Einfluß der struktur auf einige eigenschaften von polyurethan‐ und polyestermelamin‐lacken

Huntjens, F. J.

doi:10.1002/apmc.1979.050760106

Cited by 11 publications

(1 citation statement)

References 2 publications

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“…This can be attributed to the absence of soft segments and the high content of isocyanate. Crosslink density (XLD), defined as the number of crosslinks per unit volume or weight of the polymer, is one of the fundamental characteristics of thermosetting polymers that directly influence their mechanical and thermal properties [39][40][41][42][43][44]. In this study, the effect of a high-functional bio-polyol on the crosslink density of the PU network was calculated based on the equivalent weight (EW) and number-average molecular weight (Mn) of each PU component, assuming complete NCO conversion using Equations ( 1)-( 3) as described in [40].…”

Section: Crosslink Density Of Polyurethane Network Versus Compositionmentioning

confidence: 99%

Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks

Arshanitsa,

Ponomarenko,

Pals

et al. 2023

Polymers

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The hydrophilic extractives isolated from black alder (Alnus glutinosa) bark through hot water extraction were characterized as novel renewable macromonomers capable of forming polyurethane (PU) networks based on a commercial polyisocyanate, with partial or complete replacement of petroleum-derived polyol polyether. The bark-sourced bio-polyol mainly consists of the xyloside form of the diarylheptanoid oregonin, along with oligomeric flavonoids and carbohydrates, resulting in a total OH group content of 15.1 mmol·g−1 and a molecular weight (Mn) of approximately 750 g∙mol−1. The 31P NMR data confirmed a similar proportion of aliphatic OH and phenolic groups. Three-component PU compositions were prepared using polyethylene glycol (Mn = 400 g∙mol−1), bio-polyol (up to 50%), and polymeric diphenylmethane diisocyanate, which were pre-polymerized in tetrahydrofuran (THF) solution with tin organic and tertiary amine catalysts. The resulting mixture was cast and subjected to thermal post-curing. Calculation and experimental data confirmed the crosslinking activity of the bark-sourced bio-polyol in PU, leading to an increase in glass transition temperature (Tg), a decrease in sol fraction yield upon leaching of cured PU networks in THF, a significant increase in Young’s modulus and tensile strength. The macromonomers derived from bark promoted char formation under high temperature and oxidative stress conditions, limiting heat release during macromolecular network degradation compared to bio-polyol-free PU. It was observed that amine catalysts, which are active in urethane formation with phenolic groups, promoted the formation of PU with higher Tg and modulus at tensile but with less limitation of heat liberation during PU macromolecular structure degradation. The high functionality of the bark-derived bio-polyol, along with the equal proportion of phenolic and aliphatic OH groups, allows for further optimization of PU characteristics using three variables: increasing the substitution extent of commercial polyethers, decreasing the NCO/OH ratio, and selecting the type of catalyst used.

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Section: Crosslink Density Of Polyurethane Network Versus Compositionmentioning

confidence: 99%

Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks

Arshanitsa,

Ponomarenko,

Pals

et al. 2023

Polymers

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High Solids Coatings

Storey

1987

Surface Coatings—1

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Curing behavior and physical properties of cured films in high solids coatings based on hexamethoxymethyl-melamine

Nakamichi

1986

Progress in Organic Coatings

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Einfluß der struktur auf einige eigenschaften von polyurethan‐ und polyestermelamin‐lacken

Cited by 11 publications

References 2 publications

Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks

Impact of Bark-Sourced Building Blocks as Substitutes for Fossil-Derived Polyols on the Structural, Thermal, and Mechanical Properties of Polyurethane Networks

High Solids Coatings

Curing behavior and physical properties of cured films in high solids coatings based on hexamethoxymethyl-melamine

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