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We demonstrated thermal curing encapsulation adhesive sheets for the flexible organic light emitting diodes. The thermal curing adhesive sheets were newly designed for the face-sealing encapsulation sheet and had sufficient interface adhesion between the device surface and gas barrier films, high optical transparency, and flexible properties.

A novel cross-linkable electron-transport material has been designed and synthesized for use in the fabrication of solution-processed OLEDs. The material exhibits a low LUMO level of −3.51 eV, a high electron mobility of 1.5×10−5 cm2 V−1 s−1, and excellent stability. An average 9.3 % shrinkage in film thickness was observed for the film after thermal curing. A maximum external quantum efficiency (EQE) of 15.6 % (35.0 cd A−1) was achieved for blue-phosphorescent OLEDs by spin-coating and 13.8 % (31.0 cd A−1) for an ink-jet-printed device, both of which are better than the EQE of a control device prepared by vacuum-deposition (see figure).

For paper coatings with organic nanoparticles of poly(styrene-co-maleimide), dispersive Raman spectroscopy and confocal Raman microscopy are applied for qualitative and quantitative analyses of the lateral distribution of chemical moieties as a function of different coating grades (degree of imidization) and thermal curing temperatures (120-250 degrees C). Raman mapping with band intensity ratios, single band intensities, and average spectral intensities illustrates that surface locations with imide moieties are sensitive to the thermal curing temperature due to the reactivity of an amount of ammonolyzed (nonimidized) maleic anhydride, whereas the styrene moieties are not sensitive to the thermal curing. A maximum in imide functionalities at the surface occurs after curing at 135-150 degrees C depending on the coating grade. The surface coverage of the coating moieties is complementary to the cellulose components, but local variations in specific Raman bands for the latter suggest interactions due to hydrogen bonding. Principal component analysis with two parameters allows for a good quantification of the imide content and surface coverage. Samyn, P (reprint author), Univ Hasselt, Inst Mat Res IMO IMOMEC, Appl & Analyt Chem, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium. pieter.samyn@uhasselt.be

In the present study, the curing behavior of polycardanol prepared by enzymatic oxidative polymerization of thermally treated cashew nut shell liquid, which can be available from naturally renewable resources, was explored in the presence of methyl ethyl ketone peroxide (MEKP) and cobalt naphthenate (Co-Naph). The curing behavior was monitored varying Co-Naph concentration and curing temperature by means of Fourier transform infrared (FT-IR) spectroscopy. The result revealed that the characteristic absorption bands were significantly affected by the given curing condition, resulting mainly from the unsaturated moiety in the polycardanol molecule. The extent of curing of polycardanol strongly depended on curing temperature, showing a typically sigmoidal curve reaching almost 1.0 upon processing at 200°C for 120 min. The thermal curing conditions for preparing polycardanol with an optimal state of cure were provided in the work. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Polybenzoxazines are newly developed thermoset polymers exhibiting versatility in a wide range of applications including in the electronics and aerospace industries. When combined as composites, the attractive characteristics of both components are apparent. The chemistry of benzoxazine synthesis offers wide molecular design flexibility and thus facilitates preparation of various polybenzoxazine-based composites. This article reviews recent developments in the preparation and thermal curing of benzoxazine composites with a focus on structure–property relations of cured materials. Copyright © 2010 Society of Chemical Industry

A collection of printed fabrics for men’s shirts was designed and prepared using computer-aided design/computer-aided manufacturing technology. The colours for designs were ink-jet printed on cotton fabrics with pigments and ultraviolet-cured. These prints represented the target colours for subsequent flat-screen printing, which was performed using pigment printing pastes and thermal curing. For an exact transfer of colours of the ink-jet-printed standard into the screen-printing process, a computer recipe prediction method was used. A comparison of colorimetric parameters of fabrics printed with both printing techniques shows minimal and acceptable differences in the CIELab colour values. A comparison of colour fastness properties proves that very good colour fastness is achieved on the pigment-printed fabrics produced with both printing techniques. The flat-screen-printed fabrics show better colour fastness to washing, perspiration and rubbing, while ink-jet-printed fabrics show better colour fastness to dry-cleaning and light. The fabrics printed with both printing techniques have high rigidity and non-elastic properties. The mechanical and physical parameters are strongly dependent upon the amount of the dry substance of the printing media applied on the cotton fabric surface, which is higher on screen-printed fabrics. The ink-jet-printed fabrics show better air permeability than flat-screen-printed fabrics.

