Synthesis and photopolymerization of 2‐(acryloyloxy)ethyl piperidine‐1‐carboxylate and 2‐(acryloyloxy)ethyl morpholone‐4‐carboxylate

Two low‐viscosity monomers, 2‐(acryloyloxy)ethyl piperidine‐1‐carboxylate (AEPC II) and 2‐(acryloyloxy)ethyl morpholone‐4‐carboxylate (AEMC), were synthesized with a non‐isocyanate route. The photopolymerization kinetics was monitored by real‐time infrared spectroscopy with a horizontal sample holder. The results indicated that AEPC II and AEMC had high ultraviolet curing rates and final double‐bond conversions, which could reach 90 and 95%, respectively. The glass‐transition temperatures of AEPC II/urethane acrylate resin (1/4 w/w), AEMC/urethane acrylate resin (1/4 w/w), and isobornyl acrylate/urethane acrylate resin (1/4 w/w) mixtures were 37.5, 45.6, and 57°C, respectively. The crosslink density of the AEMC/urethane acrylate resin (1/4 w/w) mixture was lower than that of the isobornyl acrylate/urethane acrylate resin (1/4 w/w) mixture. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Regulation of trans‐1,4‐polyisoprene crystallinity and mechanical properties of styrene‐butadiene rubber/trans‐1,4‐polyisoprene vulcanizate

The effects of processing temperature and bis‐[γ‐(triethoxysilyl)‐propyl]‐tetrasulfide (Si69) on crystallization, morphology, and mechanical properties of styrene‐butadiene rubber (SBR)/trans‐1,4‐polyisoprene (TPI) vulcanizate are investigated. The crystallinity and crystalline melting temperature (T_m) of TPI in the vulcanizates with TPI/silica/(Si69) pre‐mixed at 150 °C are much lower than that pre‐mixed at 80 °C. At the same pre‐mixing temperature, the presence of 1 phr Si69 leads to a decreased crystallinity and T_m. The TPI domains with phase size of about 1 μm and silica are well dispersed in the vulcanizate, and TPI crystals get smaller in size and less in amount by pre‐mixing TPI, silica and Si69 at 150 °C. The vulcanizates with TPI/silica/(Si69) pre‐mixed at 150 °C have decreased tensile strength and modulus at a given extension than that pre‐mixed at 80 °C. At the same pre‐mixing temperature, the tensile strength and modulus of the vulcanizate increase with the addition of 1 phr Si69. The crystallinity of TPI component in SBR/TPI vulcanizate is effectively controlled by changing processing temperature and adding Si69, which is important for theoretical research and practical application of TPI. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44395.     

Solid‐state polymerization of poly(ethylene 2,6‐naphthalate)

The solid‐state polymerization (SSP) of poly (ethylene 2,6‐naphthalate) (PEN) was studied and compared with that of poly(ethylene terephthalate) (PET). The SSP of PEN, like that of PET, could be satisfactorily described with a modified second‐order kinetic model, which was based on the assumptions that part of the end groups were inactive during SSP and that the overall SSP followed second‐order kinetics with respect to the active end‐group concentration. The proposed rate equation fit the data of the SSP of PEN quite well under various conditions. PEN prepolymers in pellet and cube forms with intrinsic viscosities (IVs) ranging from 0.375 to 0.515 dL/g, various particle sizes, and various carboxyl concentrations were solid‐state polymerized at temperatures ranging from 240 to 260°C to study the effects of various factors. The SSP data obtained in this study could be readily applied to the design of commercial PEN SSP processes. Because PEN and PET share the same SSP mechanism, in general, the SSP behaviors of PEN are similar to those of PET. Thus, the SSP rate of PEN increased with increasing temperature, increasing prepolymer IV, and decreasing prepolymer particle size. However, because of the much higher barrier properties of PEN, the prepolymer particle size and carboxyl concentration had much greater effects on the SSP of PEN than on the SSP of PET. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1075–1084, 2007     

Photocure properties of high‐heat‐resistant photoreactive polymers with cinnamate groups

