Comprehensive Guide to Plant Fibers: Types, Properties, and Examples

Definition of Plant Fibers

Plant fiber refers to a hair-like material directly obtained from various parts of plants, such as seeds, stems, leaves, or fruits. These fibers are composed primarily of cellulose, a long-chain carbohydrate molecule. They are characterized by their long, narrow structure and significant length compared to their diameter. Plant fibers can be converted into nonwoven fabrics like felt or paper or, after spinning into yarns, woven into textiles. Plant fibers, often called vegetable fibers, play an increasing role in daily life (1).

Historical Facts about Plant Fibers

The use of plants for textiles dates back to prehistoric times. The oldest evidence of fiber use dates back to the Stone Age of Europe, as discovered in the remains of the Swiss Lake Dwellers. Hemp is also one of the oldest cultivated fiber plants; originated in Southeast Asia and reached China by 4,500 BCE (Before the Common Era). In Egypt, the advanced techniques of spinning and weaving linen by 3,400 BCE suggest even earlier cultivation of flax. There are indications that cotton spinning in India began around 3,000 BCE. The development of silk cultivation and sericulture in China started around 2640 BCE. The Industrial Revolution stimulated significant advancements in fiber processing during the 18th and 19th centuries, boosting production and discovering new fiber plants. Despite the rise of synthetic fibers in the 20th century, plant fibers have remained crucial due to their unique properties and environmental advantages.

Different types of fiber plants

Below, the most common types of fiber are presented:

Bast Fiber: is obtained from the stems of dicotyledonous plants and is used in the textile industry. Its chemical composition mainly consists of cellulose, hemicellulose, and lignin (2). Their flexibility and fineness usually characterize them. They are widely used to manufacture strong materials such as ropes, twines, and industrial fabrics. With the increasing environmental awareness, governmental regulations are promoting the use of bast fibers to replace energy-intensive synthetic fibers. Representative examples of bast fibers are:

flax (Linum usitatissimum),
hemp (Cannabis sativa),
kenaf (Hibiscus cannabinus), etc.

Leaf fibers: also known as hard fibers, are obtained from the leaves of monocotyledonous plants. Their chemical composition consists of cellulose (as high as 70%) and low contents of lignin (3). They are more flexible and softer than bast fiber. The leaf fibers are the longest compared to the other types. They are mainly used to produce cordage, rope, and twine. They can also be used for woven fabrics but usually require no spinning. Representative examples of leaf fibers are:

abaca (Musa textilis),
pineapple (Ananas comosus),
papyrus (Cyperus papyrus)
banana (Musa acuminata),
cantala (Agave cantala), etc.

Seed fibers: are obtained from the seeds or seed pods of various plants. Their chemical composition is predominantly cellulose, which can constitute up to 67% of the fiber, along with smaller amounts of lignin (4). Seed fibers are characterized by their softness and versatility. They are extensively used in the textile industry to make comfortable and breathable fabrics. Cotton (Gossypium sp.) is the most well-known seed fiber, and it is and it is known for its application in clothing, bedding, and other textiles. Additionally, seed fibers are utilized to produce stuffing materials, insulation, and nonwoven fabrics (like felt). With the growing focus on sustainability, seed fibers are encouraged to provide eco-friendly alternatives to synthetic materials. Important examples of seed fibers are:

cotton (Gossypium sp.)
kapok (Ceiba pentandra), and
brazilian nut (Bertholletia excelsa)

Fruit fibers: are derived from the fruit of various plants. Their chemical composition primarily consists of cellulose, like other plant fibers. These fibers are characterized by their robustness and durability. Fruit fibers are primarily used to produce coarse materials such as ropes, mats, and brushes. Coir (Cocos nucifera), obtained from coconut husks, is a well-known example of a fruit fiber. Other examples of fruit fibers are oil palm (Elaeis guineensis).

Stalk fibers: are obtained from the stalks of many different plant species. These fibers are recognized for their strength and versatility. Stalk fibers are commonly used to produce textiles, paper, and building materials. Examples include fibers from wheat (Triticum aestivum), rice (Oryza sativa), and bamboo stalks (Bambusa vulgaris).

What plants are used for fiber?

The picture below shows some of the most common plants cultivated to produce fiber.

Classification-of-plant-fibers

Source: Güven et al, 2016

Properties of natural plant fibers

Plant fibers offer several significant advantages over synthetic fibers due to their properties (6):

Biodegradability: Plant fibers naturally decompose over time, making a sustainable solution to substitute synthetic fibers.
Strength and Durability: Their structure makes them robust, and chemical treatment can enhance their durability.
Rigidity and Tensile Strength: They are stiff and have high tensile strength, meaning they can resist tension well.
Low Cost: The production of natural plant fiber is generally inexpensive.
Abundant availability and Renewability: As they are obtained from plants, they are a renewable resource.

However, properties such as poor bonding, increased water absorption, and comparatively worse thermal and mechanical properties compared to artificial fibers are significant obstacles in practical applications of plant fibers (7). Current research is focused on addressing these issues.