Research Article Characterization of Agave americana L. plant as potential source of fbres for composites obtaining Zaida Ortega1 · Jessica Castellano1 · Luis Suárez1 · Rubén Paz1 · Noelia Díaz1 · Antonio N. Benítez2 · María D. Marrero1 © Springer Nature Switzerland AG 2019 Abstract This paper summarises the results obtained from the characterization assays from century plant (Agave americana L.), determining the chemical composition of diferent parts of the plant. Fibres were obtained by means of a mechanical device, specifcally designed and built for Agave americana leaves processing. Obtained fbres were subjected to ther- mogravimetric analysis and infrared spectra, and their chemical composition was also determined by quantitative acid hydrolysis. Once obtained, fbres were blended up to 40% (in weight) to obtain composites by compression moulding, using polyethylene as matrix; mechanical testing show improvements in elastic modulus for both tensile and fexural tests; increase in fexural maximum strength were also found for the composites, while tensile strength is slightly reduced with the introduction of agave fbres. The research is part of a project developed in the Macaronesian region, which aim is to demonstrate the feasibility of using biomass from invasive plant species in the composites sector as a way of fnancing control campaigns and habitats conservation labours, which is the main novelty of this research. Keywords Characterization · Natural fbres · Agave americana L. · Composites · Polyethylene 1 Introduction compete with endemic species in resources, vary soil con- ditions (salinity and pH) and also contribute to fre propa- Invasive species are a thread to the preservation of ecosys- gation, due to the high amount of biomass they produce. tems, being their presence especially dangerous in areas Agave americana L. was introduced in Canary Islands in with high biodiversity. In particular, some plant species the XVI century, and belongs to the Agavaceae family (also such as giant reed (Arundo donax L.), fountain grass (Pen- sisal belongs to this family), originally coming from Cen- nisetum setaceum), century plant (Agave americana L.) or tral America (East of Mexico). This plant leaves from 10 to castor oil plant (Ricinus communis) have spread widely in 30 years and only fowers once in its life. Each plant occu- Macaronesia. These plants, among others, are included in pies a space around 1.8–3.0 m, and has green–grey leaves the Spanish catalogue of invasive species, produced by of about 1 m length, with a prickly margin and a heavy the Ministry of Agriculture and Environment [1], and also spike at the tip. The plant fower consists in a branched in the list of invasive plants of the Canary Islands Gov- high stalk (up to 9 m tall), laden with yellow blossoms [2]. ernment [2]; some of them, such as giant reed, are also EcoFIBRAS project aims at obtaining an updated pic- included in the TOP100 of most dangerous species of the ture of the current situation of habitats conservation state International Union for Conservation of Nature (IUCN) [3]. and the distribution of these species in the Macaronesia These plants produce changes in the hydrological regime, region (more specifcally in Canary Islands, Madeira and * Zaida Ortega, [email protected] | 1Departamento de Ingeniería Mecánica, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafra Baja, 35017 Las Palmas, Spain. 2Departamento de Ingeniería de Procesos, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafra Baja, 35017 Las Palmas, Spain. SN Applied Sciences (2019) 1:987 | https://doi.org/10.1007/s42452-019-1022-2 Received: 29 May 2019 / Accepted: 31 July 2019 / Published online: 5 August 2019 Vol.:(0123456789) Research Article SN Applied Sciences (2019) 1:987 | https://doi.org/10.1007/s42452-019-1022-2 Azores archipelagos), and also in the assessment of their (by burying the leaves in the ground for 3 months) had possibilities as reinforcement or fllers of polymers for the better mechanical properties than fbres from water ret- production of composites by rotational or compression ting [15]. Other authors have used a pectinase solution for moulding. It is well known that natural fbres have experi- fbres obtaining [16, 17] or a hydrolysis process followed by enced a great rise in the last years due to their renewable leaf calendaring [18]. Traditional process consist in drying character, low price and high specifc properties; moreo- the leaves, boiling them (or water retting them) [19] and ver, their market is expected to continue registering high then removing the non—fbrous materials by squashing growth in the coming years [4]. The increased demand of leaves [14] or by means of a knife [12]. Mechanical scrap- sisal, ramie and curaua fbres, due to their high mechanical ping process is also used for fbres obtained from agave properties is contributing to the market growth. Natural [20, 21]. Some papers dealing with the fbre extraction fbres production