Development of PBAT-Modified Photopolymer Resin Micro-Composites for More Sustainable SLA Additive Manufacturing

Abstract

The photopolymer resins commonly utilized in stereolithography (SLA) additive manufacturing are non-renewable, brittle in nature and have low impact and thermal insulation properties, limiting their applications in sustainable and functional applications. To overcome these shortcomings, this paper introduces the initial research on the use of Polybutylene Adipate Terephthalate (PBAT), a biodegradable polymer, into SLA resins to create partially sustainable micro-composites with enhanced mechanical and thermal capabilities. PBAT micropowder was mixed with standard resin at 1, 5 and 10 wt% and 3D printed using SLA. To determine performance and interfacial morphology, mechanical testing (tensile and impact), thermal conductivity measurements and SEM fracture surface analysis were carried out. Introduction of PBAT significantly increased toughness, flexibility and the impact strength of the 1% PBAT composite stood at 168.63 J/m² with 68.69 J/m² of pure resin whereas the 10% PBAT sample was found to be 16% more efficient in thermal insulation. These findings indicate that partially replacing the photopolymer resin with biodegradable PBAT can enhance impact strength and thermal insulation while reducing the overall amount of petrochemical resin required. The article provides a new avenue of eco-friendly, high-performance photopolymer composites to facilitate sustainable additive manufacturing.

1. Introduction

Stereolithography (SLA) has emerged as a transformative additive manufacturing technique, significantly influencing numerous industries due to its exceptional accuracy, versatility, and capability to fabricate intricate geometries [1,2]. Since its invention by Charles W. Hull in the mid-1980s, SLA has pioneered the approach of constructing three-dimensional objects through a precise layer-by-layer photopolymerization process [3]. This method involves selectively curing a liquid photopolymer resin using a computer-controlled ultraviolet (UV) laser or digital projector, resulting in the seamless integration of consecutive layers and enabling the production of highly complex designs with outstanding dimensional reliability [4]. The distinctive advantage of SLA lies in its ability to create parts with exceptionally fine features, intricate detailing, and superior surface finishes, attributes highly valued across various critical sectors, including healthcare, automotive, consumer goods, and jewelry [5]. For example, in healthcare, SLA rapidly fabricates anatomical models for surgical planning, custom implants, and prosthetics, enhancing patient outcomes and procedural safety [6,7]. The automotive sector leverages SLA for rapid prototyping of complex components, such as grilles, dashboards, and internal structures [8]. Additionally, SLA’s precision benefits the jewelry and consumer products industries, where fine detailing and superior finishes are essential for market competitiveness [9,10].

The mechanical properties of parts produced through Stereolithography (SLA) are highly sensitive to a variety of factors, each playing a critical role in determining the final performance of the printed components [11]. The choice of resin directly influences the strength, flexibility, and durability of SLA parts and must be aligned with application-specific demands, whether for high-stress industrial components or fine, intricate parts, while appropriate post-processing techniques play a crucial role in further enhancing their mechanical properties [12,13,14]. These processes, including curing and heat treatment, significantly improve the strength, durability, and flexibility of the printed components [15]. Post-processing ensures that the final parts achieve optimal mechanical performance by refining the material properties and removing residual stresses from the printing process [16,17]. Additionally, printing parameters like layer thickness and exposure times critically influence mechanical characteristics such as tensile strength, elongation, and impact resistance [18]. Precise control of these variables allows for tailored mechanical properties, maintaining SLA’s versatility across diverse applications [19,20,21].

