Antonio J. F. Carvalho

Journal of Renewable Materials, Vol.2, No.2, pp. 118-122, 2014, DOI:10.7569/JRM.2014.634108

Abstract Two nanocelluloses from eucalyptus, namely microfi brillated cellulose (MFC) and cellulose nanocrystals (CNC), were prepared and compared by transmission electron microscopy (TEM). The MFC fi bers are 20–30 nm wide and are composed of very homogeneous bundles of aligned regular elementary fi brils of 3–5 nm diameter. They show long straight portions and short fl exible zones, attributed to crystalline and amorphous zones, respectively. The needle-shaped CNC was approximately 200 nm long and 10 nm wide in the wider portion. A model for the MFC structure, whose fl exible zones are formed by alignment of the amorphous portion of the… More >

Antti Ojala^1,*, Lisa Wikström¹, Kalle Nättinen², Jani Lehmonen³, Karita Kinnunen-Raudaskoski⁴

Journal of Renewable Materials, Vol.2, No.4, pp. 278-284, 2014, DOI:10.7569/JRM.2014.634126

Abstract This article presents a new method of producing thermomoldable nonwoven materials based on kraft lignin (KL) and softwood kraft pulp (KP). A mixture of starch acetate (SA) and triethyl citrate (TEC) was used as a water insoluble plasticizer for KL. The thermoplastic lignin (TPL) material with the optimized ratio of KL, SA and TEC was prepared in a twin-screw extruder. The TPL compound was ground and mixed with KP fi bers to produce thermoformable sheets using foam-laid technology. The formed webs were compression molded (CM) into plates and mechanically tested. The foam-laid composites had tensile strengths and modulus of 67… More >

Gustavo de Souza, Ricardo K. Kramer, Antonio J. F. Carvalho^*

Journal of Renewable Materials, Vol.8, No.10, pp. 1257-1268, 2020, DOI:10.32604/jrm.2020.011906

Abstract Oil spills and oil/water wastewater are among the great concerns regarding oil pollution. Existing technologies face many limitations and in some cases are responsible for causing secondary pollution, therefore there is as seek for environmental friendly solutions. Biomass, from which celluloses are highlighted, are being employed for oil/water separation or oil absorbents membranes. Usually, these membranes are obtained by freeze drying of CNF (cellulose nano- fibrils) suspensions followed by chemical modification for hydrophobization, which involves expensive process as chemical vapor deposition and expensive reactants as sylanes, turning these processes hardly scalable. Here, we produced a natural porous structure paper from… More >

Nadezda Stevulova^1,*, Viola Hospodarova¹, Adriana Estokova¹, Eva Singovszka¹, Marian Holub¹, Stefan Demcak¹, Jaroslav Briancin², Anton Geffert³, Frantisek Kacik³, Vojtech Vaclavik⁴, Tomas Dvorsky⁴

Journal of Renewable Materials, Vol.7, No.11, pp. 1121-1145, 2019, DOI:10.32604/jrm.2019.07556

Abstract The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content (from 47.4 percent up to 82 percent), to compare and to analyze the potential use of the recycled fibers for building application, such as plastering mortar. Changes in the chemical composition, cellulose crystallinity and degree of polymerization of the fibers were found. The recycled fibers of lower quality showed heterogeneity in the fiber sizes (width and length), and they had greater surface roughness in comparison to high purity wood pulp samples. The high… More >

Emanoele Maria Santos Chiromito¹, Eliane Trovatti², Antonio Jose Felix Carvalho^1,*

Journal of Renewable Materials, Vol.7, No.5, pp. 403-413, 2019, DOI:10.32604/jrm.2019.01846

Abstract Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics, its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character. Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils, and a resin of poly (styrene-methyl-methacrylate-acrylic acid) used as water-based emulsion. Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions. The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension, leading to… More >