Transcript
Page 1: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Greening Plastics: Modifying plastics with functional additives based on condensed

tannin esters

Warren GrigsbyJamie Bridson, Cole Lomas Carmen Schrade and Jaime-Anne Elliot

[email protected]

Page 2: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Overview

Highlights of a greater study evaluating tannin esters in plastics

Introduction Tannins & plastic additives

Tannin esters in plastics Filler v compatible, active ingredient Providing functional equivalence

Specific performance

Page 3: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Introduction: Condensed Tannins

Nature provides a range of condensed tannins Leaf, fruit, stem and bark

Provide a protection role for plant/tree Secondary metabolites Polyphenolic structure Extractable

Procyanidin: flavonoid base structure

OHO

OH

OH

H(OH)

OH

OHn

Page 4: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannins: Providing Function

Blueberries, bark, wine,… antioxidant, protein inhibition, UV absorption

Neutriceuticals, food, industrial oxidative stress-cognitive function protein inhibition antimicrobial tanning leather

Page 5: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Additives: Adding Performance

Additives provide functionality and longevity colour, flame retardant, plasticizers

Longevity antioxidants and UV stabilisers

not so well known synthetic, petrochemical

BHT, hindered amines

Why not bio?

Page 6: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannin usually a crosslinked molecule in adhesives Phenol formaldehyde, Bakelite chemistry

PLA plastic modified with tannins reinforcement, melt-spun filaments

Electrospinning protein nanofibres tannin → functionality

Tannins: Synthetics & Plastics

Grigsby, Kadla, Macromolecular Materials and Engineering, 299(3) 2013 368–378. Dallmeyer, Grigsby, Kadla, J Wood Chem Tech 33(3) (2013) 197-207.

10m

10m

Page 7: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Aims & Goals

Can functionality a tree uses be applied to plastics?

Hypothesis Tannin efficacy in bark can be applied to protect plastics

from oxidative aging and UV-induced degradation

Evaluate tannins as bio-sourced plastic additives

Page 8: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannins: water soluble extracts → inherently hydrophilic Modify → change miscibility/compatibility with plastics

Tannins & Chemical Modification

Tannin+

Alkyl Anhydride

Tannin EstersC2–C6 chain length

Mixed Esters

Vary:Degree of substitution (DS)

Antioxidant CapacityMacromolecular properties

UV absorption

OR1O

R2

OR1

H(OR 2)

OR2

OR2 R1,2 = Ac, Pr, Bu, Hex…

Grigsby, et al. Polymers, 2013, 5(2), 344-360

Page 9: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannins: water soluble extracts → inherently hydrophilic Modify → change miscibility/compatibility with plastics

Tannins & Chemical Modification

Tannin+

Alkyl Anhydride

Tannin EstersC2–C6 chain length

Mixed Esters

Vary:Degree of substitution (DS)

Antioxidant CapacityMacromolecular properties

UV absorption

OR1O

R2

OR1

H(OR 2)

OR2

OR2

250 300 350 400 450

Abs

orba

nce

Wavelength (nm)

Vary UV absorption

Change meltbehaviour

Page 10: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Processing & Evaluation Tannin esters compounded in plastics 0-10% w/w

Master Batch

Tannin Ester (10%)

compounded with plastic

PP, PBS PLA, PHA, PHB

Extrusion

MB blended with plastic

0%, 0.5%, 1%, 3%,

& 5%, 10%

Injection Moulded

ASTM Test specimens

Flexural & Tensile bars

Thermal AnalysisDSC, TGA, DMTA

Mechanical TestingFlex & Tensile

Accelerated AgingThermallyUV & weathering

Fluorescence & lightmicroscopy

Page 11: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Additive or Filler? Longer ester chains show progressive solubility and

diminished particle domains within PLA

TanAc (C2) retained as distinct domains

→ poor miscibility or phase separation

TanHex (C6) → fully dispersed within the plastic

TanAc TanPr TanBu TanHex

(image 500 x 500 m)Confocal microscopy: PLA containing 5% tannin esters using tannin inherent autofluorescence

Grigsby, et al. Polymers, 2013, 5(2), 344-360

Page 12: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Additive or Filler? Tannin esters contribute up to 15% decreased PLA stiffness

ester chain length & greater content decrease MOE native tannin stiffens PLA → acts as a filler

