Flexibility IS US!
Plasticisation, i.e. softening plastics

Polymer materials are virtually non-existent in "pure," unmodifiable form. Modi-fying polymers with various additives allows us to obtain a wide range of applications of a plastic. The type and amount of additives used in processing affect the perfor-mance properties of the end product. One of them is flexibility obtainment, which allows fulfilment of a product’s basic functions in a given application.

Published: 23-10-2020

Flexibility can be achieved by using softening agents called plasticisers. When added to a polymer, they facilitate its processing and change the end performance properties by reducing the glass transition temperature (polymer’s plastic to glass transition point). In chem-ical terms, the mechanism of a plasticiser consists in the penetration of its molecules in poly-mer chains, reduction of inter-molecular forces and simultaneous increase in mobility.

The most commonly softened polimer is polyvinyl chloride (PVC) – over 80% of world’s production of plasticisers is used every year for products based on flexible polyvinyl chloride. The use of a numer of additives facilitates its processing, changes the functional properties of the end product and allows for a variety of applications of this material. Even rigid PVC products, such as sewage pipes, contain 5-10 phr (parts hundred resin) of plasticis-ers that facilitate processing.

Types of plasticisers

There are two main plasticiser groups for PVC: primary and secondary. The first group includes plasticisers characterised by high compatibility with polyvinyl chloride, e.g. dioctyl phthalate (DOP), diisononyl phthalate (DINP), dioctyl terephthalate (DOTP) and phos-phoric esters (phosphates).

Due to their appropriate chemical structure and the presence of phosphorus in their structure, plasticisers combine the plasticising and the flame retardant features, which allow them to be used in specialised solutions that require increased fire resistance.

Secondary plasticisers are less compatible with PVC. In industrial solutions, they are used together with primary plasticisers to provide additional properties, i.e. reduced plasticiser migration capacity, flexibility improvement at low temperatures, higher oil resistance and low volatility. They include, among others, adipates, sebacates, citrates, trimellitates and epoxi-dised vegetable oils – soybean oil (ESBO) or rapeseed oil (ERO).

PCC Group’s solutions

PCC Rokita’s Phosphorus Chemistry Business Unit produces flame retarding plasticis-ers offered under the Roflex name. These products belong to the group of phosphoric esters (phosphates) and are dedicated for the production of flexible PVC with an increased flamma-bility profile.

Current legal regulations regarding the plastics sector impose on manufacturers requirements related to not only fire propagation, but also to the phenomena accompanying this process. The most important of these is the release of toxic gases and smoke during combustion. At the same time, great emphasis is placed on the additional advantages of the additives used, i.e. the ability to provide plasticising effect at low temperatures, low plasticiser migration or product environmental friendliness.

The future

In order to keep up with the growing market requirements, the Phosphorus Chemistry Business Unit is expanding its plasticisers portfolio with products combining several desirable functions.

In the near future, the following products will be added to the portfolio:

  • a “green” plasticiser – dedicated for products with high requirements regarding environmental performance and flame retardancy;
  • a low smoke plasticiser – combines excellent plasticising and flame retarding properties with a low smoke formation profile;
  • a low temperature plasticiser – an additive providing flexibility at low tempera-tures and the ability to generate small amounts of toxic smoke during combus-tion.

Introducing these new products will result in greater possibilities in using flame retard-ing plasticisers in applications previously unavailable due to the abovementioned specialist requirements. Potential applications of the new product range can be found in such industries as wires and cable, PVC flooring, transportation and automotive.

Magdalena Janus
Junior Technical Support Specialist
PCC Rokita

Patryk Juszczak
Technical Support Specialist
PCC Rokita

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