Tetraacylgermanes as highly efficient photoinitiators for visible light cured dimethacrylate resins and dental composites

Tetrabenzoylgermane 1 and various substituted tetrabenzoylgermanes 2 – 7 were investigated as visible light (VL) photoinitiators (PIs) for dental dimethacrylate resins and dimethacrylate‐based composites. The tetrabenzoylgermanes 1 – 7 show a very strong VL absorption between 400 and 450 nm. Substituents on the benzoyl chromophore strongly influence their properties such as melting point, solubility, absorption behavior, or PI reactivity. A good photobleaching behavior and a very high reactivity as VL PI was found in photo‐differential scanning calorimeter experiments for selected tetrabenzoylgermanes. Composite pastes containing only ～0.1 wt % of Ge‐PI exhibited a sufficient photocuring due to the high PI‐reactivity of the tetraacylgermanes. Among the investigated germane PIs, tetrakis(2‐methylbenzoyl)germane 2 shows the best performance as VL PI for restorative composites and enables the composites to be photocured using an LED with an emission maximum of 500 nm. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46115.     

Rheological behavior of polyamide 11 with varying initial moisture content

The rheological behavior of polyamide 11 samples with different initial moisture levels is investigated. More specifically, the time evolution of the linear viscoelastic properties is monitored at a given frequency. The time dependence of these properties is exponential in time, reflecting postcondensation reactions in the samples. The crossover time, at which the storage modulus and loss modulus intersect, can be used as a characteristic timescale for the reaction. This crossover time and the corresponding complex viscosity can be used as fingerprints of the material, reflecting the moisture content in the material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 666–670, 2005     

Synthesis and properties of UV-curable waterborne urethane modified acrylic coatings with varying vinyl content

It has been an effective method to improve the metal protective performance of UV-curable waterborne coatings by increasing the crosslinking degree. Hence, a series of UV-curable waterborne urethane modified acrylic (UV-WUA) coatings with different vinyl content were prepared. Firstly, a functional prepolymer containing carboxyl and hydroxyl groups was synthesized by free radical copolymerization (FRCP) using acrylic acid (AA), 2-hydroxyethyl acrylate (HEA), methyl methacrylate (MMA) and butyl acrylate (BA). Next, it was grafted with different amounts of semi-adduct of isophorone diisocyanate (IPDI) and HEA (IPDI-HEA), and finally neutralized and hydrated, obtaining UV-WUA dispersions which were then cured by UV to acquire cured films and coatings. Meanwhile, molecular structures, molecular weights, particle sizes, and Zeta potentials were characterized. Then, the heat resistance, mechanical performance, adhesion and the pencil hardness of the coatings were also investigated. Moreover, their protective performance was tested by electrochemical methods, and the surface morphology was analyzed by atomic force microscopy. The results showed that the coating had desirable comprehensive performance when vinyl content reached 0.86 mmol·g⁻¹.     

Electron‐beam curing of bismaleimide‐reactive diluent resins

Electron‐beam (E‐beam) curing of 4,4′‐bismaleimidodiphenylmethane (BMPM)/BMI‐1,3‐tolyl/o,o′‐diallylbisphenol A (DABPA)–based bismaleimide (BMI) systems and their mixing with various reactive diluents, such as N‐vinylpyrrolidone (NVP) and styrene, were investigated to elucidate how temperature, electron‐beam dosage, and diluent concentration affect the cure extent. The effect of free‐radical initiator on the cure reactions was also studied. It was found that low‐intensity E‐beam exposures cannot cause the polymerization of BMI. High‐intensity E‐beam exposures give high reaction conversion attributed to a high temperature increase, which induced thermal curing. It was shown that the dilution and activation of NVP in BMI cause a more complete BMI cure reaction under E‐beam radiation. BMI/NVP can be initiated easily by low‐intensity E‐beam without thermal curing. FTIR studies indicate that about 70% of the reaction is complete for BMI/NVP with 200 kGy dosage exposure at 10 kGy per pass. The sample temperature only reaches about 75°C. The free‐radical initiator, dicumyl peroxide, can accelerate the reaction rate at the beginning of E‐beam exposure, but does not affect the final reaction conversion. The increase of the concentration of NVP in the BMI/NVP systems increases the reactive conversions almost linearly. © 2004 Wiley Periodicals Inc. J Appl Polym Sci 94: 2407‐2416, 2004     

