Enhancement of the high‐temperature properties of an SEBS thermoplastic elastomer by chemical modification

A procedure was developed for benzoylating the polystyrene segments in polystyrene‐b‐poly(ethylene‐co‐butene)‐b‐polystyrene (SEBS) triblock copolymers. The products were characterized by NMR spectroscopy, gel permeation chromatography, dynamic mechanical thermal analysis, and membrane osmometry. The mechanical properties of the parent and benzoylated copolymers, measured from 25 to 150°C, indicated that benzoylation increases the utility of the polymers at elevated temperatures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1203–1210, 2002     

Tetrafunctional epoxy as an all‐purpose modifier for homopolymerized bisphenol A diglycidyl ether

In some applications, homopolymerized epoxies, which offer better biocompatibility and lower water absorption than amine‐ and anhydride‐cured epoxy, are more preferable; however, using homopolymerized epoxy as matrix in composites still remains a challenge. Herein, homopolymerized bisphenol A diglycidyl ether curing systems with simultaneously improved tensile strength, impact strength, and glass transition temperature (T_g) were achieved by addition of small amounts of tetra‐functional epoxies (TFTEs) with different spacer lengths. Effects of spacer length in TFTE on thermal and mechanical properties were investigated. Results indicated that TFTE with the longest spacer length shows the best mechanical performance. In addition, effects of TFTE loading on thermal and mechanical properties were discussed. Compared with neat bisphenol A diglycidyl ether, addition of 5% tetraglycidyl‐1,10‐bis(triphenylmethane) decane leads to simultaneous improvements in tensile strength, impact strength, and T_g. Effects of thermal cycling on the mechanical properties were also reported. Results suggest that the modified homopolymerized epoxy shows good performances and could be used as matrix materials and possibly in some dental applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46431.     

Copolymers of poly(arylene sulfide sulfone)/poly(ether sulfone): Synthesis,structure, and rheology properties

In order to overcome the poor flowability of poly(arylene sulfide sulfone) (PASS), we introduced ether bonds into the polymer main chain. A series poly(arylene ether sulfide sulfone) copolymers (PAESS) containing different proportion of ether bonds were synthesized with 4,4′‐dichlorodiphenyl sulfone (DCDPS), sodium sulfide (Na₂S·xH₂O), and 4,4′‐dihydroxydiphenyl ether (DHDPE). The copolymers were characterized by Fourier transform infrared (FTIR), ¹H‐nuclear magnetic resonance (NMR), differential scanning calorimetry, dynamic mechanical analysis (DMA), and rheometer. The results of FTIR and ¹H‐NMR indicate the copolymers are synthesized successfully. PAESS were found to have excellent thermal properties with glass transition temperature (T_g) of 175.7–219.1 °C and 5% weight lost temperature were all above 420 °C. The tensile and DMA test indicates that these resultant copolymers have good mechanical properties with tensile strength of 60 MPa and storage modulus of 1.5 GPa. From the results of rheology properties testing, we found that the melt stability and melt flowability of PASS were improved distinctly from 25,470 Pa s down to 355 Pa s with the incorporation of ether bonds. That will be quite beneficial to the processing of PASS, especially for the thermoforming of precision products. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46534.     

Morphologies and dynamic mechanical properties of core‐shell emulsifier‐free latexes and their copolymers for P(BA/MMA)/P(MMA/BA) and P(BA/MMA)/PSt systems in the presence of AHPS

Different poly(methyl methacrylate/n‐butyl acrylate)/poly(n‐butyl acrylate/methyl methacrylate) [P(BA/MMA)/P(MMA/BA)] and poly(n‐butyl acrylate/methyl methacrylate)/polystyrene [P(BA/MMA)/PSt] core‐shell structured latexes were prepared by emulsifier‐free emulsion polymerization in the presence of hydrophilic monomer 3‐allyloxy‐2‐hydroxyl‐propanesulfonic salt (AHPS). The particle morphologies of the final latexes and dynamic mechanical properties of the copolymers from final latexes were investigated in detail. With the addition of AHPS, a latex of stable and high‐solid content (60 wt %) was prepared. The diameters of the latex particles are ～0.26 μm for the P(BA/MMA)/P(MMA/BA) system and 0.22–0.24 μm for the P(BA/MMA)/PSt system. All copolymers from the final latexes are two‐phase structure polymers, shown as two glass transition temperatures (T_gs) on dynamic mechanical analysis spectra. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3078–3084, 2002     

