We conducted a systematic investigation into the thermal stability and oxidation resistance of polycarbonate (PC) and acrylonitrile-butadiene-styrene copolymer (ABS) blends for use in UAV drone structural components. The rapid adoption of UAV drones in aerial photography, logistics, and power line inspection demands materials that can withstand prolonged exposure to high temperatures, thermal‑oxidative aging, and dynamic mechanical loads. PC offers high heat deflection temperature and rigidity but lacks impact toughness, while ABS provides excellent impact resistance and processability but suffers from poor thermal stability. By blending PC and ABS, we aimed to achieve a balanced combination of mechanical strength, thermal resistance, and aging durability. Furthermore, we incorporated graphene (GN), an organic phosphorus flame retardant (OP), antioxidant 1010, and UV absorber UV‑327 to enhance the material’s longevity under real‑world UAV operating conditions.
In the experimental phase, we prepared PC/ABS composites with mass ratios ranging from 100/0 to 0/100. The PC resin (Makrolon® grade, dried at 120 °C for 8 h to moisture <0.02 wt%) and ABS resin (PA‑757 grade, dried at 80 °C for 6 h) were pre‑mixed in a high‑speed mixer at 1500 rpm for 10 min. The blends were extruded using a twin‑screw extruder (diameter 36 mm, L/D = 40, barrel temperatures 240 °C/250 °C/260 °C, screw speed 45 rpm, vacuum vent at 0.09 MPa). The extrudate was cooled in a 25 °C water bath, pelletized, and dried again. Test specimens and 1:5 scale UAV drone components (fuselage brackets and wing connectors) were injection‑molded (mold temperature 80 °C, injection speed 40 cm³/s, pressure 70 MPa, packing pressure 50 MPa for 15 s, cooling 25 s). All specimens were stress‑relieved at 40 °C for 24 h and conditioned at 25 °C, 50 % relative humidity before testing. Long‑term thermal‑oxidative aging was performed in an air‑circulating oven at 80 °C, 50 % RH, 21 % O₂ for 0, 24, 48, 72, and 168 h.
The mechanical and thermal properties of the PC/ABS composites as a function of PC content are summarized in Table 1. We observed that increasing PC content up to 60 wt% improved tensile strength significantly, from 55 MPa for pure ABS to 78 MPa for the 60/40 blend. Beyond 60 wt% PC, the tensile strength increase slowed, reaching 84 MPa at 100 wt% PC, but the impact strength dropped sharply. The 60/40 blend exhibited the highest impact strength of 18.7 kJ/m², indicating optimal toughening by the ABS phase. The heat deflection temperature (HDT) at 1.82 MPa rose steadily with PC content, reaching 118 °C at 60/40, which is adequate for UAV drone ground‑exposure scenarios (e.g., 70 °C tarmac temperatures). The hardness (R‑scale) reached 121 ± 3 for the 60/40 blend, and the density was 1.15 g/cm³—a favorable trade‑off between stiffness and lightweight requirements for UAV drone structures.
| PC/ABS (w/w) | Tensile strength / MPa | Impact strength / (kJ·m⁻²) | HDT / °C | Hardness (R‑scale) | Density / (g·cm⁻³) |
|---|---|---|---|---|---|
| 0/100 | 55 | 12.3 | 92 | 98 ± 2 | 1.05 |
| 20/80 | 62 | 14.8 | 100 | 105 ± 2 | 1.08 |
| 40/60 | 70 | 16.5 | 108 | 114 ± 3 | 1.12 |
| 60/40 | 78 | 18.7 | 118 | 121 ± 3 | 1.15 |
| 80/20 | 81 | 15.1 | 125 | 124 ± 3 | 1.18 |
| 100/0 | 84 | 10.2 | 132 | 128 ± 4 | 1.20 |
To further improve the thermal‑oxidative stability, we incorporated four types of additives: GN (0.5 phr), OP (1.0 phr), antioxidant 1010 (2.0 phr), and UV‑327 (0.3 phr), both individually and in combinations. The oxidation induction time (OIT) was measured using DSC at 200 °C in oxygen atmosphere. As shown in Table 2, adding 2 phr antioxidant 1010 alone increased the OIT from 28.5 min (neat 60/40 blend) to 42.6 min, a 49.5 % improvement. The synergistic combination of GN and antioxidant 1010 yielded the highest OIT of 48.3 min, representing a 69.5 % increase. This indicates that GN acts as a physical barrier to oxygen diffusion while the antioxidant scavenges free radicals, effectively retarding oxidative degradation in UAV drone components exposed to long‑duration flights.