Native Tannin

TanAcC2

EsterLongerChain

C6 Esters

Short Chain C3-C4 Esters

Page 13: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Polymer Properties

10% C6 esters lower PLA Tg reduced effect

lower ester quantity shorter chain length

At typical additive content minimal impact on polymer properties

TgCrystallisation

Crystallization decreased melt temp. unchanged

Melt

DSCDMTA

Page 14: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Thermal & Oxidative Stability Tannin esters promote plastic thermal stability

Oxidation induction time (OIT) TanHex in PP → increased OIT, TanHexAc → not

residual antioxidant capacity important

Increased thermal stability

Reprocessed PP (up to 10x)→ reduced thermal stability

10% TanHex → increase thermal stability

potential to lower plastic oxidative degradation on processing

TGA

Grigsby, et al., Macromolecular Materials and Engineering, 299 (10) (2014)1251–1258.

Page 15: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Accelerated Aging Tannin esters provide UV stability on aging polypropylene

biopolyesters challenged by aging

Native Tannin Mixed

C2-C6 Esters

LongerChain

C6 Ester

Mechanical properties before/after UV and condensation exposure cycling

Page 16: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Accelerated Aging Bionolle (PBS) samples increase in stiffness

tannin hexanoate ester → excellent flexural strength retention similar results on thermal aging

Functional equivalency comparable to commercial UV stabilisers

Native Tannin Mixed

C2-C6 Esters

LongerChain

C6 Ester

Grigsby et al, J. Appl. Polym. Sci., 132(11) (2014) 41626

Page 17: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Accelerated Aging → plastic colour tended to surface bleach seen as undesirable, but gauge for tannin efficacy

Measure efficacy

Colour Stability and UV inhibition

0.00

50.00

100.00

150.00

200.00

250.00

0.50 1.00 1.50 2.00 2.50 3.00

Distance in mm

Inte

nsi

tyVisible

bleaching0.24 mm

Intensity across

the surface

Tannin sacrificial bleach depth → extent of UV inhibition PBS: TanHex 0.25 mm v. TanAc 0.47 mm

consistent with tannin dispersion by microscopy

Grigsby et al, J. Appl. Polym. Sci., 132(11) (2014) 41626

Whit

e In

tensi

ty

Page 18: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Take home information

Tannin esters can be functional additives in biodegradable polyesters Longer chain C6 esters desirable for compatibility Do not impact plastic properties at typical additive loadings Provide stabilising role reduce oxidative and UV-induced degradation

Similar to bark on a tree

PLA & Tannin esters C6 ester chains lower Tg onset up to 5-6C Can reduce flexural properties by 15% (TanAc to Hex) C6 esters retain PLA flexural properties on aging

Overall Scope for tannin esters as sustainable additives for bioplastics

Page 19: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Acknowledgements

This work was supported by Biopolymer Network Ltd Funding through New Zealand Ministry of Business, Innovation and

Employment.

Jamie Bridson, Cole Lomas and Jaime Elliot are grateful for studentships provided by Scion through BSc(Tech) placements with the University of Waikato (NZ)

Carmen Schrade (MSc thesis) is grateful to assistance provided by Department of Applied Chemistry, Reutlingen University (Germany)

Page 20: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade
Page 21: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade
Page 22: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Plastic Polymer Properties DMTA → 10% TanHex/TanHexAc lower PLA Tg

Lower ester quantity or shorter chain length → reduced effected

DSC → melt temperature unchanged Crystallization decreased with tannin ester content

At typical additive content minimal impact on polymer properties

TgCrystallisation

Page 23: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Accelerated Aging

Biopol samples show similar increases in flexural modulus longer chain tannin esters still maintain relatively lower flexural

modulus than pure maintain flexural strength compared to pure polymer

Page 24: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannin Ester Modified Biopolyesters

Microscopy: Hexanoate C6 chains compatible polyester plastics

Mechanical & Polymer PropertiesDo not detrimentally impact mechanical properties at loadings up to 5% (w/w)Do not significantly influence polyester melt or Tg

As plastic additives provide: UV stability Antioxidant and thermal stability

Dependency on ester chain length, DS and content

Page 25: Greening Plastics: Modifying plastics with functional additives based on condensed tannin esters Warren Grigsby Jamie Bridson, Cole Lomas Carmen Schrade

Tannin Ester Modified Biopolyesters

Tannin ester addition contributes colour white/colourless preferred brown colour → undesirable for some applications ester modification reduces colour

Accelerated weathering revealed colour instability surface bleaching by UV light inherent property of tannins

biopolyesters unsuited to exterior conditions


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