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

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.

Effect of Polyolefin Elastomers’ Characteristics and Natural Magnesium Hydroxide Content on the Properties of Halogen-Free Flame-Retardant Polyolefin Composites

“…Polymer compounds that are used in electrical cables usually require 150% of elongation at break and 10 MPa or 12.5 MPa of tensile strength (for sheathing and insulating applications, respectively), therefore dosages of FUSABOND N525 that are higher than 3% were considered to be suitable (Figure 4) (per the reference standards CEI 20-11, BS7655 6.1, and DIN VDE 0207) [34]. This result is also confirmed by our previous work in which the 3% coupling agent was found to be the best compromise between mechanical and rheological properties [35].…”

“…Micro 2022, 2, FOR PEER REVIEW 8 Polymer compounds that are used in electrical cables usually require 150% of elongation at break and 10 MPa or 12.5 MPa of tensile strength (for sheathing and insulating applications, respectively), therefore dosages of FUSABOND N525 that are higher than 3% were considered to be suitable (Figure 4) (per the reference standards CEI 20-11, BS7655 6.1, and DIN VDE 0207) [34]. This result is also confirmed by our previous work in which the 3% coupling agent was found to be the best compromise between mechanical and rheological properties [35]. Moreover, the melt flow index (MFI, Table 2), which is a measurement of the resistance of a melting thermoplastic polymer to flowing, decreased from 7.4 ± 0.4 to 2.9 ± 0.1 g/10 min with the addition of the compatibilizer, thus suggesting the existence of effective interactions between compatibilizer and the POE matrix.…”

A Systematic Investigation on the Effect of Carbon Nanotubes and Carbon Black on the Mechanical and Flame Retardancy Properties of Polyolefin Blends

“…The brucite surface's clogged pores likely caused the surface area to decrease, which may have led to lower tensile strength values and increased elongation at break. According to Haveriku et al [43], fatty acid-based thermoplastic treatments often increase elongation and impact resistance while decreasing modulus, tensile strength, filler dispersion, and melt viscosity.…”

Feedstock agnostic upcycling of industrial mixed plastic from shredder residue pragmatically through a composite approach

“…In addition to this, commercial polymer formulations may contain up to 70 wt% additives, including colour pigments, lubricating agent, antioxidant and others. [33][34][35][36][37] Selecting the wrong processing temperature may cause the degradation of these additives, forming voids within the melt consolidated mixed plastic. The degradation product of a polymer could also cause hydrolysis of another polymer in the same batch.…”