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Article

Study of Mechanical Properties of Gelatin Matrix with NaTPP Crosslink Films Reinforced with Agar

by
Rebecca Giffard-Mendoza
1,
Adalberto Zamudio-Ojeda
1,*,
Erick Cisneros-López
1,
Santiago J. Guevara-Martínez
2 and
Ernesto García
3,*
1
Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara 44430, Mexico
2
Departamento de Farmacobiología, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara 44430, Mexico
3
SECIHTI—Departamento de Ingeniería Industrial, Universidad Politécnica del Valle de México, Tultitlan 54910, Mexico
*
Authors to whom correspondence should be addressed.
Coatings 2025, 15(9), 992; https://doi.org/10.3390/coatings15090992
Submission received: 15 July 2025 / Revised: 18 August 2025 / Accepted: 19 August 2025 / Published: 26 August 2025
(This article belongs to the Special Issue Thin Films and Nanostructures Deposition Techniques)
Browse Figures
Versions Notes

Abstract

The majority of the polymeric materials used in the industry are derived from petroleum and decompose slowly, resulting in waste that poses environmental issues. As a result, there has been a concerted effort to find alternative materials that cover their engineering performance. Biopolymers have emerged as leading contenders because they can mimic the properties of synthetic polymers while being derived from natural and renewable sources. Several projects are focused on developing biomaterials for these applications. This study presents a modification of the mechanical properties of a gelatin-based material with the crosslinking agent sodium tripolyphosphate (NaTPP) by reinforcement with agar. The gelatin–agar (G-Ax) samples exhibited a homogeneous color and flexibility, sharing similar crystalline structures and functional groups. However, the transversal section of the gelatin-only film was modified by the addition of agar, from a porous morphology to a lamellar morphology at nanometric scale thickness. Notably, the agar samples demonstrated greater stress resistance, yield stress, and strain than the gelatin-only sample. These findings highlight the potential of biopolymers such as gelatin and agar as viable alternatives to conventional materials, contributing to the research on eco-friendly solutions for different engineering applications.

1. Introduction

Currently, there is a global reliance on food resources. This dependence has resulted in a significant need for efficient production, processing, distribution, and food preservation. Packaging plays a crucial role in facilitating the mass export of these items. Although synthetic polymers have been widely used for packaging for decades, there is a growing trend toward using biopolymers such as chitosan, starch, and collagen as alternatives. These biopolymers possess properties similar to synthetic ones, with the benefit of being biodegradable and environmentally friendly [1]. Biodegradable polymers like polylactic acid (PLA), starch, cellulose, and collagen offer good accessibility and properties for use in the food packaging industry. However, their production processes or property variations can limit their market usefulness [2,3,4,5].
Numerous projects have focused on studying gelatin-based materials, among the most promising options. Gelatin (G) possesses favorable properties, which may be enhanced by adding reinforcements, additives, and crosslinking agents to modify its physical, chemical, and other characteristics to improve specific properties to be applied in several industrial systems [6,7,8,9,10,11,12]. Gelatin is a polymer derived from collagen, specifically from mammalian proteins. It can be categorized as type A or B, depending on whether it is produced through acid or alkaline methods, respectively [6,7,8,9,10,11,12,13]. Crosslinking agents are utilized in gelatin-based materials to improve properties such as mechanical strength, thermal resistance, hydrophobicity, and degradation rates [8,14,15,16,17,18,19,20]. Sodium tripolyphosphate (NaTPP, Na5P3O10) is a crosslinking agent used to enhance the properties of ceramics and polymers, particularly their mechanical performance. NaTPP creates bonds between polymer chains, forming a network that increases stress resistance [21,22,23,24,25].
Agar (A) is a polysaccharide derived from various red seaweed sources. It is employed in several studies to improve the gelation, rheology, polymerization, thermal stability, and mechanical properties of biopolymer films, including those made from starch, alginate, and chitosan [26,27,28,29,30]. Combining gelatin with various crosslinking agents and reinforcement materials like sodium tripolyphosphate (NaTPP) and agar fosters innovation in developing biodegradable materials with tailored properties. The versatility of gelatin in forming networks and its ability to be modified with additives such as NaTPP and agar permit the production of materials for different applications.
Although the inclusion of a crosslinking agent (NaTPP) increases the stress resistance of gelatin-based materials, these materials present a high brittleness and low toughness. For that, the inclusion of agar could improve the elastoplastic performance of the gelatin-based material, increasing its stress and strain resistance due to the modification of the gelatin-based material’s morphology and the material’s cohesion [10,31,32,33,34].
These advancements bolster the transition toward sustainable materials and place gelatin-based composites at the forefront of eco-friendly research, addressing critical environmental sustainability and materials science challenges. This study aims to characterize gelatin-based films with the reinforcement of crosslinking agents (NaTPP) and varying amounts of agar to evaluate their mechanical properties for potential use in engineering applications in the industry.