Additives in resins, whether in the form of nano-fillers, fine powders, or micro-powders, play a crucial role in enhancing material properties for advanced applications. These additives are introduced to improve mechanical strength, thermal stability, electrical conductivity, and magnetic behavior, depending on the specific requirements of the final composite [22]. They can be synthesized through various techniques, including milling, grinding, and chemical processes, ensuring precise control over particle size and distribution. Due to their high surface area and interaction with the resin matrix, these additives enhance performance by modifying structural integrity, increasing stiffness, and improving durability [23]. Ceramic-based fillers, for example, contribute to thermal stability and resistance to degradation, making them ideal for high-temperature applications in electronics, aerospace, and automotive components. Similarly, conductive additives can improve electrical properties, while magnetic fillers enable specialized functionalities in sensor or shielding applications [24]. The incorporation of these materials expands the versatility of resin-based composites, allowing for tailored properties suited to demanding industrial and technological environments. They are intended for applications requiring lightweight, durable, and partially biodegradable components—such as protective housings, functional prototypes, biomedical models, and low-load structural components in consumer, packaging, and medical device industries.

The use of poly (butylene adipate-co-terephthalate) (PBAT), which is a biodegradable polymer that is flexible [25], tough, and environmentally friendly [26], in resin systems is one of the major advances in the direction of sustainability in additive manufacturing. PBAT does not only improve fundamental traits of materials like impact resistance and flexibility, but it also provides an avenue to avoid the use of non-renewable photopolymer resin. PBAT stands out from PHB by offering much greater flexibility and toughness—reviews and experiments consistently show PBAT delivering high elasticity/elongation and effectively toughening brittle biopolyesters, whereas PHB (and even PHBV) remains comparatively brittle [27].

In resin matrices, PBAT blends exhibit good interfacial compatibility that can be further boosted with surface-modified bio-nanofillers (e.g., CNC, lignin) and photopolymerization-aware surface chemistry, enabling tougher, better-bonded SLA/VP composites [28]. Although it is a promising material, none of the past research has recorded the application of PBAT in resin systems of SLA, or examined its influence on the mechanical and thermal properties. Few studies have explored biodegradable modifiers in resin systems; most focus on nano or mineral fillers rather than biodegradable elastomers. This research gap will be bridged by the current work, which is expected to formulate and describe biodegradable PBAT-resin micro-composites to use in more sustainable SLA additive manufacturing, which will integrate environmental friendliness with enhanced material performance. The study aims to achieve a twofold goal by partially replacing conventional photopolymer resin with PBAT, enhancing mechanical toughness and thermal resistance while introducing biodegradability into SLA-printed materials. The work is guided by the hypothesis that small PBAT additions will improve ductility and impact performance through energy-dissipating mechanisms, while higher concentrations will increase thermal insulation through phonon scattering and PBAT-domain interfaces. A systematic combination of tensile, impact, and thermal testing, supported by scanning electron microscopy (SEM), is used to evaluate both macroscopic performance and microstructural behavior. SEM observations further confirm PBAT dispersion and reveal microvoids and crack-like features consistent with improved toughness at low PBAT loadings. Together, these analyses demonstrate PBAT’s potential as a sustainable and effective modifier for developing eco-friendly, high-performance resin composites designed for next-generation additive manufacturing applications.

2. Materials and Methods

2.1. Materials

This section describes the experimental workflow, including material preparation, SLA fabrication, and subsequent mechanical, microstructural, and thermal characterization. All experiments were conducted using identical processing conditions to ensure consistency across compositions. Standard clear UV resin (acrylate-based) was selected as the base material, complemented by PBAT micropowder to modify the resin’s characteristics. The photopolymer used in this study was ANYCUBIC Standard Resin V2 (Clear), obtained from ANYCUBIC Technology Co., Ltd. (Shenzhen, China). The biodegradable polymer Poly(butylene adipate-co-terephthalate) (PBAT) was incorporated as the biodegradable modifier owing to its flexible aliphatic–aromatic copolyester structure, fine powder availability, and well-documented compatibility with acrylate resin systems, supporting the sustainability objectives of this work. The PBAT powder (99.9% purity, ultrafine grade) was procured from Magerial Science^® (Shanghai, China). The PBAT powder had a nominal size of 200 mesh (≈74 µm) per supplier specification and was incorporated at varying concentrations of 1%, 5%, and 10% by weight. This addition was intended to explore the impact of different PBAT levels on the resin’s properties. The choice of PBAT aims to introduce specific performance traits to the UV resin. The standard clear UV resin’s mechanical properties are listed in

Table 1. Mechanical properties of the used resin [29].

