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14 pages, 4477 KiB

Open AccessArticle

Catalyst-Free Cardanol-Based Epoxy Vitrimers for Self-Healing, Shape Memory, and Recyclable Materials

by Yu Zhu, Wenbin Li, Zhouyu He, Kun Zhang, Xiaoan Nie, Renli Fu and Jie Chen

Polymers 2024, 16(3), 307; https://doi.org/10.3390/polym16030307 - 23 Jan 2024

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Bio-based vitrimers present a promising solution to the issues associated with non-renewable and non-recyclable attributes of traditional thermosetting resins, showcasing extensive potential for diverse applications. However, their broader adoption has been hindered by the requirement for catalyst inclusion during the synthesis process. In [...] Read more.

Bio-based vitrimers present a promising solution to the issues associated with non-renewable and non-recyclable attributes of traditional thermosetting resins, showcasing extensive potential for diverse applications. However, their broader adoption has been hindered by the requirement for catalyst inclusion during the synthesis process. In this study, a cardanol-based curing agent with poly-hydroxy and tertiary amine structures was prepared by a clean synthetic method under the theory of click chemistry. The reaction of a cardanol-based curing agent with diglycidyl ether of bisphenol A formed catalyst-free, self-healing, and recyclable bio-based vitrimers. The poly-hydroxy and tertiary amine structures in the vitrimers promoted the curing of epoxy-carboxylic acid in the cross-linked network and served as internal catalysts of dynamic transesterification. In the absence of catalysts, the vitrimers network can achieve topological network rearrangement through dynamic transesterification, exhibiting excellent reprocessing performance. Moreover, the vitrimers exhibited faster stress relaxation (1500 s at 180 °C), lower activation energy (92.29 kJ·mol⁻¹) and the tensile strength of the recycled material reached almost 100% of the original sample. This work offers a new method for preparing cardanol-based epoxy vitrimers that be used to make coatings, hydrogels, biomaterials, adhesives, and commodity plastics in the future. Full article

(This article belongs to the Special Issue Advances in Bio-Based Polymers and Additives: Innovation, Properties and Applications)

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20 pages, 2895 KiB

Open AccessArticle

Influence of Epoxy Functional Chain-Extenders on the Thermal and Rheological Properties of Bio-Based Polyamide 10.10

by Rafael Erdmann, Mirko Rennert and Thomas Meins

Polymers 2023, 15(17), 3571; https://doi.org/10.3390/polym15173571 - 28 Aug 2023

Viewed by 945

Abstract

Bio-based polyamide 10.10 (PA 10.10) has excellent properties compared to other bio-based polymers such as polylactic acid (PLA) or polyhydroxyalkanoates (PHAs) and is therefore used in more technical applications where higher strength is required. For foam and filament extrusion, a good balance between [...] Read more.

Bio-based polyamide 10.10 (PA 10.10) has excellent properties compared to other bio-based polymers such as polylactic acid (PLA) or polyhydroxyalkanoates (PHAs) and is therefore used in more technical applications where higher strength is required. For foam and filament extrusion, a good balance between strength and stiffness of the polymer is needed. Therefore, two commercial chain-extenders (Joncryl^® ADR types) with different epoxy functionalities are used to modify the melt properties of PA 10.10. The chain-extenders are used in a concentration range up to 1.25 wt.%. The range of glass transition temperature widens with increasing Joncryl^® content, and the apparent activation energy shows a maximum at a concentration of 0.5 wt.%. Furthermore, the melting temperatures are constant and the crystallinity decreases with increasing chain-extender content due to the formation of branches. During the second heating run, a bimodal melting peak appeared, consisting of

α

-triclinic and pseudo

γ

-hexagonal crystals. The weight average molar masses (M_w) measured by gel permeation chromatography (GPC) increased linearly with increasing ADR 4400 content. In contrast, the compounds containing ADR 4468 show a maximum at 0.5 wt.% and it begins to decrease thereafter. The rheological data show an increase in viscosity with increasing chain-extender content due to branch formation. ATR spectra of the compounds show a decrease at the wavelength of the primary (3301 cm⁻¹) and secondary (1634 cm⁻¹) (-NH stretching in PA 10.10) amine, indicating that chain-extension, e.g., branching, takes place during compounding. Full article

(This article belongs to the Special Issue Advances in Bio-Based Polymers and Additives: Innovation, Properties and Applications)

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23 pages, 7860 KiB

Open AccessArticle

Improvement of the Thermo-Oxidative Stability of Biobased Poly(butylene succinate) (PBS) Using Biogenic Wine By-Products as Sustainable Functional Fillers

by Benedikt T. Hiller, Julia L. Azzi and Mirko Rennert

Polymers 2023, 15(11), 2533; https://doi.org/10.3390/polym15112533 - 31 May 2023

Cited by 3 | Viewed by 1855

Abstract

Biobased poly(butylene succinate) (PBS) represents one promising sustainable alternative to petroleum-based polymers. Its sensitivity to thermo-oxidative degradation is one reason for its limited application. In this research, two different varieties of wine grape pomaces (WPs) were investigated as fully biobased stabilizers. WPs were [...] Read more.

Biobased poly(butylene succinate) (PBS) represents one promising sustainable alternative to petroleum-based polymers. Its sensitivity to thermo-oxidative degradation is one reason for its limited application. In this research, two different varieties of wine grape pomaces (WPs) were investigated as fully biobased stabilizers. WPs were prepared via simultaneous drying and grinding to be used as bio-additives or functional fillers at higher filling rates. The by-products were characterized in terms of composition and relative moisture, in addition to particle size distribution analysis, TGA, and assays to determine the total phenolic content and the antioxidant activity. Biobased PBS was processed with a twin-screw compounder with WP contents up to 20 wt.-%. The thermal and mechanical properties of the compounds were investigated with DSC, TGA, and tensile tests using injection-molded specimens. The thermo-oxidative stability was determined using dynamic OIT and oxidative TGA measurements. While the characteristic thermal properties of the materials remained almost unchanged, the mechanical properties were altered within expected ranges. The analysis of the thermo-oxidative stability revealed WP as an efficient stabilizer for biobased PBS. This research shows that WP, as a low-cost and biobased stabilizer, improves the thermo-oxidative stability of biobased PBS while maintaining its key properties for processing and technical applications. Full article

(This article belongs to the Special Issue Advances in Bio-Based Polymers and Additives: Innovation, Properties and Applications)

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