Environmental and Agricultural Microbiology. Группа авторов

Читать онлайн книгу.

Environmental and Agricultural Microbiology - Группа авторов


Скачать книгу

      Definition

      NylonTM is a necessary term that represents an important class of PAs. PA with amide linkage exhibits high thermomechanical properties and higher softening temperature because of hydrogen bonding, which provides chain symmetry [9]. Presence of amide linkages in PA used as engineering thermoplastics as a film or fibers form. Nylon 6-6 is the most commercialized polymer widely used because of its high thermomechanical properties [11].

      4.2.1 Bioavailability and Production

      Nondegradable polymers are one of the big issues and create lots of stress over the environment because of PA dumping. A sustainable polymer helps in reducing this stress over the environment. Variety of bio-PAs are derived from renewable raw materials such as PA 4,6; PA 4,4; PA 4,10; PA 4; PA 6,10; PA, 10,10; PA 10,12; and PA 11 [6, 9]. Five decades back, European company Arkema first developed Rilsan, which is 100% castor oil-based PA (PA-11) [6]. Many bio-based polymers were synthesized from castor oil-based with 60% sebacic acid, which exhibits superior performances than petroleum-derived PA 6 and PA 6,6. Nylon 4 is synthesized after ring-opening polymerization of 2-pyrrolidone [2, 5a, 7]. Recently, itaconic acid-based heterocyclic PA has been introduced environmentally degradable, which can reduce the burden of polymer waste [8].

      4.2.2 Biodegradability of Polyamides

      4.2.3 Degradation of Nylon 4 Under the Soil

      Nylon 4 is synthesized from 2-pyrrolidone, which means it is lactam of γ-aminobutyric acid (GABA). It has been reported that nylon 4 is different from other nylon because it degrades under the soil in the activated sludge [7, 12, 14]. Further, nylon 4 was blended with nylon 6, and its degradability was investigated, only nylon 4 part was degraded. Further, Yamano et al. found to degrade the nylon 4 inside the activated sludge further isolated Pseudomonas sp. with the strain ND-10 and ND-11 and GABA as a byproduct [14].

      4.2.4 Fungal Degradation of Nylon 6 and Nylon 66 (Synthetic Polyamide)

      Both white-rot fungi are well known for lignolytic activity, which attacks the lignin. PA sheets were exposed through submerges cultivation process for microbial degradation, and nylon sheets decreased its thickness and molecular weight. Jozefa Friedrich et al. (2007) had tested 58 fungi for their degradation ability; out of these fungal strain, two fungi were more labile toward the degradation. The white-rot fungi, B. adusta and P. chrysosporium can degrade the polymer, but especially the Bjerkandera adusta disintegrated the fibers. U. Klun et al. (2003) were also tested the same kind of fungus P. chrysosporium that is well known for its lignolytic activity [12–15]. Abiotic (PA-6 placed without fungus) showed a partially weight loss, which means lesser than biotic (PA-6/fungus). Degradation of nylon-6 was observed in the culture of the basidiomycete B. adusta inside the submerged medium, initially break the surface part of the PA. Nylon 6 and Nylon 66 are also degraded in the presence of bacteria Pseudomonas aeruginosa NCIM 2242, which only targets the chain which contains an amide linkage.

      4.2.5 Itaconic Acid-Based Heterocyclic Polyamide

Chemical structure of itaconic acid-based heterocyclic polyamide.

      4.2.6 Summary and Future Development


Скачать книгу