New high‐heat‐resistant photoreactive polymers with cinnamate groups were synthesized by the reaction of cinnamic acid (CA) and epoxy resins. Their photocure properties were investigated with Fourier transform infrared spectroscopy, UV–visible spectroscopy, and thermogravimetric analysis (TGA). Their photocure reaction rates and the extent of reaction conversion increased with the intensity of UV irradiation. To investigate their photocure reaction kinetics, their reaction conversion rates were plotted against reaction conversion so that their photocure reactions could be analyzed in terms of an nth‐order kinetics reaction equation. The YX4000H–CA photoreactive polymer with a biphenyl moiety, which was expected to have strong molecular interactions, showed a lower reaction conversion rate and reaction constant, and the highest reaction conversion rate and reaction constant was observed in XP2030–CA with an optimum cure reaction space and a reduction of molecular interactions compared with the other photoreactive polymers. Thermal stability was studied by observation of the changes in the transmittance of the photocured polymer films upon heating and by measurement of the weight loss with temperature with TGA. These photoreactive polymers showed good thermal properties, with almost no transmittance change in the visible range even after they were heated at 250°C for 1 h, and they exhibited little weight loss up to about 250°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study on propene polymerization using a novel spherical Ziegler‐Natta catalyst and its kinetics

The effects of the Al/Ti ratio and external donor (ED) on the catalytic activity and kinetics of propene polymerization catalyzed by a spherical Ziegler‐Natta (Z‐N) catalyst were investigated. The preparation conditions of the catalyst play an important role in the polymerization kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3737–3740, 2003     

Synthesis and characterization of organosoluble and transparent polyimides derived from trans‐1,2‐bis(3,4‐dicarboxyphenoxy)cyclohexane dianhydride

A novel dianhydride, trans‐1,2‐bis(3,4‐dicarboxyphenoxy)cyclohexane dianhydride (1,2‐CHDPA), was prepared through aromatic nucleophilic substitution reaction of 4‐nitrophthalonitrile with trans‐cyclohexane‐1,2‐diol followed by hydrolysis and dehydration. A series of polyimides (PIs) were synthesized from one‐step polycondensation of 1,2‐CHDPA with several aromatic diamines, such as 2,2′‐bis(trifluoromethyl)biphenyl‐4,4′‐diamine (TFDB), bis(4‐amino‐2‐trifluoromethylphenyl)ether (TFODA), 4,4′‐diaminodiphenyl ether (ODA), 1,4‐bis(4‐aminophenoxy)benzene (TPEQ), 4,4′‐(1,3‐phenylenedioxy)dianiline (TPER), 2,2′‐bis[4‐(3‐aminodiphenoxy)phenyl]sulfone (m‐BAPS), and 2,2′‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]sulfone (6F‐BAPS). The glass transition temperatures (T_gs) of the polymers were higher than 198°C, and the 5% weight loss temperatures (T_d5%s) were in the range of 424–445°C in nitrogen and 415–430°C in air, respectively. All the PIs were endowed with high solubility in common organic solvents and could be cast into tough and flexible films, which exhibited good mechanical properties with tensile strengths of 76–105 MPa, elongations at break of 4.7–7.6%, and tensile moduli of 1.9–2.6 GPa. In particular, the PI films showed excellent optical transparency in the visible region with the cut‐off wavelengths of 369–375 nm owing to the introduction of trans‐1,2‐cyclohexane moiety into the main chain. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42317.     

Semicontinuous emulsion copolymerization of 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (3‐MDG) and butyl acrylate (BA). Monomer feed addition

New polymer colloids based on the saccharide monomer, using of 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG), were prepared by semicontinuous emulsion polymerization, a widely used industrial process. The copolymerization of 3‐MDG and butyl acrylate (BA), by the monomer‐addition technique, at 70°C, using sodium persulfate (Na₂S₂O₈) as an initiator, was investigated. The influence of some reaction parameters, such as the type and concentration of the surfactants as well as the monomer addition rate (R_m) on the polymerization rate (R_p), the colloidal properties, and the stability of the latexes, was studied. It was found that under starved‐feed conditions the polymerization rate and the particle size (D) increased with an increasing rate of monomer addition. The weight‐average molecular weight (M _w) also increased by enhancing R_m and a narrower molecular weight distribution was obtained. Furthermore, the type and the concentration of the surfactants strongly influenced the particle size and its distribution. The effect of the seed stage on the particle size and its distribution was also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2091–2102, 2003     