Polystyrene with trifluoromethyl units: Monomer reactivity ratios,thermal behavior,flammability, and thermal degradation kinetics

Chemical modification based on incorporation of flame retardants (FR) into the polymer backbone was used in order to reduce polystyrene flammability. 3‐(trifluoromethyl)styrene (StCF₃) and 3,5‐bis(trifluoromethyl)styrene (St(CF₃)₂) were applied as reactive FR. Copolymers were synthesized with different feed ratios and it gave series of copolymers with various amounts of StCF₃ and St(CF₃)₂ (5–50% mol/mol of St). Glass transition temperature (T_g) and thermal stability of obtained (co)polymers were determined from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa and Kissinger models. Pyrolysis combustion flow calorimeter (PCFC) was applied as a tool for assessing the flammability of the synthesized (co)polymers. Relative reactivity ratios were determined by applying the conventional linearization Jaacks method (r_St = 1.34_, r_StCF3 = 0.54), (r_St = 0.47_, r_St(CF3)2 = 0.13). The results suggest that incorporation of fluorinated styrenes into PSt enchance flame retardance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42839.     

Synthesis and characterization of emulsion copolymer of N‐cyclohexylmaleimide and methyl methacrylate

Copolymers of N‐cyclohexylmaleimide (ChMI) and methyl methacrylate (MMA) were synthesized by the emulsion semibatch copolymerization method. The effects of the monomer mixture composition on the average molecular weight (M_n and M_w ), glass transition temperature (T_g), degradation temperature, mechanical properties, and rheological behavior of the copolymers were investigated. The results show that M_n and M_w have maximum values when the ChMI feed content was about 20% (by wt). The degradation temperature and T_g of the copolymers increase with increasing ChMI moieties in the copolymer. The mechanical properties (tensile strength and impact strength) decrease with an increasing ChMI feed content. All copolymers in the melt show pseudoplastic behavior. The flow index n increases with an increasing ChMI feed content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1070–1075, 2002; DOI 10.1002/app.10394     

Influence of DMF on the polymerization of tert‐butyl acrylate initiated by 4‐oxo‐TEMPO‐capped polystyrene macroinitiator

BACKGROUND: In a number of studies it has been shown that 2,2,6,6‐tetramethylpiperidinooxy (TEMPO)‐mediated polymerization of acrylates is not facile. Therefore, the object of the study reported here was to prepare poly[styrene‐block‐(tert‐butyl acrylate)] (PS‐b‐PtBA) block copolymers using 4‐oxo‐TEMPO‐capped polystyrene macroinitiator as an initiator, in the presence of small amounts of N,N‐dimethylformamide (DMF). The kinetic analysis and the effect of DMF on the reaction mechanism are also discussed. RESULTS: PS‐b‐PtBA block copolymer was prepared through polymerization of tert‐butyl acrylate (tBA) initiated by 4‐oxo‐TEMPO‐capped polystyrene macroinitiator at 135 °C. The polymerization rate of tBA could be increased by adding a small amount of DMF, and the number average molecular weight of the PtBA block in PS‐b‐PtBA reached 10 000 g mol^?1 with narrow polydispersity. The activation rate constant k_act?tBA of alkoxyamine increased and the recombination rate constant k_rec?tBA decreased with increasing DMF concentration. CONCLUSION: DMF was shown to be a rate‐enhancing additive for the polymerization of tBA using a 4‐oxo‐TEMPO‐capped polystyrene macroinitiator. From the kinetic analysis, it was concluded that the improvement of polymerization with the addition of DMF was due to an increase in k_act?tBA and a decrease in k_rec?tBA. Copyright © 2008 Society of Chemical Industry     

