Question

Some materials, such as poly(dimethyl siloxane) or PDMS, have a wide variety of applications, such as breast implants, contact lenses, and knuckle replacements. Other materials, such as poly(propylene) (PP) are primarily used for only one application (in this case, sutures). Using a popular search engine compare the structures of PP and PDMS. Fill out the attached table. Using your answers, answer the following questions:

	Poly(propylene)	Poly(dimethyl siloxane)
Chemical formula
Sketch the molecule
Mechanical properties
Thermal properties
Chemical properties
Degradation properties
Susceptibility to degradation

Answer 1

	Poly(propylene)	Poly(dimethyl siloxane)
Chemical formula	(C3H6)n	(C2H6OSi)n
Sketch the molecule
Mechanical properties	The density of polypropylene is 0.895 and 0.92 g/cm³. The Young's modulus of PP is between 1300 and 1800 N/mm². it is commodity plastic. it can be copolymerized with ethylene. This is due to its property of tough and flexible nature. it is having good resistance against fatigue.	PDMs is viscoelastic or it acts as a viscous liquid such as honey. At low temperatures it becomes elastic solid like rubber. The shear modulus of PDMS varies with various preparatory conditions and usually occurs in the range of 100 kPa to 3 MPa Density is 0.97 kg/m3 . Young's modulus is 360-870 KPa
Thermal properties	PP is having melting point of 171 °C. Below 0°C PP    becomes brittle. Thermal expansion is large but less than polyethylene.	Melting point of PDMS is -49.9–40°C and thermal conductivity is 0.15 W/m K. The specific heat of PDMS is 1.46 kJ/kg K.
Chemical properties	At room temperature PP is resistant to all fats and organic solvents. Nonoxidizing bases and acids can be stored in PP containers. At increased temperatures, PP can be dissolved in nonpolar solvents like xylene, tetralin and decalin. Three types of PP exist are homopolymer, random copolymer, and block copolymer.	Polymerization and cross linking in PDMS exposes a hydrophobic surface externally. The hydrophobic surface is shiy and not dissolved in polar solvents. Plasma oxidation modifies the surface to become hydrophilic. Oxidized PDMs surface resist the adsorption of hydrophobic and negatively charged groups. Organic solvents diffuse into PDMS and cause it to swell. PDMS is used as surfactant and antifoaming agent. It is also used as herbicidal penetrant to form water repelling coating.
Degradation properties	PP an be decgradable by high temperatures and UV radiation of sunlight. Carbon black protects from UV and antioxidants prevent the degradation.	Nonbiodegradable. Degraded by waste water treatment using various clays.
Susceptibility to degradation	PP is degraded by wide variety of microbial communities in soil and reported to be degraded in    human body as implantable mesh devices	Nontoxic and no adverse effects reported and degraded by treatment with clays.