Mechanical Properties	Standard Resin
Tensile Strength (MPa)	38
Elasticity Modulus (GPa)	1.6
Elongation at Break	12%
Flexural Modulus (GPa)	1.25
UV curing wavelength (nm)	365–405
Viscosity (mPa·s)	250–350
Density (g/cm3)	1.05–1.25

. In Figure 1, a schematic showing the work principle of this study can be seen.

2.2. Preparation and Fabrication of Samples

The UV resin and PBAT micropowder were thoroughly mixed to ensure consistent material quality. The PBAT and photopolymer resin mixture was ultrasonically dispersed using a Fisher Scientific Ultrasonic Bath (1.9 L, 40 kHz, ~120 W) sourced from Fisher Canada Partnership, Mississauga, Canada. Operated at its maximum power setting (60 sonics) for 1 h at room temperature (≈25 °C) to ensure uniform dispersion and homogeneity of the blend. The interaction between PBAT and the photopolymer resin occurs primarily through physical and secondary chemical bonding rather than full copolymerization. Although this study does not directly measure molecular interactions between PBAT and the photopolymer resin, previous literature reports that PBAT can form secondary interactions with acrylate-based matrices through hydrogen bonding or dipole–dipole interactions [30]. In this work, these descriptions are presented as literature-supported interpretations intended to contextualize potential compatibility during mixing and curing, rather than experimentally verified mechanisms. Once the mixture was homogeneous, it was transferred to the resin tank of the Anycubic Photon Mono X (Shenzhen Anycubic Technology Co., Ltd., Shenzhen, China), an advanced 3D printer that uses stereolithography (SLA) technology. 70% UV power and its default wavelength of 405 nm were used. All tensile, impact, and thermal specimens were printed flat on the build platform with their longitudinal axes in the X–Y plane. The Z-axis served as the transverse build direction through the specimen thickness. All formulations were printed using identical orientation and minimal support geometry to ensure consistent anisotropic effects across all groups. Following the preparation, the production process began with a thorough cleaning of the 3D printer to eliminate any residual old resin. The platform lifting and lowering speeds were kept constant for all printed specimens to eliminate kinematic variability between compositions. The default printing parameters were then used to fabricate all samples. In

Table 2. Printing Parameters.

Parameter	Value
Layer Thickness (mm)	0.05
Normal Exposure Time (s)	2
Off Time (s)	0.5
Bottom Exposure Time (s)	23
Bottom Layers	6
Z Lift Distance (mm)	8
Z Lift Speed (mm/s)	2
Z Retract Speed (mm/s)	3
UV Light Power	70%
Post curing time (Hr)	1

the printing parameters are given.

After printing, each object was carefully removed from the build platform and immediately cleaned using isopropyl alcohol to remove any uncured resin. This cleaning was crucial to prepare the parts for the final curing phase. The cleaned parts were placed in an Anycubic curing station and exposed to UV light for one hour. This additional UV exposure ensured that the parts were fully cured, enhancing their durability and mechanical strength and ensuring that even the internal areas of the parts, which might not have fully hardened during the initial printing, achieved optimal curing. This rigorous process results in final products that are robust, durable, and meet the highest quality standards.

