Question

met 14400 lab
izod impact testing
test methods
discussion questions:

1. what practical significance does the izod impact resistance test have in making material selections for plastics products? give an example of at least one product where impact resistance is important.
2. what do you think happens to most polymers’ impact strength as the temperature decreases? why?
3. what general property (or properties) of materials are related to impact strength?
4. did your izod impact resistance values correlate with published data? if they do not agree, discuss what you believe caused the discrepancy. identify the source of your published data, if not found in these directions.
5. does the izod impact resistance test performed in this experiment meet astm d256 requirements? if not, what would disqualify this as an astm test?

Explanation:

1. The Izod Impact Resistance test helps in choosing plastics that can withstand impacts, reducing breakage. For example, in automotive dash - boards, high impact - resistant plastics are used to ensure safety during collisions.
2. As temperature decreases, most polymers' impact strength decreases because the polymer chains become more rigid and less able to absorb energy.
3. General properties related to impact strength include toughness (ability to absorb energy before fracture), ductility (ability to deform without breaking), and elasticity (ability to return to original shape after deformation).
4. Without specific test data, it's hard to say. Discrepancies could be due to differences in testing conditions (temperature, humidity), sample preparation, or instrument calibration. Sources of published data could be scientific journals, material standards organizations' reports.
5. To determine if the test meets ASTM D256 requirements, one must check if the test setup (e.g., specimen size, shape, support conditions), testing procedure (e.g., pendulum type, impact velocity), and data - collection methods follow the standard. Deviations in any of these aspects could disqualify it as an ASTM test.

Answer:

1. The Izod Impact Resistance test is significant for choosing plastics that can resist breakage. Example: Automotive dash - boards.
2. Most polymers' impact strength decreases as temperature decreases because polymer chains become more rigid.
3. Toughness, ductility, and elasticity are related to impact strength.
4. Without specific data, discrepancies could be due to testing conditions, sample prep, or instrument calibration. Sources: Scientific journals, standards reports.
5. Check test setup, procedure, and data - collection against ASTM D256. Deviations could disqualify.