Chemical modification of poly(1-butene) resins through reactive processing

Controlled-rheology poly(1-butene) resins have been produced by chemical modification of commodity poly(1-butene) (PB-1) resins through reactive processing with an organic peroxide. Using various amounts of peroxide, samples have been produced and have been analyzed in terms of their molecular and rheological properties. Molecular weight distributions (MWD) as determined by gel permeation chromatography (GPC) indicate that polydispersity (PDI) remains approximately constant but weight-average molecular weight (M_w) decreases with increasing peroxide concentration. These trends are in agreement with predictions from a kinetic model previously developed for the production of controlled-rheology polypropylene. Linear viscoelastic measurements indicate that the modified samples are thermorheologically simple and that zero-shear viscosity decreases with increasing peroxide concentration while flow activation energy remains approximately constant. Finally, no significant variation in melting and crystallization properties was observed for the range of peroxide concentrations used. Based on these results, it is proposed that tailor-made controlled-rheology poly(1-butene) resins can be produced easily through reactive extrusion operations similar to those used for the production of controlled-rheology polypropylene (CRPP).     

Rheological properties of ionically and covalently crosslinked polypropylene‐type thermoplastic elastomers

Maleic anhydride was grafted onto a polypropylene‐type thermoplastic elastomer PER by reactive processing with a screw extruder, and a maleated PER (MPER) was prepared. Aiming at ionic crosslinking, magnesium 12‐hydroxy stearate (MgStOH), zinc oxide (ZnO), and zinc sulfide (ZnS), and aiming at covalent crosslinking, melamine as an amino compound, and Epocizer and GRYCI‐ALE as epoxy compounds, were added to the MPER, melt‐mixed by use of the screw extruder, and crosslinked compounds were obtained. The rheological properties such as capillary flow properties and dynamic viscoelasticities of the compounds were measured and their melt processabilities were evaluated. The degree of crosslinking was in the order of epoxy compounds > MgStOH > melamine > ZnO, ZnS > MPER (blank). In the case of the compound with MgStOH of a moderately high degree of crosslinking, the non‐Newtonian behavior is remarkable and the die swell ratio is low and suitable for extrusion. However, in the case of compounds with epoxy compounds of an excessive degree of crosslinking, fine extrudate cannot be obtained due to the lack of fusion and the control of degree of crosslinking is necessary. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 762–773, 2002     

Blends of epoxy–amine resins with poly(phenylene oxide) as processing aids and toughening agents: I. Uncured systems

The effect of two different bisphenol‐A‐based diepoxides—nearly pure DGEBA340 and a DGEBA381 oligomer—and an aromatic diamine curative (MCDEA) on the solubility and processability of poly(phenylene oxide) (PPO) was studied. The solubility parameters of the diepoxies and the curative calculated from Fedors's method suggest miscibility of PPO with the components, and this was observed at the processing temperature; however, some of the blends were not transparent at room temperature, indicating phase immiscibility and/or partial PPO crystallization. The steady shear and dynamic viscosities of the systems agreed well with the Cox–Merz relationship and the logarithmic viscosities decreased approximately linearly with increasing amounts of DGEBA381, DGEBA340 or MCDEA, thus causing a processability enhancement of the PPO. The dynamic rheology of intermediate PPO:DGEBA compositions at 200 °C showed gel‐like behaviour. Dynamic mechanical analysis of blends with varying PPO:DGEBA ratios showed that the main glass transition temperature (T_g) of the blends decreased continuously with increasing epoxy content, with a slightly higher plasticizing efficiency being exhibited by DGEBA340 compared to DGEBA381. However, blends with 50 and 60 wt% PPO had almost identical T_g due to the phase separation of the former blends. The blends of MCDEA and PPO were miscible over the concentration range investigated and T_g of the blends decreased with increasing MCDEA concentration. © 2013 Society of Chemical Industry     

Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings

Four different UV‐curable poly(urethane acrylate)s were prepared through the reaction of two diisocyanates [i.e., toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI)] and two polyols [i.e., polycaprolactone triol (PCLT) and polycaprolactone diol (PCLD)], and they were characterized with Fourier transform infrared spectroscopy. The mechanical properties, thermal properties, and water sorption of the cured poly(urethane acrylate)s were also investigated with respect to the chemical structures of the polyols and diisocyanates. In comparison with linear PCLD–TDI and PCLD–IPDI, crosslinked PCLT–TDI and PCLT–IPDI with trifunctional PCLT showed relatively high thermal decomposition temperatures. The hardness and modulus of the UV‐cured poly(urethane acrylate) films, which were measured by a nanoindentation technique, were in the following increasing order: PCLD–IPDI ～ PCLD–TDI < PCLT–IPDI ～ PCLT–TDI. The pencil hardness was 3H for PCLT–IPDI and PCLT–TDI and HB for PCLD–IPDI and PCLD–TDI. Two urethane acrylates prepared from the trifunctional polyol showed better acid and alkali resistances than those made from the bifunctional polyol. These mechanical properties and chemical resistances may have been strongly dependent on the chain flexibility of the molecules and crosslinking density. Regardless of the functionality in the polyol, the change in the yellowness index showed a lower value in the poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI in comparison with the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Gelation and crosslinking characteristics of photopolymerized poly(ethylene glycol) hydrogels

The gelation and crosslinking features of poly(ethylene glycol) (PEG) hydrogels were scrutinized through the UV polymerization processes of poly(ethylene glycol) methacrylate (PEGMA) and poly(ethylene glycol) dimethacrylate (PEGDMA) mixtures. The real‐time evolutions of the elastic moduli of the prepolymerized mixtures with different crosslinking ratios of PEGMA and PEGDMA and the photoinitiator concentrations were measured during photopolymerization. The rheological properties were compared with other properties of the PEG hydrogels, including the relative changes in the C?C amounts in the mixtures before and after UV irradiation, water swelling ratio, gel fraction, mesh size, and mechanical hardness. As the portion of PEGDMA as a crosslinker increased, the final elastic modulus and gel fraction increased, whereas the swelling ratio and scratch penetration depth at the hydrogel film surface decreased because of the formation of compact networks inside the hydrogels. These results indicate that there was a good correlation between the rheological analysis for predicting the crosslinking transition during photopolymerization and the macroscopic properties of the crosslinked hydrogels. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41939.     

Photopolymerizable bisallylcarbonate and bisacrylic monomers useful in the formulation of dental composite resins and in the crosslinking of methyl methacrylate

Two new bisallylic monomers [allyl p‐allyl carbonate benzoate (ApACBz) and 1,4‐phenylenbis(methylene)diallyl carbonate (1,4‐FMDAC)] and one bisacrylic monomer [1,4‐bis(acryloyloxymethyl)benzene (1,4‐BAMB)] were synthesized and used as crosslinking agents of methyl methacrylate (MMA) at different mass ratios (10, 20, 40, and 50%). All of the obtained copolymers showed improved thermal stability in comparison with that of the MMA homopolymer. Also, ApACBz and 1,4‐FMDAC were used as bisphenol A glycidyl methacrylate (Bis‐GMA) eluents to prepare dental resin composites. When compared to the control, the Bis‐GMA–new eluent composites had a higher double‐bond conversion, a higher solubility (p < 0.05) and a lower flexural strength (p < 0.05), whereas the elastic modulus and water sorption values were not statistically different (p > 0.05). The 1,4‐FMDAC and ApACBz monomers are promising eluents of Bis‐GMA for the preparation of dental composites with high degrees of conversion. In addition, the ApACBz, 1,4‐FMDAC, and 1,4‐BAMB monomers are potentially useful crosslinking agents when polymer networks of poly(methyl methacrylate) with a high thermal stability are desired. The application‐oriented tests of the monomers in dental composite formulations showed a sufficient storage stability, high photocuring activity, excellent crosslinking of MMA, and good thermal and mechanical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42920.     

