Polyamides

Abstract

The article contains sections titled: 1. Introduction 2. Nomenclature 3. General Considerations in Polyamidation 3.1. Molecular Mass 3.2. Equilibrium and Rate Constants 3.3. Effects of Monomer Structure 3.4. Amide Interchange 3.5. Structure‐Property Considerations 4. Other Polymerization Techniques 4.1. Variants of Hydrolytic Polymerization 4.2. Interfacial and Solution Polymerization 4.3. Ionic Polymerization 4.4. Solid‐Phase Polymerization 5. Commercial Processes 5.1. PA 46 5.2. PA 66 5.2.1. Batch Production 5.2.2. Continuous Production 5.3. Other AABB‐Polyamides 5.4. PA 6 5.5. PA 11 5.6. PA 12 6. Properties 6.1. Properties of Unmodified Polyamides 6.2. Copolymerization 6.3. Modification by Additives 6.3.1. Filled and Reinforced Polyamides 6.3.2. Blends and Alloys 6.3.3. Flame‐Retardant Polyamides 6.3.4. Conductive Polyamides 6.3.5. Other Formulations 7. Processing 8. Uses 9. Ecological Aspects and Toxicology 9.1. Recycling 9.2. Polyamide Monomers 9.3. Other Aspects 10. Economic Aspects

Chemical Recycling of Aliphatic Polyamides by Microwave-Assisted Hydrolysis for Efficient Monomer Recovery

“…At the HCl/amide mole ratio of 2.5 instead of 1.25, only 10 min reaction time at 200 °C was necessary to completely depolymerize PA 11 (Table , entry 26, Figure ) and PA 12, while PA 1010 required 17 min (Table ; entries 34 and 40, respectively). The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups .…”

“…The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups . Because of the low density of long-chain PAs, the pellets float on the top of reaction mixtures, while on the other hand, PA 66 pellets of higher density sink to the bottom of the microwave vial.…”

Chemical Recycling of Aliphatic Polyamides by Microwave-Assisted Hydrolysis for Efficient Monomer Recovery

“…At the HCl/amide mole ratio of 2.5 instead of 1.25, only 10 min reaction time at 200 °C was necessary to completely depolymerize PA 11 (Table , entry 26, Figure ) and PA 12, while PA 1010 required 17 min (Table ; entries 34 and 40, respectively). The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups .…”

“…The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups . Because of the low density of long-chain PAs, the pellets float on the top of reaction mixtures, while on the other hand, PA 66 pellets of higher density sink to the bottom of the microwave vial.…”

Hexaphenoxycyclotriphosphazene as FR for CFR anionic PA6 via T‐RTM: a study of mechanical and thermal properties

“…To produce APA6, molten ε‐caprolactam is polymerized in an anionic ring opening reaction, induced usually by a basic catalyst, for example, sodium salt of ε‐caprolactam, directly in the mold . Because of the much lower viscosity of ε‐caprolactam compared with PA6, molds of complex design can be fulfilling easier , and of particular importance is that fiber fabrics for fiber reinforcements are easier to be infiltrated. Consequently, for the production of CFR PA6 with high fiber content via T‐RTM processing, APA6 should produce better material properties because of good fiber infiltration .…”

Back-to-monomer recycling of polycondensation polymers: opportunities for chemicals and enzymes

“…Monomers such as (1) dicarboxylic acids and diamines, (2) ω-amino acids, and (3) lactams are typically used in the synthesis of polyamides. 116 Due to the wide range of available monomers, polyamides can exhibit a broad range of properties suitable for many specific application areas. 116 At their end-of-life, depolymerization of polyamides is mainly performed using hydrolysis and solvolysis techniques, which are detailed in the following sections.…”

Chemical Recycling of Aliphatic Polyamides by Microwave-Assisted Hydrolysis for Efficient Monomer Recovery

