High Thermo-oxidative Stability Research Articles

Rheological and Functional Properties of Mechanically Recycled Post-Consumer Rigid Polyethylene Packaging Waste.

The properties of recycled post-consumer rigid polyethylene packaging waste were studied, using sorted waste washed in the laboratory with water alone and with added detergent, and compared with large-scale high-intensity washed flakes. The washed flakes were compounded using three different temperature profiles in a twin-screw extruder and then injection molded. A higher compounding temperature reduced the thermo-oxidative stability, the average molecular mass, and the viscosity of the samples. Rheological measurements suggested that changes in chain branching occurred at different compounding temperatures. The strength and the elongation at break were also influenced by the compounding temperature in both the molten and solid states. Detergent washing maintained the thermo-oxidative stability in contrast to washing with water. The large-scale washed samples had a relatively high thermo-oxidative stability, a higher melt elasticity, and a lower elongation at break in both the molten and solid states than the laboratory-scale washed samples. The thermal properties, melt elasticity, Young's modulus, yield stress, and yield strain of the samples were not, however, significantly affected by either the compounding temperature or the washing medium and intensity. The results indicated that recycled post-consumer rigid polyethylene packaging waste has properties that can support further applications in new products.

Analysis of physicochemical and tribological properties of nano alumina-based gear oil developed from effluent of lube oil blending plant

Industrial wastewater, also known as effluent has been identified as one of the leading sources of environmental pollutions worldwide. The establishment of lube oil blending plants in Nigeria has led to a continuous discharge of industrial effluent in densely populated areas. This threatens the well-being of humanity, plants, aquatic lives and construction soils. This research paper focused on developing a nano alumina-based effluent gear oil from effluent of lube oil blending plants as an alternative means of mitigating its threats on the environment. Nano lubricant are used in gearboxes for better thermal, friction and anti-wear properties. This is due to the small size and high specific surface area to volume ratio of the nanoparticles. Furthermore, due to their excellent mechanical and thermal properties, easy dispersal in most fluids, inexpensiveness, ease of manufacture, and aspect ratio, the Al2O3 nanoparticles are recently being used by researchers as an additive in gear oils to improve tribological properties, increase power efficiency, extend equipment lifetimes, and lower operating cost. In this work, the alumina nanoparticle was synthesized using co-precipitation method, after which it was characterized using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysers. After the development of Al2O3-based gear oil from the effluent, the physicochemical and tribological properties of the alumina-based effluent gear oil samples were investigated with varied weight percentages of Al2O3 nanoparticles. The Differential Scanning Calorimetry (DSC) and Computational Fluid Dynamics (CFD) thermal analyses of nano alumina-based gear sample was investigated after obtaining the suitable sample among the sample blends developed. The dispersion of the nanoparticle in the effluent oil improved the specific gravity and pour point whereas a slight reduction was observed in kinematic viscosity at 100 °C, viscosity index and flash point. However, viscosity index and flash point values are conforming to the minimum requirements of API EP 85W90 and ISO 100 standard values. The anti-wear property was observed to significantly improved by 26.14%, at 0.4 wt% nanoparticles concentration. The results showed that, the pure effluent oil recovered is more thermally stable than the 0.4 wt% nano alumina-based effluent gear oil sample, whereas the nano gear oil sample has a higher thermo-oxidative stability than the pure effluent oil. Finally, temperature profiles from the simulation results also ensured a better performance of the 0.4 wt% alumina-based effluent gear oil developed, at 1500 rpm speed of rotation by 6.7% and 8.9% and at 4000 rpm is by 5.9% and 7.8% than the API EP 85W90 and pure effluent oil samples respectively. Hence, based on the results obtained, the study indicated that the effluent oil from lube oil blending plants can be used as gear oil with the dispersion of alumina nanoparticles.

