Non-Isothermal Crystallization Behavior and Crystal Morphology of EPDM/PP Thermoplastic Vulcanizates Containing TAC and OV-POSS Coagents
5 affiliations
- 1Department of Chemical Engineering, Kocaeli University, 41001 Kocaeli, Türkiye
- 2Department of Machinery and Metal Technologies, Hereke Asım Kocabıyık Vocational School, Kocaeli University, 41800 Kocaeli, Türkiye
- 3Polymer Science and Technology Graduate Program, Kocaeli University, 41001 Kocaeli, Türkiye
- 4Department of Chemistry, Istinye University, 34396 Istanbul, Türkiye
- 5Xplore Instruments B.V., 6135 KT Sittard, The Netherlands
Abstract
Ethylene propylene diene monomer rubber/polypropylene (EPDM/PP) thermoplastic vulcanizates containing triallyl cyanurate (TAC) or octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) coagents were prepared by dynamic vulcanization. The effects of coagent type, loading level, and EPDM/PP ratio on non-isothermal crystallization were investigated using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction (XRD). Crystallization kinetics were evaluated using the Avrami, Ozawa, and combined Avrami-Ozawa models, while nucleation activity and apparent activation energies were assessed using the Dobreva-Gutzow, Kissinger, Takhor, and Friedman approaches. Both coagents, particularly OV-POSS, shifted crystallization onset toward higher temperatures, demonstrating enhanced heterogeneous nucleation. The decreasing Avrami-derived half-times t0.5 with increasing cooling rate were qualitatively consistent with the experimental DSC half-times t1/2. The Ozawa model did not adequately describe the investigated systems, while the combined Avrami-Ozawa model provided satisfactory correlations. The influence of the coagents on the overall crystallization rate depended on composition, loading, and cooling rate. In particular, high OV-POSS loading promoted earlier nucleation but did not consistently shorten t0.5, especially in the EPDM-rich TPVs. POM revealed earlier crystal formation, increased nucleation density, and smaller spherulites in the coagent-containing samples. DSC analysis revealed an increase in PP-normalized crystallinity upon OV-POSS incorporation, while XRD confirmed an increased crystalline fraction, predominantly associated with the α-crystalline form. This effect was particularly pronounced in the PP-rich formulations. Although OV-POSS promoted heterogeneous nucleation and crystalline structure development, its influence on the overall crystallization rate remained dependent on blend composition, coagent loading, and cooling conditions, suggesting a complex interplay between nucleation and subsequent crystal growth.
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BibTeX
@article{cakır2026nonisothermal,
title = {{Non-Isothermal Crystallization Behavior and Crystal Morphology of EPDM/PP Thermoplastic Vulcanizates Containing TAC and OV-POSS Coagents}},
author = {Nazlı Yazıcı Çakır and Özgenur İnan Coşkun and Merve Ergün and Mehmet Kodal and Güralp Özkoç},
journal = {Polymers},
year = {2026},
month = oct,
doi = {10.3390/polym18212675},
url = {https://www.mdpi.com/2073-4360/18/21/2675},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Non-Isothermal Crystallization Behavior and Crystal Morphology of EPDM/PP Thermoplastic Vulcanizates Containing TAC and OV-POSS Coagents
AU - Nazlı Yazıcı Çakır
AU - Özgenur İnan Coşkun
AU - Merve Ergün
AU - Mehmet Kodal
AU - Güralp Özkoç
PY - 2026
DA - 2026/10/28
JO - Polymers
DO - 10.3390/polym18212675
UR - https://www.mdpi.com/2073-4360/18/21/2675
AB - Ethylene propylene diene monomer rubber/polypropylene (EPDM/PP) thermoplastic vulcanizates containing triallyl cyanurate (TAC) or octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) coagents were prepared by dynamic vulcanization. The effects of coagent type, loading level, and EPDM/PP ratio on non-isothermal crystallization were investigated using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction (XRD). Crystallization kinetics were evaluated using the Avrami, Ozawa, and combined Avrami-Ozawa models, while nucleation activity and apparent activation energies were assessed using the Dobreva-Gutzow, Kissinger, Takhor, and Friedman approaches. Both coagents, particularly OV-POSS, shifted crystallization onset toward higher temperatures, demonstrating enhanced heterogeneous nucleation. The decreasing Avrami-derived half-times t0.5 with increasing cooling rate were qualitatively consistent with the experimental DSC half-times t1/2. The Ozawa model did not adequately describe the investigated systems, while the combined Avrami-Ozawa model provided satisfactory correlations. The influence of the coagents on the overall crystallization rate depended on composition, loading, and cooling rate. In particular, high OV-POSS loading promoted earlier nucleation but did not consistently shorten t0.5, especially in the EPDM-rich TPVs. POM revealed earlier crystal formation, increased nucleation density, and smaller spherulites in the coagent-containing samples. DSC analysis revealed an increase in PP-normalized crystallinity upon OV-POSS incorporation, while XRD confirmed an increased crystalline fraction, predominantly associated with the α-crystalline form. This effect was particularly pronounced in the PP-rich formulations. Although OV-POSS promoted heterogeneous nucleation and crystalline structure development, its influence on the overall crystallization rate remained dependent on blend composition, coagent loading, and cooling conditions, suggesting a complex interplay between nucleation and subsequent crystal growth.
SN - 2073-4360
ER -