Utilization of softwood lignin as both crosslinker and reinforcing agent in silicone elastomers

Zhang, Jianfeng; Chen, Yang; Sewell, P. R.; Brook, Michael A.

doi:10.1039/c4gc02409e

Cited by 69 publications

(60 citation statements)

References 43 publications

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“…However, the values of storage and loss moduli at T m + 50°C dropped if higher temperatures or longer post cures were used ( postcuring temperature beyond 170°C, Table 3). 50,59 The fabrication of lignin-silicone foams via a Piers-Rubinsztajn (PR) reaction is beneficial with respect to its efficiency, simple formulations and processing. 50,59 The fabrication of lignin-silicone foams via a Piers-Rubinsztajn (PR) reaction is beneficial with respect to its efficiency, simple formulations and processing.…”

Section: Mechanical Properties Of Lignin-silicone Foamsmentioning

confidence: 99%

“…47,48 The process leads to the conversion of phenol, arylmethoxy groups, and other ethers into alkyl groups or silyl ethers (Scheme 1A). 50 The resulting lignin-silicone elastomer has excellent mechanical properties, even when filled with as much as 40 weight% lignin. This permitted the use of raw softwood lignin as a reinforcing/crosslinking filler in silicone elastomers in a one step process.…”

Section: Introductionmentioning

confidence: 99%

“…[50][51][52] While the evolution of gas can cause vacancies/defects in an elastomer, it can be useful for generating foamed materials. [50][51][52] While the evolution of gas can cause vacancies/defects in an elastomer, it can be useful for generating foamed materials.…”

Section: Introductionmentioning

confidence: 99%

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Foamed lignin–silicone bio-composites by extrusion and then compression molding

2015

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The use of lignin, one of the most abundant natural products, has not gained wide use as a feedstock due to the difficulty of processing it. We have developed a simple route to produce lignin-silicone composite foams via first extrusion and then compression molding. The formulation consists of raw lignin particles, suitable mixtures of hydrosilanes, and a catalyst B(C 6 F 5 ) 3 . In order to balance the reaction rates between extrusion and molding, as well as to find other optimized conditions for producing foamed structures, a series of optimizations established that a uniform, closed cell lignin-silicone foam was most effectively made by extrusion at room temperature followed by molding at elevated temperatures under pressure for up to 5 minutes. The morphology and uniformity of the foamed structure depended on many factors, including the quantity of lignin, the catalyst, the crosslinking silicone PHMS, the molecular weight of the spacer silicone H-PDMS-H, and the molding temperature. The content of lignin, acting as both a reinforcing filler and a crosslinker (chemically bonded to the siloxane network), could be varied over a wide range from 25 to 55%. The mechanical performance of the lignin-silicone foam was characterized using DMA and tensile tests (tensile strength up to 0.42 MPa, break-at-elongation up to 249%). The strength of the foam was improved by post-curing at 140°C. Although the lignin-silicone foam loses some elasticity after post-curing, it maintains reasonable stability even after heating to 300°C for 12 h. This processing method for lignin-based bio-composites provides new opportunities for better utilization of lignin in silicones and more broadly in organic materials.

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Section: Mechanical Properties Of Lignin-silicone Foamsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Foamed lignin–silicone bio-composites by extrusion and then compression molding

2015

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“…An interesting example is the work of Brook et al, who employed softwood lignin, acting as a crosslinker, and at the same time as a reinforcing agent in silicone elastomers [11]. Furthermore, in other approaches the biodegradability of various elastomers has extensively been investigated and finally improved [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Green silicone elastomer obtained from a counterintuitively stable mixture of glycerol and PDMS

Mazurek¹,

Hvilsted²,

Skov³

2016

Polymer

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“…[19][20][21][22][23][24][25] Their poor mechanical properties usually requiret he Ac omparative approachf or the surface silylation of nanofibrillated cellulose (NFC) in water is proposed through an environmentally friendly sol-gelr oute based on alkoxysilanes. These elastomeric polymers display ac ombination of unique properties and find applicationsi nm anyf ields, such as elastomeric seals, adhesives, coatings, electrical ando ptical devices,a nd biomaterials.…”

Section: Introductionmentioning

confidence: 99%

Controlled Silylation of Nanofibrillated Cellulose in Water: Reinforcement of a Model Polydimethylsiloxane Network

et al. 2015

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A comparative approach for the surface silylation of nanofibrillated cellulose (NFC) in water is proposed through an environmentally friendly sol-gel route based on alkoxysilanes. NFC suspensions were freeze-dried under controlled conditions in the presence of methyltrimethoxysilane used as a model alkoxysilane. Two different protocols that involve different pH values (0.4 and 4) and post-treatment procedures were investigated and compared. Protocol 1 led to a network of nanofibrils in which polysiloxane particles were dispersed, and protocol 2 produced a scaffold of cellulosic fibrils coated by a polysiloxane layer bonded firmly to the cellulosic substrate. Different from protocol 1, protocol 2 imparted the cellulosic material with hydrophobic properties and improved its thermal stability. Moreover, if 1 wt % of fibrils treated by protocol 2 were incorporated into a model polydimethylsiloxane network, substantial improvements of the static and dynamic mechanical properties of the composite were noted.

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Utilization of softwood lignin as both crosslinker and reinforcing agent in silicone elastomers

Abstract: Composite foams result from one-shot integration of unmodified lignin into a silicone pre-elastomer, where it performs as both crosslinker and reinforcing agent.

Cited by 69 publications

References 43 publications

Foamed lignin–silicone bio-composites by extrusion and then compression molding

Foamed lignin–silicone bio-composites by extrusion and then compression molding

Green silicone elastomer obtained from a counterintuitively stable mixture of glycerol and PDMS

Controlled Silylation of Nanofibrillated Cellulose in Water: Reinforcement of a Model Polydimethylsiloxane Network

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