Polycaprolactones applications

Polycaprolactones (see also Section 25.11), although available since 1969, have only recently been marketed for biodegradable purposes. Applications include degradable film, tree planting containers and slow-release matrices for pharmaceuticals, pesticides, herbieides and fertilisers. Its rate of biodegradability is said to be less than that of the polylactides. 

Polybutadienes, polycaprolactones, polycarbonates, and amine-terminated polyethers (ATPEs) are shown in Scheme 4.4 as examples of other commercially available polyols. They are all specialty materials, used in situations where specific property profiles are required. For example, ATPEs are utilized in spray-applied elastomers where fast-reacting, high-molecular-weight polyamines give quick gel times and rapid viscosity buildup. Polycarbonates are used for implantation devices because polyuredtanes based on them perform best in this very demanding environment. Polycaprolactones and polybutadienes may be chosen for applications which require exceptional light stability, hydrolysis resistance, and/or low-temperature flexibility. 

While PHB and PHV are not considered true plastics, another biodegradable polymer polycaprolactone (PCL) is a plastic material because its monomer e-caprolactone is obtained on an industrial scale from petrochemical products (cyclohexanone and peroxyacetic acid). This synthetic plastic with its low melting point is easily extrudable and applications in the packaging area are envisioned. 

Polycaprolactone aliphatic polyesters have long been available from companies such as Solvay and Union Carbide (now Dow Performance Chemicals) for use in adhesives, compatibilisers, modifiers and films as well as medical applications. These materials have low melting points and high prices ( 4-7 per kg in 2005). PCL is predominantly used as a component in polyester/starch blends such as... 

Aliphatic polyesters like polycaprolactone (PCL) or polybutylene adipate (PBA) are readily biodegradable, but because of their melting points of 60 °C are unsuitable for many applications. On the other hand, aromatic polyesters like polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) have high melting points above 200 °C and very good material properties, but are not biodegradable. 

APPLICATIONS - RELEASE PROFILE OF PVC/ POLYCAPROLACTONE-POLYCARBONATE AGED IN AQUEOUS ENVIRONMENTS... 

Until recently, hot-melt extrusion had not received much attention in the pharmaceutical literature. Pellets comprising cellulose acetate phthalate were prepared using a rudimentary ram extruder in 1969 and studied for dissolution rates in relation to pellet geometry. More recently, production of matrices based on polyethylene and polycaprolactone were investigated using extruders of laboratory scale. Mank et al. reported in 1989 and 1990 on the extrusion of a number of thermoplastic polymers to produce sustained release pellets.A melt-extrusion process for manufacturing matrix drug delivery systems was reported by Sprockel and coworkers.As one can see, a review of the pharmaceutical scientific literature does not elucidate many applications for hot-melt extrusion in this field. 

There are also several external plasticisers with almost no proven toxicity, such as, tri-(2-ethylhexyl)trimellitate (TEHTM), di-2-ethylhexyl adipate (DEHA), and acetyl triburyl citrate, (ATBC), which are economically unfeasible for industrial applications, i.e., TEHTM is three times (and for DEHA, four times) as expensive as DEHP. In any case, the use of adipate, mellitate and azoalate type external plasticisers are expected to grow in use at the expense of different phthalate types [19]. Butene based alcohols are also used in the manufacture of flexible PVC [20], whereas polycaprolactone is used as a permanent and safer plasticiser for PVC [21],... 

Polycaprolactone (PCL) is obtained by ring-opening polymerization of the six-membered lactone, e-caprolactone (Figure 30.4f), which yields a semicrystalline polymer with a melting point of 59°C-64°C and a glass transition temperature of 60°C with great organic solvent solubility. Anionic, cationic, coordination, or radical polymerization routes are all applicable for synthesis. " " " ... 

Wang, Y. Rodriguez-Perez, M.A. Reis, R.L. Mano, J.F. Thermal and thermomechanical behaviour of polycaprolactone and starch/polycaprolactone blends for biomedical applications. Macromol. Mater. Eng. 2005, 290(8), 792-801. 

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