Core Concepts
This smallest repeating chemical unit builds polymers like polyethylene.
What is a monomer?
Polymers found in nature like starch, cellulose, or natural rubber fall into this origin-based category.
What are natural polymers?
This non-stick PTFE from tetrafluoroethylene suits cookware coatings.
What is Teflon?
Polymers plus solid fillers like fibres create these reinforced materials for boats and planes.
What are fibre-reinforced plastics (FRPs)?
Polymers like polyacetylene or polyaniline that conduct electricity due to conjugation or doping.
What are conducting polymers?
The process converting monomers like ethylene into long-chain polyethylene.
What is polymerization?
Lab-made examples like polyethylene (PE), PVC, or nylon belong to this source classification.
What are synthetic polymers?
Phenol-formaldehyde resin, the first synthetic plastic, used in electrical insulators.
What is bakelite?
Most common FRP using durable, acid-proof glass fibres from silica melts at 1260°C.
What is glass fibre-reinforced plastic (GFRP)?
This biodegradable thermoplastic from lactic acid (via starch/sugarcane) is used in medical implants.
What is polylactic acid (PLA)?
Number of repeating monomer units (n) in a chain, e.g., 100 for a specific ethylene polymer.
What is degree of polymerization (DP)?
SBR from styrene and butadiene exemplifies this, using more than one monomer type.
What is a copolymer?
Teflon's high chemical resistance and density (2.1-2.3 g/cc) come from electronegative fluorine.
What are its properties?
FRPs excel here with light weight, corrosion resistance, and high strength-to-weight for auto parts.
What is the main advantage (or high strength-to-weight ratio)?
Smart polymers like PTFE or PLA that return to original shape via heat or light stimulus.
What are shape memory polymers (SMPs)?
Minimum reactive sites (at least 2) a monomer needs, like the double bond in vinyl compounds.
What is functionality?
HDPE with straight chains (high MP, tensile strength) vs. LDPE (branched, low density) represents this structure type for the former.
What are linear polymers?
Kevlar, this aromatic polyamide, has 5x steel's tensile strength on weight basis.
What is poly p-phenyleneterephthalamide?
Carbon fibres in this FRP offer fatigue resistance and low thermal conductivity for spacecraft.
What is carbon fibre-reinforced plastic (CFRP)?
Heat above Tg to deform, cool to fix temporary shape, then reheat for this recovery step.
What is triggering (or recovery)?
Phenol's 3 sites allow cross-linking, but low DP (<600) lacks engineering strength.
What are oligopolymers?
Bakelite or vulcanized rubber, with covalent cross-links making them rigid and non-melting, is this structural class.
What are cross-linked polymers?
Bakelite forms via condensation, creating cross-links for this permanent, non-remouldable trait.
What is thermosetting?
Woven glass filaments bonded with polyester or epoxy resins form mats in this FRP production.
What is GFRP?
PLA's properties include Tg of 60-65°C, MP 173-178°C, and good biocompatibility for these uses.
In drug delivery or sutures