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Polymers
Published in Bryan Ellis, Ray Smith, Polymers, 2008
Processing & Manufacturing Routes: Carothers' original patent [22] first indicated the means of preparation of Nylon 12 and industrial production was first considered after the development of a method for preparing cyclododecatriene [23]. Polymerisation of Nylon 12 is similar to Nylon 6 and is based on high pressure hydrolytic ring opening of laurolactam using acid catalyst and temps. of 300-350° in an autoclave reactor, polymer being extruded into cold water. Unlike Nylon 6, only small levels ( <0.5%) of unreacted monomer remain. Alternatively, anionic polymerisation may be carried out in the absence of water using alkali/alkaline earth metals and co-catalysts [1]. The polymerisation of nylons, including 12-aminododecanoic acid [43,44,45,46], can be effected at 270-280° in the presence of a suitable catalyst, such as ammonium or manganese hypophosphite, in a suitable reactor or autoclave to prod. material with relative viscosity 0.7. This low MW prepolymer may be pelletted and fed to a twin screw reactor to be converted to higher MW grades up to relative viscosity 1.4, suitable for injection moulding and extrusion. Lower MW grades may be powdered and used for powder coating applications [48]. The microwave polymerisation of 12-aminodo- decanoic acid to Nylon 12 has been reported [49]. A new form of Nylon 12 is manufactured by a non-pressurised casting process and can be cast around metal components to provide gears, pinions, propellors etc. It is claimed to have superior creep props. compared to other available nylons, and retains excellent mech. props. up to 120° [12]. Lauramid PA12G is made by this process displaying higher crystallinity and MW than conventional Nylon 12, with advantages in chemical, thermal and mech. props. [13]
Industrial Polymers
Published in Manas Chanda, Plastics Technology Handbook, 2017
Nylon-12 is produced by the ring-opening polymerization of laurolactam (dodecyl lactam) such as by heating the lactam at about 300°C in the presence of aqueous phosphoric acid. Unlike the polymerization of caprolactam, the polymerization of dodecyl lactam does not involve an equilibrium reaction. Hence, an almost quantitative yield of nylon-12 polymer is obtained by the reaction, and the removal of low-molecular-weight material is unnecessary.
Microwaves in Lactam Chemistry
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Dr. Debasish Bandyopadhyay, Bimal Krishna Banik
Caprolactam (C6H11NO), a seven-membered (ε-) lactam, is a precursor of the widely-used synthetic polymer nylon 6. Approximately 6.5 million tons of caprolactam is produced every year globally [1]. Examples of ω-lactam include laurolactam, an industrially important 13-membered (ω-) lactam, is mainly used as a monomer to synthesize nylon 12 and copolyamides.
A review on reinforcement learning algorithms and applications in supply chain management
Published in International Journal of Production Research, 2023
Benjamin Rolf, Ilya Jackson, Marcel Müller, Sebastian Lang, Tobias Reggelin, Dmitry Ivanov
The global interconnectedness and complexity may result in a lack of visibility and risks of devastating disruptions. An explosion at the Evonik Factory is a notable example. In 2012, the explosion, followed by a fire, destroyed the chemical factory in Marl, Germany. The factory produced cyclododecatriene, used by the chemical industry to make laurolactam. Laurolactam is, in its turn, used by plastics manufacturers to derive polyamide-12, a plastic essential for strong, lightweight components. Polyamide-12 is in the bill of materials of any car, scattered across thousands of different parts and manufactured by a multitude of different suppliers. The accident created the ripple effect and threatened to disrupt the entire automobile industry. Only collaboration among competing automakers and dozens of suppliers prevented the catastrophe (Sheffi 2020). Other examples of complexity include the semiconductor supply chains (Khan, Mann, and Peterson 2021) and the supply chains behind vaccine production and distribution (Sheffi 2021). Given high levels of complexity, supply chains are prone to disruptions and suboptimal performance caused by operational failures and information miscoordination. The most notable examples of disruptive phenomena include bullwhip and ripple effects. The bullwhip effect, also widely known as the Forrester effect, can be defined as the amplification of demand variation on production and order quantities as they propagate downstream in supply chains (Xun Wang and Disney 2016). On the other hand, the ripple effect occurs when a disruption, rather than being localised within one part of the supply chain, cascades downstream and undermines the performance of the entire supply chain (Dolgui, Ivanov, and Rozhkov 2019). Both effects cause significant problems for supply chain managers because they eventually give rise to over- and under-production cycles, leading to excess inventory levels, potential stockouts, and suboptimal network performance. These problems may be further worsened if structural and operational vulnerabilities in the supply chain are interconnected (Ivanov 2020a). Besides, the ongoing COVID-19 pandemic demonstrated a new kind of disruption, characterised by the long-term presence and unpredictable scale (Ivanov 2020b). Since the severe impact of such disruptions cannot be easily mitigated, supply chain participants require recovery planning and adaptation in the presence of disruption (Ivanov 2021b, 2022a, 2022c). In this regard, the full potential of the supply chain is unlocked if and only if it becomes synchronised, namely, all the critical stakeholders obtain accurate real-time data, identify weaknesses, streamline processes, and mitigate risk.