Polymer Syntheses

• Polyethylene synthesis
• Polypropylene synthesis
• Syntheses of other polymers
• Experimental equipment available

The polymer synthesis research in PIB has a long tradition; it involves highly qualified personnel and very special equipment (polymerisation reactors, work in an extremely pure/inert atmosphere, semi-pilot and pilot plant facilities, preparation and evaluation of catalyst systems and resulting polymers).

The research teams are focused predominantly to ethylene and propylene polymerisation in the presence of heterogeneous Ziegler-Natta, chromium or metallocene catalyst systems. The experimental equipment allows also the studies of catalyst poisons influence upon the catalyst performance.

Polyethylene synthesis

Supported catalysts

Activities connected with the supported catalyst research represent:

• activation of the support (silica)
  (activation temperatures up to 950°C, pilot scale samples up to 5 kg)
• determination of the number of active groups on the support (reaction with R₃Al, IR analysis)
• development of one-phase supported catalyst for ethylene polymerisation and its copolymerisation with 1-alkenes in gas phase. Development of a proprietary highly active two-phase catalyst for slurry polymerisation
• development of a proprietary supported catalyst based on Cr, especially suited for HDPE pipe and film grades

Homogeneous catalysis

Studies of soluble Al-Ti-Mg based catalyst complexes have been focused mainly on the elucidation of principles controlling the molecular weight distribution (e.g. influence of ligands in TiX₄ and organometallic compounds, influence of transition metal oxidation state and influence of p-bonded ligands in titanium component).

Polymerisation catalysts testing

A special bench stainless steel reactor with a number of unique features has been developed. The reactor enables a close simulation of the UNIPOL gas phase polymerisation process.

This arrangement allows the testing of the performance of various catalyst systems. The study of the polymerisation kinetics (i.e. the polymerisation rate-time profile), and a study of the behaviour of a supported catalyst in the course of gas phase polymerisation (e.g. the formation of chunks and reactor wall deposits (fouling), side reactions, such as oligomerisation or hydrogenation).

The same reactor, with small modifications, can be used to study ethylene homo- and copolymerisation with 1-alkenes in slurry.

Analysis of composition distribution (CD) of polyethylene copolymers is essential for understanding the relation between the structure and physico-mechanical properties of the polyethylene resins.

The following techniques are used for evaluating CD:

• TREF - temperature rising elution fractionation (solution method)
• SIS - stepwise isothermal segregation (fractionation in melt)

The result of the CD analysis is short-chain branching/molecular weight relation.

Polypropylene synthesis

The main activity is focused on homo- and copolymerisation (random and sequential) of propylene with other 1-alkenes, both in hydrocarbon slurry and liquid propylene as well as in the gas phase. Computer controlled reactors with GC facility and a data processing system are available.

Synthesised polymers may be studied from the viewpoint of their structure and physico-mechanical properties. The following parameters can be determined:

• melt flow rate, soluble fractions, extractable fractions, density, particle size distribution, bulk density, morphology, porosity and bulk properties of polymer powder
• structure characterisation by means of DSC, ¹H- and ¹³C-NMR and pulsed ¹H-NMR, GPC, FTIR, SIS/DSC, TREF and other methods
• tensile strength, toughness, hardness, heat resistance

Examples of activities:

• assessment of structure and properties of materials based on polypropylene
• examination of the influence of specific impurities in raw materials upon the kinetics of the process and the polymer properties
• polymerisation and analytical evaluation of raw materials used for industrial olefin polymerisation
• fine purification of raw materials to polymerisation purity (down to a level below 10 ppb of the most critical impurities)
• development of catalyst systems based on commercial catalysts to fit the industrial process
• cooperation with major world producers of catalysts for olefin polymerisation both on a contract and non-commercial basis
• theoretical studies of polymerisation kinetics (including determination of concentration of active centres) in cooperation with a number of universities and academic institutions at home and abroad
• development of new or modified PP grades (homopolymers, random and sequential copolymers)

Syntheses of other polymers

Fundamental research in the field of polymer synthesis is effected either as a part of a project from applied research or in form of a diploma or PhD work. The themes are selected in such a way that they overlap with the Institute research interests in the field of polymer syntheses (e.g. synthesis of syndiotactic polystyrene, ethylene-styrene interpolymers, etc.)

Experimental equipment available