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Enhanced Orientation of PVC PipeUsing Acrylic Processing Aids Manoj Nerkar, John Cornetta, Ted Price, Steve Rapacki, Ian Drake, Ramesh Iyer

Dow Plastics Additives

SPE Plastic Pipe Conference, Philadelphia, PA 04/16/2019

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Agenda

Background• PVC-O Technology• PVC-O Market Review

Fundamental PVC-O Material Properties• Tensile Testing• Effect of temperature and speed on orientation• PVC-O in-house capabilities

Acrylic Process Aids• Melt strength• Melt Processing

Summary

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Oriented PVC (PVC-O) Technology

PVC-O

PVC-STD

Picture courtesy of PVC-O molecular orientation, Molecore

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PVC-O Market Opportunity

2022 global installed PVC-Ocapacity projections

5 Year CAGR of 14% (’17-22)

Estimate of PVC-O installed capacity growth (kT) 2017-2022 (1)

Global number of PVC-O lines (2)

60 PVCO lines globally(# of lines tripled since ’08)

Prior 10 year CAGR of 13% (’08-’18)1. Molecor published estimate from Pipes and Profile Extrusion Magazine Oct. 2018 2. Andre Nijland (Wavin) Pipes in Infrastructure Conference, London April 2018

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Learning from Material Test: Tensile Property

• To understand the temperature effect on the PVC-O process, extruded PVC material property is evaluated at different temperature

• As temperature increases, PVC changes from elastic plastic to hyperelastic material behavior

0

10

20

30

40

50

60

70

0 100 200 300 400

Engi

neer

ing

Stre

ss [M

Pa]

Engineering Strain [%]

25°C50°C75°C100°C115°C130°C

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Effect of Temperature on PVC Tensile Strain Limit

• For the PVC-O process, it is better to maintain the temperature where material can achieve highest strain and relatively lower modulus

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Tensile Testing: Effect of Pulling Rate

Base PVC-O Formulation:• Modulus increases with increasing

expansion rate• Max strain decreases• Failure in hoop expansion predicted

at increased expansion rate

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T=50 °C

T=100 °C

T=130 °C

2 in/min

20 in/min

PVC Tensile Testing

Pulling Speed: 2 in/min

T=100 °C

Effect of Temperature Effect of Pulling Speed

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In-house Lab Scale PVC-O Set-up

• Pre-extruded pipe is tested for the PVC-O process by a solid mandrel • Temperature, pipe expansion and lubrication is controlled in this test• Expansion force is measured during the PVC-O expansion process

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Pulling Force on Mandrel

0

5000

10000

15000

20000

25000

0 50 100 150 200 250 300

Pulli

ng F

orce

On

Man

drel

[N]

Mandrel Travelling [Mm]

85°C

97°C

• As indicated from material test, force measurement from tensile test confirms that Temperature has a significant effect on the pipe expansion

• A few degree temperature drop can lead to significant force increase

78°C

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Improved Material Properties: Effect of Processing Aids

100°C and 50 in/min

• PVC pipe compound baseline fails at 300%• New Dow Processing Aid at 5phr 21527-XP

(6515-5) shows higher strain limit

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Improved Material Properties: Effect of Processing Aid (PA)

300%

350%

400%

450%

500%

0 1 2 3 4 5 6 7 8 9 10

Engi

neer

ing

Stra

in L

imit

(%)

Process Aid Loading (PHR)

100°C, 20 in/min 21527-XP

Paraloid ™K120ND

Surecel™ T-50

K120ND: Generic PA21527-XP: PVC-O PAT-50: Reactive PA

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Short stiff chainsLow molecular weight

Long flexible chainsUltra high molecular weight

PVC

Acrylic Processing AidPVC chains entangled with

processing aid chains

• Enhances melt strength and rheology, enabled by their high compatibility, flexibility and Mw, orders of magnitude greater than the PVC

• Rheology control has become the primary function of PA, driving exact selection and usage level

• MMA-rich, acrylic copolymers with Mw typically >1MM

• Highly compatible with PVC

• Promotes fusion / gelation of rigid PVC

• Without PAs, rigid PVC fusion and melting can be VERY slowunder typical processing conditions

No Effect on Color and Clarity

How Acrylic Processing Aid Works?

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Haake Rheocord: Melt Strength Evaluation

Haake Extruder Zone 1 Zone 2 Zone 3 AD Die

Temperature (°C) 150 155 165 170 170

Haake Rheocord Screw Speed: 10 RPM Feeder Speed: 10 RPM

Melt Strength Tester Height: 75 mm Gap: 0.6 mm

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Processing Aid Loading Level

• Higher level of processing aid increase melt strength, however, its critical to monitor torques and pressures in extruder and die

0

100

200

300

400

500

600

700

800

900

0.68 PHR 0.76 PHR 0.85 PHR 2 PHR

Max. Velocity (mm/s)Sample ID Torque Z 3 die Z 3 Die

21527-XP (phr.) ( m*g ) (PSI) (PSI) (

oC) (oC)

0.68 2622 1094 837 170 181

0.77 2702 1146 866 170 182

0.85 2800 1175 901 170 181

2.00 3060 1292 982 170 182

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Choosing Right Processing Aid

• 21527-XPgives higher melt strength at lower loading level

0

100

200

300

400

500

600

700

800

900

2.0 PHR K120ND 2.0 PHR 21527XP 0.85 PHR K120ND 0.85 PHR 21527XP

Max. Velocity (mm/s)K120ND2 PHR

21527-XP2 PHR

K120ND0.85 PHR

21527-XP0.85 PHR

Torque (m*g) 2807 2800 2760 3060

Barrel Pressure

(PSI)1140 1175 1108 1292

Die Pressure

(PSI)834 901 843 982

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In-house Biaxial Orientation

2X increase in rate

21527-XP

Generic PA

• 21527-XP sustained increased(doubled) orientation speed

35 to 70 mm/s in TD and MD

Orientation Biaxial

Heat Soak Time (Min) 8

Temperature (°C) 100

Distance TD 3X

Distance MD 2X

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Summary

• PVC-O process was evaluated from material perspective• Maximum elongation was achieved at lower pulling rate• Optimum temperature (100°C) is critical to get maximum orientation• Higher elongation was achieved by addition of acrylic process aid (PA)• 21527-XP improved biaxial orientation as demonstrated by tentering frame data • Improved melt strength was attributed to specifically designed 21527-XP • Right acrylic PA can improve PVC-O process and productivity

Enhanced Orientation of PVC Pipe�Using Acrylic Processing Aids AgendaOriented PVC (PVC-O) TechnologyPVC-O Market OpportunityLearning from Material Test: Tensile PropertyEffect of Temperature on PVC Tensile Strain LimitTensile Testing: Effect of Pulling Rate PVC Tensile TestingIn-house Lab Scale PVC-O Set-upPulling Force on MandrelImproved Material Properties: Effect of Processing AidsImproved Material Properties: Effect of Processing Aid (PA)How Acrylic Processing Aid Works?Haake Rheocord: Melt Strength Evaluation Processing Aid Loading LevelChoosing Right Processing AidIn-house Biaxial OrientationSummary