Polymers aliphatic polyketone

Launching new polymers of medium-range performance is a difficult operation economically, as proved by the case of the aliphatic polyketones. New polymer families are rarely marketed but there are some examples where they provide improved processing performances, which is a particularly needed property to satisfy economic requirements. Modification of existing polymers is also an interesting route. Let us quote some examples ... 

Aliphatic polyketone based on carbon monoxide, ethylene and a small amount of propylene, commercialised by Shell under the trademark CARILON Polymer (PK-EP), see Chapter 9. 

A unique catalyst invention at the Shell Research Laboratories in Amsterdam in 1982 [l, 2, 3] made it possible to polymerise carbon monoxide and alpha-olefins such as ethylene into linear, perfectly alternating structures. This led directly to the development of a new class of thermoplastic polymers known as aliphatic polyketones (PK), which Shell is commercialising under the trademark CARILON. 

The copolymerization of ethylene and carbon monoxide to give alternating copolymers has attracted considerable interest in both academia and industry over recent decades [1, 2]. Attention was focused on aliphatic polyketones such as poly(3-oxotrimethylene) (1) because of the low cost and plentiful availability of the simple monomers. The new family of thermoplastic, perfectly alternating olefin/ carbon monoxide polymers commercialized by Shell provides a superior balance of performance properties not found in other commercial materials the an ethylene/ propene/CO terpolymer is marketed by Shell imder the tradename Carilon . About the history of polyketones see Refs. [3-11],... 

Pri ce. The price of a thermoplastic resin is basically determined by the cost of preparation, which in turn strongly depends on the cost of reagents (monomers, catalysts, etc), the complexity of the manufacturing process, and the dimension of production plants. Aliphatic polyketones, for instance, are made from very cheap raw molecules as ethylene, propylene, and CO their cost is determined by the need for expensive catalysts, based on Pd complexes, and the relatively complex production plant. On the other hand, PEN, which can easily be prepared in the same reactors used for PET, suffers from the difficult availability of its basic monomer dimethyl 2,6-naphthalene dicarboxylate. Most engineering polymers contain aromatic monomers, which are difficult to synthesize and polymerize, with slow and sophisticated mechanisms (condensation, substitution, oxidative coupling). 

Fig. 28. Scanning electron micrograph of damage occurring below crack surface in an aliphatic polyketone polymer (Ref 114). Note that the highest density of crazes occurs near the crack surface.

Aliphatic polyketones described here are a family of semicrystalline thermoplastics obtained by co- or terpolymerization of CO and ethene and/or higher a-olefins. Main emphasis will be on CO/ethene/propene-based terpol5uners [PK-EP]. These polymers can be produced with a wide range of compositions and molecular weights. Various aspects of polyketone catalysis, the pol5mierization process, the types and properties of polyketones, and their applications are reviewed. A number of reviews on polyketones have appeared in recent years (1-5). 

Aliphatic polyketones are still in an early phase of product development and at present, only terpolymers based on CO, ethene, and propene are in a well-enough advanced state of development for use as engineering thermoplastics. Future research into the structure-performance relationships of co- and terpolymers based on these and other olefinic monomers will lead to a controlled molecular tailoring and designing of polymers with desired properties. 

LNP also sought licenses from polymer producers to manufacture compounds based on imique materials, such as Dow s syndiotactic polystyrene, DuPont s amorphous LCPs, and Shell Chemicals aliphatic polyketone "Carilon" (no longer in commercial production). These were not exclusive agreements, but they served to protect LNP s rights to develop patented compounds based on unique materials in cooperation with the polymer producer, but without fear of the results being shared with other compounders... 

Kalay G and Bevis M J (1997), The effect of shear controlled orientation in injection moulding on the mechanical properties of an aliphatic polyketone ,/PoZym Sci Polym Phys, 35,365-291. 

Polyketone resins n. A new and unique family of aliphatic polymers composed of carbon monoxide, ethylene and minor amounts of other alpha olefins. This family of semi-crystalline resins exhibits many of the properties of engineering resins while processing similarly to polyolefins. 

Nearly 40 years have evolved between the first discovery by Reppe of transition-metal-catalyzed CO/ethene copolymerization and the discovery in 1983, at Shell, of a class of highly active, high yield palladium catalysts for the synthesis of high molecular weight, perfectly alternating CO/ethene copolymers [PK-E, Fig. 1], This class of catalysts is also active for the co- and terpol5unerization of CO with alkenes other than ethene, both simple aliphatic and heteroatom functionalized, thus providing access to a family of completely new polyketone polymers. 

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