2.3. Microstructural Analysis

To analyze the structure and fracture behavior of PBAT-resin micro-composites, the microstructural features and fracture behavior of the fractured tensile specimens were examined through a FEI Quanta FEG 250 scanning electron microscope (SEM). SEM imaging was conducted at 10–15 kV in secondary electron mode. Two representative regions were imaged for each specimen at 500× and 1000× magnifications to record fine-scale variation of texture, phase distribution, as well as interfacial properties. The characteristics that were identified in this analysis include matrix continuity, PBAT dispersion and microvoids or pull-out regions that determine the character of interfacial bonding between the domains of resin and PBAT. The morphology of the fracture surfaces was useful in identifying the prevailing failure modes which indicated that the pure resin had a brittle fracture whereas the PBAT-modified composites had more ductile or energy-absorbing fracture modes, thus relating the microstructural integrity to the mechanical performance.

2.4. Mechanical Testing

For mechanical testing, dog bone tensile and impact specimens were prepared in accordance with ASTM D638-14, Type IV and D256 standards (https://store.astm.org/standards/d256, accessed on 9 November 2025), encompassing four sample groups with 0%, 1%, 5%, and 10% PBAT compositions [31]. Each composition was tested three times to ensure the experimental results were statistically reliable. Following the completion of the 3D printing process, the samples were allowed to stabilize at room temperature for two days before testing. The uniaxial tensile tests were then conducted on an Instron 5966 (Instron, Norwood, MA, USA; 10 kN load cell; Bluehill v5.0). Tensile tests were conducted under displacement control mode with a crosshead speed of 5 mm/min, a sampling rate of 10 Hz, and a gauge length of 25 mm. All measurements were performed at 23 ± 2 °C and 50 ± 5% relative humidity [31]. In Figure 2 the dimensions of the used standard samples are given. The impact strength of the specimens was measured using a SATEC BTL Impact Tester (SATEC Systems, Inc., Grove City, PA, USA) with a 2 ft·lb (2.7 J) base capacity pendulum. These specimens were analyzed to evaluate the influence of PBAT addition on the tensile strength and impact resistance of the resin-based composites, providing critical insights into how the biodegradable PBAT affects the mechanical performance of photopolymer resins. This data is essential for optimizing material properties to suit specific applications, thereby enhancing the functional utility of the composites.

2.5. Thermal Conductivity Measurements

Thermal conductivity is a key property in evaluating a material’s heat conduction ability, crucial for applications in electronics, automotive, and construction. In this study, the KD2 Pro Thermal Properties Analyzer (Decagon Devices, Pullman, WA, USA) was employed to accurately measure the thermal conductivity of the prepared microcomposites. The device operates based on the transient line heat source method in accordance with ASTM D5334 [32] and IEEE 442 standards [33]. Measurements were conducted under controlled conditions at 23 ± 1 °C and 45–55% relative humidity, with samples stabilized for at least 30 min prior to testing to ensure thermal equilibrium. The TR-1 single-needle sensor was used, offering a range of 0.02–2.00 W m⁻¹ K⁻¹ and an accuracy of ±5%, with each reading requiring approximately one minute. Understanding the thermal behavior of these microcomposites is essential for optimizing their performance in thermal management systems, where quantitative analysis of their conductivity and corresponding insulation properties enables the design of more efficient and application-specific materials.

3. Results and Discussions

3.1. Microstructural Evaluation

Scanning electron microscopy (SEM) is an important analysis method used to assess the surface of polymer composite and microstructure. SEM is an invaluable part of the evidence needed in the development process of biodegradable PBAT-resin micro-composites used in sustainable SLA additive manufacturing due to the distribution possibilities and bonding of the resin matrix with PBAT. The microstructural features visible in SEM may correlate with key performance metrics such as tensile strength and impact resistance. The analysis of surface texture, phase implementation, and possible void formation allows the study of PBAT to define the extent of compatibility with the resin using SEM. Thus, SEM analysis is pivotal to the study of structure-property relationship of these composites and the confirmation of the success of the material formulation and processing strategy, as demonstrated in Figure 3 of the 0, 1, 5 and 10% PBAT to resin ratios.