Improved processibility of silicone composites by MQ silicone resins

Processibilities of silicone composites were always a problem for their high content of SiO₂ powders. This article found that the substitution of silicone resins for linear polydimethylsiloxanes (PDMS) made processibilities easier. Three silicone resins (MQ1.0, MQ1.1, and MQ1.2) with clarified chemical structures (by FT IR, ²⁹Si NMR, and GPC) were adopted. Their shearing viscosities [η()] were greatly higher than PDMS with higher molecular weight, which could be assigned to stronger molecular interactions as surface tension and flowing activation energy ΔE indicated. On the contrary, η() of MQ‐PDMS binary blends greatly decreased to that even lower than either components (about 85% utmost decrease comparing to PDMS), for the variation of molecular interaction rather than dilution effect. Furtherly, when PDMS were partly replaced with MQ resins, process time of PDMS–SiO₂ silicone composites were greatly shortened (from >6 to 2 h), while with better SiO₂ dispersion (Mooney viscosity greatly decreased from 30.0 to 5.0 MU). Better dispersion of SiO₂ fillers in composites could be confirmed by SEM and mechanical properties. For the better dispersion, mechanical properties of composites were improved with higher elastic modulus, higher tensile strength, and higher hardness, especially with higher elongation at break (utmost increased from 190% to 277%). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46445.     

Plastic scintillators with efficient light output and pulse shape discrimination produced via photoinitiated polymerization

Poly(vinyl toluene) (PVT) overdoped with 2,5-diphenyloxazole and using 1,4-bis(5-phenyloxazol-2-yl)benzene as a fluorescent secondary dopant can be used to detect and differentiate neutron and gamma radiation via scintillation. The low cost of PVT makes these plastic scintillators attractive for both portable and larger sized first line detection of special nuclear materials. Current fabrication methods rely on thermally initiated radical polymerization that generally requires an approximately 5-day heating process in order to produce high quality scintillators. In this work, we report a proof-of-concept photopolymerization process to prepare plastic scintillators up to 20 g in size in 1 day. These plastic scintillators were comparable to standard thermally polymerized samples in terms of their physical properties and response to various radiation sources. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47381.     

Impact of salts on polyacrylamide hydrolysis and gelation: New insights

Polyacrylamide (PAM) and its derivatives are the most commonly used polymers in the preparation of polymeric gels for water control in petroleum reservoirs. This study involved the use of polyethylenimine (PEI) as a crosslinker for PAM. In this study, we investigated PAM alkaline hydrolysis at high temperatures. The effects of salts [sodium chloride (NaCl) and ammonium chloride (NH₄Cl)] on the degree of hydrolysis (DH) of PAM were investigated. These salts were used as retarders to elongate the gelation time of the PAM/PEI system. The data obtained from ¹³C‐NMR was used to understand the retardation mechanisms by salts. We found that NH₄Cl accelerated the extent of hydrolysis more in comparison with NaCl. Moreover, the apparent viscosity of the hydrolyzed samples was measured. PAM hydrolysis in the presence of NH₄Cl resulted in a lower solution viscosity than that in the presence of NaCl. Therefore, NH₄Cl was more effective in shielding negative charges on the carboxylate groups of the partially hydrolyzed polyacrylamide (PHPA) chain. NaCl and NH₄Cl were compatible with the PHPA/PEI system, but sodium carbonate showed a white precipitate. In addition, high‐temperature/high‐pressure elastic modulus data were reported for the first time for this system. Differential scanning calorimetry was coupled with rheology to explain the PAM/PEI crosslinking in the presence of salts. Models were developed to assess the impact of the salts on the PAM DH and the induction period before gelation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41185.     

