Optimization of the Mechanical Properties of Polyolefin Composites Loaded with Mineral Fillers for Flame Retardant Cables

Sara Haveriku,Camillo Cardelli,Marco Badalassi,Giacomo Ruggeri,Andrea Pucci,Michela Meucci

doi:10.3390/micro1010008

Sara Haveriku, Camillo Cardelli + Show 4 more

Open Access

https://doi.org/10.3390/micro1010008

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Abstract

Formulations based on mineral fillers and polymeric matrices of different nature were studied to obtain halogen-free flame retardant compounds (HFFR) for cable applications. The work was carried out by comparing fire-retardant mineral fillers of natural origin with synthetic mineral ones available on the market. As a reference, a formulation based on micronized natural magnesium hydroxide (n-MDH, obtained from brucite) and an ethylene-vinyl acetate copolymer with 28% by weight (11% by moles) of vinyl acetate were selected, and the mechanical and flame retardant properties compared with formulations based on secondary polymers combined with EVA, metal hydroxides, and carbonates. Notably, we found a synergistic effect in the mechanical, rheological and flame retardant properties for the composite containing a mixture of n-MDH and boehmite in a 3:1 weight ratio. Overall, the present work provided a complete and optimized recipe for the formulation of polymer composites characterized by the required flame retardant and mechanical features in electric cables applications.

Highlights

Since their discovery, mineral fillers have strongly contributed to the growth of the thermoplastic polymers industry
Formulations frequently used in the cable industry were selected and investigated (Table 4), i.e., by varying the nature of the polymer matrix and the mineral filler, respectively
Our studies showed that the presence of a coupling agent is necessary to obtain good tensile strength and elongation at break

Summary

Introduction

Mineral fillers have strongly contributed to the growth of the thermoplastic polymers industry. The addition of mineral materials to polymers was initially considered an accessible way of reducing compounds cost, and their utilization as functional additives was proposed only later [1,2,3]. There are a lot of fillers used for different applications depending on their functionalities, properties and origin, since their natural or synthetic nature involves different production processes [4,5,6,7]. When dispersed in the polymeric composite, their features deeply depend by many characteristics, such as morphology, color, refractive index, presence of impurities, density, hardness, moisture content, thermal stability, modulus, surface chemistry and toxicity [4]. The morphology of fillers including particle size, shape, surface area, and particle packing capacity is the key to understanding their

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