## 1 Introduction  
Poly(3-hydroxybutyrate) (P3 HB) is a member of the polyhydroxyalkanoate family, distinguished by its short side chain. P3 HB has attracted significant attention for its potential in biomedical and packaging due to its biodegradability, biocompatibility, and ease of production via bacterial fermentation, typically using _Raltonia eutrolpa_ and propionate-rich carbon sources [1]. Although the 3-hydroxybutyrate (3 HB) unit has a chiral center, bacteria produce only one optically active form, resulting in a highly crystalline polymer, typically exceeding 50% crystallinity [2]. P3 HB has a glass transition temperature of around 10 \({}^{\circ}\)C and mechanical properties similar to those of polyethylene and polyethylene terephthalate, though it is more hydrophilic [3]. However, its high crystallinity also leads to significant limitations, such as stiffness, britteness, and slow degradation [4, 5, 6, 7]. Additionally, P3 HB exhibits a high melting temperature of around 170 \({}^{\circ}\)C, which is, unfortunately, very close to its thermal decomposition temperature [8, 9]. This characteristic makes P3 HB challenging to process in its molten state, such as when using typical twin-screw extruders, due to the significant thermal degradation caused by the high temperatures, shear stress, and pressure over extended periods. Consequently, the polymer has a limited processing window, restricting its application and making it difficult to meet many industrial demands. Efforts to address these processing challenges have included the addition of plasticizers, structural modifications of the polymer, and blending with other materials [10; 11; 12]. Incorporating nanoclays has shown promise in improving the properties of P3 HB by forming intercalated or exfoliated nanostructures that enhance its thermal and mechanical stability [13]. Nanoclays are often surface-modified with organic compounds, such as quaternary ammonium salts, to improve compatibility with hydrophobic polymers [14; 15]. However, in P3 HB nanocomposites, the use of quaternary ammonium salts can be problematic, as they may lead to increased thermal degradation under typical preparation conditions (i.e., molten state and elevated temperatures) [15]. Alternatively, several studies have demonstrated a positive impact of certain nanoclays on P3 HB properties. For instance, montmorillonite modified with tributlyhexadecylphosphonium bromide have been shown to form intercalated structures using both casting and extrusion processes, effectively slowing the degradation rate [13]. P3 HB nanocomposites with Cloisite 30B exhibited a reduction in both glass transition temperature (by 7 \({}^{\circ}\)C) and melting temperature (by 15 \({}^{\circ}\)C) at a 3% weight clay content. Additionally, there was a slight increase in crystallinity (by 3%) and a significant rise in degradation temperature (by 11 \({}^{\circ}\)C) [15; 16]. These findings suggest that the intercalated clay acts as a plasticizer, enhancing processability by increasing the temperature gap between melting and decomposition. High-power ultrasound waves have emerged as a promising alternative for polymer processing, particularly through ultrasound micromolding (USM). This technique has been shown to reduce thermal degradation, enhance spatial resolution, and minimize material waste by significantly shortening the processing time and lowering processing temperatures [17; 18; 19; 20]. USM has already demonstrated advantages in processing various polymers, such as polylactide, polypropylene, and polyamides, with minimal molecular degradation and high product consistency [21; 22; 23; 24; 25]. Recent studies suggest that USM can facilitate the homogeneous dispersion of nanoclay in polymer matrices, even achieving exfoliated structures without requiring surface modification [17]. However, the full potential of USM for biodegradable polymers like P3 HB, particularly in combination with nanoclays, has not been systematically explored.