DOS (DEHS) Plasticizer
GOST 8728-88 with amend 1
Plasticizers are substances infused into polymeric materials to provide or improve their elasticity and (or) plasticity required for reprocessing or use. They facilitate free-flowing ingredients dispersion; bring down the polymeric materials flow (reprocessing) point, brittle point (improve frost resistance) and vitrifying point variables; some of them, namely dioctyl sebacate, improve the polymeric materials fire, light and heat resistance properties.
All plasticizers shall meet the following common requirements: thermodynamic compatibility with a given polymeric material; low volatility; absence of odour, chemical resistance, resistance to fluid medium (e.g. oil), detergent or solvent extraction from the given polymeric material. Plasticizer efficiency is determined by its own structure and by the polymeric material molecular and supermolecular structure. As a rule, flex-chain polymers plasticization process follows the intra-fusion plasticization pattern, i.e. the polymer properties change proportionally to the plasticizer quantity without extremes. Plasticization of polymers with a pronounced secondary structure (e.g. PVC) develops in accordance with either the intra-fusion or the inter-fusion pattern, depending on the infused plasticizer quantity. Consequently, when PVC compositions are plasticized with dicarboxylic acid esters, plasticizer efficiency directly depends on the number of methylene groups in the ester composition and on the infused plasticizer quantity.
Dioctyl sebacate (DOS) is the best plasticizer for PVC polymers. DOS is remarkable for its lowest volatility as compared to other industrial plasticizers - DBS, DOP and DBP (Table1). This quality provides the lowest plasticizer migration from the given PVC polymer, long-term stability of the polymeric composition properties and its resistance to solvents. Polyvinyl chloride compositions, which contain dioctyl sebacate have much higher abrasion resistance that those plasticized with monomeric plasticizers. The DOS plasticizer pour point is equal to -60°C.
Sebacic acid and phthalic acid esters boiling points:
DOS - boiling point=249°C at 4 mm. of the mercury column
DBS - boiling point =344°C at 760 of the mercury column
DOP - boiling point =340°C at 760 of the mercury column
DBP - boiling point =340°C (various) at 760 of the mercury column.
Practically all polymers can be plasticized, however, plasticization efficiency and plasticized polymer properties are mainly determined by the plasticizer chemical composition and molar weight.
Plasticizer contents of a given polymeric composition can very from 1-2 to 100 shares of the total polymer weight.
The most common phthalic acid esters are phthalates and carboxylic aliphatic esters; the most common phosphoric esters are phosphates and low-molecular-weight polyesters.
Sebacic plasticizers have a number of advantages as compared to the most commonly used phthalic and phosphoric esters.
PVS plasticization efficiency
|Plastifier||ΔTv||Breaking elongation, %||Tv|
ΔTv - decrease of vitrifying point at the infusion of 1% (molar weight) plasticizer;
Tv- vitrifying point value at the infusion of 8% (molar weight) plasticizer.
Safety requirements (quotation from GOST 8728-88 with amend. 1)
|Ambient working area air standard, mg/m3||0,5||0,5||1,0||10||10|
|Hazard class according to GOST 12.1.007-76||2||2||2||3||3|
In this way, dioctyl sebacate is one of the safest currently used industrial plasticizers.
Dioctyl sebacate is used for the production of NGP-30-32 and NGP-40-32 (nonflammable); O-45, O-50 and O-55 (frost resistant) soft cable compounds and PL-1m, PLP-2m (shoe plasticate).