler in comparison with silica filler. Furthermore, shorter curing cycle with greater crosslink density and hot temperature reversion resistance were achieved through the use of sepiolite filler in NR. Lorenz-Parks and Kraus models utilized for assessing rubber-filler interactions revealed stronger interactions of sepiolite filler with the rubber matrix. As a result of the good interactions between sepiolite filler and rubber matrix, larger reinforcement indexes and tensile strengths were achieved with sepiolite filler in comparison with silica filler. This was due to the higher aspect ratio of sepiolite (~5.32) compared to that of silica (~1.09) as demonstrated by SEM analysis. The highest tensile strength was achieved at 1 phr sepiolite loading which was about 17% improvement over unfilled sample.

 

Keywords:  composites, fillers, rubber, sepiolite, silica

 

Abstrak

Komposit getah asli yang diisi dengan sepiolit dan silika telah disediakan dalam kajian ini. Kesan kedua-dua pengisi dengan memuatkan (1-10 phr) pada kelikatan, kelonggaran tekanan, tempoh pematangan dan sifat mekanikal komposit telah disiasat. Kelikatan getah biasanya meningkat dengan pengisi yang memuatkan dari 7-22% dengan sepiolite dan kira-kira 3-37% dengan silika, bergantung kepada kandungan pengisi. Kadar kelonggaran tekanan yang lebih kecil didapati dengan sepiolit berbanding dengan pengisi silika. Juga, tempoh pematangan yang lebih pendek dengan ketumpatan sambung silang yang lebih tinggi dan rintangan perkembalian suhu panas dicapai dengan menggunakan pengisi sepiolit dalam getah asli. Model Lorenz-Parks dan Kraus yang digunakan untuk menilai interaksi pengisi getah mendedahkan interaksi yang lebih kuat dari pengisi sepiolit dengan matriks getah. Indeks pengukuhan yang lebih tinggi dan kekuatan tegangan dicapai dengan pengisi sepiolit daripada pengisi silika. Ini disebabkan oleh interaksi pengisi getah yang lebih baik yang timbul daripada nisbah aspek sepiolit yang lebih tinggi (~ 5.32) daripada silika (~ 1.09) seperti yang kemudiannya didedahkan oleh analisis SEM. Kekuatan tegangan tertinggi dicapai pada 1 phr pemuatan sepiolite iaitu kira-kira 17% peningkatan berbanding sampel yang tidak diisi.

 

Kata kunci:  komposit, pengisi, getah, sepiolit, silika

 

 

Graphical Abstract

 

 

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