Polycaprolactone

• 2- Oxepanonhomopolymer
• 6- caprolactone

1.21 g · cm -3

58 ° C

-72 ° C

Up to 0.848 · 10-2 mol % at 330 K and 22.4 MPa in supercritical CO2 and ethanol (molecular weight: 1000 g · mol -1)

Polycaprolactone ( PCL), poly - ε -caprolactone, more precisely, is a biodegradable plastic which is produced on the basis of oil. It is thermally deformable and is classified according to the thermoplastics. Made it is a chain of caprolactone, ε - lactone of the caproic acid.

Construction

Polycaprolactone consists of a sequence of methylene units between which the ester groups are formed. Through this very simple construction, a nearly unlimited rotation of the individual chain elements is possible, and the glass transition temperature T g, that is, the curing temperature is very low. At room temperature for short-chain amorphous polycaprolactone according to soft and rubbery. Due to the uniform structure, however, it is well crystallized, creating a reinforcement of the material occurs.

Material properties

Crystalline polycaprolactone similar to the crystal structure of the polyethylene. It has a melting point at about 63 ° C, a tensile strength of 26-42 MPa and an elongation at break of 600 to 1000 %. The glass transition temperature of the amorphous polymer is at about -70 ° C, so it is rubbery at room temperature. However, polycaprolactone has a high tendency to crystallize, which, even when applying rapid cooling and thus the glass transition temperature increases to about -60 ° C. The polymer has a high molar mass, so it is a reaction product of many individual molecules, it is strong and flexible by the partial crystallization, the molecular mass, however, is low, it becomes brittle.

Polycaprolactone is biodegradable. The reduction is carried out by microorganisms, usually in the absence of oxygen ( anaerobic). The material is readily miscible and also combines with other plastics, as well as lignin, gels, starch and other materials. Also, it adheres to a variety of surfaces. It is easy to apply, easy to melt and non-toxic.

Synthesis

Polycaprolactone is produced by ring -opening polymerization of ε -caprolactone under the action of heat and with the aid of a catalyst, usually an alcohol or a diol. The result is a regular polymer which crystallizes to about 50 % in the form of spherulites.

Is produced polycaprolactone by DAW in the United States and of the two British companies Perstorp (former Solvaygeschäft ) and Bostik Findley with different molecular weight.

Use

Polycaprolactone is used due to its beneficial properties for a number of different applications. In addition to classic applications for plastics as packaging or similar, it is mainly used in the medical field for use. Here it is used for products with controlled release ( sustained release ) of drugs, adhesives and synthetic wound dressings and orthopedic casts. In the current research, there is also explored as a carrier material for stem cells in regenerative osteogenesis or cartilage cells for tissue engineering.

Polycaprolactonische resins are mixed with each other and compatible with many other plastics, including polyethylene (PE ), polypropylene ( PP), polystyrene (PS ), styrene -acrylonitrile copolymer (SAN ), polycarbonate (PC) and polyethylene terephthalate ( PET).