Inductive Heating Using a High-Magnetic-Field Pulse to Initiate Chemical Reactions to Generate Composite Materials
Total Page：16
File Type：pdf, Size：1020Kb
polymers Article Inductive Heating Using a High-Magnetic-Field Pulse to Initiate Chemical Reactions to Generate Composite Materials Cordelia Zimmerer 1,* , Catalina Salazar Mejia 2, Toni Utech 1, Kerstin Arnhold 1, Andreas Janke 1 and Joachim Wosnitza 2,3 1 Leibniz Institute of Polymer Research Dresden e.V., Polymer Materials, Reactive Processing, 01069 Dresden, Germany; [email protected] (T.U.); [email protected] (K.A.); [email protected] (A.J.) 2 Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany; [email protected] (C.S.M.); [email protected] (J.W.) 3 Institute of Solid State and Materials Physics, Electronically Correlated Matter, Dresden University of Technology, 01062 Dresden, Germany * Correspondence: [email protected] Received: 5 February 2019; Accepted: 8 March 2019; Published: 21 March 2019 Abstract: Induction heating is efficient, precise, cost-effective, and clean. The heating process is coupled to an electrically conducting material, usually a metal. As most polymers are dielectric and non-conducting, induction heating is not applicable. In order to transfer energy from an electromagnetic field into polymer induction structures, conducting materials or materials that absorb the radiation are required. This report gives a brief overview of induction heating processes used in polymer technology. In contrast to metals, most polymer materials are not affected by electromagnetic fields. However, an unwanted temperature rise of the polymer can occur when a radio frequency field is applied. The now available high-field magnetic sources provide a new platform for induction heating at very low frequencies, avoiding unwanted thermal effects within the material. Using polycarbonate and octadecylamine as an example, it is demonstrated that induction heating performed by a magnetic-field pulse with a maximum flux density of 59 T can be used to initiate chemical reactions. A 50 nm thick Ag loop, with a mean diameter of 7 mm, placed in the polymer-polymer interface acts as susceptor and a resistive heating element. The formation of urethane as a linker compound was examined by infrared spectroscopic imaging and differential scanning calorimetry. Keywords: induction heating; high-magnetic-field; polycarbonate; bonding polymers; susceptor material 1. Introduction 1.1. Induction Heating for Materials Processing Induction heating (IH) is used in industry, medicine, household, et cetera [1–40]. As non-ionizing radiation it is applied to trigger or to control physical processes and chemical reactions (see Figure1). IH provides a high efficiency because electrically conductive materials are internally heated by induced currents. Polymers 2019, 11, 535; doi:10.3390/polym11030535 www.mdpi.com/journal/polymers Polymers 2019, 11 FOR PEER REVIEW 2 of 17 Polymers 2019, 11, 535 2 of 17 Figure 1. Different applications of induction heating for various materials and their processing temperatures.Figure 1. Different applications of induction heating for various materials and their processing temperatures. In applying IH, no direct contact, e.g., to heating plates, is required [11]. IH can be considered as an alternativeIn applying technology IH, no direct to thermal contact, or e.g., radiation to heating processing plates, is of required plastics [11]. and polymersIH can be [considered16]. Further as advantages,an alternative in technology polymer chemistry to thermal in particular,or radiation are pr environmentalocessing of plastics sustainability, and polymers the reduction[16]. Further or completeadvantages, exclusion in polymer of solvents chemistry needed in for particular, the curing ar ofe environmental coatings [16,28 ],sustainabi and axinglity, the the use reduction of a catalyst. or Thiscomplete is caused exclusion by reaching of solvents a high needed temperature for the very curi quickly,ng of coatings a high productivity, [16,28], and andaxing a reductionthe use of of a cyclecatalyst. times This [24 ].is IHcaused provides by reaching great process a high variability, temperature it allows very quickly, heating ofa high opaque productivity, composites and [16 ],a forreduction joining complexof cycle componentstimes [24]. [IH34 ],provides and the jointsgreat are process ready-to-use variability, after processing.it allows heating In comparison of opaque to conventionalcomposites heating[16], for methods joining appliedcomplex in polymercomponents synthesis, [34], IHand leads the to joints similar are results ready-to-use for conversion after rates,processing. polymerization In comparison degree, to andconventional glass transition heating temperature methods applied of the formedin polymer polymer synthesis, and theIH