Thermo-mechanical and morphological studies of Hal-reinforced PEEK

This study is focused on exploring the thermo-mechanical properties and behaviour of PEEK-Hal nanocomposites as a case study for understanding the interactions between nanoparticles and polymers, as well as to explore potential applications of nanocomposites in the field of engineering. The selection of Poly (ether ether ketone) (PEEK) polymer is based on its notable chemical resistance, exceptional mechanical properties and high thermo-oxidative stability. Halloysite nanotubes (Hal) are chosen for their environmentally friendly nature, non-toxic properties, cost-effectiveness, tuneable release and rapid adsorption rates. This research paper focuses on the fabrication of PEEK-Hal polymer composites with varying concentrations using a co-rotating twin screw extruder. The prepared composites are thoroughly characterized using various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The mechanical properties are assessed using a universal testing machine (UTM), impact tester, and hardness tester, respectively. The surface morphology is examined using field emission scanning electron microscopy (FE-SEM) technique. The results highlight the substantial benefits of incorporating Hal, improving interfacial adhesion, and establishing favourable interactions between the PEEK and Hal. The incorporation of Hal notably enhances the stiffness and storage modulus of the PEEK-Hal composites. Additionally, the presence of Hal restrains the mobility of the macromolecular chains within the composite. This study demonstrates that the PEEK-Hal composite with a 3% concentration of Hal (PH3) exhibits remarkable thermo-mechanical properties.

Synthesis of a novel organic-inorganic hindered phenol antioxidant derived from polyhedral oligomeric silsesquioxane and its anti-oxidative behavior in polypropylene

To explore antioxidants with high anti-aging efficiency and admirable anti-extraction ability, a novel organic-inorganic hindered phenol antioxidant (AO-POSS) derived from polyhedral oligomeric silsesquioxane (POSS) was successfully synthesized via a nucleophilic substitution reaction. Chlorinated polyhedral oligomeric silsesquioxane with 8 silicon cores was first synthesized by hydrolysis-polycondensation of (3-chloropropyl)trimethoxysilane and further used for preparing AO-POSS by reacting with the sodium salt of hindered phenolic precursor 3-(3,5-Di‑tert‑butyl‑4-hydroxyphenyl)propionic acid (AO). According to the 29Si-NMR spectra, the T8 cores of Cl-POSS occurred cage-rearrangement under the catalytic effect of propionate anion to produce a thermodynamically stable mixed product, AO-POSS (T8, T10, and T12: 23.8 %, 60.5 %, and 15.7 %). When AO-POSS was incorporated into polypropylene (PP), the oxidation induction time (OIT) of the PP/AO-POSS compound (15.8 min) was slightly longer than that of the PP/1010 compound (13.8 min) at the same molar amounts of hindered phenols. Furthermore, the OIT value of PP/AO-POSS/168 (50.7 min) was obviously higher than that of PP/1010/168 (38.1 min), pointing out the enhanced levels of positive synergism between AO-POSS and secondary antioxidants in inhibiting PP oxidation degradation. Hence, it is apparent that AO-POSS possesses high thermo-oxidative stability and anti-aging efficiency in PP. Notably, even after 48 h of Soxhlet extraction, the OIT value of PP/AO-POSS was retained at 69.5 %, while that of PP/1010 was only 32.2 %, indicating the much better anti-extraction ability of AO-POSS.

Study of the Effect of ZnO Functionalization on the Performance of a Fully Formulated Engine Oil.

The automotive sector is demanding higher specifications to achieve maximum efficiency; in this sense a new generation of lubricants with higher thermo-oxidative stability and superior tribological properties is being explored. The formulation of nanolubricants based on the nature of different nanomaterials is one of the most recent approaches, with several gaps to cover, such as dispersion stability, related to the compatibility of proposed nanomaterials with conventional additives and baseoils used in lubricant formulation. This study evaluated the effect of ZnO nanomaterial dispersed in a commercial engine oil using two different approaches; the use of surfactant and nanomaterial surface functionalization to promote higher stability and lower cluster size. Experimental evidence shows a synergetic effect between the tribological protection mechanism and the antioxidant properties in the lubricant. The effect of nanoparticle cluster size, functionalization level, and nanomaterial content are presented.

