Thermal–Mechanical and Spectroscopic Analysis of Fast-growing Tropical Hardwoods Paraserianthes falcataria and Neolamarckia cadamba

Abstract

Thermo-mechanical and chemical behaviour of two tropical plantation timbers, Batai (Paraserianthes falcataria) and Laran (Neolamarckia cadamba), were investigated using dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR). The DMA was conducted with a heating rate of 2 °C/min at frequencies of 1, 2, and 5 Hz. The results revealed frequency- and species-dependent differences in storage modulus (E′), loss modulus (E″), and damping factor (tan δ) across 25 to 250 °C. Batai exhibited lower stiffness but higher damping capacity, with sharper tan δ peaks corresponding to hemicellulose relaxations, whereas Laran demonstrated higher stiffness, broader transitions, and reduced damping due to its lignin-rich matrix. The glass transition temperature (T_g) determined from tan δ peaks was more distinct for Batai (95 to 102 °C) than Laran (83 to 126 °C), confirming contrasting relaxation behaviours. The FTIR spectra further distinguished the species: Batai showed sharper carbohydrate-associated peaks, indicating more crystalline cellulose domains, while Laran displayed stronger hydroxyl, carbonyl, and aromatic absorbance linked to hemicellulose and lignin. Correlating DMA and FTIR findings highlighted that Batai’s greater damping arises from its accessible amorphous domains, while Laran’s enhanced stiffness stems from its crosslinked lignin–hemicellulose network.