An algorithm-based approach Dipl.Ing., Dipl.Ing., B.Sc., M.B.A. - - PowerPoint PPT Presentation

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

Comparison of naturally and artificially weathered wood-polymer composites: An algorithm-based approach

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• Compolytics Independent Research, Neunkirchen, Germany
• Lecturer at Baden-Württemberg Cooperative State University of Mosbach,

Germany

• Lecturer at the SRH University of Heidelberg, Germany
• MC Member and Communication Manager of COST ACTION CA16114
• d.friedrich@lehre.mosbach.dhbw.de

Dipl.Ing., Dipl.Ing., B.Sc., M.B.A. Daniel Friedrich

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

Contents

• 1. Wood-Polymer Composites (WPC)
• 2. Comparison between natural and artificial weathering
• 3. Computing of WPC ageing
• 4. Summary

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Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich 3

• 1. Wood-Polymer Composites (WPC)

Petrochemical or bio-based thermoplastics (PP, PE, PVC) + Wood fibers + Additives = WPC 1.1 WPC Components:

• Fig. 1: WPC composition.

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich 4

• 1. Wood-Polymer Composites (WPC)

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Cladding Decking Flooring Fencing

Source: www.upm.com

Currently all WPC products are petrochemical-based 1.2 WPC Applications in the Building Scope:

• Fig. 2: WPC applications.

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich 5

• 2. Comparison between natural and artificial weathering

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2.1 Artificial versus natural weathering: WPC strength-decrease is measured by:

• Change in Modulus of Rupture (MOR) [MPa]
• Change in Modulus of Elasticity (MOE) [MPa]

Natural weathering trials (EN 15534-1):

• Depend on climate zone
• Mix of UV radiation, frost/thaw, wet/dry periods
• Unsteady change of influences

Artificial weathering testing (DIN 4892-1/2/3):

• UV-dosage of 60W
• Water spraying optional
• Constant conditions

www.Q-lab.com

• Fig. 3: Global climate zones.
• Fig. 4: Setup of a climate chamber.

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

• 2. Comparison between natural and artificial weathering

2.2 Impact of weathering on WPC: UV-radiation:

• Polymer crystallinity
• Chain scissions
• Delignification of wood fibers

Wet-dry cycling:

• Fiber swelling
• Fiber detachment
• Degradation of interfacial bonding

Frost-thaw cycling:

• Embrittlement of polymer matrix
• Surface erosion
• Reduction of profile`s cross-section
• Fig. 5: Naturally weathered specimen
• 1 year
• Central Europe
• PP-matrix / 70% pine-fibered
• Brushed surface

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Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

• 2. Comparison between natural and artificial weathering

2.3 Research questions arising:

• 1. How many years of natural weathering correspond to x-days of artificial

weathering?

• 2. How does fibre content affect the durability of WPC?
• 3. Which formula can be used to calculate the natural durability in years from

artificial weathering given in days? 2.3 Study approach:

• Literature research about artificial and natural weathering of WPCs
• Clustering data according to fiber content and exposure duration
• Comparison of empiric data on strength loss under both weather regimes
• Interpolation of lacking data
• Derivation of acceleration factors and setup of algorithm model

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Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

• 3. Computing of WPC ageing

3.1 Results from literature review:

Reference Duration t [hrs.] wood content μ [%] MOR loss [%]

Soccalingame et al. [1] 336 10 2.5 Kallakas et al. [2] 500 20 1.8 Sélden et al. [3] 480 25 5.0 Sélden et al. [3] 960 25 9.0 Sélden et al. [3] 1344 25 19.0 Soccalingame et al. [1] 336 30 4.2 Kallakas et al. [2] 500 35 6.5 Beg and Pickerig [4] 500 40 8.0 Beg and Pickerig [4] 1000 40 13.0 Sélden et al. [3] 480 50 12.0 Sélden et al. [3] 1344 50 20.0 Stark et al. [5] 1000 50 15.0 Falk et al. [6] 1500 50 19.5 Stark et al. [5] 2000 50 19.0 Stark et al. [5] 3000 50 47.0

