Lara Greiner^1,*, Philipp Kukla², Sebastian Eibl¹, Manfred Döring³

Journal of Renewable Materials, Vol.10, No.7, pp. 1931-1950, 2022, DOI:10.32604/jrm.2022.019548

Abstract A novel, versatile flame retardant substructure based on phosphorylated salicylic acid (SCP) is described and used in the synthesis of new flame retardants for HexFlow^® RTM6, a high-performance epoxy resin used in resin transfer molding processes as composite matrix. The starting material salicylic acid can be obtained from natural sources. SCP as reactive phosphorus chloride is converted with a novolak, a novolak containing 9, 10-dihydro-9- oxa-10-phospha-phenanthrene-10-oxide (DOPO) substituents or DOPO-hydroquinone to flame retardants with sufficient thermal stability and high char yield. Additionally, these flame retardants are soluble in the resin as well as react into the epoxy network. The determined… More >

Hongxiang Liu^1,2,,*, Neng Xiong^1,2, Songli Wang^1,2, Wei Zhang^1,2, Bo Yong^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 549-561, 2022, DOI:10.32604/fdmp.2022.017979

Abstract

The effects of a magnesium-based layered composite on the flammability of a phenolic epoxy resin (EP) are studied. In order to produce the required composite material, first, magnesium hydroxide, aluminum salt and deionized water are mixed into a reactor according to a certain proportion to induce a hydrothermal reaction; then, the feed liquid is filtered out using a solid-liquid separation procedure; finally, the material is dried and crushed. In order to evaluate its effects on the flammability of the EP, first, m-phenylenediamine is added to EP and vacuum defoamation is performed; then, EP is poured into a polytetrafluoroethylene mold, cooled… More >

Li Wang^1,2,#, Rongbai Tong^3,#, Juanli Wang^1,2,*, Jintao Wan^1,2,*, Yuhu Li^1,2, Pujun Jin^1,2, Daodao Hu^1,2

Journal of Renewable Materials, Vol.10, No.5, pp. 1349-1364, 2022, DOI:10.32604/jrm.2022.019372

Abstract Quest for bio-based halogen-free green flame retardant has attracted many concerns in recent years. Herein a reactive functional flame retardant containing phosphorus VDP is synthesized from vanillin, 9,10-dihydro-9-oxa-10-phosphophene-10-oxide (DOPO) and phenol via a facile way. VDP is characterized with ¹H NMR, ³¹P NMR, FTIR and Time of Flight Mass Spectrometry, and used as a new reactive flame retardant for bisphenol epoxy thermosets. Thermogravimetry analysis shows that when the VDP loading is only 0.5P% (based on phosphorus content), the residue increases from 14.2% to 21.1% at 750°C in N₂ compare with neat DGEBA. Correspondingly, the limit oxygen index increased to 29.6%,… More >

Hongliang Ding, Xin Wang^*, Lei Song, Yuan Hu

Journal of Renewable Materials, Vol.10, No.4, pp. 871-895, 2022, DOI:10.32604/jrm.2022.018150

Abstract Benzoxazines have attracted wide attention from academics all over the world because of their unique properties. However, most of the production and preparation of benzoxazine resins depends on petroleum resources now, especially bisphenol A-based benzoxazine. Therefore, owing to the environmental impacts, the development of bio-based benzoxazines is gaining more and more interest to substitute petroleum-based benzoxazines. Similar to petroleum-based benzoxazines, most of bio-based benzoxazines suffer from flammability. Thus, it is necessary to endow bio-based benzoxazines with outstanding flame retardancy. The purpose of this review is to summarize the latest advance in flame retardant bio-based benzoxazines. First, three methods of the… More > Graphic Abstract

Xue Xin^1,#, Yu Rong^1,#, Linping Su¹, Zhengmei Qiu¹, Chenjun Yang¹, Ming Liang^1,*, Ping Ji², Guoqiang Zhong³, Zhanyong Yao^1,*

Journal of Renewable Materials, Vol.10, No.4, pp. 1081-1095, 2022, DOI:10.32604/jrm.2022.018021

Abstract As the important matrix material, epoxy resin has been widely used in the composites for various fields. On account of the poor toughness of epoxy resin limiting their suitability for advanced applications, considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements. In this study, the bio-based polyurethane (PU) modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions. Aiming to illuminate the curing behavior, mechanical and thermal properties, the blended epoxy systems were characterized by viscosity-time analysis, dynamic mechanical analysis (DMA) at different frequencies and temperatures, mechanical tensile… More >

