A Comparative Analysis of Viscose and Polyester

Sustainable fashion has emerged as a significant movement within the broader context of environmental conservation and ethical consumerism. It aims to address the environmental, social, and economic impacts of the fast fashion industry, which is one of the largest polluters globally. Among the numerous amounts of materials used in textile production, viscose and polyester are two of the most prevalent. This article delves into the differences and similarities between these materials, their applications, and the implications for sustainable fashion. Additionally, it explores consumer preferences and provides guidance on how to shop sustainably when the majority of clothing is made from either viscose or polyester.
Viscose: An Overview
Viscose, often referred to as rayon, is a semi-synthetic fiber derived from cellulose, primarily from wood pulp. While these trees can be grown sustainably, the demand for wood pulp often leads to deforestation and habitat destruction, particularly in regions where forest management practices are inadequate or nonexistent. Sustainable sourcing of cellulose involves using wood from responsibly managed forests certified by such as the Forest Stewardship Council (FSC). The production of viscose itself process involves dissolving cellulose in a chemical solution to produce a viscous solution, which is then extruded through spinnerets to form fibers. These fibers are subsequently processed into yarns and fabrics. Viscose is prized for its silk-like feel, breathability, and drape, making it a popular choice for clothing such as blouses, dresses, and linings.
Environmental Impact: Producing viscose is resource-intensive, involving significant water and energy consumption. Additionally, the chemical processes used can release hazardous substances, such as carbon disulfide, into the environment. However, advancements in production technologies, such as the Lyocell process, offer more environmentally friendly alternatives by using closed-loop systems that minimize chemical waste.
Chemical Processes and Pollution
One of the most critical environmental concerns associated with viscose production is the use of hazardous chemicals. The traditional viscose process involves several chemical treatments:
- Preparation of Cellulose: Wood pulp is treated with sodium hydroxide (caustic soda) to produce alkali cellulose.
- Xanthation: The alkali cellulose is reacted with carbon disulfide to form cellulose xanthate, a highly toxic and flammable compound.
- Dissolution: The cellulose xanthate is dissolved in sodium hydroxide to create a viscous solution (viscose).
- Regeneration: The viscose solution is extruded through spinnerets into an acid bath (usually sulfuric acid), where it coagulates and regenerates into fibers.
Each of these steps can release harmful substances into the environment. Carbon disulfide, in particular, is a volatile organic compound (VOC) that poses severe health risks to workers and contributes to air pollution. Exposure to carbon disulfide can cause neurological damage, cardiovascular problems, and other health issues. Additionally, sulfuric acid and sodium hydroxide can lead to water and soil contamination if not properly managed.
Sustainability Considerations: While viscose is biodegradable, its sustainability is contingent upon responsible sourcing of raw materials and environmentally conscious manufacturing practices. Sustainable viscose production involves sourcing cellulose from sustainably managed forests and employing less harmful chemicals in the manufacturing process.
Advancements in Production Technologies
In response to the environmental challenges posed by traditional viscose production, several advancements have been made to develop more sustainable alternatives. One notable innovation is the Lyocell process, which is used to produce a type of rayon known as Tencel. The Lyocell process offers several environmental benefits:
- Closed-Loop System: Unlike traditional viscose production, the Lyocell process uses a closed-loop system that recovers and recycles nearly all of the solvents used. The primary solvent in Lyocell production is N-methylmorpholine N-oxide (NMMO), which is less harmful than carbon disulfide and can be almost entirely recovered and reused.
- Reduced Chemical Use: The Lyocell process involves fewer harmful chemicals and generates less toxic waste. The solvents and chemicals used are easier to manage and pose less risk to the environment and human health.
- Lower Water and Energy Consumption: While still resource-intensive, the Lyocell process is generally more efficient in terms of water and energy use compared to traditional viscose production. The closed-loop system and modern technologies contribute to overall reductions in resource consumption.
- Biodegradability: Like viscose, Lyocell is biodegradable and can break down naturally in the environment, reducing the long-term impact of textile waste.
Polyester: An Overview
Polyester is a fully synthetic fiber made from petrochemical derivatives, primarily polyethylene terephthalate (PET). The production process involves several key steps, including polymerization, where monomers are chemically bonded to form long chains of polymers. These polymers are then melted and extruded through spinnerets to form fibers. Polyester is valued for its durability, resistance to wrinkles and shrinking, and ease of care. It is extensively used in a wide range of clothing, from activewear to casual wear, as well as home textiles.
Environmental Impact: Polyester production is highly energy-intensive and relies on non-renewable fossil fuels, contributing significantly to greenhouse gas emissions. Moreover, polyester is not biodegradable, leading to persistent plastic pollution. Microplastics shed from polyester garments during washing further exacerbate environmental contamination.
Chemical Use: The production of polyester involves various chemicals, including catalysts, stabilizers, and colorants. These chemicals can lead to environmental pollution if not properly managed. For example, antimony, a catalyst used in polyester production, is toxic and can contaminate water sources.
Microplastics: One of the most concerning environmental impacts of polyester is the release of microplastics. When polyester garments are washed, tiny fibers are shed and enter waterways, eventually reaching oceans and other aquatic ecosystems. These microplastics pose a threat to marine life and can enter the food chain, potentially affecting human health.
Sustainability Considerations: Recycling initiatives, such as converting PET bottles into polyester fibers, offer a more sustainable approach to polyester production. However, the overall environmental impact remains substantial, and the challenge of microplastic pollution persists.
Waste Management and End-of-Life Impact
Non-Biodegradability: Polyester is not biodegradable, meaning it can persist in the environment for hundreds of years if not properly managed. This contributes to the growing problem of plastic pollution.