Effect of oxygen on the crosslinking and mechanical properties of a thermoset formed by free‐radical photocuring

In this article, we report on the formation of optically transparent photopolymer films from hexanediol diacrylate (HDDA) by inkjet printing, where droplets of monomer approximately 5 μm in diameter were deposited onto a surface. The films were cured by irradiation with a UV‐light‐emitting‐diode light source. It was found that the inkjet‐printed HDDA films picked up a considerable amount of absorbed O₂ during printing. Exposure to increasing amounts of O₂ during photocuring severely restricted both the degree of conversion and the UV dose required for gelation in proportion to the O₂ concentration. Viscoelastic property data indicated that exposure to reduced oxygen concentrations during thermal postcuring (dark reaction) resulted in linear trends of increasing modulus above the glass‐transition temperature (T_g) and increasing T_g itself. Thus, the final crosslink density was greater in fully cured samples that were exposed to atmospheres with increasing inert gas concentrations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kinetic study of the aqueous free‐radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid via an online proton nuclear magnetic resonance technique

The free‐radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) in aqueous media and in the presence of potassium persulfate (KPS) as a thermal initiator was studied. The ¹H‐NMR method was applied to record the reaction data in online gain. The effects of the monomer and initiator concentrations and also the reaction temperature were studied. The order of reaction with respect to the monomer was much greater than unity (1.94). None of the three theories describing an order of reaction higher than unity could predict the AMPS polymerization mechanism in this study. So, a new mechanism is presented. It is suggested that initiation took place through the formation of a complex between the initiator and monomer, and termination occurred not only by a bimolecular reaction but also by a monomolecular reaction. The order with respect to KPS was 0.49; this was consistent with classical kinetic theory. The determined activation energy at the overall rate of reaction was 92.7 kJ mol^?1 K^?1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Evaluation of the chemical resistance of high‐density polyethylene geomembranes

The chemical resistance of high‐density polyethylene geomembranes (GMs) with smooth and textured surfaces in notched and unnotched forms at different pH values and in the range of 20–80°C was examined with stress crack resistance testing. Surface microcracks in GMs were observed in scanning electron microscopy images. Smooth and textured GMs did not show significant differences in their mechanical behaviors. The yield strength decreased with the temperature, pH, and exposure time. The yield strain increased with the temperature, but there were no good correlations with pH values. The break strength also decreased with the temperature and showed no significant correlation with pH variations. The break strain did not show a good correlation with the temperature and pH variations. The stress crack resistance was independent of pH variations but significantly depended on the temperature. It was negatively correlated with the exposure time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modeling of the copolymerization,with depropagation,of α‐methyl styrene and methyl methacrylate at an elevated temperature

We propose a dynamic model for the copolymerization of α‐methyl styrene (α‐MS) and methyl methacrylate (MMA) in a batch reactor. The parameters are based on data from the literature and our own laboratories over the full conversion range. A two‐parameter model with constant reactivity ratios shows the most reasonable results. The dynamic model depicts the reaction kinetics and reactor behavior more clearly. Termination occurs mainly by the cross reaction of unlike radicals, and its rate increases with the molar ratio of α‐MS to MMA. The model enables us to predict the instantaneous and cumulative properties of the copolymer and also provides us with a basic tool for the optimization and control of industrial reactors. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 261–270, 2004     

Multiple shape memory effects of trans‐1,4‐polyisoprene and low‐density polyethylene blends

A novel series of shape memory blends of trans‐1,4‐polyisoprene (TPI) and low‐density polyethylene (LDPE) were prepared using a simple physical blending method. The mechanical, thermal and shape memory properties of the blends were studied and schemes proposed to explain their dual and triple shape memory behaviors. It was found that the microstructures played an important role in the shape memory process. In TPI/LDPE blends, both the TPI crosslinking network and LDPE crystalline regions could work as fixed domains, while crystalline regions of LDPE or TPI could act as reversible domains. The shape memory behaviors were determined by the components of the fixed and reversible domains. When the blend ratio of TPI/LDPE was 50/50, the blends showed excellent dual and triple shape memory properties with both high shape fixity ratio and shape recovery ratio. © 2017 Society of Chemical Industry     

