IMPACT MODIFIERS AND THEIR INFLUENCE IN TOUGHNESS AND PLATE OUT IN HIGHLY FILLED RIGID PVC FORMULATIONS

Transcription

1 IMPACT MODIFIERS AND THEIR INFLUENCE IN TOUGHNESS AND PLATE OUT IN HIGHLY FILLED RIGID PVC FORMULATIONS Enrique Torres, Dr. Mark T. Berard and Dr. Michael Schiller* The Dow Chemical Company *Chemson Polymer - Additive AG 1

2 OUTLINE Impact Modification Fundamentals Window Profile Extrusion and Impact Filler level study with CPE, High Mol. Wt. CPE & Acrylic Plate Out Experiments Calibrator plate out with CPE & Acrylic IM in Ca/Zn stabilized formulation Conclusions 2

3 Brittle Crack, Craze or Shear Band? Why do some polymers tend to craze, while others have shear bands? Craze is low energy absorption, and so low impact Shear band is high energy absorption PS Brittle and Craze ABS Craze and Shear Band PVC Shear Band and Craze PC Shear Band 3

4 Henkee & Kramer Elegant experiments looking at entanglements PS film on wire grid stretched grid and looked at craze determined chains were breaking to form craze fibrils e-beam crosslinked PS film stretched grid and saw transition from craze to shear bands, depending on crosslink density if go too far, suppress shear bands, become brittle 4

5 Entanglements Henkee & Kramer proved polymer chain entanglements were controlling the craze to shear band transition 5

6 PVC Particulate Structure PVC Crystallite ~100Å Stage I Particle μ Stage II "Primary Particle" 100 μ Stage III Particle 6

7 PVC Network Formation PVC fusion is a measure of the network formation Entanglement Density = Network PVC is unusual in that it isn t fully melted during extrusion, so the entanglements are a function of the fusion level Generally see properties increase with fusion level, because of increase in entanglement density Nice papers by Summers and Rabinovitch on this J. Vinyl Technol., 13, 54, J. Vinyl Additive Technol., 3(2), 130,

8 Impact Modifiers Fundamental Understanding of Impact Mechanism Volume of Rubber Cavitation of Rubber Stress Redistribution Shear Bands and Crazing in PVC Crazing and Shear Bands in ABS Crazing in PS and HIPS Controlling Factors for Impact Modifier Domain Size < 0.5 μ for PVC μ for ABS Bimodal for ABS 1-3 μ for PS Distribution Interparticle distance Glass Transition 8

9 Mechanism of Impact Modification Matrix r y 3r y Plastic Zone Crack tip Rubber Cavitated Rubber 9

10 Filler as Flaw a 10

11 Filler as Flaw a CPE 11

12 Formulation Ingredient phr PVC (suspension, K68) 100 Calcium/Zinc one-pack 4.3 Titanium Dioxide 4 Impact Modifier (CPE, Hi Mol. Wt. CPE, Acrylic) Calcium Carbonate (fine or standard size) 7.0 5, 10, 15 12

13 Extrusion Conditions 13

14 Charpy V at 23 C CPE HMW CPE (TYRIN ) AIM Charpy-V Notch at 23 C BS7413 (kj/m 2 ) Fine 15phr 10phr 5phr Std. 15phr 10phr 5phr Fine 15phr 10phr 5phr Std. 15phr 10phr 5phr Fine 15phr 10phr 5phr Std. 15phr 10phr 5phr

15 Plate Out Causes Formulation components: stabilizer, lubricants, CaCO3, TiO2, PVC Processing conditions dryblending, storage time of dryblend moisture & other volatiles in dryblend extrusion parameters- Tm, p, rpm, dwell time Machine components design, materials, surface quality 15

16 Plate out Mechanism Components soluble in melt separate once melt is cooled down and deposit in calibration Test Calibrator with removable plates 16

17 Dow Horgen calibrator: 17

18 lab test- calibrator 18 plate out

19 Plate-out Test Formulations Ingredient Phr S PVC k Impact Modifier 6, 8 Ca/Zn one-pack TiO2 5 CaCO3 (standard size) 10 19

20 Process Temp Phase Diagram Upper Critical Solution Temperature Miscible UCST Miscible Temperature Immiscible RT 0%Polymer 100% Lubricant 20 Composition (%Polymer) 100%Polymer 0% Lubricant

21 Partitioning CPE or Acrylic Lubricant PVC 21

22 Calibration Unit Plate Out 50 Calibration Unit Plate-Out (mg) phr IM 8 phr IM CPE HMW CPE AIM

23 Chemical Analysis of Plate Out 6phr HMW CPE 8phr HMW CPE 6phr AIM 8phr AIM Amount of plate out 30.0 mg 19.3 mg 30.0 mg 28.1 mg Chemical Origin C16-Alcohol One-Pack PS-Methylester One-Pack PS One-Pack C18-Alcohol One-Pack STS-Methylester One-Pack STS One-Pack DiOA PVC Paraffine Pos Neg Pos Pos One-Pack Laurylstearate One-Pack 23

24 Conclusions Thermoplastic impact modifiers have good filler acceptance in Window Profiles Higher molecular weight aids filler acceptance Low plate out levels can be achieved with proper choice of Ca/Zn Stabilizers High molecular weight TYRIN CPE seems to show positive interactive effect with Ca/Zn stabilized system 24 TYRIN is a trademark of The Dow Chemical Company

25 Thank You Questions? 25