Developmet of a green composite ba sed on Aga ve Tequila na W eber (ATW ) fibres for food pa cka ging.

O ma r Huerta Supervisors: Adria na Encina s-O ropesa

Philip Longhurst

College Rd, Cranfield, Bedford MK43 0AL. o.i.huertacardoso@cranfield.ac.uk a.encinas-oropesa@cranfield.ac.uk - p.j.longhurst@cranfield.ac.uk

www.cranfield.ac.uk/sas/

Food packaging waste forms a very significant part of municipal waste. Mostly non-biodegradable and due to mixed levels of contamination represent difficulties for itsrecyclability. Economic-cultural issues, such as the preparedness to separate materials fordisposal at home or as the lack of facilities and technological conditions of the placedifficult the plastic waste management. The global packaging market size in 2012 was$400B from which food packaging accounts for more that the 50%.

The widespread use of oil-basedplastics has become a significantconcern caused by their negativeimpact on the environment, whilstbio-based materials have gainedgreat attention, due to theirbiodegradability andbiocompatibility. Biodegradable andcompostable materials may closethe loop on the carbon cycle as along-term solution in landfilldisposal (Tolinski, 2011)*. The useof biodegradable materials canmaintain a CO2 balance in theenvironment.

Lyfe cycle of biodegra da ble polymers

The Bio-plastics Feedstock Alliance says that is “possible to envision a future whererenewable carbon from plants replaces fossil carbon in the production of chemicals andmaterials”. This new system has been called bio-economy and within it is possible toexplore a real opportunity of reducing the carbon intensity of materials such as those usedin packaging.

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Length distribution

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Statistical treatment of tensile properties for untreated ATW fibreParameter Gauge Length (mm) CSA (µm) SD YM (Gpa) SD UTS (Mpa) SD Strain (%) SDMean 30.00 74.99 0.02 3.29 1.37 79.34632 37.9 13.09 9.45SD - standard deviation; CSA - cross sectional area; YM - Young's modulus; UTS - Ultimate tensile strength.

Surface modification to improve interfacial adhesion between thermoplastic matrix and fibre reinforcement.

Acetic a nhydride 50 % - 120 min Na O H 8 % - 180 min

Pecta te Lya se 0.4% - 60min (3-Aminopropyl)triethoxysila ne 10 %- 60min

Acetylation

Alkali treatment

Silanecoupling agent

Enzymatic bio-scouring

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Typical pull-out test load–displacement curves for PLA andBlue agave fibres subjected to different surface treatments.

Alkali

Untreated Acetylation

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Bio-scouring

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Typical pull-out test load–displacement curve for PLA and untreated ATWfibres

Stage I: Linear load displacement up to the initiation of debonding,

Stage II: Stable crack propagation with friction between the crack faces.

Stage III: Unstable crack growth with a sudden drop in the load.

Stage IV: Frictional slidding after complete debonding of the interface

debonding dynamic sliding quasi-static sliding

The use of Agave Tequilana Weber (ATW) bagasse and fibres, which are considered wasteor by-products from the tequila production, may pose a new economic alternative as asource for reinforcement fibres for green composites.

New green materials offer a potential solution to reduce oil consumption and lead to lower CO2emissions as they exhibit renewability of the source, biodegradability, compostability, andenvironmentally friendly processing for its use as food packaging materials.

Agricultural or industrial wastes or by-products such as ATW fibres may confer an importantimprovement in green composites’ properties such as biodegradability, compostability, high specificstrength, high specific stiffness, fatigue strength, impact resistance, thermal conductivity, and gooddimensional stability.Composting as a way of dispose green composite materials is a feasible alternative mostly whererecycling conditions are not fully established. “Composting allows disposal of biodegradablepackages and is not as energy intensive compared to sorting and reprocessing for recycling” (Kale,Auras, & Singh, 2006).**

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Ima ge: Ha rvesting of a ga ve stems (© Joseph A. Tyson –http://www.tequilasource.com)

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ESEM-Longitudina l section of Untrea ted ATW fibre

C ross section of Untrea ted ATW fibre

Further work Prepare the green composite by compounding ATW fibres and Polylactic acid (PLA) at different ratios in a co-extruder.Characterization of ATW fibres and PLA based green composite.Assess the compostability and degradability of the developed composite.

Surface treatments have shown to improve interfacial bonding for ATW fibres in a PLA matrix. 8%NaOH for 60 minutes and 0.4% Pectate Lyase enzyme for 60 minutes presented the best results inpull-out test load-displacement curves with a mean Interfacial Shear Strength of 5.21 MPa and 4.02MPa respectively.

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Effect of surface treatment in Interfacial shear strength

Acetylation Alkali Bio-scouring Silane Untreated

**Kale, G., Auras, R., & Singh, S. P. (2006). Degradation of commercial biodegradable packages under real composting and ambient exposure conditions. Journal of Polymers and the Environment, 14 (3), 317-334. doi:10.1007/s10924-006-0015-6 *Tolinski, M. (2011). Plastics and sustainability: Towards a peaceful coexistence between bio-based and fossil fuel-based plastics (1st ed.). New Jersey: John Wiley & Sons