Hydrogels based on alkylated chitosan and polyelectrolyte copolymers

Hydrogels formed by alkylated chitosan with N‐(3‐chloro‐2‐hydroxypropyl) trimethylammonium chloride and synthetic copolymers forming polyelectrolyte complexes are presented. The copolymer polyelectrolytes were synthesized through free‐radical polymerization. Their compositions and reactivity parameters were determined by the Finemann–Ross and Kelen–Tüdos methods. The copolymers have structures that tend to be alternating. The hydrogels were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy, and water solubility tests at different pH values. For the formation of the hydrogels, they were prepared using different molar ratios of alkylated chitosan and polyelectrolyte copolymers. Their stability was determined by rheological analysis, evaluating the response as a function of strain and frequency. The rheological tests showed that the stability of the polyelectrolyte complexes followed the trend ChT‐CP2 > ChT‐CP3 > ChT‐CP1 due to the presence of greater electrostatic interactions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46556.     

Nanocomposites based on titanium dioxide,modified by β‐cyclodextrin containing copolymers

The range of titanium dioxide (TiO₂) samples, modified by β‐cyclodextrin containing copolymers was synthesized. The copolymers obtained were investigated by different methods, such as ultraviolet‐, Fourier transform infrared‐spectroscopy, thermal mass spectroscopy, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy. The modification of TiO₂ is shown to promote a significant positive impact on the process of methyl orange absorption and photodegradation on its surface. The modified TiO₂‐photocatalysts prepared in such way could be promising objects for water purification from organic pollutants. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46373.     

Morphology and thermal properties of liquid crystal p‐PAEB/n‐propyl methacrylate copolymers

The copolymers of p‐phenylene di{4‐[2‐(allyloxy) ethoxy]benzoate} (p‐PAEB) with n‐propyl methacrylate (PMA) were synthesized. The liquid crystalline behavior and thermal properties of copolymers were studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), X‐ray diffractometer (XRD), and torsional braid analysis (TBA). The results of XRD, POM, and DSC demonstrate that the phase texture of copolymers is affected by the composition of liquid crystal units in copolymers. The POM and XRD reveal that liquid crystal monomer (p‐PAEB) and copolymers of p‐PAEB with PMA are all smectic phase texture. The dynamic mechanical properties of copolymers are investigated with TBA. The results indicate that the phase transition temperatures and dynamic mechanical loss peak temperature T_p of copolymers are affected by the composition of copolymers and liquid crystal cross networks. The maximal mechanical loss T_p is 114°C and is decreased with added PMA. The behaviors of phase transition are affected by the crosslinking density, and it is revisable for lightly crosslinking LC polymer networks, but it is nonreversible for the densely crosslinking of LC polymer networks. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(styrene‐co‐N‐butylmaleimide) macroinitiators by controlled autopolymerization and related block copolymers

Autopolymerization of styrene‐N‐butylmaleimide mixtures at 125 or 140°C in the presence of a stable nitroxyl radical [2,2,6,6‐tetramethylpiperidin‐1‐yloxyl (TEMPO)] was found to proceed in a pseudoliving manner. Unimolecular initiators, which were originated by trapping self‐generated radical species with TEMPO, took part in the process. Under the studied experimental conditions, the TEMPO‐controlled autopolymerization with a varying comonomer ratio provided virtually alternating copolymers of narrow molecular weight distributions. The molecular weights of the copolymers increased with conversions. The obtained styrene‐N‐butylmaleimide copolymers containing TEMPO end groups were used to initiate the polymerization of styrene. The polymerization yielded poly(styrene‐co‐N‐butylmaleimide)‐polystyrene block copolymers with various polystyrene chain lengths and narrow molecular weight distributions. The compositions, molecular weights, and molecular weight distributions of the synthesized block copolymers and the initial poly(styrene‐co‐N‐butylmaleimide) precursors were evaluated using nitrogen analysis, gel permeation chromatography, and ¹H‐ and ¹³C‐NMR spectroscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2378–2385, 1999     

