What is Sisal Fiber? Properties, Structure, and How It Made?

What is Sisal Fiber?

Sisal Fiber is sourced from the Agave sisalana plant and is a well-known natural fiber. It’s completely biodegradable, making it environmentally friendly. Sisal fiber is highly durable, requiring minimal maintenance, and it can endure wear and tear admirably. The sisal plant forms rosettes of sword-shaped leaves with initially toothed edges that become smooth as the leaves mature. Each leaf contains numerous long, straight fibers that are obtained through a process known as decortication. In decortication, the leaves are beaten to separate the fibers from the pulp and plant material, leaving the strong fibers behind.

History of Sisal Fiber

Sisal natural fiber comes from the big leaves of the Agave Sisalana plant, which is originally from Southern Mexico. People have been growing sisal for a long time, even before Christopher Columbus arrived in the Americas. But it wasn’t until the late 1930s that they started growing it for business, realizing its economic benefits around the world. In the 1980s and 90s, the sisal market went down because synthetic fibers became cheaper. However, in the 21st century, sisal has made a comeback because more people care about natural fibers, and like that sisal fiber is eco-friendly and good for the environment. Traditionally, people used sisal fiber to make ropes and twine. But now, they’re finding new ways to use sisal because it’s such a useful material. These days, people grow sisal all over the world, and the biggest producers are Brazil and Tanzania.

Sisal Fiber Structure

In a cross-section of sisal fiber, you’ll discover around 100 fiber cells. These cells have walls with multiple layers of fibrils. In the primary wall, the fibrils form a reticulated structure. In the outer secondary wall (S1), found within the primary wall, the fibrils are arranged in spirals at a 40° angle relative to the cell’s longitudinal axis, specifically for sisal fiber. Within the inner secondary wall (S2) of sisal fibers, the fibrils have a steeper slope, with angles ranging from 18° to 25°. The thin tertiary wall closest to the core encloses the lumen and exhibits a parallel fibrillar structure. These fibrils are constructed from microfibrils, each about 20µm thick, which, in turn, consist of cellulose molecular chains measuring 0.7µm in thickness and just a few µm in length.

Chemical Composition

Cellulose: 65%
Hemicelluloses: 12%
Lignin: 9.9%
Waxes: 2%

Properties of Sisal Fiber

Sisal fibers are smooth, straight, and yellow.
Sisal can be coarse and inflexible, resulting in varying fiber lengths.
Sisal fibers are anti-static, so they don’t attract dust or easily absorb moisture.
They also absorb sound and impact well.
Sisal fiber is both biodegradable and recyclable.

Processing of Sisal Fibers

First, the process starts with extracting textile fibers from fresh leaves.
Workers pick fresh leaves from the plants, carefully trimming the sharp 10mm tips to avoid any injuries.
After the tips are removed, the fresh leaves undergo a series of steps: decortication, a water wash, binding, cleaning, drying, and a final cleaning phase.
At this stage, the leaves are trimmed at their bases and transported to the factory. There, they are rolled and squeezed to remove any remaining soft tissues from the fibers.
Following that, the sisal fibers are washed, left to dry in the sun, and can be directly dyed.

Advantages

Sisal Environmentally friendly.
A sustainable and renewable resource.
Fully biodegradable.
Absorbs more carbon dioxide than it emits.
Naturally flame retardant.
Functions as a noise insulator.
Aids in preventing soil erosion with its extensive root system, contributing to watershed management.
Organic waste and leaf residues have various uses, including bioenergy generation, animal feed, fertilizer production, and eco-friendly building materials.
Effective as a vegetative hedge, protecting crops and forests from both animals and intruders.
Easily takes on different colors through dyeing, offering versatile options.
Known for its exceptional durability, suitable for high-traffic areas like hallways and entryways when used in area rugs.

Disadvantages

Sisal fibers are strong and rigid.
Sisal fiber less comfortable area rugs and carpets.
They are highly vulnerable to moisture damage, so it’s best to avoid placing sisal rugs in areas where spills are common, like kitchens, dining rooms, bathrooms, basements, and outdoor spaces such as patios and decks.
Over time, sisal rugs can become slippery, making them unsuitable for use on stairs.
The fiber’s porous nature means it can easily stain and develop mildew if spills are not promptly cleaned.
Excessive humidity can adversely affect sisal, causing it to wrinkle due to too much moisture, and it may never fully regain its original shape.