Figure 3 shows the micrographs of the fracture surface of PBAT-resin micro-composites containing 0, 1, 5 and 10 wt% of PBAT (Figure 3A–D). Surface crack-like features present in the tensile fracture SEM images were quantified using the corresponding scale bars. The visible crack lengths ranged approximately from 10 to 40 µm, with apparent surface openings of 1–4 µm. The images represent tensile fracture surfaces (longitudinal section) of broken tensile specimens, aligned parallel to the loading axis. These values represent surface-level fracture morphology, and therefore do not include crack depth or subsurface propagation.

At 0% PBAT (Figure 3A), the fracture surface is smooth and featureless which is a characteristic of brittle fracture in a homogeneous resin matrix. The fact that it does not exhibit deformation characteristics or microvoids indicates that it does not absorb much energy upon failure.

At 1% PBAT (Figure 3B) very thin shear lines and shallow ridges start to form suggesting that adding such a small fraction of PBAT does slightly change the fracture mode. The highlighted areas show that there has been localized deformation of the matrix and initial-stage dispersion of PBAT, indicating the occurrence of enhanced toughness due to restricted energy loss at the interface.

The surface is even more rough with a high number of microvoids and pulled-out areas at 5% PBAT (Figure 3C), which shows increased ductility and better stress than 1%, PBAT and resin. The presence of microvoids and pulled-out regions at 5% PBAT suggests increased local plastic deformation and micro-crack deflection mechanisms. Although SEM provides qualitative evidence only, these features are consistent with the observed changes in tensile curves reported. Such characteristics prove that PBAT particles are stress concentrators, which facilitate plastic deformation and micro-crack deflection.

The morphology changes to a more irregular structure at 10% PBAT (Figure 3D) whereby the PBAT-rich domains can be distinguished, and larger voids may indicate inter-phase separation and low interfacial bond strength. The observed increased heterogeneity shows that large amounts of PBAT in the structure decrease structural uniformity resulting in early failure when tensile loaded. Comprehensively, the SEM observations support the progressive brittle to more ductile fracture behavior change under increasing PBAT content to an optimal point and then interfacial degradation becomes preeminent.

3.2. Analysis of Mechanical Properties

The tensile stress–strain curves for each sample are depicted in Figure 4. These curves were obtained from tests conducted to measure the elasticity and ultimate tensile strength of the composites. Each composition was subjected to controlled tensile testing, where a steady increase in tensile force was applied until failure occurred. The data collected from these tests were crucial in assessing the mechanical behavior of the materials.

The graphs reveal that pure resin exhibits the highest stiffness and tensile strength, as indicated by the steepest initial slope and the highest peak in stress reaching 43 MPa. This suggests superior load-bearing capabilities inherent in pure resin. Introducing 1% PBAT slightly reduces tensile strength, as seen by a lower peak compared to pure resin, though the curve’s overall shape remains similar, indicating only a minor reduction in mechanical performance. Increasing the PBAT content to 5% results in a noticeable decrease in both stiffness and peak stress reaching 34 MPa, implying reduced load-bearing capacity. The 10% PBAT sample also shows a decrease in peak stress when compared to pure resin, confirming a trend where increasing PBAT content reduces material strength but may enhance other properties like flexibility and energy absorption during deformation. The decrease in stiffness and strength with increased PBAT content can be attributed to its lower elastic modulus and inherent flexibility compared to more rigid materials like pure resins. PBAT’s flexibility enhances energy absorption, beneficial for applications demanding higher impact resistance, but reduces the composite’s overall rigidity and load-bearing capacity. These changes are also due to alterations in the composite’s microstructure, disrupting load transfer efficiency within the material [34,35,36].

When considering photopolymer composites, it is important to assess Youngs modulus to explain the effect of addition of PBAT on the elastic characteristics and hardness of the resin matrix. Since the content of PBAT increases, differences in the stiffness may indicate differences in the efficiency of the molecular interaction and load transfer between the resin and the biodegradable phase. These observations play a vital role in defining the appropriateness of the developed PBAT-resin composites to be used in structural or flexible additive manufacturing. The values of Young’s modulus of the various compositions that were calculated are shown in Figure 5.

