M.C. Basso^1,2, S. Giovando³, A. Pizzi^2,4,*, M.C. Lagel^2,3, A. Celzard⁵

Journal of Renewable Materials, Vol.2, No.3, pp. 182-185, 2014, DOI:10.7569/JRM.2013.634137

Abstract Condensed fl avonoid tannin foams were obtained under alkaline conditions. This entailed the elimination of furfuryl alcohol from these formulations, as under alkaline conditions, foam preparation could not rely on the heat generated by the self-condensation of furfuryl alcohol, which occurs only under strongly acidic conditions. The approach used to formulate the alkaline foam was: (i) the total elimination of furfuryl alcohol from the formulation, (ii) coupled with the use of an aldehyde hardener different from formaldehyde (for environmental reasons) and (iii) the application of moderate heat to allow foaming. These were not tannin/ furanic foams as their acid-curing counterparts,… More >

A. Paberza^*, L. Stiebra, U. Cabulis

Journal of Renewable Materials, Vol.3, No.1, pp. 19-27, 2015, DOI:10.7569/JRM.2014.634138

Abstract Rigid polyurethane foams were obtained from pulp production byproducts. Three different polyols were used—tall oil polyol, lignopolyol and commercially available polyol for comparison. The obtained rigid polyurethane foams underwent photodegradation at 60°C temperature and at 0.89 W/m² intensity of UV light radiation up to 1000 h. Changes in chemical structure were observed by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy was used to study changes in cell morphology. Spectrophotometery was used to determine yellowing of the foams. Results showed that the thickness of degraded layer for rigid polyurethane foams obtained from pulp production byproducts was ~25% less than for… More >

Sławomir Michałowski, Aleksander Prociak^*

Journal of Renewable Materials, Vol.3, No.1, pp. 14-18, 2015, DOI:10.7569/JRM.2014.634131

Abstract This article describes the effects of the modifi cation of polyurethane system with rapeseed oil-based polyol on the cell structure and physical-mechanical properties of conventional fl exible polyurethane foams. The foams were prepared by substituting a part of the petrochemical polyether-polyols mixture with the bio-polyol based on rapeseed oil. Selected physical-mechanical properties of these foams were examined and compared to the properties of reference foam. The properties such as apparent density, resilience, comfort factor and stress-strain characteristics were analyzed in compression tests. It was found that the modifi cation of polyurethane formulation with rapeseed oil-based polyol improves the selected properties… More >

Tamara Calvo-Correas¹, Mirna A. Mosiewicki², M. Angeles Corcuera¹, Arantxa Eceiza¹, Mirta I. Aranguren^2,*

Journal of Renewable Materials, Vol.3, No.1, pp. 3-13, 2015, DOI:10.7569/JRM.2014.634132

Abstract Rigid polyurethane foams were synthesized by using a vegetable oil-based polyol and 4,4-diphenylmethane diisocyanate prepolymer as the majority of reactives,. The polyol was produced by hydroxylation of crude linseed oil with performic acid generated in situ by the reaction of hydrogen peroxide and formic acid. The characterization by FTIR, H1 NMR, iodine and hydroxyl values of the polyol and its comparison with the original linseed oil supports the success of the reaction. The reference foam was subsequently modifi ed by substituting part of the linseed oil polyol with glycerol, diethylene glycol, and a polyethylene glycol (all of them of lower… More >

X. Li¹, A. Pizzi^1,2,*, X. Zhou^3,*, V. Fierro⁴, A. Celzard⁴

Journal of Renewable Materials, Vol.3, No.2, pp. 142-150, 2015, DOI:10.7569/JRM.2014.634117

Abstract Tannin/furanic foams, typically 95% composed of materials of natural origin such as prorobinetinidin/ profi setinidin tannins and furfuryl alcohol, are potential alternatives to oil-based synthetic foams such as phenol-formaldehyde, and polyurethane foams. This article describes the development of second generation tannin/furanic foams, which are not only formaldehyde free, but also use nonvolatile, nontoxic aldehydes. Both glyoxal and glutaraldehyde were tried to substitute formaldehyde in tannin/furanic foams. The physical properties of these new foams are described and discussed. It was found that glutaraldehyde can totally substitute formaldehyde during tannin/furanic foam preparation, but that glyoxal cannot. The optimized proportion to prepare such… More >

Elham Azadeh¹, Xinyi Chen², Antonio Pizzi^2,*, Christine Gérardin¹, Philip Gérardin¹, Hisham Essawy³

