Biopolyester

Moving beyond Sustainability into Regeneration

How can bio-based polyester support a truly circular fashion economy?

Introduction

Biopolyester is a master’s thesis focused on the imperative need for transforming the fashion industry’s supply chain towards a circular production and consumption.
Polyester stands out as the most widely produced and utilized fabric in the fashion sector, despite its substantial environmental impact across its lifecycle, encompassing carbon emissions, pollution, microplastic release, and landfill accumulation. Yet synthetic fibers are forecasted to comprise 98% of all future fibers, 95% of which is expected to be polyester.
Through the fusion of design, material science, and circularity, the research aim is to develop a regenerative material to replace petroleum-based polyester. By focusing on the material composition of what makes our clothes, we are targeting the problem at its core, addressing concerns of microplastic release, carbon emissions, pollution, and landfill accumulation.

Institute
Dessau Department of Design

Student
Vanessa Song

SUPPORT
BioLab: Materiability Research Group
Model: Sophia Reichelt

SUPERVISION
Virginia Binsch
Prof. Dr. Manuel Kretzer

Category

Biomaterials

Bacterial Cellulose and Kombucha

Bacterial cellulose, an extensively studied resource, holds remarkable properties including excellent permeability, high purity, and high mechanical strength. Kombucha is an accessible form of bacterial cellulose, employing bacteria and yeast in fermenting a brew (traditionally black tea, sucrose, kombucha starter liquid, scoby, and apple cider vinegar) to produce a biofilm over the surface of the brew.
The research explores the potential of kombucha bacterial cellulose to develop a biodegradable textile thread. Experiments assess a resource-conserving recipe, questioning the importance of traditionally used ingredients like sucrose, black/green tea, apple cider vinegar, and scoby in the production of a strong biofilm. Wheat starch-derived glucose replaces sucrose, aiming to broaden sourcing options and repurpose pasta wastewater, an abundant food waste byproduct.

Circular Model of Design

By regenerative material, this means being 100% bio-based, 100% biodegradable, and sourced from locally abundant biomass that is otherwise underutilized. It’s the sole use of bio-based materials, such as kombucha and wheat starch, throughout the entire process that helps ensure complete product biodegradability at its end of life. Exploring wheat starch as a food source not only helps to diversify sourcing beyond traditional sucrose, but also presents an opportunity to repurpose food waste, such as pasta wastewater for a closed loop system.
This circular approach fosters an integrated horizontal supply chain – a collaboration between the food service and fashion industries – encouraging a shared systemic commitment towards circular practices. By moving beyond sustainability into regeneration, we are referring to a goal that is not merely to minimize environmental impact, but to create materials that revive and give back to the environment, in hope of establishing a fashion economy built on circularity—where materials and products circulate for as long as possible, waste eliminates, and pollution vanishes.

Experiments

Glucose Preparation

To use wheat starch as the food source for kombucha fermentation, it is first converted into glucose through a process called starch hydrolysis using two enzymes: amylase and glucoamylase. The resulting glucose mixture is then filtered to remove the impurities from the wheat starch.

Kombucha Fermentation

The material, referred to as pellicle in the project, is grown in sealed containers over 2 to 3 weeks of fermentation with the optimum temperature of 28 to 29°C. Several recipes are prepared, experimenting varying ingredients and wheat starch concentrations, followed by a tensile strength test to select the recipe producing the strongest material.

Pellicle and Tensile Strength

Once the pellicles have grown thick enough, they are harvested and washed with dish soap to remove any brew residue. A segment of each sample is dried and prepared for tensile strength test. Notably, a resource-conserving recipe of 75g wheat starch concentration, requiring only three ingredients (glucose, distilled water, and kombucha starter liquid) yields the highest tensile strength material. This recipe is then scaled up for final production.

Pellicle into Thread

The remaining segment is used to experiment methods in transforming the wet pellicle into a thread, involving blending, dissolving, extruding, and cutting. The most promising method results in cutting the wet pellicle into thin strands, which is then air-dried while retaining a slight moisture for seamless binding when handspinning into threads.

Design Process

When considering the textile application of the kombucha thread as a replacement for polyester, weaving accentuates the structural integrity of the kombucha thread as a fabric material. This choice was motivated by the desire to create an abstract design rather than a traditional fully woven dress, aligning with the overarching concept of the project that centers on the development of a fully biodegradable material and product. Additionally, dried hibiscus is used as a natural, vibrant dye.

Final Garment

Using plain weave on a handloom, the threads are woven into a top and bottom, then connected with loose threads to create the envisioned concept of biodegradation.

Conclusion

The kombucha material is strongest in its wet state, but as it dries, it tends to stiffen and become brittle. Interestingly, these properties are reversible and influenced by environmental humidity levels. In humid conditions, the material becomes more flexible, soft, and resilient, while in dry environments, it stiffens and becomes more fragile. Weaving with kombucha threads has proven to be challenging due to their tendency to snap as they dry, which is reconnected using a weaver’s knot. However, its reversibility in properties presents a fascinating groundwork for further research and development aimed at stabilizing its properties.

Despite the challenges, a new fully biodegradable thread is successfully developed during this research project, highlighting the possibilities of utilizing natural ingredients to create regenerative materials in support of a circular approach of designing.

Institute
Dessau Department of Design

Student
Vanessa Song

SUPPORT
BioLab: Materiability Research Group
Model: Sophia Reichelt

SUPERVISION
Virginia Binsch
Prof. Dr. Manuel Kretzer

Category

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