Fiber-shaped stretchable strain sensors with small testing areas can be directly woven into textiles. This paves the way for the design of integrated wearable devices capable of obtaining real-time mechanical feedback for various applications. However, for a simple fiber that undergoes uniform strain distribution during deformation, it is still a big challenge to obtain high sensitivity. Herein, a new strategy, surface strain redistribution, is reported to significantly enhance the sensitivity of fiber-shaped stretchable strain sensors. A new method of transient thermal curing is used to achieve the large-scale fabrication of modified elastic microfibers with intrinsic microbeads. The proposed strategy is independent of the active materials utilized and can be universally applied for various active materials. The strategy used here will shift the vision of the sensitivity enhancement method from the active materials design to the mechanical design of the elastic substrate, and the proposed strategy can also be applied to nonfiber-shaped stretchable strain sensors. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Silvered polyimide films have been fabricated by direct ion exchange of a damp-dry poly(amic acid) film with an aqueous silver solution such as silver nitrate. Thermal curing of the silver(I)-containing films under tension leads to cycloimidization of the poly(amic acid) into polyimide with a concomitant silver(i) reduction and aggregation at both film sides to give reflective and conductive double-surface-silvered polyimide films. The metallized films retain the essential properties of the parent polyimide.

The T g -conversion relationship, during the thermal curing of different stoichiometric formulations of 1,1'-(methylene-di-4,1-phenylene) bismaleimide (BMI), modified with o,o'-diallyl bisphenol A (DABA), was investigated. The DiBenedetto equation was used to model this relationship for the formulation of DABA-1 (BMI: DABA, 1: 1). Based on this model, the T g -conversion relationship of formulation DABA-0.5 (BMI: DABA, 1: 0.5) was modeled. The high consistency between the model curve and experimental data showed that the change of T g , attributed to copolymerization between BMI and DABA in DABA-0.5, in the low-conversion regime, was the same as that in DABA-1. This also verifies that, for the formulation DABA-0.5, copolymerization and homopolymerization do not overlap with each other. The reactions progressed sequentially and homopolymerization occurred after completion of copolymerization.

Interpenetrating polymer networks (IPNs) based on different ratios of modified bismaleimide (BMI) resin [BMI/2,2′-diallylbisphenol A (DBA)] and cyanate ester (CE) (b10) have been synthesized via prepolymerization followed by thermal curing. A systematic study of both static and dynamic mechanical properties of the cured BMI/DBA–CE IPN resin systems was conducted through flexural, impact testing, and dynamic mechanical analysis (DMA). The static mechanical investigation shows that the flexural strength, flexural strain at break, and impact strength of the cured BMI/DBA–CE IPN resin systems are relatively lower than that calculated by rule of mixture of two individuals: BMI/DBA and b10. However, the flexural moduli of the IPN resin systems have more consistent features compared to that calculated by rule of mixture. Single damping peaks are detected for the cured BMI/DBA–CE IPN resin systems, which suggests a substantial degree of interpenetration between two networks. The damping peaks of the cured BMI/DBA–CE IPN resin systems do tend to become broader with increasing concentration of BMI/DBA, whereas the intensity of damping peaks of the IPN resin systems decreases. The obtained results not only provide insight information about the characteristic structures of these BMI/DBA-–CE IPN resin systems, but also give guidelines for their applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2000–2006, 2003

Polyesteramide (PEA) and alumina-filled polyesteramide (APEA) resins were synthesized from N,N′-bis(2 hydroxyethyl) linseed amide. The FTIR, 1H-NMR, DSC, TGA, thermal curing, and physico-chemical characterization of these polymers were carried out. The coatings of PEA and APEA were made on mild steel strips. The mechanical behavior and protective efficiency of these coatings in acid, alkali, and organic solvents were investigated. APEA coatings have been found to show superior performance in comparison to other coatings. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1679–1687, 1999

