RESEARCH ARTICLE Obtaining of a PET/SiC hybrid multifilament: Non-isothermal crystallization studies Marta Riba-Moliner , Gabriela Mijas, Davinia Roig and Diana Cayuela INTEXTER, Universitat Polit ecnica de Catalunya (UPC), Terrassa, Spain ABSTRACT Thermal processing properties are a key factor in the industrial processing industry. The obtaining of a PET-based hybrid composite multifilament with textile properties (yarns) is presented. The system is composed by ceramic silicon carbide (SiC) nanoparticles and a dispersing agent included in a PET matrix. With the objective to produce a suitable nanocomposite, the study is divided in three parts: (i) evaluation by non-isothermal crystallization of three different dispersing agents (two of them based on esters of montanic acids and, the other on an amide wax) to achieve an homogeneous nanocom- posite; (ii) study of the influence of the concentrations of SiC and of the more suitable dispersing agent on the thermal properties of the PET-hybrid composite; and (iii) the obtaining of a PET-hybrid multifilament with textile properties together with its characterization by Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC) and mechanical properties. ARTICLE HISTORY Received 2 July 2020 Accepted 21 October 2020 KEYWORDS SiC nanoparticles; PET nanocomposites; non- isothermal kinetics; textile composite; multifilament yarn; dispersing agent 1. Introduction The pursuit of the increase of thermal and mechanical prop- erties of polymeric fibres through composite materials has been an important target in the field of high performance textiles. Optically active particles to produce modulated- emissive fabrics for thermal responsive textiles (Pooley et al., 2016; Shin & Park, 2018) or biomimetic particles for developing reinforced textile-based tissue engineered scaf- folds (Xue et al., 2019), are some of those examples. In this context, studies of the inclusion of ceramic nano- particles of titanium dioxide (TiO 2 ) and calcium fluoride (CaF 2 ) as fillers in a matrix of poly(ethylene terephthalate) (PET) were previously developed by the research group (Cayuela et al., 2016; Manich et al., 2015; Riba-Moliner et al., 2020). In those studies, the use of three additives as dispersing agents was tested. Two esters of montanic acids, one with multifunctional alcohols (MAWMA) and another one partially saponified with butylene glycol and the rest with calcium hydroxide (PSEMA) and, an amide wax based on N,N’-bisstearoylethylene-diamine (AW) were the analysed additives. In the both cases of ceramic-based composite sys- tems, MAWMA agent showed the most suitable behaviour in terms of non-isothermal crystallization, dispersion degree and compatibility, which are important parameters from the industrial processing point of view (Riba-Moliner et al., 2020). In the present work, SiC is studied as filling material for the production of a multifilament with textile properties. SiC is one of the most important carbide ceramics and, although it is manufactured in different varieties, all of them show similar properties. From high to very high mechanical resist- ance, corrosion resistance even at very high temperatures, high thermal resistance, low thermal expansion, very high thermal conductivity, significant hardness and semiconductiv- ity are some of the most relevant and interesting properties of this ceramic material (Agarwal et al., 2013; Bhattacharjee & Nanda, 2017; Deng et al., 2018; Mullaikodi et al., 2019; Patnaik & Nayak, 2018; Shen et al., 2017). The objective of this study is to produce a hybrid compos- ite filament based on PET filled with SiC particles and a dis- persing agent to ensure both, homogeneous mixtures and final properties, avoiding the aggregation of the ceramic part. Firstly, non-isothermal crystallization studies of the nanocom- posited system (PET/SiC) with different dispersing agents (MAWMA, PSEMA and AW) are developed by DSC in order to determine the contribution of each one in the crystalliza- tion process. Once the more promising nanocomposited (NCP) system is found, a study of the influence of the con- centrations of SiC and dispersing agent to the thermal proper- ties of the NCP in plate form is determined by DSC. Finally, the PET/SiC/dispersing agent system obtained at the more favourable conditions is transformed into a multifilament with textile properties by extrusion. Molecular weight determin- ation, thermal and mechanical properties are evaluated by Gel Permeation Chromatography (GPC), DSC and mechanical tests, respectively, to characterize those resulting substrates. 2. Experimental part 2.1. Materials 2.1.1. Poly(ethylene terephthalate) (PET) PET textile quality was used in the determination of the suitability of the dispersing agent to produce composites marta.riba@upc.edu