Hierarchical nanoclay–glass fiber hybrid reinforcement for improved fatigue life in rubber V-belts

The service life of industrial V-belts is often curtailed by fatigue failure under cyclic loading. In this work, a styrene–butadiene/polybutadiene/smoked rubber (SBR/PBR/SMR) blend was reinforced with 5 phr Cloisite® 15A nanoclay and 5 phr short A-glass fibers. The composite was processed via Banbury mixing, calendaring, layering with PET cord, and vulcanization. Rheological analysis revealed distinct filler effects: short glass fibers (SGF) yielded the fastest cure rate (CRI), while the hybrid system achieved the highest final crosslink density ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi>M</mml:mi> </mml:mrow> </mml:math> ). Compared to the unfilled compound, the hybrid composite exhibited superior performance, including a 29% increase in tensile strength, a 14% improvement in abrasion resistance, and a 79% rise in glassy storage modulus ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>E</mml:mi> <mml:mrow> <mml:mi>g</mml:mi> <mml:mi>l</mml:mi> <mml:mi>a</mml:mi> <mml:mi>s</mml:mi> <mml:mi>s</mml:mi> <mml:mi>y</mml:mi> </mml:mrow> <mml:mo>′</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> at −80°C). Dynamic mechanical analysis (DMA) confirmed this reinforcement through a higher glass transition temperature ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:mi>g</mml:mi> </mml:msub> </mml:mrow> </mml:math> ) and revealed that the hierarchical filler network maximized energy dissipation (highest <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">tan</mml:mi> <mml:mo> </mml:mo> <mml:msub> <mml:mi>δ</mml:mi> <mml:mi mathvariant="italic">max</mml:mi> </mml:msub> </mml:mrow> </mml:math> ), establishing a direct, quantitative link to fatigue performance. Consequently, the compound’s fatigue life increased by 42% (from 1.30 × 10 5 to 1.85 × 10 5 cycles), which translated directly into a 40% extension of the V-belt’s operational life (from 100 to 140 h) under multi-pulley dynamic testing. This work establishes a validated framework demonstrating that engineering viscoelastic and interfacial properties at the material level is a powerful strategy for developing more durable power transmission belts.