This effort's objective was to determine whether enhancements to the properties of fully conventionally cured epoxy resin systems (ERSs) consisting of EPON 830, a diglycidylether of bisphenyl A epoxy resin, and methylene dianaline could be found by thermally curing the resins while simultaneously exposing them to economically generated magnetic fields (MFs). Stoichiometric mixes were thermally cured with one of the following profiles: 5 at 121°C or 4 h at 149°C. While being thermally cured, they were also exposed to MFs of strengths between 0.1290 and 0.8810 Tesla. Exposed and control specimens were simultaneously generated from the same ERS mix in each run. The resulting specimens were mechanically and thermally tested. This effort determined that under these conditions there were no modifications to the properties of MF-exposed, fully thermally cured, ERSs relative to their associated controls. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2539–2568, 1998

A novel process was developed to adapt the pultrusion process to utilize radiation polymerization instead of thermal curing. Using UV-light and a methacrylate-based, 3-D-network copolymer matrix, 0.5 mm diameter round quartz-fiber-reinforced-composite profiles were formed at a rate of 1.25 mm per second. Faster rates resulted in partial curing. Materials were produced with various amounts of reinforcement, and evaluated in tension and in three-point bending. Mechanical properties varied linearly with fiber content, approaching the rule of mixtures.

The thermal reaction between N-phenylmaleimide and 2-allylphenol was taken as a model reaction in order to obtain information about chain extension and crosslinking mechanisms of the thermal curing of bismaleimides with diallylbisphenol A. Isolation (preparative HPLC) and characterization ( 1 H and 13 C NMR, FT-IR, HPLC/SM) of a monoadduct and two original triadducts (principally low molecular weight products of the reaction) and studies as a function of time (0-6 h) of this thermally induced reaction (160-250 o C) with equimolar quantities of N-phenylmaleimide and 2-allylphenol, as well as with an excess of N-phenylmaleimide, give direct evidence of the occurrence of an ene-reaction and further Diels-Alder and retro Diels-Alder reactions with rise in temperature

A high-pressure curing technique was developed to help determine the effects of solvent presence during the thermal curing of the polyimide poly (N,N'-bis-phenoxyphenylpyro-mellitimide) (PMDA-ODA). A powder form of this aromatic polyimide was produced from a polyamic acid solution using the high-pressure thermal curing technique. Preliminary characterization of the powder indicates a high degree of crystallinity with a measured density of 1.46 ± 0.01 g/cm3 and a distinct melting point of 594°C. The addition of chemical curing agents to the polyamic acid solution prior to thermal treatment reduced the amount of crystallinity observed in the cured material. Molecular weight measurements of the polyamic acid precursor and powder suggest that the high degree of order observed in the powder is a result of degradation during cure. © 1994 John Wiley & Sons, Inc.11

Model compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds (CN) formed by the nucleophilic attack of primary amines on imide carbonyls. The CN stretching mode appears at 1649–1664 cm−1 in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm−1. These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides at 1656 and 1742 cm−1 were assigned as the CN and associated CO modes, respectively. It has also been confirmed that the CN stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. © 1993 John Wiley & Sons, Inc.

