Test 1

Element X has an electronic configuration 2,8,7. Its valancy is ____

1

The 1st and 2nd shell of an atom are full. Its atomic number is ____

10

Ceramics are also present inside the body in the form of natural ceramics. Give two examples where they reside inside the body and how this type of ceramic can be used synthetically? How is this ceramic compared to synthetic ceramics?

Bone & enamel: calcium phosphate (bone replacement & bone cement)

A polymer sample is provided in class. The present form of this polymer has some defects, which are included to obtain certain properties. Discuss the defect present in the sample and properties that are governed by this defect.

Defect: porous (3D) vacancy --> cluster Properties: tissue engineering application (bone) bio-mineralization interconnected pores replaced by healthy tissue (biodegradibility) better tissue response controlled mechanical strength 150-180mm

Bio-degradibility is the primary goal for designing an implantable biomaterial. True or false?

False (biocompatibility)

Transfer of electrons take places in ____

Ionic bond

Which one of the following does IONIC bonding predominate ____

NaCl

Automobile tail-light covers are made from a polymer due to its characteristic properties. The same polymer is used for intra-ocular lenses. Discuss the name and properties of this polymer.

PMMA (Polymethyl Meth acrylate) 1. transparency/optical clarity --> high refactive index 2. scratch resistant --> superior mechanical strength 3. chemically inert

Material X is an insulator and can be easily re-shaped. Material X is _____

Polymer

In invitro cell cultures the material of choice for culturing cells is Tissue Culture PolyStyrene (TCPS), which is derived from ordinary PolyStyrene (PS) by way of a surface modification. Explain why TCPS supports cell adhesion, spreading and growth much better than PS. In your answer include the role of the polymer surface properties, the role of proteins involved in this process, and the message that can be derived from this observation.

Proteins can attach better (hydrophillicity) protein adosrption = better cell attachment = spread better (multiply)

Increasing molecular weight of polymer generally increases strength. True or false?

True (more intermolecular interactions)

Polymer sample has a crystallinity of 75% & density of amorphous structure is 0.85 g/cm^3. Which of the following is true? a. density of the sample is >0.85 b. density of the sample is <0.85 c. None of the above

a. density of the sample is >0.85

Which of the following is true about biomaterials? a. naturally derived or synthetic b. always synthetic c. always natural d. metal only

a. naturally derived or synthetic

What is the tissue response to the following types of implants? a. if material is toxic b. non-toxic & biologically inactive c. non-toxic & biologically active d. non-toxic & dissolves

a. tissue dies b. fibrous tissue of variable thickness grows c. interfacial bond forms d. surrounding tissue replaces it

Pick a composite. a. wood b. steel c. nylon

a. wood

Cooling and non crystallizable polymer liquid below Tg results in the formation of a: a. ordered solid b. glass c. less viscous material d. opaque material

b

Figure out ODD statement about ceramics. a. good insulators b. ductile c. contains both metallic & non-metallic

b. ductile

Strong covalent bonds exist between polymer chains is: a. thermoplasts b. thermosets c. elastomers d. all polymers

b. thermosets

PVC tubing is being used for transporting water. If organic solvents are run through this tubing it becomes stiff and somewhat brittle. This is because: a. the solvent plasticizes the tubing, raising the Tg. b. the solvent removes the plasticizer, lowering the Tg. c. the solvent removes the plasticizer, raising the Tg.

c

Molecular weight of a polymer usually: a. decreases Tg value b. stabilizes Tg value c. increases Tg value d. does not affect Tg value

c - longer chains --> more secondary bonds --> decreases flexibility

One of the characteristic properties of polymeric materials: a. high temperature stability b. high mechanical strength c. high elongation d. low hardness

c. high elongation

Which of the following is a strong & ductile material? a. polymer b. ceramic c. metal d. semiconductor

c. metal

Of the families of materials which are hard & brittle? Which are the least hard & brittle?

ceramics; polymers

Which of of the following is NOT the characterization of IONIC compounds? a. Electrical conductivity in the molten/solution state b. brittle nature c. strong forces of interaction d. None of the above

d. None of the above

Which of the following is an example of a biomaterial? a. Titanium b. ceramics c. bone d. a & b e. a & c f. a, b, & c

d. a & b

Which is NOT a ceramic? a. aluminum b. glass c. porcelain d. silicon

d. silicon

Assertion: transition through Tg to Tm leads to highly ordered crystalline state Reason: polymer chain energy and motion increases through Tg to Tm i. assertion and reason are both correct but reason does not explain assertion ii. assertion and reason are both correct and the reason explains the assertion iii. both assertion and reason are incorrect iv. assertion is correct and reason is incorrect v. assertion is incorrect and reason is correct

i

Assertion:Twin boundary occurs when there is a mirror image of atomic placement across the boundary Reason: Crystal structure is same both inside and outside the twin i. assertion and reason are both correct but reason does not explain assertion ii. assertion and reason are both correct and the reason explains the assertion iii. both assertion and reason are incorrect iv. assertion is correct and reason is incorrect v. assertion is incorrect and reason is correct

i

Assertion: external surface is in higher energy state Reason: coordination number of surface atoms is not satisfied i. assertion and reason are both correct but reason does not explain assertion ii. assertion and reason are both correct and the reason explains the assertion iii. both assertion and reason are incorrect iv. assertion is correct and reason is incorrect v. assertion is incorrect and reason is correct

ii

The word polymer meant for materials made from ____

multiple entities

If you had to produce an artificial artery, what are the essential properties you will incorporate in your design? Which type of material would you first consider and why?

polymer: elasticity, mechanical strength (sustains changes in blood pressure), smooth surface (prevents blood clots), non-reactive

Why is ceramic head preferred over metal head against the high molecular weight polyethylene for hip implants?

there will be a lot of mechanical stress (leads to corrosion)

Assertion: Dislocation ends in a defect free region of a crystal Reason: localized lattice strains develop as a result of the dislocation i. assertion and reason are both correct but reason does not explain assertion ii. assertion and reason are both correct and the reason explains the assertion iii. both assertion and reason are incorrect iv. assertion is correct and reason is incorrect v. assertion is incorrect and reason is correct

v