Polydicyclopentadiene
Encyclopedia
Polydicyclopentadiene is a polymer
which is formed through ring opening metathesis polymerisation
(ROMP) of dicyclopentadiene
(DCPD). The difference between the various systems lies in the type of catalyst used to create the polymer, but the final polymer properties are similar. Any difference which can be seen is often insignificant to the end user unless the application requires to go to the limits of the PDCPD material properties. The three tradenames are Telene, Metton and Pentam.
, since the reaction is not stoichiometric. The 1:1 ratio for DCPD moulding is not critical since this is not a combination of two different chemical element
s to form a specific matrix
. Significant changes in ratio will slow down the system's reactivity because fewer active reaction nuclei are being formed. This also changes the final properties somewhat. The current industrial pumps used on RIM equipment are accurate enough to ensure that the mixing ratio stays within the necessary limits.
blanket in the tanks. The tools or moulds are closed tools and are being clamped using a hydraulic press
. Because the resins shrink about 6% in volume during reaction, these presses (also called clamping units) don't have to handle high pressures such as for Sheet Moulding Compound
(SMC) or expanding polyurethane.
. Flat parts can be made from machined aluminium while deeper 3D-shaped
parts are often made in cast aluminium tools. It is important to know that these tools have to take the volumetric shrinkage into account, cannot have any undercuts and need gaskets all around the cavities.
A reacting system is always governed by temperature - in any form. This means that the temperature of the liquid components has a strong influence on the reactivity. So do the temperatures inside the tool. To ensure that one side has an excellent surface finish, the temperature on that side needs to be higher than on the core side. Both tool-halves are therefore tempered at a different temperature with typical values of 60°C and 80°C.
Typical cycle times for moulding parts range between 4 and 6 minutes.
For the best information on all properties of this resin system and polymer, it is best to contact the material supplier or to visit their respective websites.
PDCPD does not contain any fiber reinforcement although a fiber reinforced version has been developed by Telene S.A.S.
PDCPD allows to vary the thickness throughout a part, to incorporate ribs and to overmould inserts for an easy assembly of the parts.
PDCPD cannot be painted in mass and needs to be painted after moulding.
s, construction equipment
, truck
s and bus
es. In the industrial applications, the main success story is components for chlor-alkali production (e.g. cell covers for electrolyzers).
Other applications can be developed where impact resistance in combination with rigidity, 3D design and/or corrosion resistance is required.
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
which is formed through ring opening metathesis polymerisation
Ring opening metathesis polymerisation
Ring-opening metathesis polymerization is a type of olefin metathesis chain-growth polymerization that produces industrially important products. The driving force of the reaction is relief of ring strain in cyclic olefins and a wide variety of catalysts have been discovered...
(ROMP) of dicyclopentadiene
Dicyclopentadiene
Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula C10H12. At room temperature, it is a white crystalline solid with a camphor-like odor. Its energy density is 10,975 Wh/l....
(DCPD). The difference between the various systems lies in the type of catalyst used to create the polymer, but the final polymer properties are similar. Any difference which can be seen is often insignificant to the end user unless the application requires to go to the limits of the PDCPD material properties. The three tradenames are Telene, Metton and Pentam.
The Chemical System
The reacting system is formulated in such a way that two components need to be mixed at equal volume (1:1 ratio). Both components contain mainly DCPD with some additional additives. The difference between both components is crucial, but constitutes only a small fraction of the total formulation: the catalyst system is divided into two parts, each part going into a separate component. When both components are mixed, the complete catalyst system is recombined and becomes active. This is an important difference from other Reaction Injection Moulding (RIM) systems like polyurethanePolyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
, since the reaction is not stoichiometric. The 1:1 ratio for DCPD moulding is not critical since this is not a combination of two different chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
s to form a specific matrix
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...
. Significant changes in ratio will slow down the system's reactivity because fewer active reaction nuclei are being formed. This also changes the final properties somewhat. The current industrial pumps used on RIM equipment are accurate enough to ensure that the mixing ratio stays within the necessary limits.