Radiation and thermal curing of unsaturated polyester resins with styrene were investigated by combining differential thermal analysis with electric and mechanical relaxation techniques. A microprocessor controlled combined relaxation equipment of special construction was used. By radiation initiated curing the reaction was interrupted at different stages and the products were analyzed. Relaxation and simultaneous differential thermal measurements were also made during the course of gamma radiation and peroxide initiated thermal curing. By this way the shift of the characteristic transitions of the resin as a function of conversion could be studied. Also the change of the phase-structure of the resin caused by the reaction was monitored. By deconvolution of the dielectric spectrum band the physical structure was found to become heterogeneous by crosslinking. Besides the shift of the transition temperatures the oscillator strength of the dielectric transition was found to decrease with conversion. Electrical polarization and depolarization studies were also performed. A special intermittent load thermomechanical technique was used for separating elastic from viscous response of the sample subjected to external mechanical force. The transitions exhibited by the thermomechanical curves were found to shift to higher temperatures by crosslinking and the compliance plateaus decreased. Durch Strahlung und Temperatur initiierte Hartungsreaktionen von ungesattigten Polyesterharzen mit Styrol wurden durch Kombination von Differentialthermoanalysen mit elektrischen und mechanischen Relaxationsmessungen untersucht. Dazu wurde eine speziell konstruierte, mikroprozessorgesteuerte, kombinierte Relaxationsapparatur benutzt. Durch strahleninduzierte Hartung wurde die Reaktion auf verschiedenen Stufen unterbrochen, und die Produkte wurden analysiert. Relaxationsmessungen mit simultanen differentialthermoanalytischen Messungen wurden eben falls im Verlauf von durch Gammastrahlung und Peroxid inituerten thermischen Hartungsvorgangen durchgefuhrt. Durch diese Methode konnten die Verschiebungen der charakteristischen Ubergange des Harzes als Funktion des Umsatzes verfolgt werden. Auserdem wurde die durch die Reaktion verursachte Anderung in der Phasenstruktur des Harzes aufgezeichnet. Durch Zerlegung des dielektrischen Spektralbandes wurde gefunden, das die physikalische Struktur durch Vernetzungsvorgange heterogen wird. Abgesehen von der Verschiebung der ubergangstemperaturen wurde festgestellt, das die Oszillatorstarke des dielektrischen Ubergangs mit fortschreitendem Umsatz abnimmt. Auch Untersuchungen zur elektrischen Polarisation und Depolarisation wurden durchgefuhrt. Eine spezielle thermomechanische Technik mit intermittierender Belastung wurde benutzt, um das elastische vom viskosen Verhalten einer Probe zu unterscheiden, die einer au-seren mechanischen Kraft ausgesetzt wird. Die Ubergange, die sich in den thermomechanischen Kurven zeigten, verschoben sich durch die Vernetzung zu hoheren Temperaturen, und die zugehorigen Plateaus nahmen ab.

New Processable Polyaromatic amides were prepared from 2,2′-diiododiphenyl-4,4′-dicarbonyl dichloride (I) and several aromatic diamines. Phenylethynyl groups were introduced in these polymides by replacing the iodine groups with copper phenyl acetylide. On thermal curing, 2,2′-di(phenylethynyl)biphenyl group undergoes intramolecular cyclization to form 9-phenyl dibenzanthracene derivative. The cured polymers showed increased heat and chemical stabilities. No melting points were observed for all the polymers below 500°C. The viscosity of the polymers was decreased on substitution of the iodine by phenylethynyl groups.

Die thermische Hartung ungesattigter Polyesterharze last sich durch hydrolytischen Abbau der Harze mit KOH/Benzylalkohol und Extraktionsversuche in ihrem zeitlichen Verlauf verfolgen, insbesondere last sich der Zeitpunkt einer vollstandigen Aushartung bestimmen. Die Zusammensetzungen der polymeren Hydrolyseprodukte bestatigen in Erganzung fruherer Arbeiten die Gultigkeit der fur die lineare Copolymerisation von Fumarsaurediathylester mit Styrol bestimmten Copolymerisationsparameter uber einen weiten Umsatzbereich. Die mit steigendem Umsatz kleiner werdenden Viskositatszahlen der veresterten polymeren Hydrolyseprodukte lassen den Schlus zu, das bei der thermischen Hartung ungesattigter Polyesterharze in groserem Umfang Ubertragungsreaktionen stattfinden konnen. The course of the thermal curing reaction of unsaturated polyester resins can be determined by hydrolytic degradation and extraction experiments; it is especially possible to determine the time of complete curing. Supporting previously published results, the compositions of the polymer degradation products show that the copolymerization parameters, determined for linear copolymerization of diethylfumarate and styrene, are applicable over a wide range of conversion. With increasing conversion decreasing intrinsic viscosities of esterified polymer degradation products are found. It can be concluded that during thermally initiated copolymerization of unsaturated polyester resins transfer reactions take place to a certain extent.