ANIL KUMAR VEERAPANENI¹, CHANDRASEKAR KUPPAN^2,*, MURTHY CHAVALI^3,*

Journal of Polymer Materials, Vol.37, No.3-4, pp. 121-130, 2020, DOI:10.32381/JPM.2020.37.3-4.1

Abstract The mechanical properties of hybrid nanocomposites made of epoxy/glass fibre dispersed with nano-α-Al₂ O₃ powder at different weight percentages were studied.The effect of nano-α- Al₂O₃ size and wt% on mechanical properties like tensile, flexural, interlaminar shear stress and hardness enhanced because of their higher surface area and interfacial polymer-metal interaction. The nanoparticle embedded laminates have shown improvement in flexural strength,and hardness when compared to laminate without nano-α-Al₂ O₃. The properties varied with the loading and size of the nanoparticles. The tensile strength was highest for 0.5 wt% of 200nm nano-α-Al₂O₃, which is 167.80 N/m₂.The highest flexural strength was observed for… More >

JALPA V. CHOPDA, DHARMESH B. SANKHAVARA, JIGNESH P. PATEL, P. H. PARSANIA^*

Journal of Polymer Materials, Vol.38, No.1-2, pp. 35-48, 2021, DOI:10.32381/JPM.2021.38.1-2.4

Abstract Conventional curing study of epoxy resin of (2E, 6E)-bis (4-hydroxybenzylidene)-4-methyl cyclohexanone (EMBHBC) was conducted at 140 0 /150 0 C by using 4,4’-diaminodiphenylmethane (DDM),4,4’-diaminodiphenylsulphone (DDS),4-4’-diaminodiphenyl ether (DDE), p-phenylenediamine (PDA), 1,2,3,6-tetrahydrophthalic anhydride(THPA), maleic anhydride (MAH) and pyromellitic dianhydride (PMDA). The gel time for DDS, THPA and DDM hardeners are found considerably longer than those of DDE, PDA, MAH and PMDA systems indicated different reactivity towards curing of EMBHBC. Sol–gel analysis of cured resins was carried out in DMF at room temperature. Diamines cured samples showed 76.3-97.5% gel fractions, while anhydrides cured samples showed 84.6-99.6% gel fractions. DDM, PDA and THPA are… More >

DHARMESH B. SANKHAVARA, JALPA V. CHOPDA, JIGNESH P. PATEL, PARSOTAM H. PARSANIA^*

Journal of Polymer Materials, Vol.38, No.1-2, pp. 11-19, 2021, DOI:10.32381/JPM.2021.38.1-2.2

Abstract The curing of epoxy resin of (2E, 6E)-2,6-bis(4-hydroxy benzylidene) cyclohexanone (EBHBC) was carried out at four different heating rates in the nitrogen atmosphere by using 4,4’-diamino diphenylmethane (DDM), 4,4’-diamino diphenyl sulfone (DDS), and 1,2,3,6-tetrahydrophthalic anhydride (THPA) as hardeners. From DSC curves onset, peak exotherm and end set temperatures, as well as heat release, were derived. The energy of activation was derived following Kissinger and Ozawa methods. Observed trend in Ea is EBHBC-THPA > EBHBCDDS > EBHBC-DDM > EBHBC. Nature and chemical structure of the hardeners affected the curing of EBHBC. More >

Antonio Pizzi^*

Journal of Renewable Materials, Vol.11, No.9, pp. 3403-3415, 2023, DOI:10.32604/jrm.2023.030930

Abstract This brief article reviews a very particular and quite narrow field, namely what has been done and what is needed to know for tannin adhesives for wood panels to succeed industrially. The present fashionable focus on bioadhesives has led to producing chemical adhesive formulations and approaches for tannin adhesives as a subject of academic publications. These, as good and original they might be, are and will still remain a rather empty academic exercise if not put to the test of real industrial trials and industrial use. They will remain so without the “little” secrets and techniques outlined here that show… More >

Benoit Ndiwe^1,2,3, Antonio Pizzi^4,*, Hubert Chapuis⁵, Noel Konai⁶, Lionel Karga⁷, Pierre Girods⁴, Raidandi Danwe^6,8

Journal of Renewable Materials, Vol.10, No.8, pp. 2015-2027, 2022, DOI:10.32604/jrm.2022.019891

Abstract In this work, the thermal degradation and drying of bio-hardeners are investigated. Four bio-hardeners based on exudates of Senegalia senegal, Vachellia nilotica, Vachellia seyal, and Acacia Siebteriana were analyzed by FTIR and thermogravimetric analysis, and a desorption study was also conducted. The analysis by infrared spectroscopy indicates the existence of oligomers of different types all giving 5-hydroxy-2-hydroxymethylfuran and 2, 5-dihydroxymethylfuran which are then the real hardening molecules. The pyrolysis of these extracts reveals three main regions of mass loss, a first region is located between 25°C and 110°C reflecting the loss of water from the adhesive and the formation of… More > Graphic Abstract

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 >