The Young’s modulus values show a clear trend across PBAT loadings: 0.67 ± 0.03 GPa at 0 wt%, increasing slightly to 0.77 ± 0.04 GPa at 1 wt%, and then decreasing to 0.55 ± 0.02 GPa at 5 wt% and 0.45 ± 0.02 GPa at 10 wt%. This initial increase at 1 wt% PBAT suggests that a small amount of well-dispersed PBAT may provide localized constraint within the resin matrix, reflected in the steeper initial slope of the stress–strain curve. At higher PBAT contents, however, the modulus decreases as the softer PBAT phase becomes more dominant, reducing the effective stiffness of the composite. The reduction at 5 wt% and 10 wt% is consistent with the introduction of a more compliant second phase and a larger number of interfaces that deform more easily under load. These interpretations are qualitative and are provided to contextualize the observed mechanical trends rather than to propose a verified molecular mechanism.

This section of the research focuses on how the integration of PBAT affects the composites’ ability to resist impact forces, with varying concentrations of the additive altering the behavior and performance of the materials under such conditions. The subsequent analysis of impact strength will further delineate the potential of these innovative composites for a range of practical uses, particularly in environments subjected to shocks or high-impact loads. Figure 6 shows the impact strength results of each sample.

The impact strength graph elucidates the influence of PBAT concentrations on the energy absorption capabilities of biodegradable polymer-resin micro composites. The 1% PBAT Composite exhibits a significant increase in impact strength compared to the pure resin, achieving the highest value among all tested samples. The initial improvement in impact strength is consistent with enhanced energy dissipation mechanisms at low PBAT loading, attributed to the addition of PBAT. However, as the PBAT concentration increases to 5% and 10%, there is a notable decrease in impact strength. This decline may be due to oversaturation introduced by higher PBAT levels, which, while increasing the material’s ability to deform, might reduce its capacity to absorb impact energy effectively. The data from the graph illustrates a non-linear relationship between PBAT content and the impact resistance of the composites. While the initial addition of PBAT (at 1%) greatly enhances impact strength, further increases appear to compromise this property, potentially due to the material becoming overly soft. This trend highlights the complex interplay between PBAT concentration, material density, and mechanical performance, providing crucial insights for optimizing the formulation of biodegradable composites. These findings are pivotal for developing materials that balance mechanical properties such as impact resistance with environmental sustainability, aiming to meet specific application needs in industries where high impact resistance is essential without sacrificing material strength. This trend highlights the complex interplay between PBAT concentration, material density, and mechanical performance, providing crucial insights for optimizing the formulation of biodegradable composites. The initial improvement in impact strength with PBAT addition is attributed to enhanced interfacial adhesion, facilitating effective stress transfer and energy dissipation during impact [37]. Although direct imaging of impact fracture surfaces was not performed, the crack initiation and propagation mechanisms during impact loading can be inferred from tensile fracture SEM features, which show microvoid nucleation, PBAT pull-out, and shear deformation paths consistent with energy-dissipating behavior.

3.3. Thermal Conductivity

Exploring the thermal conductivity of micro-composites that incorporate PBAT is key to understanding their potential applications in industries where heat management is critical. Such data is fundamental for advancing the design and application of new composites, ensuring they are ideally suited for their intended uses in electronics, automotive manufacturing, and energy-efficient building materials. Figure 7 displays the thermal conductivity capabilities of each composite formulation. The interaction between PBAT and the base materials modifies the microstructure, potentially affecting thermal conductivity, which is crucial for optimizing these composites for specific applications [38].

Figure 7 illustrates the variation in thermal conductivity (W/m·K) for different PBAT loadings, showing a consistent reduction from 0.196 W/m·K in the pure resin to 0.163 W/m·K at 10 wt% PBAT. This decreasing trend signifies a progressive enhancement in thermal insulation, confirming PBAT’s effectiveness as a biodegradable thermal barrier additive.