Electrochemical and optical properties of dicyclohexylmethyl substituted poly(3,4‐propylenedioxythiophene) analogue

An analogue of disubstituted 3,4‐propylenedioxythiophenes, namely 3,3‐bis(cyclohexylmethyl)‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin (ProDOT‐CycHex₂), was synthesized and its electrochemical polymerization was carried out successfully in an electrolyte solution of 0.1 M tetrabutylammonium hexafluorophosphate dissolved in a mixture of acetonitrile and dichloromethane (3/1: v/v). The corresponding polymer called PProDOT‐CycHex₂ has a reduced band gap of 1.85 eV and an electrochromic property: blue/violet when neutralized and highly transparent when oxidized. Also, PProDOT‐CycHex₂ film exhibited faster response time (0.7 s) and higher coloration efficiency (769 cm²/C) during oxidation when compared to its benzyl substituted analogue. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46214.     

Copolymerization and addition of styrene and N‐phenylmaleimide in the presence of nitroxide

The copolymerization and addition reaction of styrene (S) with N‐phenylmaleimide (PMI), either neat or in xylene, have been found to proceed at 125°C in the presence of 2,2,6,6‐tetramethylpiperidin‐1‐yloxy (TEMPO) radicals. TEMPO‐terminated alternating S‐PMI copolymers and comonomer adducts were obtained. The amounts of the low molecular weight compounds increased with the increasing content of PMI in the initial mixture. The reaction suggests formation of monofunctional unimolecular initiators. In the autopolymerization of neat comonomers, a mediating role of TEMPO was observed. The synthesized copolymers containing TEMPO end groups were used as macroinitiators to initiate polymerization of styrene. The molecular weight distributions of resulting poly(styrene‐alt‐N‐phenylmaleimide)‐block‐polystyrene copolymers indicated the presence of both low molecular weight termination products and some copolymer precursor. The copolymers and comonomer adducts were characterized using the nitrogen analysis, size‐exclusion chromatography (SEC), and NMR spectroscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1093–1099, 2000     

Enhanced thermal conductivity and mechanical properties of hybrid MoS2/h‐BN polyurethane nanocomposites

Nanocomposites based on molybdenum disulfide (MoS₂), hexagonal boron nitride (h‐BN) and hybrid MoS₂/h‐BN nanofillers with different wt % in elastomeric polyurethane (PU) were studied with respect to their microstructure, thermal and mechanical properties. Tensile tests showed increases up to 80% in Young`s modulus for both h‐BN and hybrid MoS₂/h‐BN composites. These results agree with dynamic mechanical analysis tests, which confirm an increase of up to 106% in storage modulus for hybrid MoS₂/h‐BN with 0.5 wt % content. When the hybrid MoS₂/h‐BN nanofillers were incorporated into the polymeric matrix, increases up to 102% in crosslink density were observed, indicating that strong interactions between the hybrid nanofillers and PU were established. However, the most important synergistic effect between the mixture of MoS₂ and h‐BN nanoadditives was the increase of up to 752% in thermal conductivity with respect to neat polymer. Therefore, hybrid composites based in two‐dimensional MoS₂/h‐BN nanofillers with multifunctional attributes can be applied in advanced polymeric materials that require high mechanical and thermal performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46560.     

Synthesis of sub‐micrometer core–shell rubber particles with 1,2‐azobisisobutyronitrile as initiator and deformation mechanisms of modified polystyrene under various conditions

