by Eric Maziers, Total Refining and Chemicals
From polymer supplier to solution provider
Total recently expanded its strategy for rotomolding. For many years, the company has focused on sales of its Lumicene® metallocene PE resins in Europe. More recently, it also started offering the global rotomolding market a number of proprietary 2nd and 3rd generation metallocene PE’s, as well as metallocene PP, EVA, PLA (polylactic acid, a bio-sourced polymer), tailor-made compounds and innovative rotomolding technologies. These technologies are specifically designed to extend material performance beyond what is possible with other rotomolding polymers currently on the market.
Today the company announced its ambition to be a global player, integrated from resins to tailor-made compounds, designing innovative solutions to meet tomorrow’s customer performance needs.
New materials designed for new opportunities
Total’s focus on rotomolding is driven by industry growth in many regions of the world. The versatility of the rotomolding process drives its success in a wide range of applications, in areas such as tanks, construction equipment, furniture design and toys. With the right materials Total believes its potential is far larger.
Continual requests from rotomolders, designers, and OEMs for enhanced material performances and improved productivity are driving the development of rotomolding polymers at Total. The company’s integrated development model, under which it develops everything from resins to tailormade compounds, has put it in a strong position to meet these requests.
An expert team understanding every step in the rotomolding process
Total’s global rotomolding business is managed by a dedicated team based in Brussels and supported by regional production and technical-sales organizations around the world. To further strengthen its commercial capabilities, it has built strong partnerships in North and South America, Australia and New Zealand.
Total has been known for many years for its expertise in designing new rotomolding materials. At its site in Feluy, Belgium, the company has brought together all of its R&D teams under one roof: from the development of new polymers to the creation of the final compounds, ready for customer testing, it’s all done at one site. All teams are working closely together to master all the steps of the rotomolding process and to provide the best solutions to the customers (see figure 1).
• New resins design: Total has developed innovative proprietary catalysts and polymerization processes for the production of polymers for rotomolding applications. For this purpose Total uses its own polymer pilot plant in Feluy (see figure 2). The R&D facilities are also equipped with state-of-the-art single and twin-screw extruders for developing specialty rotomolding compounds and polymer alloys.
• Assessment of powder quality: Powder quality is a key factor in the rotomolding process. Total developed new tools that allow it to better understand the relationship between powder characteristics and processability. TP-Picture® (a 2D image-processing tool) is used to characterize a rotomolding powder or micopellet in terms of the following characteristics (see figure 3):
– The size and shape of the powder particles
– Material-sintering time
– Densification behaviour
The company has also invested in a new pulveriser for its laboratory in Feluy for further research into powder quality.
• Rotomolding machine and process conditions: Total has a long and fruitful collaborative relationship with Queen’s University in Belfast, Northern Ireland, in the field of rotomolding.
– Based on a technique known as design of experiments, many fundamental and applied studies have been performed at Queen’s University to model processes in terms of cycle time, sintering, densification , crystallisation, shrinkage and warpage and thus to enhance the industry’s understanding of the correlations between process conditions and the properties of parts.
– Unique structures in rotomolded parts have been also developed, including skin/foam/skin, composite structures and thermoplastic multilayers.
– Total has developed 3D analytical tools to characterise sagging behaviour during the rotomolding process (see figure 4).
– Recent studies have been focused on understanding the release of parts from the molds.
In view of the huge demand for R&D projects and for customer support, the company recently invested in a new rotomolding machine for its R&D facility (see figure 5). The company chose a Leonardo Smart machine, a high-performance system manufactured by Persico SpA of Italy and considered to be the industry standard for the rotomolding of conventional and engineering materials. A dedicated state-of-the-art application lab is now available for rotomolding development activities, all grouped together in one location including extrusion, grinding, rotomolding, and the characterisation of powder and parts.
• Assessing the quality of rotomolded parts: A substantial R&D time investment has been made in understanding the shrinkage and warpage properties of rotomolded parts. A 3D-analytical approach was developed to generate the 3D surface-mapping information on rotomolded parts (of any size). This technique makes it possible to monitor the 3D properties of parts that are to be compared to models developed from the mold (see figure 6).
While routine part characterizations involving both tensile and impact properties are commonly performed in the lab, Total has developed particular expertise in the following areas:
• Fuel permeation and compatibility
• Chemical compatibility
• Stacking tests
• Unique creep testing
• Unique fatigue testing
• Skin/foam/skin characterisation
• A complete database developed for the majority of the materials to be used for static, creep and dynamic calculations made with FEA tools (see figure 7)
In 2011, the company’s long-standing expertise in designing new rotomolding materials, as well as catalysts and final rotomolded parts, led it to design a concept car that was built around a rotomolded two-piece car body (see figure 8).
What’s next?
This series of RotoWorld Magazine articles is intended to provide insight into the technologies and methods used by Total in the development of new rotomolding materials designed to meet both new and existing challenges presented by rotomolding customers. The next two papers will describe more specific material developments including biopolymers, clarified and impact modified PP, EVA, semi-conductive and flame retardant PE grades currently under test.
from an article at RotoWorld®
https://rotoworldmag.com/total-gives-a-new-spin-%e2%80%a8to-rotational-molding/
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