Rigid polyurethane foams containing lignin oxyalkylated with ethylene carbonate and polyethylene glycol

Zhang, Xuefeng; Kim, Yunsang; Elsayed, Islam; Taylor, Madison; Eberhardt, Thomas L.; Hassan, El Barbary; Shmulsky, Rubin

doi:10.1016/j.indcrop.2019.111797

Cited by 64 publications

(43 citation statements)

References 28 publications

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“…Beech and birch lignins were then reacted with ethylene carbonate (EC). This reaction, depicted on Scheme 1, has been developed by some of us as a powerful method to convert the phenolic OH of lignins into primary aliphatic OH (Scheme 1a), [17] which are much more reactive towards esterification [18,19] or the formation of urethanes, [20] thus opening new applications for lignins in polymer science.…”

Section: Modification Of Lignins With Ethylene Carbonate (Ec)mentioning

confidence: 99%

“…Such lignins modified with EC can indeed be directly esterified by fatty acids in the absence of catalyst or solvent [18,19] . They also show a higher reactivity towards isocyanates and can thus be employed in the synthesis of polyurethane foams [20] …”

Section: Introductionmentioning

confidence: 99%

“…[18,19] They also show a higher reactivity towards isocyanates and can thus be employed in the synthesis of polyurethane foams. [20] Recently, a mild acetone organosolv fractionation process was developed and successfully applied to various hardwoods and herbaceous biomass. [21] Pilot runs of the so-called Fabiola™ process have been performed with two hardwoods, beech and birch.…”

Section: Introductionmentioning

confidence: 99%

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Isolation of Low Dispersity Fractions of Acetone Organosolv Lignins to Understand their Reactivity: Towards Aromatic Building Blocks for Polymers Synthesis

et al. 2020

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Two organosolv lignins extracted during pilot runs of the Fabiola process were analyzed, fractionated and chemically modified with ethylene carbonate (EC) to produce building blocks suitable for polymer synthesis. Isolation of low dispersity fractions relied on the partial solubility of the lignins in organic solvents. Lignins solubility was first evaluated and analyzed with Hansen and Kamlet-Taft solubility parameters, showing a good correlation with the solvents dipolarity/polarizability parameter π*. The results were then used to select a sequence of solvents able to fractionate the lignins into low dispersity fractions of increasing molar masses, which were analyzed by 31 P NMR, SEC and DSC. The lignins were then reacted with EC, to convert the phenolic OH groups into primary aliphatic OH groups. The reactivity of the organosolv lignins was high, and milder reaction conditions than previously reported were sufficient to fully convert the phenolic OH groups. A gradual reduction in reactivity with increasing molar mass was evidenced and attributed to reduced solubility of high molar mass fragments in EC. Undesirable crosslinking side reactions were evidenced by SEC, but were efficiently limited thanks to a fine control of the reaction conditions, helping to maximize the benefits of the developed lignin modification with EC.

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Section: Modification Of Lignins With Ethylene Carbonate (Ec)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Isolation of Low Dispersity Fractions of Acetone Organosolv Lignins to Understand their Reactivity: Towards Aromatic Building Blocks for Polymers Synthesis

et al. 2020

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“…Considerable scientific efforts have been devoted to control lignin hydroxyl reactivity, which have triggered many modification methods, such as hydroxypropylation [ 9 , 15 , 23 ], esterification [ 24 ] and acetylation [ 6 , 7 ], among other reactions [ 8 ]. Indeed, some modification methods successfully converted aromatic hydroxyls into aliphatic ones, minimizing the difference in hydroxyl reactivity levels.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

et al. 2021

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Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

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“…10 To more fully expand its application field, MF rigid foams must be toughened. 11 Over the past few decades, different approaches have been developed to toughen polymer foams, such as rigid polyurethane foams (PUFs), 12 phenolic foams (PFs), 13 and so on and these approaches fall into three categories: inter-fillers, 14 fiber reinforcement, 15 and chemical modification. [16][17][18] Among them, chemical modification has attracted extensive attention for its notable toughening effect.…”

Section: Introductionmentioning

confidence: 99%

Preparation and properties of melamine-formaldehyde rigid closed-cell foam toughened by ethylene glycol/carbon fiber

Zhou

et al. 2020

Cellular Polymers

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Toughing melamine-formaldehyde (MF) rigid closed-cell foams were prepared by using ethylene glycol (EG) and carbon fiber (CF) as composite toughening agents. The pulverization rate, compressive strength, bending strength, cellular structure, closed-cell ratio, water absorption ratio, thermal conductivity, thermal stability, limiting oxygen index (LOI), and char yield were characterized to study the morphology, mechanical, thermal, and fire-retardant properties of as-prepared toughing MF rigid foams. The pulverization rate result showed that introduction of composite modifier can obviously improve the toughness of MF rigid foams. The cellular structure, closed-cell ratio, and water absorption results showed that the addition of EG/CF can increase the closed-cell ratio and control the cell size of MF rigid foams. The compressive strength and bending strength results showed that the incorporation of composite modifier of MF rigid foams dramatically improved the mechanical properties. The LOI, char yield, and thermal stability results showed that the toughing MF rigid foams remained more intact char skeleton with flame-retardant effect, thus reducing the fire hazards. The as-prepared toughing MF rigid foams showed the best comprehensive performance with pulverization rate of 5.21%, compressive strength of 355.3 kPa, bending strength of 0.44 MPa, closed-cell ratio of 79.1%, water absorption of 9%, thermal conductivity of 0.031 W m−1 K−1, and LOI of 39.6%. Compared with unmodified MF rigid foams, toughing rigid closed-cell MF foams possess excellent pulverization rate, compressive strength, bending strength, cellular structure, thermal insulation, and flame retardancy.

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Rigid polyurethane foams containing lignin oxyalkylated with ethylene carbonate and polyethylene glycol

Cited by 64 publications

References 28 publications

Isolation of Low Dispersity Fractions of Acetone Organosolv Lignins to Understand their Reactivity: Towards Aromatic Building Blocks for Polymers Synthesis

Isolation of Low Dispersity Fractions of Acetone Organosolv Lignins to Understand their Reactivity: Towards Aromatic Building Blocks for Polymers Synthesis

Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Preparation and properties of melamine-formaldehyde rigid closed-cell foam toughened by ethylene glycol/carbon fiber

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