Reference no: EM133081761

Paint Casework

To successfully complete this assignment, use the classification charts and the information provided in class to interpret analytical results in the following case scenario and answer the questions.

Note:
Q = Questioned sample
K = Known sample (aka control sample).

Case Scenario

A hit and run occurred at Miami Beach during the Hip-Hop festival. Paint fragments were recovered from the victim's head and labeled as Q1. Witnesses reported that a 2010 blue Ford Fusion vehicle did not stop at the red light and hit the victim.

A suspect vehicle was located one day later, with damage in the hood and the bumper. Samples from the vehicle were submitted for analysis and labeled as questioned samples, K1 and K2.

All samples were collected, labeled and submitted to the laboratory for comparison and analysis.
Item 1 (Q1) contains paint samples collected from the victim's head.
Item 2 (K1) contains paint sample collected from the hood of the suspect vehicle (K1).
Item 3 (K2) contains paint sample collected from the bumper of the suspect's vehicle (K2).

Analytical results from the laboratory:

Item 1 (Q1)
The paint fragments contained in exhibit Q1 has the following layer structure:
1. Colorless transparent enamel (binder type similar to spectrum shown for K1)
2. Medium-blue acrylic enamel base coat with styrene modification and metallic decorative flakes
3. Colorless transparent enamel (binder type similar to spectrum shown for K1)
4. Medium-blue acrylic enamel base coat with styrene modification and metallic decorative flakes
5. Dark gray acrylic-alkyd primer enamel

Item 2 (K1)
The paint fragment contained in exhibit K1 has the following layer structure:
1. Colorless transparent enamel (binder type as shown in spectrum K1)
2. Medium-blue acrylic enamel base coat with styrene modification and metallic decorative flakes
3. Colorless transparent enamel (binder type as shown in spectrum K1)
4. Medium-blue acrylic enamel base coat with styrene modification and metallic decorative flakes
5. Dark gray acrylic-alkyd primer enamel
6. Dark-brown epoxy enamel primer

Item 3 (K2)
The paint fragment contained in exhibit K2 has the following layer structure:
1. Colorless transparent enamel (binder type as shown in spectrum K2)
2. Medium-blue acrylic-urethane enamel base coat with decorative flakes (metallic)
3. Dark-blue epoxy enamel modified with urethane primer
4. Black epoxy enamel primer
Analysis conducted on items 1, 2 and 3 included:
1. Microscopical examination (stereomicroscope, PLM, thickness, physical examination)
2. Micro-chemical tests
3. Micro-FTIR
Using the information provided answer the following questions:

1). Given the following micro-FTIR spectra obtained from automobile clear topcoats identify the binder and modifiers (if any). Justify your answer by creating a table for each sample, one column for wavelength and the second column for the corresponding chemical composition based on the spectrum peaks.

2). Given the layer sequence and chemical composition of the layers, describe for each of the 3 items if they could be identified as OEM, repainted or either one (OEM or repainted). Justify your answer.

3). Why item 2 (K1) and item 3 (K2) have different physical and chemical properties if they were sampled from the same vehicle? Explain.

4). Given the chemical composition of the items, explain which other analytical technique(s) could be conducted in the laboratory to provide additional discrimination for these samples. Explain.

5). Given that the microscopical, microchemical and instrumental comparisons of the paint fragments of item 1 and item 2 revealed that they were like one another with respect to their layer structures, layer colors, layers textures, microchemical reactivities, binder characteristics of their respective layers and pigment characteristics of their respective layers.

Explain to a jury the following conclusions:

There is an association between item 1 and item 2 even if the number of layers of item 1 and item 2 are different (5 layers vs. 6 layers).

There are fragments recovered from the victim that have similar composition and physical characteristics to item 2. Nonetheless, there were no fragments recovered from the victim that had similar composition to item 3.

Attachment:- Paint Case.rar