Strain‐induced crystallization behavior of natural rubber and trans‐1,4‐polyisoprene crosslinked blends

The strain‐induced crystallization (SIC) behaviors of crosslinked blends based on natural rubber (NR) and trans‐1,4‐polyisoprene (TPI) with different content of TPI were probed explored by using synchrotron two‐dimensional wide angle X‐ray diffraction and dynamic mechanical analysis. The results showed that when TPI content is less than 70% no reflection peak of TPI but NR crystallite diffractions can be observed and the diffractions of TPI βform appear when TPI content is 70 wt % in the cocured blend. SIC of cocured blends started at smaller strain ratio than the pure NR. By calculating ΔS_def, it is found that the drop in entropy upon strain decreased when TPI is incorporated into NR due to the reduction of molecular mobility of NR. The degree of SIC and crystallization rate index in crosslinked blends monotonously decreased with the increase of TPI content. The apparent crystallite size exhibited some surprising variations. L₂₀₀ and L₁₂₀ decreased with the increase of TPI content in the cocured blends. These observations were usually caused by two factors: (i) Less number of polymer chains could involve in crystal growth due to the lower mobility of polymer chains in the cocured blends which is proved by dynamic mechanical analysis results; (ii) The mean distance between nuclei decreases, which was caused by the fluctuation of crosslink density in NR phase derived from the heterogeneous distribution of curatives in two phases supported by the varying tendency of curing degree and crosslink density. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of novel polyimides from 3‐(4‐aminophenylthio)‐N‐aminophthalimide

A novel, asymmetric diamine, 3‐(4‐aminophenylthio)‐N‐aminophthalimide, was prepared from 3‐chloro‐N‐aminophthalimide and 4‐aminobenzenethiol. The structure of the diamine was determined via IR and ¹H‐NMR spectroscopy and elemental analysis. A series of polyimides were synthesized from 3‐(4‐aminophenylthio)‐N‐aminophthalimide and aromatic dianhydrides by a conventional two‐step method in N,N‐dimethylacetamide and by a one‐step method in phenols. These polyimides showed good solubility in 1‐methyl‐2‐pyrrolidinone, m‐cresol, and p‐chlorophenol, except polyimide from pyromellitic dianhydride, which was only soluble in p‐chlorophenol. The 5% weight loss temperatures of these polyimides ranged from 460 to 498°C in air. Dynamic mechanical thermal analysis indicated that the glass‐transition temperatures of the polyimides were in the range 278–395°C. The tensile strengths at break, moduli, and elongations of these polyimides were 146–178 MPa, 1.95–2.58 GPa, and 9.1–13.3%, respectively. Compared with corresponding polyimides from 4,4′‐diamiodiphenyl ether, these polymers showed enhanced solubility and higher glass‐transition temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fourier transform infrared and wide‐angle X‐ray diffraction studies of the thermal cyclization reactions of high‐molar‐mass poly(acrylonitrile‐co‐itaconic acid)

The stabilization reactions of a high‐molar‐mass poly(acrylonitrile‐co‐itaconic acid) precursor in air at 200, 220, and 240°C were studied with Fourier transform infrared. Principally, the cyclization of nitrile groups leading to the ladder structures of tetrahydropyridine occurred. Evidence for oxidative reactions causing the conversion of the C? C structure to C?C and generating groups such as ? OH and C?O was also obtained. As the temperature of stabilization was increased, the rate of the reaction increased without causing great changes in the Fourier transform infrared spectral patterns. The maximum nitrile conversion achievable was limited by the temperature of stabilization. Although the reaction stagnated at 40 and 80% at 200 and 220°C, it was practically complete in about an hour at 240°C. Higher temperatures also favored the formation of extended conjugated structures. Wide‐angle X‐ray diffraction studies of the polymer stabilized at 300 and 400°C in argon confirmed that the aromatization index value and the crystallinity of the polymer increased proportionally to the temperature of pyrolysis. An analysis of the wide‐angle X‐ray diffraction pattern and the elemental composition of the stabilized polymer implied the formation of the tetrahydropyridine structure at 400°C. The higher pyrolysis temperature favored the formation of the lattice constituted by this group. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3055–3062, 2006     