Performance evaluation studies of PEG esters as biolubricant base stocks derived from non-edible oil sources via enzymatic esterification

Polyethylene glycol esters (PEGEs) as, environment-friendly biolubricants were produced from different fatty acids derived from plant oils by enzymatic esterification reaction in a solvent-free system using commercially available immobilized Candida antarctica Lipase B (NS 435) biocatalyst. The raw materials used were a 1:1 ratio of oleic acid: linseed oil fatty acid, linseed oil fatty acid: ricinoleic acid, and oleic acid: ricinoleic acid as mixed fatty acids. Enzymatic esterification exhibited around 98.1%, 97.8%, and 98.5% maximum yield for three different PEGEs under the following optimum reaction conditions under vacuum: the molar ratio of mixed fatty acids to polyethylene glycol 200–2:1, reaction time - 4 h, catalyst loading - 10% (w/w), and reaction temperature - 60 °C. This study aimed to improve the thermo-oxidative stability and cold flow behavior of the esterified products. The synthesized esters were confirmed and characterized by acid value, Nuclear Magnetic Resonance Spectroscopy (NMR), and Fourier Transform Infrared Spectroscopy (FTIR). The fatty acid composition of PEGEs was determined by GC-FID (Gas Chromatography). Physicochemical properties, thermo-oxidative stability, and friction-reducing properties of the PEGEs were studied thoroughly and compared against conventional petroleum-based lubricants. Results revealed that the plant oil-based biolubricants had good lubricating properties like high flash point, low pour point, high viscosity index, high thermo-oxidative stability, and improved friction-reducing properties compared with petroleum-based hydraulic lube oil. Overall, the data indicated that enzymatically esterified biolubricants have significant potential as ISO VG-32, VG-46, and VG-68 grade biolubricant base stocks for various commercialized industrial applications.

Thermo-physical Properties and Oxidative Stability of the Oil of Babassu Palm (Attalea vitrivir Zona, Arecaceae)

Population growth and the concern about its environmental impact have increased the demand for vegetable oils in recent years. Vegetable oils are used in several industry sectors and have been investigated as an alternative energy source to replace traditional fossil fuels. Knowledge of physical and chemical properties is essential to assess the potential use of vegetable oil in the production of biofuels. The present study aimed to determine the oxidative stability of the seed oil of the babassu palm tree, Attalea vitrivir, native to the Brazilian cerrado and originated from two different regions, before and after storage for 12 months. The relative density of the oil did not differ between regions and did not change over time. Kinematic viscosity was lower for area 1 and increased with storage in oils from both areas. The induction period in the Rancimat test was lower in area 2 and decreased in the stored oil, regardless of the area, though it remained higher than the minimum required for its use as biofuel. The evaluation of oxidation by the oven method also showed satisfactory results, confirming the high thermo-oxidative stability of the babassu oil rich in lauric acid.

Melamine modified phthalonitrile resins: Synthesis, polymerization and properties

Phthalonitrile resin, as a thermosetting resin, possesses high chemical resistance, high thermal resistance, high thermo-oxidative stability and good mechanical properties. However, the extremely high curing temperature needed to achieve high curing degree severely limits its large-scale application. It is found that introduction of benzoxazine moities into phthalonitrile would increase the reactivity and decrease the curing temperature. In this work, phthalonitrile resin with melamine moiety (BAph-m) is synthesized by taking advantage of benzoxazine chemistry using melamine as amine source. Its chemical structure is confirmed by Fourier infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (1H NMR) spectra. Its curing reactivity, polymerization mechanism and the properties of the resultant polymers are systematically studied. It is found that the introduction of melamine reduces the content of oxazine ring, leaving active groups like phenolic hydroxyls and secondary amines as build-in catalysts. Consequently, the modified resins show much higher reactivity. The exothermic peaks corresponding to ROP of benzoxazine ring and curing of phthalonitrile groups of BAph-30 m decreased to 197.4 °C and 278.2 °C, 77.7 °C and 30.1 °C lower than those of neat BAph. The gelation time shortened from 892 s for BAph-2m to 231 s of BAph-30 m. Moreover, it is found that the build-in active groups could catalyze the reaction of benzoxazine moities and phthalonitrile groups to form phenolic Mannich bridge structures, triazine rings, phthalocyanine rings and isoindoline. The modified resins show very high thermal stability with BAph-30m-280 showing initial decomposition temperature (Td5) of 492 °C and char yield (Yc) of 79.9%, which is 35 °C and 6.8% higher than those of BAph-280.