2. Materials and Methods

2.1. Synthesis

The quantities of gelatin (type A with 260 bloom value, Coloidales Doche S.A. de C.V.) and agar (food-grade agar–agar from a commercial source) for each film were combined into this mixture into 20 mL of double-distilled water. The solution was mixed in a magnetic stirrer at a temperature between 70 °C and 80 °C to achieve a homogeneous mixture (see Table 1). During mixing, 0.3 g of sodium tripolyphosphate (NaTPP, Sigma-Aldrich, St. Louis, MO, USA, 85% technical grade) was added to each sample. The agar percentage (x(w/w) = 5, 10, 15, 20, and 25%) was aggregated, and magnetic stirring continued until the solution was homogenous. The resulting solutions were poured into Petri dishes, each 10 cm in diameter, and placed in a drying oven at 45 °C for 24 h, obtaining films with a diameter of Petri dishes with a thickness of 0.34 ± 0.07 μm.

2.2. Characterization

The G-Ax samples underwent structural and chemical characterization using X-ray diffraction (XRD-Empyrean, Panalytica, Enigma Business Park, Grovewood Road, Malvern, WR14 1XZ, UK) and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR, Thermo Scientific iS50 ATR, 168 Third Avenue Waltham, MA, USA, 02451) spectroscopy, respectively. Morphological images of the samples were obtained using a scanning electron microscope (SEM-TESCAN headquartered in Brno, Czech Republic). To enhance conductivity to improve the quality of the SEM images, the surfaces of the specimens were coated with a layer of gold (Au) using a sputtering technique for 20 s.
The mechanical properties were assessed using a tensile tester that measured the stress–strain behavior of each specimen in real time with a continued load increment with a speed of 1 mm/min with a 1 kN load cell, following the test parameters outlined by the ASTM D638–14 standards in a universal testing machine (Instron model 4411, 825 University Ave. Norwood, MA, USA). The tension test samples were cut from the G-Ax sample films using a laser cutting machine (Guian Modelo GN 600 LS, St. Louis, MO, USA, specimen type 1). Five tension test specimens were prepared from each of the G-Ax samples. The thickness and width of the samples were measured with a digital micrometer (see Table 1), and the SEM images were analyzed to evaluate the fracture performance of the samples.

3. Results

3.1. Surface Morphology

Figure 1 shows an example of the G-Ax samples following the drying process, which displayed a homogeneous color and texture, along with high flexibility and resistance.
Figure 2 illustrates the surface morphology of the G-A0, G-A5, G-A10, G-A15, G-A20, and G-A25 samples. The G-A0 sample had a soft surface characterized by a cumulus of crystalline-like particles and semi-circular holes. A soft gelatinous surface, which lacked the cumulus, was reported by Farahnaky et al. [36], potentially resulting from the interaction of NaTPP with the gelatin matrix. The G-A5 sample showed a soft surface with smaller cumulus particles compared to the G-A0 sample, as well as areas with droplet geometries of varying sizes. The surface morphology of the G-A10 sample was similar to that of the G-A5 sample; however, the particles formed a layered structure. The G-A15 sample exhibited the accumulation of layered particles arranged linearly. The surfaces of the G-A20 and G-A25 samples were notably softer than those of the other samples, with a small cumulus of rectangular particles, especially prominent on the G-A25 surface sample. The reduction in particle cumulus on the sample surfaces was attributed to the increased solubility of G-NaTPP crystals in the G-Ax films with the increment in the amount of agar.
A detailed analysis of the surface morphology across the G-A0 to G-A25 samples provides critical insights into the structural evolution of gelatin–agar composites. Understanding how agar and NaTPP interact to influence the microstructural characteristics of these biopolymer matrices is essential for optimizing their functional properties. The observed reduction in particle formation and the trend toward softer surfaces in samples with higher agar concentrations (G-A20 and G-A25) underline the role played by agar in modifying the gelatin matrix. This performance indicates that increasing agar content enhances NaTPP solubility, resulting in a more homogeneous distribution of reinforcing material. Such morphological alterations are directly linked to improved mechanical performance, which is vital for developing advanced biomaterials with potential applications in packaging, biomedicine, and the food industry.

