Understanding high quality rotomoulding STAR 2018

Transcription

1 Understanding high quality rotomoulding STAR 2018

2 Content Why and how do tank fail? Design and material selection considerations Technical aspects of material characterisation 2

3 Failure above ground tank Failures that occur generally, during their expected lifespan: 1. Do at a stress levels below their maximum tensile strength 2. Are brittle matrixpolymers.com Bloys Rijkmans

4 Failure underground tank matrixpolymers.com

5 Underground Tank Example of a correct material specification Hexene Density > g/cm³ MFI < 4 g/10 min Colour compound powder Good thermal protection Vertical full ribs

6 Failure modes Failure mechanism is complex and could be caused by one or a combination of the following Mechanical (creep, stress, ESC, impact) Thermal degradation (during the process) Chemical (fluid, acids and basis) Radiation (UV, sunlight)

7 Common type of failure 4% ESC e noth effect 6% 21% 23% 7% 39% Chemical attack Long term properties UV attack Combination Thermal degradation Sourced by Rapra Smithers

8 Cause of failure 20% 15% 20% 45% Material Misselection and Poor specification Unsatisfactory design Poor Processing Abuse and Mis-ues Sourced by Rapra Smithers

9 Initial observations 45% of reason for failures is material mis-selection and poor specification Nearly 40% the failure is caused by notch sensitivity and environmental stress crack If we do understand those aspects we could improve dramatically the quality of the products and the image of our industry Starting from us, what can Matrix do to help you 9

10 Designed for Roto R&D programme conducted in partnership with petrochemical companies aimed at developing polymers intended to be used in rotational moulding applications 1/17/

11 The DNA of Designed for Roto Density MFI Molecular Weight Distribution Viscosity Co-monomer Thermal and light stabilisers 1/17/

12 Revolve 6329U Hexene co-monomer Density g/cm³ MFI 3.2 g/10min UV 15 AS4766 approved Widely sold in Australia, New Zealand, Malaysia and India 1/17/

13 What is the ESCR? ESCR - Environmental Stress Crack Resistance A measure of long-term properties Standard tests accelerate effects using a stress crack promoter It is not a chemical compatibility test The surfactant will speed up the crack propagation

14 Large, mobile stresscracking molecule

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17 Failure

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19 "tie" molecules prevent / slow down inter-lamellar failure

20 Co-monomers in PE The co-monomers are added to PE during the phase of the polymerisation process The co-monomers are added to PE to modify the mechanical and physical properties of PE The co-monomers create branches on the PE backbone PE backbone Co-monomer 1/17/

21 Butene vs. Hexene C-4 C-6 1/17/2018

22 Second set of observations Low melt index and hexene (at a specific density) resins will offer higher entanglements and tie molecules offering a better resistance to 1. Chemicals 2. Loads applied for long time 3. Impact 4. Toughness 22

23 Understanding creep A constant force is applied over a period of time the extension is measured Heating element can be applied at a temperature test can vary from ambient to 60 C Room temperature is very common 23

24 Creep analysis at 5000 hours Revolve 6329U 1/17/

25 Stress & design FEA Stiffening Effect of rib Exaggerated Scale highlights areas of deformation Characteristic Elephant Foot shape matrixpolymers.com Bloys Rijkmans

26 Stress & design FEA Stress = 6 MPa Stress = 2 MPa Outward wall displacement pulls floor up => Good support needed at knuckle Floor thickness also important matrixpolymers.com Bloys Rijkmans

27 Annual Sun Radiation [kly]

28 UV rating UV8, UV10, UV15, UV24? The time the sample has been exposed to accelerating test in a WOM Tensile properties are measured and are greater than 50% of the original values Subtle differences between ASTM vs. ISO standard 1/17/

29 Summary The most advanced economies such as US, EU and Australia have widely adopted hexene PE resins for tank applications because of the superiority of the polymer. In Asian countries moulders are still using butene PE resins Our belief is to help moulders in this part of the world to enhance the quality of their products by offering a hexene tank grade. Moulders who will chose hexene PE materials would benefit from exploring new opportunities by pushing their boundaries Larger agricultural water tanks, chemical containers and more demanding applications. 1/17/

30 Thank you Venkit Mahadevan < Aldo Quaratino

31 Thank you matrixpolymers.com