Ch. 1 Types of Evidence (Exam 1) Flashcards
This is an object that may have a connection with a crime.
What is evidence?
What are the 2 purposes of analyzing evidence?
1) Identification
2) Comparison
These molecules consist of large numbers of repeated chemical structural units.
What are polymers?
These polymers consist of two or more different monomer structures.
What are copolymers?
Give examples of the 3 types of copolymers using the letters A & B to represent two different monomeric structures.
1) Block - AAABBB
2) Random - ABBABA (any order is fine)
3) Alternate - ABABAB
Give 4 examples of polymers used in packaging.
1) Polyethylene (PE)
2) Polypropylene (PP)
3) Polystyrene (PS)
4) Poly (ethylene terephthalate), or PET
Give 3 examples of polymers used for adhesives.
1) Polypropylene (PP)
2) Polyvinyl Chloride (PVC)
3) Acrylic
This copolymer is used to manufacture bumper bars.
What is styrene-butadiene (SBR)?
This copolymer is used to make tires.
What is styrene-acrylonitrile (SAN)?
This polymer is used to make car light enclosures.
What is poly (methyl methacrylate), or PMMA?
Fibers can be classified into these two groups.
What are natural and man-made?
What are 3 sources of natural fiber?
Animals, plants, & minerals
What are the 2 types of man-made fibers?
Synthetic and regenerated
This often multi-layered specimen is used to cover a range of surfaces and is composed of pigments, binders, solvents, and additives.
What is paint?
This material is produced from fiber pulp, with wood being a major source of this fiber.
What is paper?
What is the purpose of a sizing agent in paper manufacturing?
It makes the cellulose component more hydrophobic to prevent the ink from running
What 3 pieces of information can ink provide document examiners?
1) If 2 inks have the same origin
2) If 2 inks were made by the same manufacturer
3) When the inks were manufactured
In what 3 ways is toner useful in document analysis?
1) Show if 2 documents have the same origin
2) Show the source of a document
3) Show if a document has been altered
This material is produced from silica and other metal oxides that are melted at a high temp and quickly cooled to produce an amorphous structure.
What is glass?
What is the purpose of a flux in glass production? Give examples of fluxes too.
Lower melting temp
Ex: Na2O & K2O
How do fluxes lower the melting point temp of a glass mixture?
They disrupt the Si—–O network in the silica
These substances, made of compounds such as CaO & MgO, are added to glass to make it more water resistant.
What are stabilizers?
Why are stabilizers needed in glass manufacturing?
The bonds in the Si—–O network weaken as cations migrate out of the matrix in the presence of water
This type of soda-lime glass is used to produce Pyrex dishes.
What is borosilicate?
This piece of evidence is a complex mixture of minerals and organic matter, as well as man-made materials such as glass.
What is soil?
Which is the better analytical method for examining soil samples? Comparison or quantification?
Comparison