3.2. XRD Diffraction and FTIR Analysis

The gelatin (G) samples exhibited a low crystalline structure, with peaks centered at 7.7° and 21.2° in 2 theta, corresponding to a collagen-like triple-helix structure, as observed in Figure 3 [37]. Similar peaks were present in the patterns of the G-A0, G-A5, and G-A25 samples (see Figure 3a). The peaks at 13° and 19° in the XRD patterns, which represent the semi-crystalline structure of agar, were absent in all samples except for the G-A5 sample, which displayed a small shoulder at 17°.
The FTIR spectra of the G samples displayed bands at 3276 cm−1 for Amide A; at 3073, 2934, and 2839 cm−1 for Amide B; at 1634 cm−1 for Amide I; at 1530, 1453, 1383, and 1335 cm−1 for Amide II; and at 1240, 1160, and 1083 cm−1 for Amide III, as presented in Figure 3b. Amide A corresponds to O–H stretching and N–H vibrations, while Amide B is associated with asymmetrical CH2 stretching. Amide I is related to C=O and C–N stretching and N-H bending. Amide II is formed by NH and CH2 bending and CN stretching. Amide III is characterized by CN stretching and CH bending. Hassan et al. [38] reported that the low intensity of Amide III may result from the loss of triple helix integrity during the gelatin process [7,38].
The G-A0 sample, which corresponds to the gelatin matrix with NaTPP, showed bands at 1236 and 1745 cm−1 due to sodium tripolyphosphate. Similar bands were observed in the G-Ax spectra, with additional bands at 887 cm−1 for the G-Ax samples with 5, 10, 15, and 20% agar content and at 704, 1130, and 3623 cm−1 for the G-A5, G-A10, and G-A15 samples. The band at 1025 cm−1 was present in the G-A15, G-A20, and G-A25 spectra. The band at 887 cm−1 corresponds to C–H bending at the anomeric carbon in β-galactose residues. In contrast, the bands at 704, 1025, and 1130 cm−1 could correspond to the C-O stretching of anhydro-galactose, and the band at 3623 cm−1 corresponds to O-H stretching [26,27,39,40,41]. Similarly, Figure 3c presents the spectra of 100% agar, featuring a band at 3316 cm−1 for O–H stretching, 2953 cm−1 for alcohol, amine, or alkane groups, 1655 cm−1 for stretching vibrations of peptide bonds (NH) or acetone groups, 1369 cm−1 assigned to alkanes and nitromethane (C–N or N=O), 1152 cm−1 for aliphatic amines (C–N), and bands at 1075, 1040, and 928 cm−1 corresponding to the C–O stretching of anhydro-galactose, as well as a band at 876 cm−1 corresponding to C–H bending at the anomeric carbon in β-galactose residues [26,27,39,40,41].

