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Formability is an important property of automotive pre-coated metals (PCMs). The purpose of this study is to investigate the effect of long alkyl chains of polycarbonatediol to control the formability of polyester coatings.

Polyester resins with long alkyl chains were synthesized using different contents of polycarbonatediol. These resins were characterised by gel permeation chromatography (GPC), ¹H nuclear magnetic resonance (¹H NMR) and fourier transform infrared spectroscopy (FT-IR). The polyester coatings were characterised according to their viscoelastic behaviour, formability, flexibility and anti-corrosion property.

The tensile strength of PCM should be larger than 5.6 MPa of the compressive stress at a strain of 23.4 per cent to overcome the harsh condition of deep drawing. To analyse the formability, F_ε (forming coefficient based on strain) and F_U (forming coefficient based on strain energy) were calculated. When F_ε and F_U were larger than 1, the polyester coatings exhibited good formability.

Long alkyl chains of polycarbonatediol gave flexibility and good formability to the polyester coatings.

There are two conditions that lead to the good formability of PCM. One is tensile strength and the other is forming coefficients based on strain and strain energy.

Long alkyl chains of polyester were a major factor to improve flexibility and formability. Thus, to have good formability, the tensile strength of PCM should be larger than 5.6 MPa, and the forming coefficients should be larger than 1.

This study examines how different stacking sequences of bamboo and flax fibers, treated with 5% aqueous sodium hydroxide (NaOH) and filled with 6wt% titanium oxide (TiO₂), affect the physical, mechanical and dry sliding wear resistance properties of a hybrid composite.

Composites with different fiber stacking arrangements were developed and tested per American Society for Testing and Materials (ASTM) standards to evaluate physical, mechanical and wear resistance properties, focusing on the impact of flax fiber mats at intermediate and outer layers.

The hybrid composite significantly outperformed composites reinforced solely with bamboo fibers, showing a 65.95% increase in tensile strength, a 53.29% boost in flexural strength and a 91.01% improvement in impact strength. The configuration with multiple layers of flax fiber mat at intermediate and outer levels also demonstrated superior wear resistance.

This study highlights the critical role of stacking order in optimizing the mechanical properties and wear resistance of hybrid composites. The findings provide valuable insights for the design and application of advanced composite materials, particularly in industries requiring high performance and durability.