Fibers & Textiles Flashcards
What are the main categories of fibers?
- Natural fibers (animal, plant, mineral),
- Artificial fibers (regenerated and synthetic).
What are examples of animal fibers?
Examples of animal fibers include wool from sheep, cashmere and mohair from goats, angora from rabbits, and hair from alpacas, llamas, and camels.
What are the properties of animal fibers?
- Good insulation and thermo-regulating qualities,
- High resistance to natural odors,
- Breathable,
- Highly elastic, resistant to stretching, wrinkling, and tearing.
What is the most commonly used plant fiber, and what are its properties?
The most commonly used plant fiber is cotton. Its properties include:
- Can absorb water,
- Insoluble in water,
- Resistant to damage from harsh chemicals,
- Can only be dissolved by strong acids,
- Becomes brittle over time.
What are mineral fibers, and what are examples?
Mineral fibers are naturally occurring fibers with a crystalline structure. Examples include fiberglass and asbestos.
What are regenerated fibers, and what is an example?
Regenerated fibers are artificial fibers made from plant cellulose. An example is rayon, which is strong and can imitate natural fibers.
What are synthetic fibers, and what are examples?
Synthetic fibers are made from polymers. Examples include:
- Polyester (wrinkle-resistant, strong),
- Nylon (easily broken down by light and acid),
- Acrylic (inexpensive, used as artificial wool),
- Olefins (quick-drying, resistant to wear).
What are the three main methods of fiber analysis?
- Physical examination (color, diameter, size),
- Microscopic examination (fiber diameter, cross-section),
- Chemical examination (dye extraction, chemical structure).
What can be determined through microscopic examination of fibers?
- Fiber diameter (size),
- Cross-section shape (natural vs. synthetic),
- Surface features (roughness, twists),
- Fabric weave (if present).
What is the purpose of polarizing light microscopy in fiber analysis?
Polarizing light microscopy is used to examine fibers’ physical characteristics, such as color, shape, twists, surface features, cross-section, and diameter. It can also identify foreign material adhering to fibers.
What is the burn test, and how is it used to differentiate fibers?
- The burn test involves burning a small piece of fabric and observing:
- How it ignites,
- The smell of the smoke,
- The residue left behind.
Different fibers have unique burn characteristics (e.g., cotton smells like burning paper, while polyester melts and smells like chemicals).
What are the steps involved in the burn test?
- Cut a small piece of fabric (1 inch square),
- Hold one side with tweezers over a fireproof dish,
- Light the other end with a match,
- Observe how it burns, the smell, and the residue,
- Let the residue cool and examine it.
What is infrared spectroscopy used for in fiber analysis?
Infrared spectroscopy is used to identify the chemical composition of fibers by analyzing their unique IR “fingerprint.” It helps differentiate between fibers with similar physical characteristics.
Why is chemical examination of fibers sometimes necessary?
Chemical examination is necessary when fibers have similar colors or physical properties. It involves extracting the dye and identifying its chemical structure, though it is a destructive method.
How can fiber diameter help determine its origin?
- Fiber diameter varies depending on the material:
- Softer materials (e.g., clothing) have smaller fibers,
- Durable materials (e.g., carpets) have larger fibers.
This can help determine if the fiber came from clothing, carpets, or other textiles.
What is the significance of cross-section analysis in fiber identification?
Cross-section analysis helps differentiate between natural and synthetic fibers:
- Natural fibers (from plants and animals) have rough edges,
- Synthetic fibers have uniform, smooth edges.
This can reveal the fiber’s origin and type.
What is the difference between direct and secondary fiber transfer?
- Direct transfer: Fibers move directly from one source to another (e.g., suspect to victim).
- Secondary transfer: Fibers move from one source to another through an intermediary (e.g., suspect to object to victim).