Preparation and properties of one epoxy system bearing fluorene moieties

Diglycidyl ether of bisphenol fluorene (DGEBF) and 9,9‐bis(4‐aminophenyl) fluorene (BPF) were synthesized to introduce more aromatic structures into an epoxy system, and their chemical structures were characterized with Fourier transform infrared spectroscopy, NMR, and mass spectrometric analysis. The dynamic curing behavior of the DGEBF/BPF system was investigated with differential scanning calorimetry. DGEBF was cured with BPF, diaminodiphenylsulfone (DDS), and diaminodiphenylmethane (DDM), and E‐44 (bisphenol A epoxide) was also cured with BPF for comparison. The thermal properties of the obtained polymers were evaluated with dynamic mechanical thermal analysis and thermogravimetric analysis. The cured DGEBF/BPF system showed a remarkably higher glass‐transition temperature, better thermal stability and lower moisture absorption in comparison with the general bisphenol A epoxy resin/BPF system but approximated the heat resistance of the DGEBF/DDS and DGEBF/DDM systems. Such properties make this epoxy system very promising for heat‐resistant applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology and mechanical properties of styrene–ethylene/butylene–styrene triblock copolymer/high‐density polyethylene composites

The morphology and mechanical properties of a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) incorporated with high‐density polyethylene (HDPE) particles were investigated. The impact strength and tensile strength of the SEBS matrix obviously increased after the incorporation of the HDPE particles. The microstructure of the SEBS/HDPE blends was observed with scanning electron microscopy and polar optical microscopy, which illustrated that the SEBS/HDPE blends were phase‐separation systems. Dynamic mechanical thermal analysis was also employed to characterize the interaction between SEBS and HDPE. The relationship between the morphology and mechanical properties of the SEBS/HDPE blends was discussed, and the toughening mechanism of rigid organic particles was employed to explain the improvement in the mechanical properties of the SEBS/HDPE blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetic study of the thermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate and 2‐hydroxyethyl methacrylate copolymers

The kinetics of nonisothermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate (PDMMA), 2‐hydroxyethyl methacrylate (HEMA), and vinyl‐pyrrolidone (VPy) copolymers were investigated by thermogravimetry (TG) and differential thermal analysis (DTA). The data indicated that the major weight loss occurs in the range of 270 to 450°C. The decomposition characteristics showed essentially two regimes and varied depending on the temperature and the copolymer composition. The apparent kinetic parameters of the decompositions were estimated from both TG and DTA data by using the alternative calculation methods. The results suggest that the weight loss rates may be represented, depending on the type of sample, by a reaction model of overall order 1.0 to 1.6, with an activation energy of approximately 65–95 kJ mol^?1. The DTA data estimated considerably higher values for the overall activation energies, around 198–240 kJ mol^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1500–1508, 2005     

Cationic curing of diglycidyl ether of bisphenol A and 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane and degradation of the thermosets obtained

Ytterbium and lanthanum triflates were used as cationic initiators to cure mixtures of diglycidyl ether of bisphenol A and 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane in several proportions. The evolution of the epoxy and lactone during curing and the linear ester groups in the final materials were evaluated with Fourier transform infrared in the attenuated total reflection mode. The shrinkage after curing and the thermal degradability of the materials with variations in the comonomer ratios and initiator used were evaluated and related to the chemical structure of the final network. The expandable character of 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane was confirmed. The obtained materials were more degradable than conventional epoxy resins because of the tertiary ester groups incorporated into the network by copolymerization. The kinetic parameters of the curing and degradation processes were calculated with differential scanning calorimetry and thermogravimetric analysis, respectively, with isoconversional procedures applied in both cases. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Reducing volume shrinkage by low‐temperature photopolymerization

Low‐volume‐shrinkage poly(triethylene glycol dimethacrylate) was made by photopolymerization at a low temperature. The final double‐bond conversion and dynamic mechanical analysis indicated the optimal cure temperature to be ?40°C, at which a cured sample had less volume shrinkage than samples cured at room temperature but similar mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1126–1130, 2007