3.3. Mechanical Properties

Figure 4 presents the results obtained from the stress–strain test of the G-AX samples. The stress–strain curve for the G-A0 samples shows lower stress and strain resistance compared to the G-A5, G-A10, G-A15, G-A20, and G-A25 samples (see Figure 4a). The G-A0 samples recorded the lowest strain and fracture stress values, measuring 3.2 ± 0.65% and 22.7 ± 1 MPa, respectively. Additionally, the G-A0 sample exhibited the lowest elastoplastic deformation, with the highest Young’s modulus recorded at 2093 ± 175 MPa and the lowest yield stress at 24.2 ± 2.6 MPa, indicating a rigid and brittle performance. This behavior aligns with observations by Rivero et al. [37], who noted that such performance is typical of unreinforced gelatin samples. However, the mechanical properties obtained were higher than those previously reported for unreinforced gelatin’s base materials [14,36,42]. This improvement can be attributed to the presence of NaTPP in the G-A0 sample, which acts as a crosslinking agent, forming ionic crosslinks between the gelatin chains [8,15,16,17,21,42,43]. The formation of these bonds is evident in the FTIR spectra, particularly in the band at 876 cm−1, which represents the C-H bending at the anomeric carbon in β-galactose residues.
The stress–strain performance of the G-A0 samples exhibits a linear increase in stress with minimal strain, resulting from the plastic deformation of the sample (Young’s modulus) until reaching the yield stress point. At this point, a slight curvature toward lower stress values and higher strain leads to crack propagation and eventual fracture. This behavior was classified as “Ductile Instability” by Martinez et al. [44]. The G-A5, G-A10, G-A15, G-A20, and G-A25 samples demonstrated higher strain and stress resistance compared to the G-A0 sample. Notably, the G-A5 and G-A25 samples exhibited a higher strain, around 16%, whereas the G-A10, G-A15, and G-A20 samples showed similar strain performance, approximately 12% (see Figure 4c).
In terms of fracture stress, except for the G-A10 sample, which recorded the highest value of 58.2 ± 2.5 MPa, the G-A5, G-A15, G-A20, and G-A25 samples displayed fracture stress values ranging between 46 and 52 MPa, with the G-A25 sample achieving the second highest value of 52.3 ± 2.2 MPa. The G-A5, G-A10, G-A15, G-A20, and G-A25 samples exhibited lower Young’s modulus, each showing a value around 1400 MPa, but they had higher yield stress values of about 50 MPa compared to G-A0 (see Figure 4b). Despite the G-A0 sample having the highest Young’s modulus among all G-Ax samples, the G-A5 to G-A25 samples demonstrated better mechanical properties due to their superior strain and stress resistance. The enhancement of the gelatin matrix’s mechanical properties for adding agar was produced for the bonds between the polymeric chains. These bonds are observed at 887 cm−1 in the FTIR spectra of films containing agar. Samples with agar were classified as “Necking” since, during tension tests, they did not show crack propagation, and fracture occurred only after neck formation [44,45,46,47]. Various authors have reported an increase in a film’s stress resistance with the incorporation of agar, citing significant improvements in both tension and compression stress due to the interlinking in the polymer chains. However, although the percentages of agar varied in the G-Ax samples, their mechanical properties remained similar, suggesting a limit to the reinforcing effect of agar on the G-NaTPP matrix.

3.4. Morphology of the Transversal Section of the Samples

The transversal sections, illustrated in the SEM images in Figure 5, were obtained from the fractured side of the samples that were fractured during the tension tests. The G-A0 sample exhibited a porous morphology with signs of plastic deformation at the connections (PD). The images also displayed fracture lines resulting from deformation to the fracture (DF) during the tension tests. The G-A5 samples showed a lamellar arrangement morphology, with thickness in the nanometric scale of the layers, aligned perpendicularly to the applied stress. This morphology significantly affects both stress and strain resistance during the tension tests. These samples exhibited plastic deformation along the borders and the presence of particle clusters between the layers, resulting in a reduction in the center due to tension stress, creating a neck geometry with high separation of the sheets.
The G-A10 samples presented a similar lamellar morphology with a nanometric thickness but without particle clusters. The sheets that formed the G-A10 sample had visible plastic deformation marks from stretching during the tension tests, without any central reduction or neck formation in the fracture section. The G-A10 samples also demonstrated higher density in their centers than the G-A5 samples, contributing to a greater resistance to fracture stress and yield stress than the G-A5 sample. The G-A15 sample continued to exhibit similar morphological characteristics, with a lamellar morphology.

