PostHeaderIcon Plasticizers

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Leo Hendrik Baekeland invented the plastic term and means molding, this quality stands during a temperature interval, properties of elasticity and flexibility that adapt to different shape by extrusion, injection molding, without losing their chemical, physical and mechanical properties. This process refers to the state of matter, not the material itself.

In 1930 B.F. Goodrich discovered that PVC (polyvinyl chloride) absorbs the plasticizer and resulting a flexible product

Plástico

PVC is a thermoplastic an addition of polymer (without loss of part of the molecule), the molecules are high rigidity and makes it unwieldy, requiring the addition of plasticizers.

It presents in dry white powder or paste then called plastisol, taking a range of  of temperatures between 80 º C and 140 ° C  softening and decomposition.

PVC is degraded by the action of heat, light, battery leakage, etc.., Due to loss of chlorine acid. The degraded PVC becomes rigid. For this reason the need of using epoxidized soybean oil as secondary plasticiser.

The process from rigid PVC to soft  is made by plasticizer.

Plasticizers should be: consistent affinity to PVC, permanent low volatility, low migration and low extraction and effective, this depends on the characteristics, strength and dosage.

We define plasticizer as an inert solvent of low volatility of molecular weight at least 300, which incorporated in a plastic (PVC), increases their flexibility, elasticity and handling.

Mechanism of lamination


The role of plasticizers is to reduce the intensity of bonds among the polymer molecules, these bonds or attractions between molecules (Van de Waals forces), give the large rigidity  to PVC.

The first plasticizer used was Dioctyl Phtalate (DOP) and from there all studies  are derived.Therefore the DOP is the value one as referenece.

Factor substitution is called the quantity of another plasticizer, other than the DOP, to plasticize the same, according to the following formulae.

Substitution factor (SF) = (phr plasticizer to 80/phr hardness of PDO with hardness 80).

We can classify the plasticizers according to: Effectiveness, flexibility at different temperatures, durability, strength, composition and implementation, given the number of parameters that come into play, we believe that can be grouped into three sections:

* Epoxidised: They are considered secondary plasticizers, due to its low dosage. Giving thermal stability above all, to light and acid hydrolysis respectively. Improving the efficiency of both rigid and flexible PVC.
* Monomers: They are considered primary plasticizers due to their large dose and have a molecular weight around 300, its action is to give the necessary flexibility.
* Polymers: They are seen as primary plasticizers therefore enters the formulation in large quantities and have a molecular weight between 1,000 and 8,000, besides acting providing flexibility given their characteristics, depending on its viscosity and permanence in time.

 


2012/05
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