| Additive system | OIT / min | Improvement / % |
|---|---|---|
| None | 28.5 | – |
| GN (0.5 phr) | 35.2 | 23.5 |
| OP (1.0 phr) | 33.8 | 18.6 |
| Antioxidant 1010 (2.0 phr) | 42.6 | 49.5 |
| UV‑327 (0.3 phr) | 30.1 | 5.6 |
| GN + Antioxidant 1010 | 48.3 | 69.5 |
| GN + OP | 44.7 | 56.8 |
| GN + UV‑327 | 36.9 | 29.5 |
Thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) of the PC/ABS (60/40) composites were performed under nitrogen from 30 °C to 800 °C at 10 °C/min. The onset decomposition temperature (T₅%, temperature at 5 % mass loss) and char yield at 800 °C are given in Table 3. The neat blend showed an onset of 388 °C and char yield of 11.3 %. Addition of GN alone increased T₅% to 402 °C and char to 14.7 %. The combination of GN and OP raised T₅% further to 410 °C and char yield to 18.2 %, while the maximum mass loss rate temperature shifted from 462 °C to 480 °C and the peak mass loss rate decreased from 22.1 %/min to 18.0 %/min. This demonstrates a strong synergistic effect: GN provides a tortuous path for volatile degradation products, while OP promotes char formation through phosphorus‑based intumescence. The enhanced char layer acts as a thermal shield, protecting the underlying polymer matrix during a UAV drone’s exposure to engine heat or solar radiation.
| Additive system | T₅% / °C | Char yield at 800 °C / % | Peak mass loss rate / (%·min⁻¹) | Peak temperature / °C |
|---|---|---|---|---|
| None | 388 | 11.3 | 22.1 | 462 |
| GN | 402 | 14.7 | 20.3 | 471 |
| GN + OP | 410 | 18.2 | 18.0 | 480 |
| GN + Antioxidant 1010 | 406 | 15.6 | 19.1 | 476 |
Thermal conductivity was measured at 25 °C and 80 °C using the transient plane source method. As shown in Table 4, the neat blend had a thermal conductivity of 0.22 W/(m·K) at 25 °C. Adding 0.5 phr GN increased it to 0.26 W/(m·K), and the combination of GN with antioxidant 1010 gave the highest values: 0.31 W/(m·K) at 25 °C and 0.35 W/(m·K) at 80 °C. This improvement facilitates heat dissipation from the UAV drone’s internal electronics and motor mounts, reducing the risk of localized overheating during prolonged operation.
| Additive system | Thermal conductivity at 25 °C / (W·(m·K)⁻¹) | Thermal conductivity at 80 °C / (W·(m·K)⁻¹) |
|---|---|---|
| None | 0.22 ± 0.01 | 0.25 ± 0.01 |
| GN | 0.26 ± 0.01 | 0.30 ± 0.01 |
| OP | 0.23 ± 0.01 | 0.26 ± 0.01 |
| Antioxidant 1010 | 0.24 ± 0.01 | 0.27 ± 0.01 |
| GN + Antioxidant 1010 | 0.31 ± 0.02 | 0.35 ± 0.02 |
| GN + OP | 0.29 ± 0.01 | 0.32 ± 0.01 |
The long‑term thermal‑oxidative aging behavior was evaluated by exposing tensile specimens to 80 °C for up to 168 h. The tensile strength retention rate, defined as
$$ R_{\text{tensile}} = \frac{\sigma_{\text{aged}}}{\sigma_{\text{initial}}} \times 100\% $$
was measured. Table 5 compares the retention rates for the neat blend and the blend with GN + antioxidant 1010. After 168 h, the neat blend retained only 74 % of its initial tensile strength, while the optimized composite retained 86 %. The combined effect of GN and antioxidant 1010 effectively suppressed chain scission and crosslinking reactions that typically occur under thermal‑oxidative conditions. This translates to improved operational reliability for UAV drone components that must endure repeated thermal cycles during day‑night missions.
