1. Rotational Molding(2) An Introduction to the Basics

2. The Use of Silica-Fume and PEG to Enhance Sintering of LLDPE Powders in Rotomolding Process

3. What is ROTATIONAL MOLDING ?

4. a technology for manufacturing hollow seamless articles

5. by heating, melting, sintering

6. of powder

7. to

8. Dissolving the bubbles If melt is in diffusion equilibrium with atmosphere gas in the bubble tend to flow outwards because of pressure difference ΔP until radius r of the bubble diminishes to zero. PiPi PiPi ΔP = P i - P atm = 2T/r P atm

9. Example of Gas Permeable Polymers: Example of Gas Permeable Polymers: Silicone Rubber: high flexibility of the silicon-oxygen chain in siloxane provides “openings” which are free volume and permit gas diffusion, see Zhang and Cloud (2006). Silicone Rubber: high flexibility of the silicon-oxygen chain in siloxane provides “openings” which are free volume and permit gas diffusion, see Zhang and Cloud (2006).

10. Gas Permeation

11. Siloxane – high flexible chain Siloxane – high flexible chain ( Si-O-Si bond) PEG – high flexible chain PEG – high flexible chain (C-O-C bond)

12. Gas Permeation of Polymers, Barrer

13. PEG + Silica Fume

15. Silica Fume

16. Novel PPA: PEG + Silica Fume

17. PEG + Carboxylic Acids +

18. What are micro-pellets?  Small regular oval shaped plastic granules with a diameter between 500- 600µm.  Produced from the same base material as powder, i.e. Qenos 711UV etc.  Differ from powder by way of the manufacturing process and particle size distribution.

19. Process comparison Customer Dust Collector Blower Bag PE pellets Cyclone Sieves Grinding Head Oversize Particles Powder 85-105 o C Source: Practical Guide to Rotational Moulding by R Crawford & M Kearns POWDER PELLETS and MICRO-PELLETS Source: Gala Industries Bag Centrifugal Dryer Extruder PE Powder Die Plate PDV Cutter Process Water Pump Water Bath 190-210 o C

20. Particle size distribution comparison. Ave = 300-350 µm Ave = 550 µm

21. IMPROVED ECONOMICS AND MORE OPTIONS FOR THE MOULDER What are the benefits of micro pellets? Manufacturing Process  Consistent quality and size  Less contamination  Dust free during mould filling Shape and Particle Size Distribution  Potential for faster cook times  Potential for lower peak internal air temperature  Greater bulk density (0.51kg/m 3 cf. 0.34 kg/m 3 )  Improved flow (10 sec cf. 32 sec)  Potential for improved mechanical properties  Improved filling and definition of difficult to fill mould areas  Moulded parts with more uniform wall thickness  Maintained / improved surface finish Other  Cheaper raw material

22. Micro Pellet Tank Trial Meet requirements of tank standard impact testing with no ductile or brittle failures using a 9.06kg drop dart @ 1.4m. Oven machine, Tank Size = 2,250L, Shot Weight = 55kgs, Wall thickness = ~5mm, Colour = Merino. > 12%

23. Rotomolding PPAs: Silica Fume (SF): "Free-Flow" Agent. PEG+SF: Densification & Processing Aid (D&PA). PEG + Carboxylic Acids (CA): Advanced D&PA. Novel Processing Additives: PEG + CA + SF. Silica Fume (SF): "Free-Flow" Agent. PEG+SF: Densification & Processing Aid (D&PA). PEG + Carboxylic Acids (CA): Advanced D&PA. Novel Processing Additives: PEG + CA + SF.

24. Extrusion PPAs: Silica Fume (SF): Thickening Agent. PEG+SF+Anti-Oxydants: Processing Aid (PA). PEG + Carboxylic Acids (CA): Advanced PA. Novel Processing Additives: PEG + CA + SF. Silica Fume (SF): Thickening Agent. PEG+SF+Anti-Oxydants: Processing Aid (PA). PEG + Carboxylic Acids (CA): Advanced PA. Novel Processing Additives: PEG + CA + SF.

25. Process comparison MICRO-PELLETS WATER COOLING Source: Gala Industries Bag Centrifugal Dryer Extruder Powder Die Plate PDV Cutter Process Water Pump Water Bath 190-210 o C Bag Extruder Powder Die Plate PDV Cutter 125-135 o C Air Cooler MICRO-PELLETS AIR COOLING