Effect of natural carbon filler on thermo-oxidative degradation of thermoplastic-based composites

Thermo-oxidative degradation of thermoplastic-based composites filled with two types of carbon filler including bituminous (Pittsburgh No.8, P8) and sub-bituminous (Powder River Basin, PRB) coals were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis. Oxidation induction time (OIT) and activation energy (AE) for coal plastic composites (CPCs), HDPE, and commercially available wood plastic composites (WPCs) were determined using isothermal and isoconversional kinetic methods. OIT values for CPC increased with coal content, indicating higher thermo-oxidative stability. AE values obtained using isothermal method were 52–116 kJ/mol for all CPC formulations, 32 kJ/mol for HDPE, and 33–114 kJ/mol for WPCs. AEs for CPCs obtained using isoconversional methods were not constant but rather dependent on the degree of degradation with CPC/ P8 coal possessing higher overall AE. Incorporating coal into HDPE increased thermo-oxidative stability of the resulting composite, indicating coal potentially acts as a natural primary and secondary antioxidant for polymer materials.

Synthesis of high thermal stability Polypropylene copolymers with pyrrole functionality

Functionalization of polyolefins has been proven to be a promising way to fine-tune their properties, among which, improved thermal stability is crucial for high performance in end-use applications. However, it still remains in academia, as some important issues still need to be resolved for this methodology to move towards industrial scale-up, the most important of them being the development of one-step processes. This work focuses specifically on the development of a single-step functionalization route for the synthesis of high thermal and thermo-oxidative stability polypropylenes. The synthesis of Polypropylene (PP) bearing N-alkyl groups by copolymerization via metallocene catalysis is studied. The copolymers are found to exhibit high thermo-oxidative stability, whose origin appears to be based, not only on the radical scavenging activity of N-alkyl moieties, but also on the associated crosslinking that takes place under processing conditions. Some exploratory results from a solid-state 13CNMR analysis provide support to a radical mechanism, involving coupling between benzyl-like pyrrolyl species.

Distigmasterol-Modified Acylglycerols as New Structured Lipids-Synthesis, Identification and Cytotoxicity.

Plant sterols, also referred as phytosterols, have been known as bioactive compounds which have cholesterol-lowering properties in human blood. It has been established that a diet rich in plant sterols or their esters alleviates cardiovascular diseases (CVD), and also may inhibit breast, colon and lung carcinogenesis. Phytosterols, in their free and esterified forms, are prone to thermo-oxidative degradation, where time and temperature affect the level of degradation. Looking for new derivatives of phytosterols with high thermo-oxidative stability for application in foods, our idea was to obtain novel structured acylglycerols in which two fatty acid parts are replaced by stigmasterol residues. In this work, asymmetric (1,2- and 2,3-) distigmasterol-modified acylglycerols (dStigMAs) were synthesized by the covalent attachment of stigmasterol residues to sn-1 and sn-2 or sn-2 and sn-3 positions of 3-palmitoyl-sn-glycerol or 1-oleoyl-sn-glycerol, respectively, using a succinate or carbonate linker. The chemical structures of the synthesized compounds were identified by NMR, HR-MS, and IR data. Moreover, the cytotoxicity of the obtained compounds was determined. The dStigMAs possessing a carbonate linker showed potent cytotoxicity to cells isolated from the small intestine and colon epithelium and liver, whereas the opposite results were obtained for compounds containing a succinate linker.

Development of <em>zero-trans</em> shortenings with high thermo-oxidative stability by enzymatic transesterification

Novel zero-trans frying shortenings were formed by enzymatic transesterification by exploring a palm stearin and canola oil mixture and stearic acid as substrates. Both immobilized (Novozym 435, Lipase PS “Amano” IM) and non-immobilized (Lipomod TM 34P) enzymes were applied as biocatalysts. Palmitic acid, the fatty acid which defines the proper type of crystal formation, was present at the 15% level in the reaction mixtures. The novel structured lipids had comparable physical properties and offered similar frying performance to those of commercial shortening. Needle-shaped crystals were predominant both in the transesterification products and the commercial frying shortening. Furthermore, solid fat content profiles of the zero-trans structured lipids produced by Novozym 435 and Lipase PS “Amano” IM were close to those of the commercial shortening.