Equipment
DCPD resins are transformed using high pressure RIM equipment as used in the polyurethane industry, with some small changes to be considered. As a reference, a widely used machine to inject DCPD resins is the Cannon A-100 fitted with a DCPD kit. The most important change is that the resin can never be in contact with air or moisture, which required a nitrogenNitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
blanket in the tanks. The tools or moulds are closed tools and are being clamped using a hydraulic press
Hydraulic press
A hydraulic is a machine using a hydraulic cylinder to generate a compressive force. It uses the hydraulic equivalenta mechanical lever, and was also known as a Bramah press after the inventor, Joseph Bramah, of England. He invented and was issued a patent on this press in 1795...
. Because the resins shrink about 6% in volume during reaction, these presses (also called clamping units) don't have to handle high pressures such as for Sheet Moulding Compound
Sheet moulding compound
Sheet moulding compound or sheet moulding composite is a ready to mould fibre-reinforced polyester material primarily used in compression moulding. The sheet is provided in rolls weighing up to 1000 kg....
(SMC) or expanding polyurethane.
Tooling
Most tooling for PDCPD is made from aluminiumAluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
. Flat parts can be made from machined aluminium while deeper 3D-shaped
Three-dimensional space
Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...
parts are often made in cast aluminium tools. It is important to know that these tools have to take the volumetric shrinkage into account, cannot have any undercuts and need gaskets all around the cavities.
Process Considerations
The liquid resin has a density of 0.97 and reacts into a solid with a density of 1.03 which constitutes a volumetric shrinkage of 6%. Since most parts are panels, most of the shrinkage will happen in the Z-axis (thickness). This makes the parts self-demoulding as they do not have a good contact with the core side of the tool [The core side is the side which will be the back side of the part. The front side of the part is called the matrix side].A reacting system is always governed by temperature - in any form. This means that the temperature of the liquid components has a strong influence on the reactivity. So do the temperatures inside the tool. To ensure that one side has an excellent surface finish, the temperature on that side needs to be higher than on the core side. Both tool-halves are therefore tempered at a different temperature with typical values of 60°C and 80°C.
Typical cycle times for moulding parts range between 4 and 6 minutes.
Properties
PDCPD has a combination of properties with the most important being:- high impact resistance
- high chemical corrosion resistance
- high Heat deflection temperatureHeat Deflection TemperatureThe heat deflection temperature or heat distortion temperature ' is the temperature at which a polymer or plastic sample deforms under a specified load...
(HDT)
For the best information on all properties of this resin system and polymer, it is best to contact the material supplier or to visit their respective websites.
PDCPD does not contain any fiber reinforcement although a fiber reinforced version has been developed by Telene S.A.S.
PDCPD allows to vary the thickness throughout a part, to incorporate ribs and to overmould inserts for an easy assembly of the parts.
PDCPD cannot be painted in mass and needs to be painted after moulding.
Applications
Since PDCPD is still a young material, the number of applications is quite limited. The major success story is in the field of body panels, mainly for tractorTractor
A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...
s, construction equipment
Construction Equipment
Construction Equipment is a trade publication and web site serving the information needs of construction contractors, materials producers, and other owners and operators of construction equipment....
, truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...
s and bus
Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
es. In the industrial applications, the main success story is components for chlor-alkali production (e.g. cell covers for electrolyzers).
Other applications can be developed where impact resistance in combination with rigidity, 3D design and/or corrosion resistance is required.
Economic considerations
PDCPD has proven to be economically interesting when considering large parts (>5 kg or >1m²) in low to medium series (1,000 to 20,000 parts per year). Factors that make this case are:- low initial investment versus injection mouldingInjection mouldingInjection molding is a manufacturing process for producing parts from both thermoplastic and thermosetting plastic materials. Material is fed into a heated barrel, mixed, and forced into a mold cavity where it cools and hardens to the configuration of the cavity...
or SMC - high capacity due to the low cycle times compared to hand lay-up or Resin transfer moulding (RTM)
- fast development cycles for new projects
External links
- Telene S.A.S. : Telene resin system
- Metton America Inc : Metton resin system
- Rimtec : Pentam resin system