polymer network synthesized using a reactant or reactants of known molar mass or masses and chemical structure.
- A model @NT07562@ can be prepared using a non-linear @P04740@ or by @CT07136@ of existing polymer chains.
- A model @NT07562@ is not necessarily a @PT07570@. If a non-linear @P04740@ is used to prepare the @NT07562@, non-@S06021@ amounts of reactants or incomplete reaction can lead to @NT07562@ containing loose ends. If the @CT07136@ of existing polymer chains is used to prepare the @NT07562@, then two loose ends per existing polymer chain result. In the absence of chain entanglements, loose ends can never be elastically active @NT07562@ chains.
- In addition to loose ends, model networks usually contain ring structures as @NT07562@ imperfections.
- Loose ends and ring structures reduce the concentration of elastically active @NT07562@ chains and result in the @S05635@ and Young´ s modulus of the rubbery networks being less than the values expected for a @PT07570@ structure.
- Physical entanglements between @NT07562@ chains can lead to an increase in the concentration of elastically active @NT07562@ chains and, hence, increases in the @S05635@ and the Young´ s modulus above the values expected for a @PT07570@ structure.
PAC, 2007, 79, 1801. 'Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)' on page 1814 (https://doi.org/10.1351/pac200779101801)