FTIR and XPS study of the reaction of phenyl isocyanate and cellulose with different moisture contents

Gao, Zhenhua; Gu, Jiyou; Wang, None Xiao‐Peng; Li, Zhi Guo; Bai, Xue

doi:10.1108/03699420510620300

Cited by 34 publications

(16 citation statements)

References 12 publications

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“…O carbamato formado reage com o isocianato, de forma que quanto mais carbamato é formado, mais forte é a ligação do isocianato com a madeira. Entretanto, quando a madeira contém umidade, ocorre uma reação competitiva, pois o isocianato também reage com a água formando a poliuréia, dificultando a formação de carbamato, o que diminui a eficácia na ligação do isocianato com a madeira [34], o que reforça a importância da fase de secagem, anterior à exposição aos isocianatos. Dentre os isocianatos mais utilizados estão o difenilmetano diisocianato (MDI) e o tolueno diisocianato (TDI) [35].…”

Section: Introductionunclassified

Desenvolvimento de biocompósitos de poli(L-ácido láctico) (PLLA) com serragem de madeira

et al. 2017

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RESUMOOs polímeros petroquímicos levam centenas anos para sofrerem decomposição, acarretando em acúmulo de resíduos nos lixões e aterros sanitários. Este impacto ambiental pode ser minimizado por meio do uso de polímeros biodegradáveis. Neste contexto, este trabalho buscou uma opção "ecologicamente amigável" para a substituição de polímeros sintéticos convencionais, por meio do estudo dos biocompósitos de poli(L -áci-do láctico) (PLLA) com a incorporação de resíduos de madeira (RM) e de aditivos, visando desenvolver novos compósitos. Assim, foram processados três diferentes tipos de amostras por extrusão, seguida de injeção, os biocompósitos de PLLA com adição de RM (PLLA/RM), com adição de um agente de acoplamento, o difenil-isocianato (MDI) denominadas de PLLA/RM/MDI e com adição ainda de um agente lubrificante, o Struktol® (s), denominadas de PLLA/RM/MDI/s, contendo de 0 a 40 % (m/m) de RM. As amostras foram caracterizadas por ensaio de resistência à tração, calorimetria exploratória diferencial (DSC), análise termogravimétrica (TGA), microscopia eletrônica de varredura (MEV), absorção de água, densidade, teor de vazios e espectroscopia no infravermelho com transformada de Fourier (FTIR). As amostras PLLA/RM/MDI/s foram também avaliadas quanto à biodegradação em solo. Os resultados revelaram que as amostras com MDI apresentaram melhores propriedades mecânicas, menor taxa de absorção de água, sem perda da estabilidade térmica, sugerindo que o MDI tenha promovido melhoria da adesão interfacial. Observou-se início do processo de biodegradação das amostras após 5 meses em solo, evidenciado por alterações visuais, bem como nas análises de TGA e DSC, sendo que o aumento do teor de RM acelerou o processo. Palavras-chave: biocompósitos, PLLA, resíduos de madeira, MDI, Struktol® ABSTRACTThe petrochemical polymers take hundreds of years to decompose, resulting in accumulation of waste in dumps and landfills. The environmental impact can be minimized with the use of biodegradable polymers. In this context, this study sought an option "environmentally friendly" to replace conventional synthetic polymers through the study of biocomposites from poly(L -lactic acid) (PLLA) with the incorporation of wood waste (WW) and additives in order to develop new products. Thus, we processed three different types of samples by extrusion followed by injection of PLLA biocomposites with the addition of WW: (PLLA/WW) with addition of a coupling agent, the diphenyl isocyanate (MDI) called PLLA/WW/MDI and even with the addition of a lubricating agent, the Struktol® (s), called PLLA/WW/MDI/s containing from 0 to 40 %wt of WW. The samples were characterized by tensile strength test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water absorption, density, void content and Fourier transformed infrared spectroscopy (FTIR). The samples PLLA/WW/MDI/s were also evaluated by biodegradation in soil. The results revealed that samples with MDI showed better mechanical properties,

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Section: Introductionunclassified

