Comparison of Aging Resistance and Antimicrobial Properties of Ethylene–Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum)
Abstract
:1. Introduction
2. Results and Discussion
2.1. Characterization of the Plant Extracts
2.2. Analysis of the Impregnation Process and Its Impact on Polymer Samples’ Properties
2.3. Characterization of the Aging Process
2.4. Antimicrobial Activity
3. Conclusions
4. Future Perspectives and Research Ideas
- investigation of the release kinetics of impregnated phytochemicals into food-grade products;
- tests on the properties of actual food products packed into impregnated films;
- combination of extraction and impregnation processes to create a simple one-pot method;
- trials of surface activation before the impregnation process, e.g., plasma, corona treatment;
- optimization of conditions of solvent-based impregnations (e.g., concentration, temperature, time) and comparison of the results with the effects of processes relying on supercritical CO2;
- further analysis of the aging processes regarding the application of plant-originated substances as color aging indicators.
5. Materials and Methods
5.1. Materials
5.2. Preparation of Polymer Composite Samples
5.3. Extraction of Phytochemicals and Impregnation Process
5.4. Solar Aging Process
5.5. Methods
5.5.1. Fourier-Transform Infrared Spectroscopy (FT-IR)
5.5.2. Static Mechanical Analysis
5.5.3. Surface Free Energy (SFE)
5.5.4. Thermogravimetric Analysis (TGA)
5.5.5. Color Change
5.5.6. Hardness Tests
5.5.7. Dynamic Mechanical Analysis (DMA)
5.5.8. Oxidation Induction Time (OIT) Experiment
5.5.9. Antimicrobial Experiment
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Sample | Δmimpregnated (wt.%) |
---|---|
EN/CE | 0.61 |
EN/E | 0.74 |
EN/TE | 1.76 |
EN/T | 1.51 |
PLA/CE | 2.01 |
PLA/E | 3.06 |
PLA/TE | 7.88 |
PLA/T | 4.84 |
Sample | Thermal Decomposition (TGA) | Oxidation Peak Parameters (DSC) | |||||||
---|---|---|---|---|---|---|---|---|---|
T05 (°C) | T10 (°C) | T15 (°C) | T20 (°C) | T50 (°C) | T90 (°C) | Onset (min) | Maximum (min) | Endset (min) | |
EN | 449.2 | 456.7 | 461.7 | 464.2 | 475.8 | 487.5 | 6.14 | 18.08 | 31.5 |
EN/CE | 450.8 | 457.5 | 461.7 | 465.0 | 474.2 | 487.5 | 39.02 | 44.65 | 49.83 |
EN/E | 449.1 | 456.7 | 461.7 | 464.7 | 473.5 | 487.5 | 21.09 | 25.9 | 37.66 |
EN/TE | 449.2 | 455.8 | 460.8 | 464.2 | 473.3 | 485.8 | 27.73 | 37.18 | 47.05 |
EN/T | 447.5 | 456.7 | 460.8 | 464.2 | 473.5 | 486.7 | 18.41 | 27.08 | 38.58 |
PLA | 330.0 | 338.3 | 343.3 | 347.5 | 360.8 | 375.8 | ------ | ------ | ------ |
PLA/CE | 304.2 | 315.0 | 322.5 | 327.5 | 345.8 | 363.3 | ------ | ------ | ------ |
PLA/E | 179.2 | 298.3 | 312.5 | 320.0 | 342.5 | 362.5 | ------ | ------ | ------ |
PLA/TE | 296.7 | 311.7 | 320.0 | 325.0 | 345.0 | 363.3 | ------ | ------ | ------ |
PLA/T | 296.7 | 3125.0 | 321.7 | 326.7 | 346.7 | 365.0 | ------ | ------ | ------ |
Sample | Storage Modulus Changes in Temperature | Tmax. E″ (°C) | Tmax. tanδ (Tg) (°C) | |||||
---|---|---|---|---|---|---|---|---|
E′-60 (MPa) | E′-40 (MPa) | E′-20 (MPa) | E′0 (MPa) | E′20 (MPa) | E′40 (MPa) | |||
EN | 2314.7 | 2174.4 | 2009.4 | 1157.4 | 187.2 | 66.4 | 2.5 | 14.3 |
EN/CE | 2560.0 | 2402.4 | 2203.4 | 1261.3 | 181.9 | 68.8 | 3.0 | 15.3 |
EN/E | 2381.9 | 2235.3 | 2057.9 | 1166.4 | 167.1 | 63.2 | 1.8 | 13.8 |
EN/TE | 2437.2 | 2269.1 | 2072.3 | 1124.2 | 164.2 | 60.1 | 0.8 | 17.2 |
EN/T | 2830.5 | 2618.5 | 2393.0 | 1303.5 | 198.4 | 75.3 | 0.3 | 19.6 |
Wavenumber Shifts between the Peaks during Aging (cm−1) | ||||
---|---|---|---|---|
EN | EN/CE | EN/E | EN/TE | EN/T |
2915 → 2915 (-) | 2915 → 2915 (-) | 2934 → 2915 (−19) | 2915 → 2922 (+7) | 2915 → 2915 (-) |
2847 → 2847 (-) | 2847 → 2847 (-) | 2864 → 2847 (−17) | 2847 → 2866 (+19) | 2847 → 2847 (-) |