4. Discussion

Gelatin is a biopolymer produced from the collagen obtained from bovine, porcine, fish, and other sources. Gelatin is biocompatible, non-toxic, accepted by the FDA, biodegradable, and can be reinforced with several materials that improve its properties [6,11,48,49]. The addition of a crosslinking material to the gelatin matrix is one of the main ways to improve its mechanical properties [34,49,50]. The effect of the NaTPP crosslink material in the gelatin matrix was observed in the increment in the cohesion of polymer chains in the gelatin film and the increment in the resistance to the tension stresses. This can be observed in the increment in the band at 1130 cm−1, representing the bonding between polymer chains.
In the same way, including other biopolymers in the gelatin matrix improves its properties. Some of the biopolymers that have been added to the gelatin matrix are chitosan [51,52,53], polylactic acid (PLA) [32,33,54], and agar [55,56,57], among others. These materials improve the thermal stability, hardness, and tensile stress resistance of the gelatin matrix. The addition of agar to the G-NaTPP matrix modified the matrix morphology from a porosity morphology to a lamellar morphology with a nanoscale layer thickness. In the same way, the G-Ax (x = 5, 10, 15, 20, and 25%) samples presented the increment in the number of C–H bonding (876 cm−1 band in the FTIR spectra) without a variation in the crystalline structure. These variations in the G-NaTPP matrix characteristics improved the mechanical properties of the gelatin matrix, causing the modification of the elastoplastic performance, a reduction in the elastic modulus, and an increment in the yield and fracture stress. These are observed with the improvement of five times the strain and two times the yield and fracture stress. The increment in the mechanical properties of the G-NaTPP matrix with the addition of agar was produced by the modification from a porosity morphology of the G-NaTPP matrix to a lamellar morphology, causing a higher stress distribution on the lamellar geometry and a reduction in the failure points on the porous borders. This performance was observed in the formation of the necking plastic deformation of the G-Ax (x = 5, 10, 15, and 20% of agar) during the stress–strain tests due to this kind of deformation implying an intrinsic plasticity behavior, causing an increment in the hardness and toughness of the polymeric films [45,46,47].

5. Conclusions

Adding agar to the G-NaTPP matrix did not significantly alter the crystalline structure, and the G-Ax samples exhibited FTIR spectra similar to that of the G-NaTPP matrix. However, the surfaces of the samples transited from a soft, porous texture with crystalline particles for the samples with 0, 10, and 15% agar to soft surfaces without pores and particles in the samples of 20% and 25% agar.
Furthermore, incorporating A into the G-NaTPP matrix improved the mechanical properties up to a saturation point (~10%–15% agar), increasing the fracture stress resistance from 20 MPa to 60 MPa. Despite this enhancement, the mechanical properties of the films with varying percentages of A were comparable. The transverse morphology of the G-A0 samples displayed a porous structure. At the same time, adding A resulted in a lamellar morphology, which enhanced the density, particularly in the G-A25 sample, leading to a denser structure. Adding A to the G-NaTPP matrix did not modify the crystalline structure, and the G-Ax samples presented a similar FTIR spectrum to the G-NaTPP matrix. Nevertheless, the surfaces of the samples changed from a soft surface with porosity and particles like crystals to a soft surface without pores and no particles neither in the samples with 20% (G-A20) nor those with 25% (G-A25) of A.
In the same way, adding A to the G-NaTPP matrix improves the mechanical properties, increasing the stress fracture resistance from 20 to 60 MPa; nevertheless, the mechanical properties of the films with different percentages of A presented similar values, indicating a saturation point of reinforcement by the addition of A. The transversal morphology of the G-A0 samples exhibited a porous morphology, while with the addition of A, the transverse morphology of the samples presented a lamellar morphology that increased its density to obtain the densest morphology of the G-A25 sample.
The mechanical properties of the gelatin matrix significantly improve with the addition of agar, demonstrating higher stress resistance and good elastoplastic performance, making it an excellent application potential for eco-friendly packaging.

Author Contributions

Investigation: R.G.-M., A.Z.-O., E.C.-L. and S.J.G.-M.; data analysis, R.G.-M., E.C.-L. and S.J.G.-M.; writing—review and editing, R.G.-M., A.Z.-O. and S.J.G.-M.; funding acquisition, A.Z.-O.; data curation, E.G.; conceptualization, E.G.; writing—original draft preparation and edition, E.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are contained within the article.