Copolymers and interpenetrating polymer networks of thermoreactive nitrogen-containing resins. Mini review

In a short review the effective methods of optimization of structure and properties of high-performance polymers obtained from thermoreactive nitrogen-containing resins such as benzoxazines, bismaleimides, cyanate esters have been analysed. High crosslinked density copolymer thermosets are synthesized through chemical interactions between reactive functional groups, which belong to the monomers/oligomers used. The different possible processes such as copolymerization or formation of interpenetrating polymer networks are discussed. The high-performance polymers and composites from thermoreactive nitrogen-containing resins are effectively used in aerospace industry and microelectronics as materials possessing high thermal and thermooxidative stability, radiation and chemical resistance, low water absorption, low dielectric loss, high dimension stability and high adhesion to different substrate. The performance characteristics of this kind of materials can be controlled by changing their composition, temperature-time curing schedule, using catalytic systems. Keywords: copolymers, IPNs, thermoreactive resins, benzoxazine, bismaleimide, cyanate ester resins.

Thermal oxidative stability of yttrium containing oligomeric silazanes with organoelement substituents and multiceramics on their basis

Characteristics of thermal transformations of oligomeric silazanes with organoelement substituents at the N atoms (M-OESs) containing one element M = Y, Zr, or Hf or a pair of elements, viz., Zr and Y or Hf and Y, in air in the temperature range 200–1500 °C were investigated. The introduction of yttrium into zirconium- or hafnium-containing oligosilazanes results in an increase in the mass loss at the stage of ceramization and to a decrease in the mass loss in the formed ceramics during subsequent stepwise heat treatment up to 1500 °C. The combination of yttrium with hafnium or zirconium in M-OESs results in a synergistic effect of overall mass loss reduction. The (Zr, Y)-OES and (Hf, Y)-OES multiceramics outperform ceramics modified with one metal in this parameter. The obtained multiceramics is characterized by high thermo-oxidative stability in the temperature range 1100–1500 °C. It is also found that yttrium-containing oligosilazane (Zr, Y)-OES exhibits oleophilic properties with respect to carbon materials.

Synthesis and Properties of Poly(1-trimethylsilyl-1-propyne) Containing Quaternary Ammonium Salts with Methyl and Ethyl Substituents

Poly(1-trimethylsilyl-1-propyne) modified with quaternary ammonium salts is synthesized. The introduction of salts into the polymer structure is carried out using a two-step method consisting in the bromination of the starting polymer followed by the addition of tertiary alkylamines—trimethylamine and triethylamine. The presence of ammonium salts is confirmed by the data of organometallic analysis and IR spectroscopy. X-ray diffraction analysis is used to study the supramolecular structure of the materials obtained. The TGA data indicate their high thermal and thermo-oxidative stability. The permeability, solubility, and diffusion coefficients of the poly(1-trimethylsilyl-1-propyne) samples containing trimethylamine and triethylamine salts for individual CO2, N2, and CH4 gases are determined. An increased ideal selectivity for the separation of gas pairs CO2/N2 and CO2/CH4 in modified poly(1-trimethylsilyl-1-propyne) is achieved owing to the increased selectivity of the dissolution of CO2 in quaternary ammonium salts.

New Proton-Conducting Polydiimidazopyridine-Based Membrane for an HT-PEM Fuel Cell

Polydiimidazopyridine was synthesized from 2,3,5,6-tetraaminopyridine and 2,5-dihydroxyterephthalic acid in polyphosphoric acid (PPA) and characterized. Polydiimidazopyridine possessed high viscosity, high thermooxidative stability, and excellent film-forming properties. The polymer was processed from a reaction solution in PPA to proton-conducting membranes featuring high proton conductivity in the temperature range of 20–200°C, being superior in this value to many known membranes.

