EoW March 2009

technical article

Type of filler

Property

Unit

Ca/Zn

SMHs

18 16

19 16.5

Tensile strength After 168h @ 100° Elongation at break after 168 h @ 100°

MPa

%

230

240

Heat stability

Minutes

120

180

LOI

%O

28*

30

2

HCl emission

mg/g

190

140

2 X 10 15

Volume resistivity

Ω.cm C° 20

1 X 10 15

Table 2 ▲ ▲ *with Sb 2 O 3

6 Conclusion Findings indicate that Na+MMT does not enhance the properties of a PVC compound, as happens with other polymer matrix such as Nylon, PA 6, PS and PP. SMHs should be a beneficial alternative to hazardous additives, such as lead stabilisers and Sb 2 O 3 . The capability to act as both stabiliser and flame retardant is especially valuable in cable applications. Insulated wire is a product with a long service life. The development of a range of PVC eco-compounds for insulated wire sheathing applications is a priority, and to eliminate hazardous substances should be a target, contributing to sustainability. The use of no hazardous additives allows products to obtain LCA (Life Cycle Assessment) with low impact in terms of the environment and human health, both during their manufacture and their service life. This paper was presented at Wire Bologna ‘07, Bologna, Italy in November 2007 and is reproduced with the permission of the organisers, International Wire & Machinery Association (IWMA), The Wire Association International Inc (WAI), Associazione Costruttori Italiani Macchine Per Filo (ACIMF) and Comité Européen de la Tréfilerie (CET). n

Table 2 shows the test results on insulation formulation.

5 Results SMHs contribute to the combustion retardancy of the polymeric matrix, producing a refractory oxide residue on the surface of the material and releasing aqueous vapour and carbon dioxide during the decomposition. This endothermic process occurs in the gas phase. The levels of flame retardance and smoke generation are strongly influenced by the choice of components of the compound and their quantity, particularly plasticisers and Sb 2 O 3 . The smoke produced by plastic samples during combustion can be measured in an NBS chamber according to ASTM E662. Tests have shown an immediate and significant increase in smoke generation even with relatively small quantities of Sb 2 O 3 . Therefore the use of SMHs and the elimination of Sb 2 O 3 could significantly reduce the smoke density of PVC compounds. Tests of smoke density according to ASTM E662 are still in progress. SMHs act as stabilisers stopping the process scavenging the HCl generated by the degradation. In this way they stop the chain propagation reaction and the initiation step. However, by scavenging HCL, this type of stabiliser avoids the autocatalytic degradation and consequently, overall degradation is much slower. This stabiliser provides very good long thermal stability. The volume resistivity values are very interesting, and frequency measures are in progress to evaluate a possible variation of dielectric properties.

B & B Compounds Srl Zona Industriale Asi Marcianise Sud I – 81025 Marcianise (CE) Italy Fax : +39 0823 584971 Email : info@bebcompounds.com Website : www.bebcompounds.com

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EuroWire – March 2009