Journal of Renewable Materials, Vol.10, No.12, pp. 3217-3227, 2022, DOI:10.32604/jrm.2022.022740

Abstract Non-isocyanate polyurethane (NIPU) foams using a hydrolysable tannin, also vulgarly called tannic acid, namely here commercial chestnut wood tannin extract was prepared. Compression strength did not appear to depend on the foam apparent density while the formulation composition of the NIPU foams has been shown to be more determinant. These NIPU foams appeared to be self-extinguishing once the high temperature flame is removed. The ignition time gave encouraging results but for improved fire resistance the foams may need some fire-retardant addition. FTIR spectrometry showed the formation of non-isocyanate urethane linkages. Thermogravimetric analysis indicated a good thermal resistance of these foams,… More >

Yuya Hanaoka^1,*, Taku Itoh², Kohei Tateyama³, Susumu Nakata⁴, Keiko Watanabe³

CMES-Computer Modeling in Engineering & Sciences, Vol.132, No.1, pp. 43-53, 2022, DOI:10.32604/cmes.2022.016831

Abstract This study evaluates the performance of a model of open-cell metal foams generated by sphere functions. To this end, an electromagnetic shield constructed from the model was inserted between two horn antennas in an electromagnetic wave propagation simulation. The foam-hole diameter in the electromagnetic shield model was varied as d = 2.5 and 5.0 mm, and the frequency of the electromagnetic waves was varied from 3 to 13 GHz. In the numerical experiments of shield effectiveness, the shields with foam holes of both diameters attenuated the electromagnetic waves across the studied frequency range. The shield effectiveness was enhanced at low… More >

Ilze Beverte^1,*, Vairis Shtrauss¹, Aldis Kalpinsh¹, Uldis Lomanovskis¹, Ugis Cabulis², Irina Sevastyanova², Sergejs Gaidukovs³

Journal of Renewable Materials, Vol.8, No.9, pp. 1151-1170, 2020, DOI:10.32604/jrm.2020.010215

Abstract Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams, mainly by means of parallel plate capacitors. In the present investigation biopolyol was synthesized from Latvia-grown rapeseeds’ oil by the transesterification method with triethanolamine, in an environmentally friendly process, without emission of harmful substances, at temperatures 175°C ± 5°C. Rigid, closed-cell rapeseed oil polyol polyurethane biofoams and petrochemical foams were made ensuring content of the renewable rapeseed oil polyol in ready foams 27 wt.%–29 wt.%. Dielectric permittivity of the polyurethane foams and the underlying monolithic petrochemical-origin polyurethane and biopolyurethane was measured with a… More >

Dzun Noraini Jimat^*, Sharifah Shahira Syed Putra, Parveen Jamal, Wan Mohd Fazli Wan Nawawi, Mohammed Saedi Jami

Journal of Renewable Materials, Vol.8, No.7, pp. 739-757, 2020, DOI:10.32604/jrm.2020.010357

Abstract Increasing usage of foams in various industry sectors had causing serious disposal problems once it reaches the end of its life-cycle. Herein, PVA-MFC foam was prepared by freeze-drying using polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC) as a reinforced material from sugarcane bagasse (SCB). In this study, the PVA-MFC foam was chemically silylated with Y-methacryloxypropyltrimethoxysilane (MPS) and tetraethoxysilane (TEOS). The wetting ability and mechanical strength of the silylated _2,20PVA-MFC foam was greatly enhanced compared with unmodified _2,20PVA-MFC foam. The silane chemicals (MPS and TEOS) had been confirmed grafted on _2,20PVA-MFC foam due to the presence of Si-C and Si-O-C stretching… More >

Fei Song^1,2, Puyou Jia^1,*, Caiying Bo¹, Xiaoli Ren¹, Lihong Hu¹, Yonghong Zhou^1,*

Journal of Renewable Materials, Vol.8, No.5, pp. 535-547, 2020, DOI:10.32604/jrm.2020.09304

Abstract In this study, we prepared a series of tung oil phenolic foams (TPF) by a one-pot method. The FT-IR and 1 H NMR spectra confirm the successful FriedelCrafts grafting of phenol to the long-chain alkyl group in tung oil. Modified TPFs exhibit enhanced mechanical properties, including compressive and flexural strengths of up to 0.278 ± 0.036 MPa and 0.450 ± 0.017 MPa, respectively, which represent increases of 68.75% and 86.72% over those of pure phenolic foam (PF). SEM spectra reveal the TPF microstructure to have uniform hexagonal cell morphology, narrower cell size distribution, and smaller mean cell size, suggesting enhanced… More >