in 2013 was estimated in 33 million tons, from residual bagasse from blue agave (Agave tequilana) being most of them cotton; other fbres, such as abaca, can also be found in the literature [22]. sisal or fax were produced in about 1.6 million tons; these The use of fibres obtained from Agave Americana L. fgures imply a value of about €45 billion [5]. Natural fbres leaves for composite productions is the strategy followed are used in diferent sectors, such as pulps for paper, spe- in the ecoFIBRAS project as a way to give an added value cialty pulp, composites for automotive industry or other to vegetable residues coming from control campaigns sectors, insulation materials, etc. [6]. which would be otherwise just burnt or buried in landflls, Agave americana L. belongs to the same family as Agave thus addressing the zero wastes and maximum efciency sisalana, and is recognised in the Spanish catalogue of in resources use strategies. invasive species as an invasive plant in Canary Islands, Basque country and Andalucía [1]. It was frst introduced with ornamental purposes and later for the obtaining of 2 Materials and methods bast fbres for textile purposes [7]. Sisal fbres are obtained from Agave sisalana leaves, mainly produced in Mexico 2.1 Plant characterization (in fact, Mexico practically had the monopoly of sisal fbre production until the beginning of the twentieth century Leaves from Agave americana L. were cut from wild plants [5]). Most part of sisal fbres used in Europe come nowa- in the area close to ULPGC facilities (campus de Tafra). Fig- days from South Africa, South America and Asia, with a ure 1 shows pictures of the plants and leaves. price around 0.56–0.74 €/kg [6]. The leaves were characterized by quantitative acid Some studies have used Agave tequilana to produce hydrolysis; Klason lignin was determined following ANSI/ bioethanol [8, 9], mainly due to its high content in carbo- ASTM 1997a [23], while the procedure described by hydrates. Saponines obtained from Agave americana were Browning [24] was used to determine the holocellulose also studied as an additive in animal feeding, efectively content; fnally, cellulose was obtained by hydrolysis of increasing lamb growth [10], while others have studied holocellulose, following standard procedure shown in the potential of salts found in Agave americana for fertiliz- ANSI/ASTM 1997b. Glacial acetic acid (from EMSURE), ers [11]. sodium hydroxide (from Honeywell Fluka), sulphuric acid Also some references have been found about the 98% (from Brenntag Química) and sodium chlorite (from extraction of fbres from Agave Americana L. leaves for Sigma Aldrich) have been used as reagents for these analy- their use in composites production [12–14]. It has been ses. For the plant, a total of 450 assays have been con- demonstrated that the fbres extraction process greatly ducted, studying 5 diferent specimens, 6 leaves of each infuences the properties of the obtained fbres; Bezazi plant, performing 5 replicas for each sample in the difer- et al. have shown that fbres obtained without water use ent parts of the leaf: entire leaves, pulp and skin. Fig. 1 Agave americana L. plant (left) and cross-section of a leaf (right) Vol:.(1234567890) SN Applied Sciences (2019) 1:987 | https://doi.org/10.1007/s42452-019-1022-2 Research Article 2.2 Fibre obtaining and characterization 2.3 Composites obtaining and characterization Fibres were obtained from leaves using a lab—made The fbres were cut to around 2 mm length and blended mechanical device, consisting in a rotatory scraping device with polyethylene (PE), from Matrix Polymers (Matrix (Fig. 2). Each leaf is cut, the sharp edges removed and then Revolve N—461); composites were produced at 10, 20, fed into the scraping device; the leaf is pulled back and the 30 and 40% (in weight) of agave fbres, by compression clean fbres are cut. moulding of the PE/fbres in an aluminium mould to pro- Obtained fbres were characterized following the above duce square fat plates of 190 × 190 mm and 3 mm thick- described procedures to also determine their chemical ness; composites were produced in a Collin P200 PM hot composition, and were also subjected to thermogravi- press, with plates temperature of 180 °C and pressure of metric analysis (TGA) and infrared spectroscopy (FTIR). 35 bar. The composite plates were machined to obtain test TGA tests were performed in a Mettler Toledo TGA/DSC bars with the shape and dimensions defned in UNE—EN 1 device, from 25 to 1100 °C at a heating rate of 5 °C/min ISO 3167, type A for tensile tests, UNE—EN ISO 178 for under nitrogen atmosphere; 9 assays were performed per fexural tests, UNE—EN ISO 180 for Izod impact tests), as type of sample. FTIR spectra were obtained in a Perkin shown in Fig. 3. Elmer spectrum Two apparatus, equipped with a attenu- Composites were tested to determine their mechani- ated total refectance (ATR) device, from 4000 to 500 cm−1, cal behaviour, by fexural, tensile and impact tests.