Rheology Systems And Thermoplastic Testing

Marco Bronzoni, Product Manager and Market Manager at Instron, talks to AZoM regarding rheology systems and thermoplastic testing.

Could you briefly explain how Instron® is involved in the measurement of the physical properties of plastics?

Instron offers a wide range of state-of-the-art instruments to investigate many physical properties of all materials, but especially since the acquisition of CEAST in 2008, a strong focus has been put on plastics and plastics-based composites.

In addition to static and dynamic mechanical properties, Instron machines can measure properties related to viscosity of plastic melts, impact resistance, heat deflection under load, and more. Different products and accessories target different sectors, from basic Quality Control to the most advanced Research or Product Development.

How are thermoplastic materials typically processed and produced?

Thermoplastics are typically processed as hot viscous fluids, taking the final shape almost in a single step with moulding or extrusion techniques. They are extremely versatile materials extending their applications from soft tissue integration to replacement of metal parts, and they are very friendly to modern energy-saving and recycling needs.

Could you briefly explain the study of rheology and how this relates to the production of thermoplastics?

Rheology is the study of flow properties. In everyday life, thermoplastics are just solid objects, but from the point of the manufacturing industry, they spend a crucial part of their life as hot viscous fluids. This often corresponds to the whole process of turning from a raw material to a finished part.

So strong knowledge of the flow properties gives the capability of designing the process machines, choosing the right raw material or developing a better one, ultimately making the manufacturing process more efficient. In the fluid state, thermoplastics are also mixed to additives and reinforcing elements, becoming, for example, an engineered material with a certain colour, flame-retardant property, and higher strength.

Quality control tests are needed every day to monitor the consistency of all properties.

Instron have recently renewed their line of CEAST melt flow testers – could you please tell us a little about the history behind this line and how they operate?

The renewed product line is based on the Modular Melt Flow line, with some 2,000 units sold worldwide, launched when CEAST was still a small family-owned company though producing melt flow testers for the previous 50 years. The current renewal is centred on the recent ISO 1133-2 requirements, and some new key options.

All melt flow testers are designed and operated following the main international standards ISO 1133 and ASTM D1238: a few grams of thermoplastic sample are inserted by the operator in a heated barrel, melted and extruded through a small capillary die, applying dead weights.

The entry level MF10 is a very simple manual unit for Quality Control. MF20 and MF30 are the most versatile models, and depending on the options, you go from manual operation up to semi-automatic procedures.

MF50 covers all methods including multi-weight procedures, where several different loads are applied in a sequence during a single test - this gives some insight on the molecular characteristics of the material in addition to the basic information on flow. MF20, MF30, and MF50 are fully compliant with ISO 1133 part 2 (MF10 is limited to part 1).

The versatile models can be equipped with a mass selector that makes a full series of test masses available – the operator doesn’t need to handle heavy weights. The operator can program a test in detail (and retrieve results) working from the on-board interface or connecting the machine to a PC. We also design and supply a dedicated CEAST-Instron software suite for this.

How are the new CEAST melt flow testers from Instron unique in their field?

They represent a unique combination of robust design, accuracy according to the latest standards, and possibility to configure and upgrade, without compromising on quality.

We have the know-how and expertise to support customers before and after sales, with a big service network for calibration.

How does the new manual mass selector option enhance thermoplastic testing?

Many laboratories need to apply different testing conditions to different materials, and this means changing parameters for heating, but also changing test masses quite often. With the manual mass selector, all the different masses you may need are permanently installed on the instrument.

You adjust to your requirement by changing the position of the selector, before the test starts. The motorized lifter will do the job of applying the load on the material when foreseen by the method, and lift it up at the end. No manual handling of heavy masses means enhanced operator safety, better work space organization, and no risk of damaging the instrument and its ancillaries during everyday operation.

What industry procedures and requirements are the CEAST melt flow testers compliant with?

The main international references are ISO 1133 and ASTM D1238, plus equivalent national or industrial standards. ISO 1133 part 2 is called ISO 1133-2 and was originally developed for highly-sensitive materials, requiring tighter tolerances on temperature stability and accuracy.

All procedures foreseen by the main standards are possible, from manual Procedure A to semi-automatic multi-weight Procedure D. For each case, our support engineers can recommend the right model and configuration depending on the customer’s needs.

The entry level model is the CEAST MF10 – what are the primary applications of this model and what are the options available with this?

MF10 is a very simple unit, and its primary application is MFR that measures for Quality Control purposes. Available options include a manual cutter for the extruded strand (this helps to collect the sample to weigh), and a die plugging system to work with low-viscosity samples, preventing the material from leaking out before it’s tested. Then, of course, you can choose test masses and different dies according to specific testing methods.

About Marco Bronzoni

Marco Bronzoni is a Materials Engineer who previously worked as a researcher at the Engineering Faculty of Turin before becoming a Product Application Manager with CEAST in 2004. When CEAST became a part of Instron in 2008, Marco was further able to develop his work with Product Development and Sales, whilst also attending ISO technical meetings on Rheology and Mechanical Properties for the development of international standards.

At Instron, Marco currently holds the position of Product Manager for Rheology systems (encompassing both capillary rheometers and melt flow testers), as well as being Market Manager for Rheology, Impact and Thermal systems for Asia, Brazil and Russia. He is responsible for managing the staff and sales agents of his key countries, as well as coordinating both product and sales support. Marco’s territories are currently responsible for generating almost 50% of CEAST revenues worldwide.