Question

kindly help me answering these quest. please type the answer, don't hand writes please.

part 1- testing the strength and degradation of polymer films:

1) properties of Teflon tape:...................

2A) initial properties of high-density polyethylene(HDPE) film:........................

2b) properties of stretched high-density polyethylene(HDPE) film:.....................

3) how did the strength of the Teflon and stretched HDPE change with direction?

part 2- synthesizing Nylon

4) properties of wet nylon strand:...........

5) properties of dried nylon strand:..............

6) how did the lengthwise strength of your nylon strand differ from its crosswise strength?

7) how did the properties of the wet nylon differ from those of the dry nylon?

part 3- synthesis of PVC gel.

8) properties of original polyvinyl alcohol solution>.......................

9) properties of the final gel...................

10) compare the properties of the PVC solution to the PVA after adding the sodium borate solution. how is the substance different?

11) how is the viscosity of the PVA affected by adding different amounts of sodium borate?

12) do you think the polymer strands in Teflon TM tape are arranged randomly or in parallel.?explain?

13) when HDPE is stretched, a"neck" can form. what do you think happens to the arrangement of the polymer strands in this region of the polymer? explain?

14) when you made nylon you were warned that monomers can be hazardous but that the polymer, once rinsed, is relatively harmless. explain the difference in hazard between the monomers and the polymer?

15) what can you claim about how polymer properties are affected by the molecular structure of the polymer? compare polymers based on chemical composition, cross-linking, and other structural features?

Answer 1

Part 1- testing the strength and degradation of polymer films:

1) properties of Teflon tape:

• Very good resistance to high and low temperatures: Melting point close to 350º. Up to that temperature, it maintains all its properties
• Very low coefficient of friction: This property gives Teflon non-stick properties.
• Good electrical insulator: Excellent dielectric properties.
• Very good resistance to the vast majority of agents and chemicals.
• Good solvent resistance.
• Fully flexible material

2A) initial properties of high-density polyethylene(HDPE) film:

• Excellent thermal and chemical resistance.
• Very good impact resistance.
• It is solid, colorless, translucent, almost opaque.
• Very good processability, that is, it can be processed by the forming methods used for thermoplastics, such as injection and extrusion.
• It is flexible, even at low temperatures.
• It is stubborn.
• It is more rigid than low density polyethylene.
• It is easy to print, paint or paste on it.
• It's very light.
• Its density is around 0.940 - 0.970 g / cm³.
• It is not attacked by acids, it is considered a maximum resistance of 60 ° C working for liquids, because at a higher temperature the useful life is reduced. Other thermoplastics offer better resistance to higher temperatures.
• It is much better for mechanical and thermal recycling.

2b) properties of stretched high-density polyethylene(HDPE) film:

• Good thermal and chemical resistance. It can withstand temperatures of 80 °C continuously and 95 °C for a short period of time.
• Good impact resistance.
• It is milky in color, it can become transparent depending on its thickness.
• Very good processability, that is, it can be processed by the forming methods used for thermoplastics, such as injection and extrusion.
• It is more flexible than high density polyethylene.
• It presents difficulties to print, paint or paste on it.
• Density in the environment of 0.910 - 0.940 g / cm³.

3) how did the strength of the Teflon and stretched HDPE change with direction?

It can be understood considering that the intermolecular forces existing between the chains are much weaker than the chemical bonds that are found along each individual chain; consequently, the short chains slide more easily over each other, which offers little or no transfer of effort. On the contrary, by increasing the molecular length, the windings between the molecules are increased and the accumulated resistance of many van der Waals bonds against slippage becomes greater.ç

part 2- synthesizing Nylon

4) properties of wet nylon strand:

• Specific Gravity: 1.13, Nylon does not float
• Polyamide is durable and strong with excellent abrasion resistance
• Nylon will stretch a lot before breaking. It is quite elastic and a good shock absorber. This makes it a good choice for live loads, including towing and anchoring.
• Melts instead of burning, if burned emits some cyanide.
• Good strength to weight ratio
• Transparent to infrared light
• Maximum Temperature: 210°F 99°C, Minimum Temperature: -94°F -70°C
• Melting Point: 420°F 216°C
• Tensile Strength: 5,800 psi
• The UV resistance of Nylon is good.
• When dry, polyamide is a good electrical insulator. Because it absorbs water the properties of Nylon can change when it is wet.

5) properties of dried nylon strand:

• Pleats and creases can be heat-set at higher temperatures.
• More compact molecular structure.
• Better weathering properties; better sunlight resistance.
• Softer "Hand"
• High melting point (256 °C/492.8 °F)
• Superior colorfastness.
• Excellent abrasion resistance.

6) how did the lengthwise strength of your nylon strand differ from its crosswise strength?

Nylon has a round cross section and is perfectly uniform along the filament. The cold stretcher aligns the chains so that they are oriented to the longitudinal direction of the fiber and are very crystalline. High tenacity filaments have longer chains. Shorter fibers do not stretch cold after spinning and therefore have less crystallites. Its tenacity is lower than that of the filaments.

7) how did the properties of the wet nylon differ from those of the dry nylon?

part 3- synthesis of PVC gel.

8) properties of original polyvinyl alcohol solution:

• Polyvinyl alcohol has excellent properties for forming films, as an emulsifier and as an adhesive.
• It is also resistant to oil, greases and solvents.
• It is odorless and non-toxic.
• It has high strength and flexibility, as well as high barrier properties for oxygen and aroma. However, these properties depend on moisture, that is, with more moisture more water is absorbed.
• Water, which acts as a plasticizer, will in turn reduce its tensile strength, but increase its elongation and tear resistance.
• The PVOH is totally degradable and dissolves quickly.
• The PVOH has a melting point of 230 °C and 180-190 °C for fully hydrolyzed and partially hydrolyzed grades respectively.
• It decomposes rapidly above 200 ° C.
• Polyvinyl alcohol does not melt like a thermoplastic, but decomposes by loss of water from two adjacent hydroxyl groups at temperatures above 150 °C.
• The double bonds remain in the chain and, as they form more in conjugate positions, an important coloration takes place.