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Questions and Answers
The most common type of regenerated fiber, which is derived from cellulose and is mostly plant in origin, is rayon.
The most common type of regenerated fiber, which is derived from cellulose and is mostly plant in origin, is rayon.
True (A)
Synthetic polymer fibers, which all originate with petroleum products, are cellulose-based fibers.
Synthetic polymer fibers, which all originate with petroleum products, are cellulose-based fibers.
False (B)
Polyester has properties similar to nylon except it is easily broken down by light and concentrated acid.
Polyester has properties similar to nylon except it is easily broken down by light and concentrated acid.
False (B)
A disadvantage of manufactured fibers is that they can deteriorate in bright sunlight and melt at a lower temperature than natural fibers.
A disadvantage of manufactured fibers is that they can deteriorate in bright sunlight and melt at a lower temperature than natural fibers.
Fibers are woven into textiles or fabrics.
Fibers are woven into textiles or fabrics.
Fibers that have been spun together are called:
Fibers that have been spun together are called:
A small molecule that may bond to other monomers to become a polymer is a:
A small molecule that may bond to other monomers to become a polymer is a:
When fibers are transferred directly from victim to suspect or suspect to victim, this is called:
When fibers are transferred directly from victim to suspect or suspect to victim, this is called:
The transfer of evidence such as a fiber from a source to a person, then to another person, is called:
The transfer of evidence such as a fiber from a source to a person, then to another person, is called:
Early collection of fibers in an investigation is critical. Within 24 hours, an estimated:
Early collection of fibers in an investigation is critical. Within 24 hours, an estimated:
A forensic scientist will ask questions about:
A forensic scientist will ask questions about:
Fiber evidence is gathered with:
Fiber evidence is gathered with:
Fibers are classified as either:
Fibers are classified as either:
Natural fibers come from:
Natural fibers come from:
Natural plant fibers are produced from:
Natural plant fibers are produced from:
All plant fibers share the common polymer that is:
All plant fibers share the common polymer that is:
One seed fiber is:
One seed fiber is:
Fiberglass is a form of:
Fiberglass is a form of:
Until the nineteenth century, only plant or animal fibers were used to make clothing and textiles. Half the fibers produced today are synthetic. They are categorized as:
Until the nineteenth century, only plant or animal fibers were used to make clothing and textiles. Half the fibers produced today are synthetic. They are categorized as:
Weave patterns have names like:
Weave patterns have names like:
The simplest weave is the plain weave or:
The simplest weave is the plain weave or:
The number of threads that are packed together for any given amount of fabric is known as the:
The number of threads that are packed together for any given amount of fabric is known as the:
Manila is a fiber extracted from the leaves of ______, a relative of the banana tree.
Manila is a fiber extracted from the leaves of ______, a relative of the banana tree.
Flax is the most common stem fiber, and is most commonly found in the textile,
Flax is the most common stem fiber, and is most commonly found in the textile,
What are things that determine transfer of fibers?
What are things that determine transfer of fibers?
When collecting fibers, which ones are you most likely to collect and why?
When collecting fibers, which ones are you most likely to collect and why?
Once collected, how are fibers analyzed in the lab?
Once collected, how are fibers analyzed in the lab?
What four methods were discussed as ways that forensic scientists can complete fiber analysis without damaging the fibers? Discuss what each of these methods allows scientists to see.
What four methods were discussed as ways that forensic scientists can complete fiber analysis without damaging the fibers? Discuss what each of these methods allows scientists to see.
How is the value of fiber evidence determined at a crime scene?
How is the value of fiber evidence determined at a crime scene?
What is the most common form of fiber transfer that is encountered at a crime scene?
What is the most common form of fiber transfer that is encountered at a crime scene?
How are textiles formed?
How are textiles formed?
Where do natural fibers come from?
Where do natural fibers come from?
How do you tell the difference between natural and synthetic fibers?
How do you tell the difference between natural and synthetic fibers?
How can you tell the difference between plant fibers and animal fibers?
How can you tell the difference between plant fibers and animal fibers?
What are some common forms of seed fibers? Where are they used?
What are some common forms of seed fibers? Where are they used?
Where are leaf fibers used?
Where are leaf fibers used?
What are mineral fibers? Give an example of mineral fibers.
What are mineral fibers? Give an example of mineral fibers.
What are synthetic fibers? Give some examples.
What are synthetic fibers? Give some examples.
How are regenerated fibers made?
How are regenerated fibers made?
Compare the strength and durability of synthetic and natural fibers.