Hamed Younesi-Kordkheili^1,*, Antonio Pizzi²

Journal of Renewable Materials, Vol.10, No.2, pp. 237-246, 2022, DOI:10.32604/jrm.2022.017851

Abstract The aim of this research was to investigate the effect of ionic liquid treated lignin-based polyacid as a catalyst for urea-formaldehyde (UF) resins. Esterification of lignin was carried out, without any catalyst, with anhydride maleic and 1-butyl-3-methylimidazolium hydrogen sulfate [Bmim][HSO₄] as acidic ionic liquid to form maleated lignin-based polyacids (MA-IL). The performance of MA-IL as UF resin catalyst was respectively compared to hyroxymethylated lignin-based polyacid (MA-HL) and to NH₄Cl. The FTIR analysis indicated that the proportion of -COOH and C-O bonds increased due to the esterification of lignin with ionic liquid rather than its hyroxymethylation. Physicochemical tests indicated that the… More >

Zhigang Wu^1,#, Sicheng Chen^1,#, Jiankun Liang², Lifen Li¹, Xuedong Xi^3,4, Xue Deng¹, Bengang Zhang^3,*, Hong Lei^4,*

Journal of Renewable Materials, Vol.9, No.11, pp. 1959-1972, 2021, DOI:10.32604/jrm.2021.016786

Abstract Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study. Chemical structural changes of lignin which was processed by plasma as well as bonding strength, tensile property, curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed. Results demonstrated that: (1) Alkali lignin was degraded after the plasma processing. The original groups were destroyed, and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls, carbonyls, carboxyls and acyls were introduced into increase the reaction activity of lignin… More > Graphic Abstract

Syed Waheedullah Ghori^1,*, G. Srinivasa Rao²

Journal of Renewable Materials, Vol.9, No.7, pp. 1283-1292, 2021, DOI:10.32604/jrm.2021.014987

Abstract Date palm fiber (DPF) and kenaf fiber were reinforced in epoxy having various fiber loading 40%, 50%, and 60% by weight. These hybrid samples were manufactured by hot press technique and then characterized for tensile, impact, and morphological behavior to evaluate the ratio of fibers in the hybrid composites; the addition of kenaf improved the tensile properties, Scanning Electron Microscopy (SEM) revealed the interfacial bonding of fiber/matrix, and dispersion and void content in composites. Impact test studies reflected the effect of natural fiber with epoxy, level of stress transfer from matrix to reinforced material, and reinforced material’s role in absorbing… More > Graphic Abstract

Yan Song^1,2, Zhixin Wang³, Xin Zhang⁴, Rong Zhang¹, Jinchun Li^1,2,*

Journal of Renewable Materials, Vol.9, No.5, pp. 943-957, 2021, DOI:10.32604/jrm.2021.014131

Abstract Lignin is a natural biopolymer with a complex three-dimensional network, commercially obtained from waste liquid of paper pulp and bioethanol production, and could be a candidate for preparation of environment-friendly bio-based polyphenol material. In the present work, the demethylated wheat straw alkali lignin (D-Lig), prepared by demethylation of wheat straw alkali lignin (Lig) using an in-situ generated Lewis acid, was used to synthesize bio-based phenol formaldehyde resin adhesive (D-LPF) applied in plywood. Effects of synthetic process’s factors, including lignin substitution for phenol, NaOH concentration and molar ratio of formaldehyde to phenol, on the bonding strength and free formaldehyde content of… More >

Achille Gnassiri Wedaïna^1,2, Antonio Pizzi², Wolfgang Nzie¹, Raidandi Danwe³, Noel Konaï^4,*, Siham Amirou², Cesar Segovia⁵, Raphaël Kueny⁵

Journal of Renewable Materials, Vol.9, No.3, pp. 477-493, 2021, DOI:10.32604/jrm.2021.012782

Abstract The Piptadeniastrum Africanum bark tannin extract was characterized using MALDI TOF, ATR-FT MIR. It was used in the development of a resin with Vachellia nilotica extract as a biohardener. This tannin is consisting of Catechin, Quercetin, Chalcone, Gallocatechin, Epigallocatechin gallate, Epicatechin gallate. The gel time of the resin at natural pH (pH = 5.4) is 660 s and its MOE obtained by thermomechanical analysis is 3909 MPa. The tenacity of Urena lobata fibers were tested, woven into unidirectional mats (UD), and used as reinforcement in the development of biocomposite. The fibers tenacity at 20, 30 and 50 mm lengths are… More >