Acknowledgments

SECIHTI—Investigadoras e Investigadores por México program and the project CIR/0022/2022. Technical support of Eulogio Orozco Guareño and Cecilia Sánchez Jiménez of Chemistry Department and Maria Guadalupe Cardenas de la Cruz and Armando Renteria Ruiz of Physic Department of CUCEI-Guadalajara University in the SEM, FTIR, and XRD characterization.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
GGelatin
AAgar
xPercentage quantity of agar in gelatin film matrix
NaTPPSodium tripolyphosphate
G-AxGelatin with NaTPP matrix reinforced with different agar quantity sample
PLAPolylactic acid
XRDX-ray diffraction
ATR-FTIRAttenuated Total Reflectance Fourier Transform Infrared
SEMScanning electron microscope
AuGold
PDPlastic deformation
DFDeformation to the fracture

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Coatings 15 00992 g001
Figure 1. Images of the flexibility and resistance of the G-Ax sample.
Figure 1. Images of the flexibility and resistance of the G-Ax sample.
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Figure 2. SEM images of the modification of the surface morphology with the addition of agar to the gelatin matrix.
Figure 2. SEM images of the modification of the surface morphology with the addition of agar to the gelatin matrix.
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Figure 3. (a) XRD patterns of G, G-A0, G-A5, and GA-25 samples and (b) FTIR spectra of gelatin (G) and gelatin–NaTPP (GA0) and (c) G-Ax samples and agar.
Figure 3. (a) XRD patterns of G, G-A0, G-A5, and GA-25 samples and (b) FTIR spectra of gelatin (G) and gelatin–NaTPP (GA0) and (c) G-Ax samples and agar.
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Figure 4. Stress–strain tests of G-Ax samples: (a) stress–strain curves, (b) Young’s modulus and yield stress, and (c) strain and fracture stress.
Figure 4. Stress–strain tests of G-Ax samples: (a) stress–strain curves, (b) Young’s modulus and yield stress, and (c) strain and fracture stress.
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Figure 5. Transversal section of the G-Ax samples after the tension tests.
Figure 5. Transversal section of the G-Ax samples after the tension tests.
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Table 1. Parameters and characteristics of the gelatin–agar (G-Ax) samples.
Table 1. Parameters and characteristics of the gelatin–agar (G-Ax) samples.
SampleGelatin % (w/w)Agar % (x = w/w) NaTPP (g)Stress–Strain Sample Measurements (ASTM D638−14 [35])
Width (W, mm)Thickness (T, mm)
G10000--
G-A010000.35.1 ± 0.40.34 ± 0.07
G-A59550.35.3 ± 0.20.51 ± 0.03
G-A1090100.35.4 ± 0.20.50 ± 0.03
G-A1585150.35.1 ± 0.20.53 ± 0.02
G-A2080200.35.1 ± 0.40.51 ± 0.01
G-A2575250.35.1 ± 0.50.44 ± 0.01
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MDPI and ACS Style

Giffard-Mendoza, R.; Zamudio-Ojeda, A.; Cisneros-López, E.; Guevara-Martínez, S.J.; García, E. Study of Mechanical Properties of Gelatin Matrix with NaTPP Crosslink Films Reinforced with Agar. Coatings 2025, 15, 992. https://doi.org/10.3390/coatings15090992

AMA Style

Giffard-Mendoza R, Zamudio-Ojeda A, Cisneros-López E, Guevara-Martínez SJ, García E. Study of Mechanical Properties of Gelatin Matrix with NaTPP Crosslink Films Reinforced with Agar. Coatings. 2025; 15(9):992. https://doi.org/10.3390/coatings15090992

Chicago/Turabian Style

Giffard-Mendoza, Rebecca, Adalberto Zamudio-Ojeda, Erick Cisneros-López, Santiago J. Guevara-Martínez, and Ernesto García. 2025. "Study of Mechanical Properties of Gelatin Matrix with NaTPP Crosslink Films Reinforced with Agar" Coatings 15, no. 9: 992. https://doi.org/10.3390/coatings15090992

APA Style

Giffard-Mendoza, R., Zamudio-Ojeda, A., Cisneros-López, E., Guevara-Martínez, S. J., & García, E. (2025). Study of Mechanical Properties of Gelatin Matrix with NaTPP Crosslink Films Reinforced with Agar. Coatings, 15(9), 992. https://doi.org/10.3390/coatings15090992

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