BACKGROUND: Sub‐micrometer core‐shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) copolymers with various ratios of polybutadiene (PB) core to polystyrene (PS) shell were synthesized by emulsion grafting polymerization with 1,2‐azobisisobutyronitrile (AIBN) as initiator. These graft copolymers were blended with PS to prepare PS/PB‐g‐PS with a rubber content of 20 wt%. The mechanical properties, morphologies of the core‐shell rubber particles and deformation mechanisms under various conditions were investigated. RESULTS: Infrared spectroscopic analysis confirmed that PS could be grafted onto the PB rubber particles. The experimental results showed that a specimen with a ‘cluster’ dispersion state of rubber particles in the PS matrix displayed better mechanical properties. Transmission electron micrographs suggested that crazing only occurred from rubber particles and extended in a bridge‐like manner to neighboring rubber particles parallel to the equatorial plane at a high speed for failure specimens, while the interaction between crazing and shear yielding stabilized the growing crazes at a low speed in tensile tests. CONCLUSION: AIBN can be used as an initiator in the graft polymerization of styrene onto PB. The dispersion of rubber particles in a ‘cluster’ state leads to better impact resistance. The deformation mechanism in impact tests was multi‐crazing, and crazing and shear yielding absorbed the energy in tensile experiments. Copyright © 2009 Society of Chemical Industry     

Dynamic mechanical and rheological properties of metallocene-catalyzed long-chain-branched ethylene/propylene copolymers

The dynamic mechanical and rheological properties of five long-chain branched (LCB) and three linear ethylene/propylene (EP) copolymers were investigated and compared using a dynamic mechanical analyzer (DMA) and an oscillatory rheometer. The novel series of LCB EP copolymers were synthesized with a constrained geometry catalyst (CGC), [C₅Me₄(SiMe₂N^tBu)]TiMe₂, and had various propylene molar fractions of 0.01-0.11 and long-chain branch frequencies (LCBF) of 0.05-0.22. The linear EP copolymers were synthesized with an ansa-zirconocene catalyst, rac-Et(Ind)₂ZrCl₂ (EBI), and contained similar levels of propylene incorporation as the CGC copolymers, but no LCB. In dynamic mechanical analysis, the dynamic storage moduli (G′) and loss moduli (G″) of the copolymers decreased with an increase of propylene molar fraction. The α- and β-transitions of the CGC copolymers were overlaid with each other. High damping (tan δ) values were found with the CGC copolymers at temperatures below 0 °C. In oscillatory rheological analysis, compared to the linear EBI counterparts, the LCB CGC copolymer melts showed higher zero shear activation energies, broader plateaus of δ and larger elastic contributions, which are essential characteristics of LCB polymers. It was found that the long chain branching was the determining factor in controlling rheological properties of the polymer melts while the short chain branching from propylene incorporation played a decisive role in affecting dynamic mechanical properties. This work represents the first rheological evidence of LCB in EP copolymers synthesized with CGC.     

Synthesis and characterization of poly (styrene‐b‐[(butadiene)1−x‐(ethylene‐co‐butylene)x] ‐b‐styrene) star‐like molecular polymers produced by partial hydrogenation of SBS

This article reports the synthesis and characterization of four arm star‐shaped poly(styrene‐b‐[(butadiene)_1?x‐(ethylene‐co‐butylene)_x]‐b‐styrene) (SBEBS) copolymers. A series of SBEBS copolymers with different compositions of the elastomeric block were produced by hydrogenating a given poly(styrene‐b‐butadiene‐b‐styrene) (SBS) copolymer using a catalyst prepared from bis(η⁵‐cyclopentadienyl)titanium(IV) dichloride and n‐butyllithium. The characterization was accomplished by proton nuclear magnetic resonance spectroscopy (¹H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicate that there is a selective saturation of the polybutadiene block over the polystyrene block; this selectivity was determined by the Ti/Li molar ratio and the concentration of Ti. It was observed that the saturation rate of the 1,2‐vinyl was higher than that of the 1,4‐trans and 1,4‐cis poly(butadiene)‐b isomers. The DSC and DMA results indicate that the degree of hydrogenation had a profound effect on the polymer's relaxation behavior. All samples exhibited a biphasic system behavior with two distinct transitions corresponding to the elastomeric and polystyrene blocks. SBEBS copolymers with higher saturation levels (>33%) exhibited a crystalline character. The TGA results indicated a characteristic weight loss temperature in all samples, with slightly higher thermal degradation stabilities in the materials with higher degrees of saturation. POLYM. ENG. SCI., 54:2332–2344, 2014. © 2013 Society of Plastics Engineers     