At 1 wt% PBAT, conductivity drops slightly to 0.188 W/m·K, corresponding to the formation of uniformly dispersed PBAT domains observed in SEM images. These fine inclusions introduce phonon scattering sites, which begin to limit heat transfer while preserving mechanical stability. Increasing PBAT to 5 wt% further decreases conductivity to 0.176 W/m·K, as interfacial boundaries and microvoids seen in SEM micrographs act as localized heat-blocking regions.

The 10 wt% PBAT sample exhibits the highest insulation efficiency, reaching a 16% reduction in conductivity relative to the pure resin. SEM observations show larger PBAT clusters and partial phase separation, forming discontinuous thermal pathways that effectively trap heat. Despite minor stiffness loss, this composition demonstrates a favorable balance between flexibility and insulation. In

Table 3. Numerical results of all tests performed in this study.

PBAT wt%	Ultimate Tensile Strength (MPa)	±SD	Strain-at-Break (εss)	±SD	Young’s Modulus (GPa)	±SD	Impact Strength (J/m2)	±SD	Thermal Conductivity (W/m·K)	±SD
0 (Pure Resin)	43	0.7	0.065	0.002	0.67	0.03	68.69	2.1	0.196	0.003
1% PBAT	41	0.8	0.058	0.004	0.77	0.04	168.63	3.2	0.188	0.004
5% PBAT	34	0.9	0.0635	0.003	0.55	0.02	117.89	2.8	0.176	0.003
10% PBAT	35	0.6	0.07	0.0015	0.45	0.02	76.44	2.3	0.163	0.004

. Numerical results of all tests performed in this study are given.

Mechanical and thermal results are reported as mean ± standard deviation (n = 3). Although formal hypothesis testing (ANOVA or confidence interval analysis) was not performed, the observed trends are consistent across all replicates, and the standard deviation values provide a quantitative measure of variability.

Overall, the decline in thermal conductivity across all PBAT loadings confirms that PBAT incorporation improves thermal insulation by creating low-conductivity, interfacial barrier regions, consistent with the morphological evolution seen in SEM.

4. Conclusions

This study investigated the effect of PBAT addition on the mechanical, thermal, and microstructural behavior of resin composites fabricated via stereolithography (SLA) additive manufacturing. The results highlight PBAT’s strong potential as a biodegradable modifier that enhances both performance and sustainability in photopolymer systems.

The incorporation of 1% PBAT increased impact strength to 168.63 J/m², a 146% improvement over the pure resin (68.69 J/m²), while 5% (117.89 J/m²) and 10% (76.44 J/m²) PBAT composites also demonstrated enhanced toughness and energy absorption. Thermal insulation improved by 16% at 10% PBAT, attributed to PBAT’s low intrinsic conductivity and phonon scattering at the resin–PBAT interfaces.

Among the investigated compositions, 1 wt% PBAT provided the most pronounced improvement in impact performance, 5 wt% PBAT offered a balance between stiffness and toughness, and 10 wt% PBAT yielded the lowest thermal conductivity at the expense of reduced stiffness.

SEM analysis of fractured tensile specimens revealed a transition from brittle fracture in the pure resin to more ductile and energy-dissipative fracture surfaces with increasing PBAT content. The formation of microvoids and pulled-out PBAT regions confirmed improved interfacial adhesion and localized stress absorption. The study is limited by a small sample size, constant printing parameters, and the absence of compatibilizers or reactive coupling agents, which may have improved tensile performance at higher PBAT loadings.

Future work will aim to optimize mechanical–thermal balance through interfacial compatibilization and evaluate long-term durability, biodegradation, and aging behavior. Overall, PBAT incorporation enables the development of high-performance SLA composites, improving impact resistance, flexibility, and insulation efficiency.