Studied by 15 people
what groups does PVC contain? (hint: what does PVC stand for?)
a vinyl chlorine group
(hint: polyvinyl chloride)
what factors promote non crystallinity in polymers?
High molecular weight
Chain branching
Copolymerization
Too fast cooling
Presence of plasticizers
Cross-linking
Steric hindrance, big groups attached to the base
Random chain orientation/ Atactic
Polymer composition
what is ethylene glycol?
which polymer can be formed from caprolactam?
Nylon-6.
Common condensation polymers
Some common condensation polymers are polyamides, polyesters, polyurethane, and polycarbonate.
What gives a polymer strong intermolecular forces?
The presence of functional groups or side chains that can form hydrogen bonds or other types of attractive interactions.
What does vulcanization do?
Sulfur and heat makes natural form cross-linked polymers that are strong.
Polymers whose backbone are made of the same type of atoms are called
homopolymers.
Tacticity is
the arrangement of functional groups on the carbon backbone. (Stereochemistry)
True or False: High density polymers are branched.
False, branching creates low density and reduces packing. Low density polymers are branched.
The process of heat softening, molding, and cooling to rigidness can be repeated for which plastics?
Thermoplastic
Polyethylene is (a) random copolymer (b) homopolymer (c) alternate copolymer (d) crosslinked polymer
Polyethylene is a (b) homopolymer.
Bakelite is obtained from phenol by reacting it with:
Bakelite is obtained from phenol by reacting it with formaldehyde.
Which is Nylon not? (a) condensation polymer (b) copolymer (c) polyamide (d) homopolymer
Nylon is not a (d) homopolymer.
Define monomer
A monomer is a molecule that can join together with other molecules to form a polymer through a process called polymerization. It is the basic building block of a polymer and typically consists of repeating units.
What is a plastic?
An organic polymer
Define thermoplastic
A polymer that can be melted and re-molded without undergoing chemical change. A material that becomes soft and pliable when heated and solidifies when cooled, allowing it to be shaped and formed into various objects. Examples of thermoplastics include polyethylene, polypropylene, and polystyrene.
What is a thermoset plastic?
A thermoset plastic is a type of polymer that, once cured or hardened, cannot be melted or reshaped by heating. Cross-linking occurs during curing, which creates a three-dimensional network of interconnected polymer chains. This gives thermoset plastics their rigid and durable properties. Examples of thermoset plastics include epoxy, phenolic, and melamine resins.
synthetic vs semisynthetic vs natural polymer
Synthetic polymers do not occur naturally, many are made from petroleum. Examples include polyethylene and polypropylene.
Semisynthetic polymers are derived from natural polymers but undergo chemical modifications to enhance their properties. Cellulose acetate is an example of a semisynthetic polymer.
Natural polymers occur in nature and are derived from living organisms. Examples include proteins, such as collagen and silk, and carbohydrates, such as cellulose and starch.
What is an elastomer?
An elastomer is a type of polymer that exhibits elastic properties, meaning it can undergo significant deformation under stress and return to its original shape when the stress is removed. Elastomers have high elasticity and are commonly used in applications such as rubber bands, gaskets, seals, and tires.
What is a fiber?
A fiber in polymer chemistry refers to a long, thin strand or thread-like structure made up of polymers. It is a type of polymer material that has a high aspect ratio, meaning its length is much greater than its diameter. Fibers can be natural, such as cotton or silk, or synthetic, such as polyester or nylon. They are commonly used in textiles, composites, and other applications where strength, flexibility, and durability are required.
What is a resin?
A resin in polymer chemistry is a solid or highly viscous substance that is typically derived from plants or synthesized chemically. It is a key component in the production of various polymers and is used as a binder or matrix material. Resins provide strength, durability, and other desirable properties to the final polymer products. These make thermoset plastics.
In polymer chemistry, Mn (number average molecular weight) and Mw (weight average molecular weight) provide different information about the distribution of molecular weights within a polymer sample.
Mn represents the average size of polymer chains and is calculated by summing the molecular weights of all chains and dividing by the total number of chains. It gives insight into the typical size of the polymer chains in the sample.
On the other hand, Mw represents the average molecular weight of the polymer chains, taking into account the weight or abundance of each chain. It is calculated by summing the product of each chain's molecular weight and its abundance, divided by the total weight of all chains. Mw is influenced more by the presence of larger chains and provides information about the overall weight distribution of the polymer sample.
Therefore, Mn provides information about the average size of the chains, while Mw provides information about the overall weight distribution of the chains in a polymer sample.
Mn, (number average molecular weight) is a measure of the average size of polymer chains in a polymer sample. It provides information about the distribution of molecular weights within the sample. Specifically, M-sub-n represents the sum of the molecular weights of all polymer chains divided by the total number of chains in the sample. It is an important parameter in characterizing the physical and mechanical properties of polymers.
Mn vs Mw
Therefore, Mn provides information about the average size of the chains, while Mw provides information about the overall weight distribution of the chains in a polymer sample.
Mn and Mw equations for polymers
Mn = Σ(Ni * Mi) / ΣNi
Mw = Σ(Ni * Mi^2) / Σ(Ni * Mi)
What are the degrees of polymerization?
The degree of polymerization refers to the number of monomer units in a polymer chain. It is calculated by dividing the molecular weight of the polymer by the molecular weight of the monomer unit.
What is the polydispersity index?
The polydispersity index (PDI) is a measure of the distribution of particle sizes in a sample. It is calculated by dividing the weight average molecular weight by the number average molecular weight. PDI values range from 0 to infinity, with lower values indicating a narrower size distribution and higher values indicating a broader size distribution. A PDI of 1 indicates a monodisperse sample, where all particles have the same size.
What are the different morphologies of polymers?
Different morphologies of polymers include amorphous, semi-crystalline, and crystalline. Amorphous polymers lack a regular arrangement of polymer chains, resulting in a disordered structure. Semi-crystalline polymers have both disordered regions and ordered crystalline regions. Crystalline polymers have a highly ordered structure with regularly arranged polymer chains.
What are the different structures in polymers?
Different structures in polymers:
Linear: Straight chain of monomers.
Branched: Main chain with side branches.
Crosslinked: Interconnected chains.
Network: Highly crosslinked structure.
Dendritic: Tree-like structure with repeating branches.
Copolymer: Two or more different monomers combined.
What are the different types of tacticity?
Isotacticity means all side groups are on the same side, syndiotacticity means they alternate, and atacticity means they are randomly distributed.
Step growth vs chain growth
Step growth vs chain growth visual
Describe the steps of initiation, propagation, and termination in vinyl monomer polymerizations
Initiation: Generates reactive species, such as free radicals or ions. Initiators, such as peroxides or azo compounds are commonly used.
Propagation: The reactive species react with the vinyl monomer molecules, leading to the formation of a growing polymer chain. This process continues as more monomer molecules react with the active end of the growing chain, resulting in the elongation of the polymer chain.
Termination: Can be combination termination, where two growing chains react with each other, or disproportionation termination, where a growing chain reacts with a dormant chain end.
Describe how spectroscopy can be used in polymer analysis
IR spectroscopy is used to identify functional groups present in polymers and to analyze their chemical structure.
NMR spectroscopy provides detailed information about the connectivity and arrangement of atoms within the polymer chain.
UV-Vis spectroscopy can be used to determine the presence of conjugated systems in polymers, which is important for understanding their optical properties.