Compare the strength and durability of synthetic and natural fibers.
What is yarn? How is it made?
What is yarn? How is it made?
What is the warp?
What is the warp?
What is a weft?
What is a weft?
Describe the weaving of textiles... How are they woven?
Describe the weaving of textiles... How are they woven?
What are other examples of weave patterns?
What are other examples of weave patterns?
What three ways do fibers differ?
What three ways do fibers differ?
What does thread count refer to?
What does thread count refer to?
What does two-ply refer to?
What does two-ply refer to?
Why can fibers not be used to convict someone?
Why can fibers not be used to convict someone?
A fiber is collected at a crime scene. When viewed under a compound microscope, what traits would indicate that the fiber was a human hair and not a piece of fiber obtained from an article of clothing?
A fiber is collected at a crime scene. When viewed under a compound microscope, what traits would indicate that the fiber was a human hair and not a piece of fiber obtained from an article of clothing?
Describe asbestos as a fiber. What is its use? Why do people who work in construction and contracting have to be cautious about it?
Describe asbestos as a fiber. What is its use? Why do people who work in construction and contracting have to be cautious about it?
What is coir?
What is coir?
What common protein do all plant fibers have in common?
What common protein do all plant fibers have in common?
Study Notes
Fibers Overview
- Rayon is the most common regenerated fiber, derived from cellulose, primarily from plants.
- Synthetic fibers originate from petroleum products, not cellulose-based fibers.
- Polyester shares similarities with nylon but is not easily broken down by light and concentrated acids, contrary to some beliefs.
Properties of Manufactured Fibers
- Manufactured fibers can deteriorate under bright sunlight and melt at lower temperatures compared to natural fibers.
- Fibers are formed into textiles or fabrics through processes like weaving and knitting.
Fiber Evidence in Forensics
- Fibers spun together form yarn, which can be found in various textiles.
- Direct transfer occurs when fibers move directly from one person to another; secondary transfer involves an intermediate person.
- Rapid collection of fibers is crucial as 95% can be lost within 24 hours of a crime.
Forensic Fiber Analysis
- Fiber evidence analysis considers fiber type, color, quantity, and placement.
- Collection tools include vacuums, tape, forceps, glue, and lint rollers.
- Fibers are classified as natural or synthetic, with natural fibers sourced from animals, plants, or minerals.
Natural Fiber Sources
- Natural fibers derive from seeds, fruits, stems, and leaves; the common polymer in plant fibers is cellulose.
- Examples include cotton (seed fiber), linen (from flax), and manila (from abaca leaves), used for ropes and twines.
- Animal fibers contain proteins, while plant fibers do not.
Synthetic Fibers
- Synthetic fibers are classified into regenerated fibers and polymers. Common examples include rayon, acetate, nylon, acrylics, and polyesters.
- Regenerated fibers, like rayon, imitate natural fibers and are smooth and silky in texture.
Strength and Durability
- Synthetic fibers are generally stronger and more durable than natural fibers.
- Unlike natural fibers, manufactured fibers resist microbial damage, although they have vulnerabilities to sunlight and heat.
Weaving Techniques
- Textiles are woven or knitted, utilizing techniques like plain weave (tabby), twill, and satin.
- Warp refers to the lengthwise yarn in a weave, while weft refers to the crosswise yarn.
- Weaving has evolved from basket-making; industrial looms are now commonly used for mass production.
Fiber Identification and Analysis
- The value of fiber evidence relies on its uniqueness to the crime scene, rather than its abundance.
- Various microscopy techniques, like polarizing light microscopy and microspectrophotometry, facilitate non-destructive fiber analysis.
Class Evidence and Limitations
- Fibers provide class evidence and cannot solely convict an individual due to their commonality.
- Natural fibers can be identified distinctly from synthetic fibers based on their sources and composition.
Health Risks and Asbestos
- Asbestos, a durable mineral fiber, has historical applications in construction but poses significant health risks, leading to decreased usage in modern building materials.
Unique Fiber Characteristics
- Coir refers to fibers from coconuts.
- Key protein found in all plant fibers is cellulose.
- Thread count represents the number of yarns woven into a square inch of fabric, influencing fabric quality.
- Two-ply signifies a weave formed from twisting two threads together.
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Description
Explore the fascinating world of forensic fiber analysis. This quiz covers the types of fibers, their properties, and the critical role fiber evidence plays in forensic investigations. Discover how fibers can be transferred and analyzed in crime scenes.