Copolymerization of N‐(4‐carboxyphenyl) itaconimide or N‐(4‐carboxyphenyl) itaconamic acid with methyl methacrylate

This paper describes the synthesis and characterization of N‐(4‐carboxyphenyl) itaconamic acid (CPA) and N‐(4‐carboxyphenyl) itaconimide (CPI) obtained by reacting itaconic anhydride with p‐aminobenzoic acid. Structural and thermal characterization of CPA and CPI was done using ¹H‐NMR, FTIR, and differential scanning calorimetry (DSC). Copolymerization of CPA or CPI with methyl methacrylate (MMA) in solution was carried out at 60 °C using azobisisobutyronitrile as an initiator and dimethyl acetamide or THF as solvent. Feed compositions having varying mole fractions of CPA or CPI ranging from 0.05–0.20 or 0.1–0.5 were taken to prepare copolymers. Copolymerizations were terminated at low percentage conversion. Structural characterization of copolymers was done by ¹H‐NMR and elemental analysis. Copolymer composition was determined using percentage nitrogen content. The reactivity ratios were r₁ (MMA) = 0.68 ± 0.06 and r₂ (CPI) = 0.46 ± 0.06. The intrinsic viscosity [η] was determined using an Ubbelohde suspension level viscometer. [η] decreased with increasing mole fraction of N‐(p‐carboxyphenyl) itaconimide or N‐(p‐carboxyphenyl) itaconamic acid in copolymers. Glass transition temperature and thermal stability of the copolymers were determined using DSC and thermogravimetric analysis, respectively. The glass transition temperature (T_g) as determined from DSC scans increased with increasing amounts of CPA or CPI in copolymers. A significant improvement in the char yield was observed upon copolymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1909–1915, 2005     

Synthesis and properties of polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene triblock copolymers

A series of well‐defined and property‐controlled polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐polystyrene (PS) triblock copolymers were synthesized by atom‐transfer radical polymerization, using 2‐bromo‐propionate‐end‐group PEO 2000 as macroinitiatators. The structure of triblock copolymers was confirmed by ¹H‐NMR and GPC. The relationship between some properties and molecular weight of copolymers was studied. It was found that glass‐transition temperature (T_g) of copolymers gradually rose and crystallinity of copolymers regularly dropped when molecular weight of copolymers increased. The copolymers showed to be amphiphilic. Stable emulsions could form in water layer of copolymer–toluene–water system and the emulsifying abilities of copolymers slightly decreased when molecular weight of copolymers increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 727–730, 2006     

Synthesis and characterization of the feed ratio of polyethylene oxide (0 ∼ 10 wt % PEO) in the nylon‐6/PEO copolymer system

In this work, we have synthesis nylon‐6/polyethylene oxide (PEO) copolymer system based on feed ratio of PEO (0～ 10 wt %) through condensation polymerization in a pilot scale. The structure of copolymer was confirmed by Fourier transform infrared (FTIR) spectroscopy and verified by ¹H nuclear magnetic resonance (¹HNMR). The thermal properties were investigated by differential scanning calorimetry (DSC) and indicated both melting temperature (T_m) and cold crystallization temperature (T_c) appearing unapparent decreased while increased PEO content in copolymers. The incorporation of PEO into the nylon‐6 chain reduced its tensile strength, modulus, and heat distortion temperature (HDT). The notched Izod impact strength of and ductility of the copolymers improved significantly as the PEO content was increased. The plasticizing effect was caused by the soft segments from PEO, which increases the mobility of the molecular chain in the copolymers. The results of mechanical tests agree closely with dynamic mechanical analysis (DMA) measurements. A rheological investigation revealed that neat nylon‐6 and its copolymer displayed similar behavior. The crystalline structure was examined by wide‐angle X‐ray diffraction (WAXD). The results demonstrate that the addition of a little PEO altered the crystallization from the α form to the γ form, mainly owing to the breaking parts of the original H‐bonds by the incorporation of ether groups. A mechanism of interaction between the amide and the ether group in nylon‐6/PEO copolymers is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011