MOR loss [%] wood content μ [%] Duration t [hrs.] Location Reference

9.8 30 5760 Brasil / PP Silva et al. [7] 11.8 8640 0.8 33 1440 China / PP Zhou et al. [8] 4.8 2880 9.8 4320 12.4 8640 8.7 45 2880 Thailand / PP Homkhiew et al. [9] 9.8 4320 13.0 5760 17.4 7200 21.7 8640 6.0 50 2000 Malaysia / HDPE Taib et al. [10] 18.4 60 11520 Thaiwan / HDPE Hung et al. [11] 17.4 25920

Table 1: Literature and data on artificial weathering Table 2: Literature and data on natural weathering

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Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

• Most reported trials are around the equator
• Fig. 6: Locations of natural weathering trials reported from scientific literature

Silva et al. [7] Zhou et al. [8] Homkhiew et al. [9] Taib et al. [1] Hung et al. [11] 9

3.2 Location of natural weather WPC trials:

• 3. Computing of WPC ageing

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

Basic assumptions needed:

• Ageing is expressed by loss in MOR↓
• MOR↓ is a linear function of exposure time t and fiber content μ

Further approach:

• Linear inter- and extrapolation of exposure times tartificial or tnatural to a common

fiber content μ and MOR↓ Basic question:

• How much longer is exposure time under natural weathering when reaching a

similar MOR-decline than under artificial weathering given equal fiber shares 3.3 Practical Problems:

• Data is limited to a low number of

scenarios on fiber contents and exposure durations

• MOR-declines (=MOR↓) from

artificial weathering not directly comparable to data from natural weathering due to differing fiber contents (=μ)

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• Fig. 7: MOR↓-matrix from each compound tested
• 3. Computing of WPC ageing

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

• Acceleration: Comparison between MOR↓nat(12/8) and MOR↓art(4/3)
• MOR↓nat at 8.5MPa loss and μ=45% fiber share
• Extrapolation to μ=25% leading to MOR↓*nat at 5.5 MPa loss
• Increasing exposure time to t*nat until MOR↓*nat equals MOR↓art

and compared with MOR↓art tested under μ=25% at tart ⇒

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• Fig. 8: Procedure of data adaption and comparison for derivation of acceleration or

deceleration factors between artificially and naturally weathered specimens.

1 3 3 3 Acceleration Factor = t*nat / tart 3.4 Procedure: 2 2 1

• 3. Computing of WPC ageing

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

Acceleration-Factors (αacc)derived from 117 single comparisons: Mean α acc = 8.1

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• Fig. 9: Acceleration-Factors received from data groups

Deceleration-Factors (αdec)derived from 117 single comparisons: Mean α dec = 7.7

• Fig. 10: Deceleration-Factors

„Smmothed" α acc/dec=7.35 Outlier values 3.5 Acceleration and Deceleration Factors:

• 3. Computing of WPC ageing

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich 13

• Fig. 11: Ageing-Topography of WPC showing MOR-decline over

exposure time and under various fiber loadings.

Algorithm for calculation of MOR↓ as a function of exposure time and fiber content : MOR↓ [%] = 5.8 • 10-3 • μ • tnat - 3.5 • 10-4 • tnat + 16 • μ - 5.0 3.6 Computed Algorithm for WPC-Durability calculations: 2880h ≤ tnat ≤ 8640h 0.30 ≤ μ ≤ 0.45 e.g.: h=2880h; μ=0.33 ⇒ MOR ↓=4.8%

(see Table 2).