The Synthesis and Characterization of Highly Fluorinated Aromatic Polyimides

The synthesis and characterization of pendant octafluoro aromatic polyimides (8 F-PIs) derived from 4, 4’-(2, 2, 2-trifluoro-1-pentafluorophenylethylidene)diphthalic anhydride (8 FDA) and several aromatic diamines is described. The synthesis of bis(3,4-dimethylphenyl)pentafluorophenyltrifluoromethylmethane (8 FTM), and2-(3, 4-dimethylphenyl)-2-pentafluorophenyl-2-trifluoromethylethanol (8 F-OH), the precursors to 8 FDA are also discussed. The synthesis of 8 FTM is accompanied by two major by-products resulting in a low yield of desired product. The presence of the pentafluorophenyl group in the backbone of the fluorinated polyimides introduces flexibility and free volume manifested by lower Tg’s than more rigid analogs. The highly fluorinated polyimides exhibited lower dielectric constants than most fluorinated polyimides. The 8 F-PIs cured at a maximum temperature 371 °C/1 hr. exhibited thermal stabilities typical of high performance fluorinated polyimides. High temperature (436 °C) and pressure (281.2 kg/m2, 4000 psi.) post cure of 8 F-PI prepared from 8 FDA and p-phenylene diamine exhibited high thermo-oxidative stability, high density and low moisture absorption.

Hybrid poly(ether ether ketone) composites reinforced with a combination of carbon fibres and graphene nanoplatelets

Poly(ether ether ketone) (PEEK), with its superb mechanical properties, excellent chemical resistance and high thermo-oxidative stability is one of the most important engineering thermoplastics for high-end applications. In this work, we investigate the elastic and viscoelastic properties along with the creep mitigation of two sets of samples: PEEK reinforced with graphene nanoplatelets (GNPs) and PEEK reinforced with a hybrid graphene/short carbon fibre (CF) filler. The melt viscosity of the PEEK nanocomposites was found to increase with increasing GNPs content; however, the viscosity of the hybrid CF-GNP samples with the highest filler content was equal to the one of the samples filled only with GNPs at low shear rates. This processability shows the advantage of GNPs over other nano and conventional fillers in the ability to use meaningful loadings. The introduction of GNPs improved significantly the stiffness and the storage modulus of the materials in both PEEK-GNP and PEEK-CF-GNP composites. Moreover, the presence of GNPs within the composites led to a restriction of the mobility of the macromolecular chains of PEEK, which resulted in enhanced creep properties at both room temperature and elevated temperatures. Overall, the nanocomposites produced displayed properties that make them attractive in applications where high stiffness and structural integrity at elevated temperatures are required.

Trace metal impurities determination in high-purity polyimide by plasma-based techniques

Polyimides are widely employed in the industry to produce several components that require resistance to temperature and chemical reagents. Due to the high thermo-oxidative stability and chemical inertness, the digestion of this kind of polymer is a challenging step, but mandatory for further analysis by plasma-based techniques, as inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). In the present work, a single method based on microwave-induced combustion (MIC) is proposed for polyimide digestion and further determination of 18 analytes (As, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Sn, Ti and V) by ICP-OES and ICP-MS. The use of NH4Cl as volatilization aid mixed with polyimide powder before the combustion was required for Cr recovery. As absorbing solution, a mixture containing HNO3 and HCl was employed providing quantitative recoveries for all analytes. The accuracy of the proposed method was evaluated by spike recovery tests, by results comparison with reference values (SEMI F48-0600 protocol) and by analysis a certified reference material (CRM) of polyethylene (EC680K – low density polyethylene). Spike recoveries were from 94 to 108%, while the results using MIC and reference values were in an agreement (better than 94%). Regarding to CRM analysis, no statistical difference was observed (t-test, 95% of confidence level) between MIC and certified values. The proposed method allows the combustion of relative high sample mass (600 mg) with high digestion efficiency (dissolved carbon lower than 100 mg L−1) that prevents eventual interferences during the determination by plasma-based techniques, caused by carbon in digests. It was possible to use diluted acids as absorbing solution, reducing the blank values and, consequently, the limits of detection that were in ng g−1 range even for ICP-OES analysis. The digests were suitable for analytes determination by ICP-OES and ICP-MS and no additional dilution was required.

Synthesis and Properties of Polymers with an Organosilicon–Acetylene Backbone

Acetylene- and diacetylene-containing organosilicon polymers continue to be of great interest in academia, government, and industry due to their high thermo-oxidative stability combined with excellent solubility and processability characteristics. Progress in this field over the past 30 years is reported herein. We present and discuss the synthesis, characterization, and structure–property relationships related to these materials. Furthermore, properties for specific applications of these polymers are briefly summarized, such as absorption and emission spectroscopy, composite mechanical analysis, four-probe conductivity measurements, and electroluminescence.