Recycling Challenges: While recycling polyester is feasible, it presents challenges. Mechanical recycling can degrade fiber quality over time, limiting the number of times polyester can be recycled. Chemical recycling, although promising, is still in the early stages of development and can be costly.
Advancements in Sustainable Alternatives
In response to the environmental challenges posed by traditional polyester production, several sustainable alternatives and innovations have emerged:
- Recycled Polyester (rPET): One of the most promising developments is the use of recycled polyester, made from post-consumer PET bottles and post-industrial polyester waste. The recycling process involves cleaning, shredding, and melting the plastic waste to form new fibers. This approach significantly reduces the demand for virgin petroleum, lowers energy consumption, and diverts plastic waste from landfills and oceans.
- Bio-based Polyester: Research is ongoing to develop bio-based polyesters derived from renewable resources such as plant sugars. These polyesters, known as polylactic acid (PLA) or bio-PET, offer the potential for reduced carbon emissions and a lower environmental footprint compared to conventional petroleum-based polyester.
- Closed-Loop Recycling: Advances in chemical recycling technologies enable the breakdown of polyester fibers into their monomers, which can be purified and repolymerized into new polyester fibers. This closed-loop system aims to create a circular economy for polyester, minimizing waste and reducing the need for virgin raw materials.
Comparative Analysis
Production Processes
Viscose production, despite being chemically intensive, has the potential for optimization through sustainable practices. The use of closed-loop systems, such as the Lyocell process, significantly reduces the release of harmful chemicals into the environment by recycling solvents and minimizing waste. Responsible sourcing of cellulose from sustainably managed forests is crucial to mitigate deforestation and preserve biodiversity. Advances in chemical treatments and waste management technologies can further lessen the ecological footprint of viscose production, making it a more sustainable option compared to its traditional manufacturing processes.
In contrast, polyester production is inherently tied to the use of petrochemicals, making it challenging to achieve sustainability. The polymerization and extrusion processes are energy-intensive and depend on fossil fuels, leading to considerable carbon emissions. While efforts to recycle polyester, such as transforming PET bottles into fibers, have made strides in reducing reliance on virgin materials and lowering energy consumption, the overall impact remains substantial. The fundamental reliance on non-renewable resources and the high energy demands of polyester production continue to pose significant environmental challenges.
Environmental Footprint
Viscose, being biodegradable, offers a lower environmental burden at the end of its life cycle compared to polyester. Its ability to decompose naturally under appropriate conditions means it does not contribute to long-term pollution. However, the chemical pollution associated with viscose production, particularly from the use of carbon disulfide and other toxic substances, remains a critical concern. The environmental and health risks to workers and communities near production facilities necessitate stringent regulatory oversight and the adoption of cleaner technologies.
Polyester, on the other hand, does not biodegrade, leading to persistent plastic pollution. Its durability, while beneficial for long-lasting garments, means that discarded polyester textiles can persist in landfills for centuries. Additionally, the shedding of microplastics during washing contributes to widespread aquatic pollution, posing risks to marine life and potentially entering the human food chain. Despite having a lower immediate chemical impact during production compared to viscose, the long-term environmental consequences of polyester are profound, highlighting the need for effective waste management and innovative recycling solutions.
Applications
The unique properties of viscose and polyester make them suitable for different applications in the textile industry. Viscose is often preferred for garments that require a soft, breathable, and drapable fabric. Its natural feel and comfort make it ideal for blouses, dresses, and linings. The aesthetic and tactile qualities of viscose provide a luxurious alternative to natural fibers like cotton and silk.
Polyester, in contrast, is valued for its durability, strength, and resistance to shrinking and wrinkles. These characteristics make it a popular choice for activewear, outerwear, and home textiles. Polyester’s ability to retain shape and color, coupled with its low maintenance, makes it highly practical for everyday use.
Blended fabrics combining viscose and polyester leverage the strengths of both materials, offering a balance of comfort and performance. These blends can provide the softness and drape of viscose with the durability and resilience of polyester, resulting in versatile textiles suitable for a wide range of applications. The use of blended fabrics also allows manufacturers to create garments that meet diverse consumer needs while optimizing resource use and potentially reducing the environmental impact associated with single-material textiles.
Consumer Preferences and Sustainable Shopping
When choosing between viscose and polyester, consumers should consider both the environmental impact and the intended use of the garment. Viscose may be preferable for its biodegradability and natural feel, particularly if sourced from sustainable production methods. Polyester, on the other hand, is advantageous for its durability and low-maintenance properties, with recycled polyester being a more sustainable option.
Tips for Shopping Sustainably:
- Research Brands: Support brands that prioritize sustainability and transparency in their supply chains. Look for certifications such as OEKO-TEX, GOTS, and FSC for viscose and GRS for recycled polyester.
- Prioritize Quality: Invest in high-quality garments that are designed to last longer, reducing the need for frequent replacements.
- Second-hand and Vintage: Purchasing second-hand or vintage clothing extends the life cycle of garments and reduces demand for new production.
- Recycling and Upcycling: Participate in recycling programs and consider upcycling old garments to give them a new life.
The choice between viscose and polyester involves a complex evaluation of environmental impacts, functional requirements, and personal values. While neither material is without its drawbacks, informed consumer choices and advances in sustainable production practices can mitigate their environmental footprint. Consumers can contribute to a more sustainable fashion industry and a healthier planet by prioritizing sustainability in their shopping habits.
References and extra resources:
Material Guide: What is Viscose and Is It Sustainable? – Good On You
7 things you need to know about viscose fibers (ispo.com)
What is Polyester Fabric: Properties, How its Made and Where | Sewport