1720 → 1735 (+15) | 1720 → 1724 (−4) | 1721 → 1727 (+6) | 1723 → 1724 (+1) | |
1514 → X | ||||
1463 → 1462 (+1) | 1461 → 1462 (+1) | 1470 → 1462 (−8) | 1461 → 1460 (−1) | 1463 → 1462 (-) |
1419 → X | 1419 → X | 1419 → X | ||
1387 → X | 1396 → X | 1397 → 1388 (−9) | 1366 → 1366 (-) | |
1364 → 1366 (+2) | 1365 → 1365 (-) | 1364 → 1358 (−6) | ||
1292 → X | 1293 → 1294 (+1) | 1292 → X | 1293 → 1294 (+1) | |
1239 → X | 1238 → 1244 (+6) | 1238 → X | 1243 → 1245 (+2) | |
1172 → 1154 (−18) | 1162 → 1193 (+31) | 1173 → 1161 (−12) | 1191 → 1193 (+2) | |
1108 → X | 1107 → X | 1107 → 1090 (−17) | 1108 → 1107 (−1) | |
1065 → X | 1065 → X | 1065 → X | ||
1045 → X | 1044 → 1046 (+2) | 1054 → 1040 (−14) | 1046 → 1047 (+1) | |
959 → X | 960 → X | 960 → 997 (+37) | 962 → X | |
934 → 928 (−6) | 933 → X | 934 → X | ||
838 → X | 816 → X | 840 → X | 807 → X | |
729 → 729 (-) | 731 → 729 (−2) | 729 → 729 (-) | 729 → 729 (-) | |
718 → 718 (-) | 718 → 718 (-) | 718 → X | 718 → 718 (-) | 718 → 718 (-) |
PLA | PLA/CE | PLA/E | PLA/TE | PLA/T |
2995 → 2995 (-) | 2996 → X | X → 2996 | 2994 → X | |
2945 → 2946 (+1) | 2944 → 2944 (-) | 2943 → 2947 (+4) | 2944 → 2945 (+1) | |
2917 → X | 2924 → 2927 (+3) | |||
2864 → X | 2863 → 2864 (+1) | 2867 → 2865 (−2) | ||
1746 → 1746 (-) | 1746 → 1746 (-) | 1720 → 1747 (+27) | 1722 → 1722 (-) | 1747 → 1722 (−25) |
1451 → 1454 (+3) | 1454 → 1455 (+1) | 1470 → 1455 (−15) | 1455 → 1456 (+1) | 1452 → 1455 (+3) |
1381 → 1382 (+1) | 1382 → 1382 (-) | 1419 → X | 1419 → 1418 (−1) | 1419 → 1419 (-) |
1359 → 1358 (−1) | 1358 → 1358 (-) | 1397 → 1382 (−15) | ||
X → 1304 | X → 1303 | 1365 → 1358 (−7) | 1366 → 1365 (−1) | 1363 → 1365 (+2) |
1266 → X | 1266 → 1210 (−58) | 1293 → 1303 (+10) | 1293 → 1293 (-) | 1292 → 1293 (+1) |
1180 → 1182 (+2) | 1180 → 1180 (-) | 1238 → 1266 (+28) | 1177 → 1174 (−3) | 1267 → 1242 (−25) |
1127 → 1131 (+4) | 1129 → 1130 (−1) | 1166 → 1180 (+14) | X → 1131 (-) | 1180 → 1178 (−2) |
1107 → 1129 (+22) | 1127 → 1130 (+3) | |||
1080 → 1084 (+4) | 1080 → 1081 (+1) | 1065 → 1081 (+16) | 1066→ 1066 (-) | 1080 → 1082 (+2) |
1042 → 1042 (-) | 1042 → 1042 (-) | 1043 → 1042 (−1) | 1035 → 1039 (+4) | 1043 → 1042 (−1) |
955 → 956 (+1) | X → 956 | 961 → 956 (−5) | 962 → 961 (−1) | |
X → 920 | X → 920 | X → 918 | 957 → 961 (+4) | |
866 → 871 (+5) | 870 → 870 (-) | 868 → 871 (+3) | X → 869 | 868 → 870 (+2) |
754 → 754 (-) | 754 → 754 (-) | 732 → 755 (+23) | X → 753 | 754 → 754 (-) |
700 → 691 (−9) | 690 → 692 (+2) | X → 689 | 688 → 686 (−2) | 695 → 688 (−7) |
Sample | Amount of Microorganisms (UFC/cm2) | D (-) | |
---|---|---|---|
t = 0 h | t = 24 h | ||
EN | 2.7 × 104 | 4.1 × 105 | −1.18 |
EN/CE | 3.0 × 100 | 3.95 | |
EN/E | 7.3 × 105 | −1.43 | |
EN/TE | 5.5 × 105 | −1.31 | |
EN/T | 3.1 × 105 | −1.06 | |
PLA | 4.9 × 104 | 3.5 × 105 | −0.85 |
PLA/CE | 2.5 × 105 | −0.71 | |
PLA/E | 1.6 × 105 | −0.60 | |
PLA/TE | 1.7 × 106 | −1.54 | |
PLA/T | 3.5 × 105 | −0.85 |
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Masek, A.; Cichosz, S.; Piotrowska, M. Comparison of Aging Resistance and Antimicrobial Properties of Ethylene–Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum). Int. J. Mol. Sci. 2021, 22, 13025. https://doi.org/10.3390/ijms222313025
Masek A, Cichosz S, Piotrowska M. Comparison of Aging Resistance and Antimicrobial Properties of Ethylene–Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum). International Journal of Molecular Sciences. 2021; 22(23):13025. https://doi.org/10.3390/ijms222313025
Chicago/Turabian StyleMasek, Anna, Stefan Cichosz, and Małgorzata Piotrowska. 2021. "Comparison of Aging Resistance and Antimicrobial Properties of Ethylene–Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum)" International Journal of Molecular Sciences 22, no. 23: 13025. https://doi.org/10.3390/ijms222313025