Study on the influence of electron beam irradiation on the thermal,mechanical, and rheological properties of ethylene‐octene copolymer with high comonomer content

Ethylene‐octene copolymer (EOC) was irradiated using electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of crosslinking reflected in increased gel content, higher elastic modulus (G′), and lower tan δ obtained by rheology measurement at 150°C. Crosslinking caused improvement in high‐temperature creep and room temperature and also elevated temperature elastic properties. Differential scanning calorimetry revealed that e‐beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of crosslinking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break. Radiation dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220°C, slightly higher C?O peak for crosslinked sample was found by Fourier transform infrared spectroscopy while for room temperature samples no C?O peak was detected. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Crosslinked chitosan doped with Y2(CO3)3 and surface energy and electrorheological properties

Novel electrorheological materials based on crosslinked chitosan doped with Y₂(CO₃)₃ were synthesized with biocompatible chitosan as the substrate of the materials. The electrorheological performance, surface energy, and thermal decomposition behavior of the materials were investigated as functions of the composition change. The results show that doping Y₂(CO₃)₃ can improve effectively the electrorheological performance of crosslinked chitosan with the formation of a metal–polymer complex when the doping degree is suitable. The surface energy plays an important role in influencing the electrorheological properties of the material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation,photoisomerization, and microfabrication with two‐photon polymerization of crosslinked azo‐polymers

We report the preparation, photoisomerization properties, and three‐dimensional (3D) microstructure fabrication with two‐photon polymerization of crosslinked azo‐polymers. A series of bi‐acrylate‐substituted azobenzene derivatives were designed and synthesized as the monomers and/or crosslinkers of the crosslinked azo‐polymers. The doping concentration of the derivatives in pre‐polymer resins was significantly increased due to the introduction of bulky tert‐butyl and flexible alkyl chains. The double‐exponential dynamics of trans‐to‐cis photoisomerization of the azo‐polymers indicated the coexistence of different processes for the azobenzene moieties in the polymeric crosslinked networks. The crosslinked azo‐polymers exhibited ideal “on–off” switching performance in the highly reversible trans–cis–trans isomerization cycles. Furthermore, we prepared a photoresist containing the azobenzene derivative for 3D microstructure fabrication based on two‐photon polymerization. A woodpile photonic crystal with a photonic bandgap at telecommunication wavelength region was successfully fabricated with the azobenzene‐containing photoresist, which would open the way for the design and manufacturing of miniature optical communication devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2947–2956, 2013     

Selection of quaternary ammonium groups for optimizing properties of water‐soluble,photosensitive phenolic resins and study of their postcuring mechanism

This article deals with the selection of quaternary ammonium groups for synthesis of water‐soluble, photosensitive phenolic resins, containing acrylate and different quaternary ammonium salt groups (AQSPRs), via ring‐opening reactions of epoxy phenolic resin (EPR) with acrylic acid and with different tertiary amine‐protonic acid salts. Conversion of epoxy groups, solubility, photosensitive properties, and thermal decomposition of the different AQSPRs were compared. Modification of AQSPR with methanol solution of KOH to form phenolic resin containing both quaternary ammonium hydroxide groups and acrylate groups (AQHPR) was also studied. Characterization by IR spectrum, DSC, and thermal gravimetric analysis was carried out. The results showed that in the synthesis of AQSPRs containing different quaternary ammonium salt groups, the efficiency of ring‐opening reaction of epoxy phenolic resin with tertiary amine salt in terms of conversion of epoxy groups decreases in the following order: for the tertiary amine, N,N‐dimethyl benzylamine (DMBA) > triethylamine (TEA) > trimethylamine (TMA) > N,N‐dimethyl aniline (DMA) > triethanolamine (TENA) > tri(n‐butylamine) (TBA); for the protonic acid, HCl > HBr > HCOOH > HI > NaHSO₃ > Cl₃CCOOH > HClO₄ > HBF₄. All the AQSPRs except that from HClO₄ can be dissolved in water, methanol, DMF, or DMSO. The gel content formed during UV exposure decreases in the following order of acids used in forming quaternary ammonium salt groups: HCl > HCOOH > NaHSO₃ > Cl₃CCOOH; or decreases in the following order of tertiary amines or hydrohalic acids used in forming the quaternary ammonium groups: TMA. > TEA > DBMA; HCl > HBr > HI. During thermal decomposition of EPR with about half epoxy groups of EPR ring‐opened with tertiary amine salt at 160°C for 0.5 h, water‐insoluble product was formed. The insoluble content and the % decrease of epoxy groups or halide ions increase in the following order: TMA < TEA < DMBA; HCl < HBr < HI. The % decrease of epoxy groups for the insoluble residue is nearly equal to the % decrease of halide ions. A crosslinking reaction mechanism occurred in the thermal decomposition was thus proposed. During the modification of AQSPR with KOH, conversion of quaternary ammonium chloride groups can reach above 90%. The decomposition temperature of the quaternary ammonium groups was lowered from 204 to 120°C after modification of AQSPR with KOH. The photosensitive properties of the resin after modification became lower. It is better to react DMBA · HCl with EPR so as to obtain a product with higher conversion of epoxy groups, good water solubility, moderate photosensitivity, lower decomposition temperature, and better postcuring. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2914–2922, 2004     