“…At the HCl/amide mole ratio of 2.5 instead of 1.25, only 10 min reaction time at 200 °C was necessary to completely depolymerize PA 11 (Table , entry 26, Figure ) and PA 12, while PA 1010 required 17 min (Table ; entries 34 and 40, respectively). The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups .…”

“…The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups . Because of the low density of long-chain PAs, the pellets float on the top of reaction mixtures, while on the other hand, PA 66 pellets of higher density sink to the bottom of the microwave vial.…”

Hexaphenoxycyclotriphosphazene as FR for CFR anionic PA6 via T‐RTM: a study of mechanical and thermal properties

“…To produce APA6, molten ε‐caprolactam is polymerized in an anionic ring opening reaction, induced usually by a basic catalyst, for example, sodium salt of ε‐caprolactam, directly in the mold . Because of the much lower viscosity of ε‐caprolactam compared with PA6, molds of complex design can be fulfilling easier , and of particular importance is that fiber fabrics for fiber reinforcements are easier to be infiltrated. Consequently, for the production of CFR PA6 with high fiber content via T‐RTM processing, APA6 should produce better material properties because of good fiber infiltration .…”

Back-to-monomer recycling of polycondensation polymers: opportunities for chemicals and enzymes

“…Monomers such as (1) dicarboxylic acids and diamines, (2) ω-amino acids, and (3) lactams are typically used in the synthesis of polyamides. 116 Due to the wide range of available monomers, polyamides can exhibit a broad range of properties suitable for many specific application areas. 116 At their end-of-life, depolymerization of polyamides is mainly performed using hydrolysis and solvolysis techniques, which are detailed in the following sections.…”

Chemical Recycling of Aliphatic Polyamides by Microwave-Assisted Hydrolysis for Efficient Monomer Recovery

“…At the HCl/amide mole ratio of 2.5 instead of 1.25, only 10 min reaction time at 200 °C was necessary to completely depolymerize PA 11 (Table , entry 26, Figure ) and PA 12, while PA 1010 required 17 min (Table ; entries 34 and 40, respectively). The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups .…”

“…The ability of a particular PA to depolymerize into the constituent monomer(s) depends mainly on the length of the alkyl segments between the adjacent amide bonds since it defines the PA polarity and thus the effectiveness of PA hydration by water. , Generally, longer alkyl segments between the amide bonds result in less polar PAs, which are more resistant to chemicals and have a lower tendency toward hydrolysis. Other important parameters are the T m , degree of crystallinity, and density of PA, which are defined by the ability of PA to form intermolecular hydrogen bonds between amide groups . Because of the low density of long-chain PAs, the pellets float on the top of reaction mixtures, while on the other hand, PA 66 pellets of higher density sink to the bottom of the microwave vial.…”

Hexaphenoxycyclotriphosphazene as FR for CFR anionic PA6 via T‐RTM: a study of mechanical and thermal properties

“…To produce APA6, molten ε‐caprolactam is polymerized in an anionic ring opening reaction, induced usually by a basic catalyst, for example, sodium salt of ε‐caprolactam, directly in the mold . Because of the much lower viscosity of ε‐caprolactam compared with PA6, molds of complex design can be fulfilling easier , and of particular importance is that fiber fabrics for fiber reinforcements are easier to be infiltrated. Consequently, for the production of CFR PA6 with high fiber content via T‐RTM processing, APA6 should produce better material properties because of good fiber infiltration .…”

Back-to-monomer recycling of polycondensation polymers: opportunities for chemicals and enzymes

“…Monomers such as (1) dicarboxylic acids and diamines, (2) ω-amino acids, and (3) lactams are typically used in the synthesis of polyamides. 116 Due to the wide range of available monomers, polyamides can exhibit a broad range of properties suitable for many specific application areas. 116 At their end-of-life, depolymerization of polyamides is mainly performed using hydrolysis and solvolysis techniques, which are detailed in the following sections.…”