| Aging time / h | Neat PC/ABS (60/40) / % | PC/ABS + GN + Antioxidant 1010 / % |
|---|---|---|
| 0 | 100 | 100 |
| 24 | 96 | 98 |
| 48 | 91 | 95 |
| 72 | 85 | 92 |
| 168 | 74 | 86 |
We also examined the melt flow rate (MFR) of the optimized PC/ABS (60/40) composite to assess processability. The MFR at 220 °C, 10 kg was 14.5 ± 0.7 g/10 min, which is suitable for injection molding of UAV drone structural parts such as fuselage brackets and wing connectors. The hardness of 121 ± 3 (R‑scale) ensures sufficient rigidity under flight loads, while the density of 1.15 g/cm³ contributes to overall weight reduction—a critical factor for extending flight endurance.
To quantitatively understand the aging kinetics, we applied the Arrhenius model to the OIT data. The relationship between OIT and temperature follows
$$ \ln(\text{OIT}) = \frac{E_a}{R} \left( \frac{1}{T} – \frac{1}{T_0} \right) + \ln(\text{OIT}_0) $$
where \(E_a\) is the activation energy for oxidation, \(R\) is the universal gas constant, and \(T_0\) is a reference temperature. Using OIT measurements at 190 °C, 200 °C, and 210 °C for the GN + antioxidant 1010 sample, we obtained an activation energy of 118 kJ/mol, which is 34 % higher than that of the neat blend (88 kJ/mol). This increase confirms the enhanced oxidative resistance conferred by the synergistic additive package, making the material more resilient under the high‑temperature excursions that a UAV drone may experience during summer operations or when hovering near heat sources.
We further characterized the fracture surfaces of impact‑tested specimens using scanning electron microscopy (SEM) to correlate microstructure with performance. The neat 60/40 blend displayed a ductile morphology with uniform dispersion of ABS droplets in the PC matrix. However, after incorporating GN and antioxidant 1010, we observed finer and more homogeneous phase domains, accompanied by the presence of well‑exfoliated GN sheets that bridged the interfaces. This morphological refinement explains the simultaneous improvement in tensile strength and impact toughness, as GN acts both as a reinforcing filler and as a compatibilizer that reduces interfacial tension. The enhanced interfacial adhesion also contributes to the improved aging resistance by limiting oxygen ingress along phase boundaries.
In the context of UAV drone applications, the optimized PC/ABS composite with 60/40 ratio and 0.5 phr GN + 2.0 phr antioxidant 1010 was successfully molded into 1:5 scale fuselage brackets and wing connectors. We performed a coupled mechanical‑thermal‑aging flight simulation test where the components were subjected to a temperature cycle of 25 °C → 70 °C (simulating tarmac heating) → −10 °C (high‑altitude cold) over 10 h, while a cyclic load of 80 % of the yield stress was applied at 1 Hz. After 1000 cycles, the components showed no visible cracks or permanent deformation, and the retained stiffness was above 90 % of the initial value. This demonstrates the practical viability of the developed material for real‑world UAV drone platforms.
We recognize that our study focused on dry conditions, while real UAV drones may encounter high humidity or rain. Future work should investigate the coupled effects of moisture absorption and thermal‑oxidative aging. Nonetheless, the current findings provide a solid foundation for designing durable PC/ABS‑based composites that meet the stringent requirements of modern UAV drones in terms of heat resistance, oxidation stability, and mechanical integrity.
In conclusion, we have demonstrated that a PC/ABS mass ratio of 60/40 represents the optimal balance for UAV drone structural applications, yielding a tensile strength of 78 MPa, impact strength of 18.7 kJ/m², and heat deflection temperature of 118 °C. The synergistic addition of GN and antioxidant 1010 significantly enhances both thermal stability and oxidation resistance, as evidenced by a 69.5 % increase in OIT, a 22 °C improvement in onset decomposition temperature, and tensile strength retention of 86 % after 168 h of thermal‑oxidative aging. The resulting composite also exhibits improved thermal conductivity (0.31 W/(m·K) at 25 °C) and excellent processability (MFR 14.5 g/10 min). These properties make the material highly suitable for manufacturing key UAV drone components such as fuselage brackets and wing connectors, thereby extending the operational lifespan and reliability of the aircraft in demanding environments.