• 3. Computing of WPC ageing

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich 14

• Natural weathering degrades WPC strength due to UV-light, humidity and

frost-thaw

• The loss in MOR is a function of exposure time and fiber content
• Degradation can be assumed as linear progressing within the first 5 years
• Strength decrease can be elaborated by artificial weathering
• The received degradation corresponds to a 7.35-times longer period under

natural conditions

• Limitations:
• The findings belong to climates in equatorial regions
• For Central European conditions αacceleration is assumed being significantly

higher

• 4. Summary

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

References

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[1] Soccalingame L., Perrin D., Benezet J.C., Mani S., Coiffier F., Richaud E., Bergeret A.

Reprocessing of artificial UV-weathered wood flour rein-forced polypropylene composites.

• Polym. Degrad. Stab. 2015;120:313-327.

[2] Kallakas H., Poltimäe T., Süld T.M., Kers J., Krumme A. The influence of artificial weathering

• n the mechanical and physical properties of woodplastic composites. Proceedings of the

Estonian Academy of Sciences 2015;64:94-104. [3] Sélden R., Nyström B., Langström R. UV ageing of poly(propylene)/wood-fiber composites.

• Polym. Compos. 2004;25:543-553.

[4] Beg M.D.H., Pickering K.L. Artificial weathering of unbleached and bleached Kraft wood fibre reinforced polypropylene composites. Polym. Degrad. Stab. 2008;93:1939-1946. [5] Stark M.N. Changes in Wood Flour / HDPE Composites after artificial weathering with and without water spray. Proceedings of the 2nd Wood Fibre Polymer Composites Symposium: Applications and Perspectives, March 24-25, 2005, Bordeaux, France. [6] Falk R.H., Lundin T., Felton C. The Effects of Weathering on Wood-Thermoplastic Composites Intended for Outdoor Applications. Proceedings of the 2nd Annual Conference on Durability and Disaster Mitigation in Wood-Frame Housing, November 6-8, 2000, USA. [7] Silva C.B, Martins A.B., Catto A.L., Santana R.M. Effect of natural ageing on the properties

• f recycled polypropylene/ethylene vinyl acetate/wood flour composites. revista Matéria, 2017:

22(2): DOI 10.1590/S1517-707620170002.0168.

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

References

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[8] Zhou X., Huang S., Chen L. Effect of Antiaging Agents on the Outdoor Natural Weathering

• f Bamboo Powder/Polypropylene Foamed Composites. J. Vinyl. Addit. Techn. 2016;22:311-

319. [9] Homkhiew C., Ratanawilai T., Thongruang W. Effects of natural weathering on the properties

• f recycledpolypropylene composites reinforced with rubberwood flour. J. Ind. Crop. Prod.

2014;56:52-59. [10] Taib, R.M., Zauzi, N.S.A., Mohd, Z.A.M., Rozman, H.D. Effects of Photo-Stabilizers on the Properties of Recycled High-Density Polyethylene (HDPE)/Wood Flour (WF) Composites Exposed to Natural Weathering. Malaysian Polymer Journal 2010;5(2):193-203. [11] Hung K.C., Chen Y.L., Wu J.H. Natural weathering properties of acetylated bamboo plastic

• composites. Polym. Degrad.S tab. 2012;97:1680-1685.

[12] Friedrich D., Comparative study on artificial and natural weathering of wood-polymer compounds: A comprehensive literature review. Case Studies in Construction Materials (2018) doi.org/10.1016/j.cscm.2018.e00196. [13] Friedrich D., An analytic algorithm-based method to assess the long term structural performance of wood-polymer composites. Journal of Building Engineering 20 (2018) 367-376. [14] Friedrich D., Comparative study on artificial and natural weathering of wood-polymer compounds: A comprehensive literature review. Case Studies in Construction Materials (2018) doi.org/10.1016/j.cscm.2018.e00196.

Polymer Testing & Analysis 2019 Session 6: DEVELOPMENTS IN POLYMER PERFORMANCE Daniel Friedrich

Thank you for your attention!

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Daniel Friedrich

• Dipl. Ing., Dipl.Ing., M.B.A., B.Sc.

T direct +49 163 765 61 40