Influence of particle size and fluid fraction on rheological and extrusion properties of crosslinked hyaluronic acid hydrogel dispersions

Crosslinked hyaluronic acid (HA) hydrogels are widely used in gel/HA fluid formulations as a viscosupplement to treat joint diseases; thus, it is important to characterize these hydrogels in terms of their particle size and to investigate the effects of the gel/fluid mixtures on their rheological properties and extrusion force. Hydrogels previously crosslinked with divinyl sulfone were sheared in an Ultra‐Turrax unit to produce particles with mean diameters ranging from 20 to 200 μm. Hydrogels with 75–100 μm mean diameters were also evaluated in dispersions containing a 20–40% mass fraction of HA fluid. The mean diameters were measured by laser light scattering and the rheological behavior was determined by oscillatory and steady measurements in parallel plate geometry. The HA hydrogels exhibited the typical behavior of so‐called weak gels, as analyzed by the storage and loss moduli G′ and G″, respectively. The viscoelasticity, the viscosity, and the extrusion force increased with the hydrogel particle size. The fluid phase dispersions decreased both moduli. At 40% fluid fraction, the gel characteristics were lost and the dispersion behaved as a fluid. Based on these results, the particle size and HA fluid fraction in hydrogel dispersions may be optimized to develop more efficient viscosupplement formulations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

In situ Dynamic Rheological Study of Polyacrylamide during Gelation Coupled with Mathematical Models of Viscosity Advancement

Acrylamide dynamic viscosity has been measured in aqueous solutions. Separate rheological measurements were performed on neat resins devoid of the curing agent over a range of shear rates to yield the initial resin viscosity. The gels were also characterized by sub‐ambient DSC to determine the phase structure as a function of formulation. The dynamic viscosity shows a marked sigmoidal behavior with a plateau viscosity. Mathematical interpretations of the gel time both by sigmoidal and power law models were comparable. The power law model allowed a direct determination of the gel time while the sigmoidal model yielded parameters associated with the initial viscosity, one associated with the plateau viscosity of the gel, and two time constants controlling the sharpness of the transition.

     

The Cole–Cole plot for cure: The cure and reversion of natural rubber

Cure rheometry is routinely used in the rubber industry for processability assessment and cure‐time determination. This article examines these rheological outputs in Cole–Cole format to explore what new insights can be gained from this alternative data plot. It differs from the conventional Cole–Cole treatment in its application to a reacting system. The plots described here are therefore of G″(t) vs. G′(t). Initially some attention is directed to the basics of the Cole–Cole treatment and the likely features to be expected when applied to systems undergoing both cure and reversion. This article goes on to consider examples of both by studying a natural rubber vulcanization at temperatures of 160 °C and above. Through the Cole–Cole approach, it is thought possible to identify the competition between intermolecular and intramolecular sulfurization, and between crosslink and main‐chain scission. The approach offers considerable potential to expand the capabilities of cure rheometry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44085.