finalleads adhesionto similar of results joints for [20 ,conversion24]. rates, polymerization degree, and glass transition temperature of the formedThe polymer rate of heating and the depends final adhesion upon the of frequencyjoints [20,24]. of the induced current. According to Faraday’s law ofThe induction, rate of heating the induced depends current upon is the correlated frequency to of the the frequency. induced current. Consequently, According high-frequency to Faraday’s electromagneticlaw of induction, fields, the suchinduced as microwaves, current is correlat are idealed forto the induction frequency. processes. Consequently, On the one high-frequency hand, in [41] aelectromagnetic microwave-based fields, rapid such polymer as microwaves, processing techniqueare ideal for is demonstrated induction processes. to initiate On chemical the one reactions hand, in and[41] acceleratea microwave-based reaction kinetics, rapid polymer to change processing the diffusional technique behavior, is demonstrated and to generate to initiate gradients chemical in polymerreactions layers. and accelerate On the other reaction hand, thekinetics, selective to degradationchange the ofdiffusional polymers wasbehavior, successfully and to applied generate to generategradients ordered in polymer crystalline layers. frameworks On the byother microwave hand, the heating selective [42]. degradation of polymers was successfullyOther IH applied approaches to generate to plastics ordered and crysta compositelline frameworks materials are by basedmicrowave on thermoset heating [42]. curing and thermoplasticOther IH bonding approaches or welding. to plastics Other and types composite of on-command materials reactionsare based comprise on thermoset polymerizations curing and andthermoplastic reactions bonding in heterogenic or welding. systems. Other types Thus, of the on-command spatiotemporal reactions control comprise of IH polymerizations makes it an interestingand reactions technology in heterogenic for traditionally systems. Thus, engineered the spat materials,iotemporal especially control of forIH temperature-sensitivemakes it an interesting substratestechnology [9 ,for21, 28traditionally], e.g., paper, engineered wood, human materials, tissue, hydrogels,especially plastics,for temperature-sensitive and natural fiber reinforcedsubstrates composites.[9,21,28], e.g., The paper, ability wood, for internally humanapplied tissue, andhydr localizedogels, plastics, heat, with and high natural gradients, fiber allowsreinforced for processingcomposites. at The room ability temperature for internally and alsoapplied for thickand localized samples heat, by avoiding with high large gradients, thermal allows stresses, for degradation,processing at or room deformation temperature resulting and inalso adhesive for thick failures. samples Another by avoiding benefit large of IH thermal is based stresses, on the possibilitydegradation, to detach or deformation and reassemble resulting hybrid in adhesive joints at thefailures. end of Another their product benefit lifetime of IH [is29 ,based34]. on the possibilityThe aim to ofdetach this study and reassemble is to demonstrate hybrid joints the potential at the end of electromagneticof their product lifetime field pulses [29,34]. with very high magneticThe aim of flux this densities study is to to join demonstrate different polymers the pote withoutntial of inducedelectromagnetic thermal field effects pulses in the with polymer very bulkhigh phases.magnetic As flux most densities applications to join of electromagneticdifferent polymers fields without in polymer induced technology thermal areeffects based in onthe high-frequencypolymer bulk fields,phases. general As most physical applications relations of and electromagnetic selected examples fields of in established polymer approachestechnology areare firstbased highlighted on high-frequency in the following fields, two general sub sections. physical relations and selected examples of established approaches are first highlighted in the following two sub sections. Polymers 2019, 11, 535 3 of 17 1.2. Interaction of Polymers with Electromagnetic Radiation Common polymers are dielectric materials as they do not have any free charges. All electrons are bound or associated with atoms. However, when an electromagnetic field is applied, a slight displacement of the bound electrons is induced. The displacement creates small electric dipoles within the dielectric material. This process is called polarization where negative charges are displaced to the opposite direction of positive charges. Peter Debye developed a model describing the interaction of an electromagnetic field with dielectric media. According to the Debye model, polar entities of the dipoles tend to align parallel to the direction of the applied electromagnetic