Desenvolvimento de biocompósitos de poli(L-ácido láctico) (PLLA) com serragem de madeira

et al. 2017

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“…Therefore, a VI was proposed in current study to further improve the mechanical properties and mechanical stabilities of Kraft‐reinforced UPE composites via the formations of chemical adhesions between the interfaces of Kraft fiber and UPE resin. Isocyanate is a highly reactive compound that can react with most materials composed of active hydrogen, and therefore, polyisocyanates have been used to prepare polyurethane resin for both bonding and impregnation‐modifying wood 27, 28. Karmarkar et al have successfully grafted an isocyanate called m‐TMI (m‐isopropenyl‐a, a‐dimethylbenzylisocyanate) onto polypropylene as a compatibilizer, which resulted in significant improvement in the tensile and flexural strength of wood‐PP composites 29.…”

Section: Resultsmentioning

confidence: 99%

Effects of vinyl isocyanate coupling agent on the tensile properties of Kraft fiber‐unsaturated polyester composites

Gao¹,

Ma²,

Lv³

et al. 2012

J of Applied Polymer Sci

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A vinyl isocyanate (VI) synthesized from toluene diisocyanate and 2-hydroxyethyl methacrylate was used as a novel coupling agent to obtain strong chemical interfacial adhesion and therefore, improve the tensile properties of Kraft fiber-reinforced unsaturated polyester (UPE) composites. Results characterized by fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and scanning electron microscope (SEM) indicated that the novel coupling agent VI had a significant effect on the tensile properties of composites due to the formation of chemical bonds between the VI-Kraft interfaces and the VI-UPE interfaces. The tensile properties of composites modified by VI were much better than those of the control composite without VI modification. The VI-modified composites after severe hygrothermal aging exhibited lower losses of tensile properties and desirable tensile durability. The improvement in tensile properties, less interfacial separation after severe hygrothermal aging, lower damping values, and higher glass transition temperature are sufficient to show that the interfacial adhesion between the Kraft fiber and the UPE matrix was significantly improved because the coupling agent VI has both active isocyano groups which react with the Kraft fiber and vinyl groups which are copolymerizable with the UPE resin.

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“…MDI may react with the hydroxyl groups as well as moisture existed on the surface of pine needles to form urethane (I) and urea linkages (II). It is reported [22] that isocyanate and water have a faster reaction rate than the isocyanate and hydroxyl groups of ligno‐cellulosics. The possibility on formation of cross‐ linked interphase would exist between the reaction products of pretreated fibers and isocyanate terminated prepolymer adhesive (III).…”

Section: Resultsmentioning

confidence: 99%

“…Isocyanate prepolymer provides the functional groups necessary for curing in the environment. Previously, several studies [6, 7, 19–24] have focused on bonding of polyisocyanates with ligno‐cellulosics with the aim of developing stronger and durable new products. It is commonly experienced that polyisocyanates have sticking problem with a caul plate and thus, causing damage to the surface of composite panels during demoulding [20].…”

Section: Introductionmentioning

confidence: 99%

Pretreatment of pine needles/wood particles and their composites with isocyanate prepolymer adhesive

Chauhan

Gupta

Singh

et al. 2012

Polymer Engineering & Sci

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Pine needles and eucalyptus wood particles were treated with 4, 4 0 diphenyl methane diisocyanate. The efficacy of treatment was assessed in terms of lowering in the contact angle, the assignment of new absorption peaks and the penetration inside the surfaces. Results indicate that needles were less wettable than the wood particles and also heterogeneitically retained isocyanate on their surfaces. A positive effect in the properties of composites was observed when pine needles were used with the composite adhesive system: monomeric isocyanate for pretreatment and isocyanate prepolymer for particle-particle bonding. Pine needles and wood particles in 50:50 ratio in the panels were optimized. It was found that composites containing both pine needles and wood particles exhibited superior mechanical properties to the composites made solely with the pine needles. During hydrothermal aging, the pine needle composites retained more internal bond strength than those made with the blended fibers. Improved resistance against natural decay was noticed with the sodium pentachlorophenate treatment and exhibiting <10% weight loss in the composites. Toxicity index based on gases emitted during the burning of composites was found in the range of 2.2-3.7 which is considered to be safe in comparison with the other similar materials. POLYM. ENG.

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FTIR and XPS study of the reaction of phenyl isocyanate and cellulose with different moisture contents

Cited by 34 publications

References 12 publications

Desenvolvimento de biocompósitos de poli(L-ácido láctico) (PLLA) com serragem de madeira

Desenvolvimento de biocompósitos de poli(L-ácido láctico) (PLLA) com serragem de madeira

Effects of vinyl isocyanate coupling agent on the tensile properties of Kraft fiber‐unsaturated polyester composites

Pretreatment of pine needles/wood particles and their composites with isocyanate prepolymer adhesive

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