Acrylonitrile copolymers containing guanidine oligomer: Synthesis and use for the preparation of nonleaching antimicrobial acrylic fibers

Nonleaching acrylic fibers with permanent antibacterial activity were prepared via a combination of copolymerization and a wet‐blend‐spinning method. Specifically, poly[acrylonitrile‐co‐modified poly(hexamethylene guanidine hydrochloride)] [poly(AN‐co‐M‐PHMG)] copolymers containing a covalently connected antibacterial guanidine oligomer were first synthesized via the precipitation copolymerization of acrylonitrile (AN) with a modified poly(hexamethylene guanidine hydrochloride) (M‐PHMG) macromonomer in water. Then, modified acrylic fibers were prepared from a mixture of the copolymer and commercial fiber‐grade AN terpolymer via a wet‐spinning process with dimethyl sulfoxide as the solvent. The influences of the reaction time, temperature, pH value of the medium, and amount of initiator on the copolymerization and the effect of the copolymer content on the mechanical properties and antibacterial activity of the modified acrylic fibers were investigated in detail. The results show that the M‐PHMG macromonomer exhibited a lower reactivity than AN. The poly(AN‐co‐M‐PHMG) copolymer with a PHMG content of 5.49% and an intrinsic viscosity of 11.2 dL/g could be synthesized under optimized conditions. With increasing copolymer content, the tensile strength of the modified acrylic fibers decreased slightly, and the antibacterial activity increased. The modified acrylic fibers with a copolymer content of 50% (i.e., a PHMG content of 2.75%) exhibited both good mechanical properties and excellent antibacterial activity. The additional antibacterial function would surely enlarge the applications of the fiber. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Biodegradable aliphatic–aromatic polyester with antibacterial property

Fast acting antibacterial property was introduced to aliphatic–aromatic polyester in the present work without sacrificing its compostability, thermal stability, and mechanical properties. Antibacterial poly(hexamethylene guanidine) hydrochloride (PHMG) was melt mixed with poly(butyleneadipate‐co‐terephthalate) (PBAT, also called Ecoflex) using a twin‐screw extruder in different amounts. The non‐reactive blending and uniform mixing was confirmed by nuclear magnetic resonance, gel permeation chromatography, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy analysis. The influence of antibacterial agent on compostability, mechanical properties, and thermal stability was studied. The presence of PHMG changed slightly the degradation profile of Ecoflex retaining the extent of degradation almost the same. The antibacterial PBAT showed high thermal stability (degradation starts around 330°C), stress at break 17–20 MPa, modulus 89–127 MPa, and elongation at break more than 700% depending upon the amount of PHMG. The combination of antibacterial activity with biodegradability makes this material a very interesting candidate for many different applications including packaging. POLYM. ENG. SCI., 56:1146–1152, 2016. © 2016 Society of Plastics Engineers     

Preparation of nonleaching antimicrobial polypropylene wax and its application in polypropylene

Antimicrobial polypropylene (PP) has been widely used. Its highly effective antimicrobial activities and nonleaching characteristics remain concerns. In this study, polypropylene wax (PPW) grafted with maleic anhydride was first prepared; this was followed by a melting reaction with polyhexamethylene guanidine hydrochloride (PHMG) to obtain antimicrobial PPW [polypropylene wax grafted with polyhexamethylene guanidine hydrochloride (PPW‐g‐PHMG)]. PPW‐g‐PHMG was then melt‐blended with PP to prepare antimicrobial PP. Fourier transform infrared spectra confirmed that PHMG was covalently bonded on the PPW chains, and transmission electron microscopy images showed a uniform distribution of PHMG in the PPW matrix. The resulting antimicrobial PP exhibited excellent antimicrobial activity against Escherichia coli. The ring‐diffusion test further disclosed its nonleaching characteristics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44190.     

Investigation on the reaction between polyhexamethylene guanidine hydrochloride oligomer and glycidyl methacrylate

Polyhexamethylene guanidine hydrochloride (PHMG) oligomer is attracting increasing attention for its highly efficient biocidal activity and nontoxicity. To make it bearing carbon‐to‐carbon double bonds and enlarge its application in production of antimicrobial materials via copolymerization, PHMG oligomer was modified via reaction with glycidyl methacrylate (GMA). The influence of reaction parameters on the conversion rate of GMA was investigated using ultraviolet absorption spectroscopy. The structures of PHMG oligomer before and after modification were characterized by Fourier transform infrared spectrometry, Raman spectrometry, nuclear magnetic resonance spectrometry, and electrospray ionization time‐of‐flight mass spectrometry. The results show that carbon‐to‐carbon double bond is successfully introduced into the modified PHMG oligomer. At a feeding molar ratio of GMA to PHMG of 1.0, the conversion rate of GMA reached up to 75% after 60 h of reaction at 60°C in dimethyl sulfoxide. Also, there is an activity difference in the different aminos of PHMG oligomer: the primary amino is ready to react with epoxy of GMA, while the guanidyl amino hardly reacts with GMA due to the p‐π conjugation. Furthermore, the modified PHMG oligomer was used as comonomer to synthesize acrylonitrile copolymer, showing excellent antimicrobial activity against Staphylococcus aureus. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of poly(hexamethylene terephthalate/hexamethylene oxamide) alternating copolyamide (alt-PA6T/62)

As a representative polyoxamide, poly(hexamethylene oxamide) (PA62) has good comprehensive performance. However, the high T_m (330°C) creates an obstacle for processing. To improve the processability of PA62, poly(hexamethylene terephthalate/hexamethylene oxamide) alternating copolyamide (alt-PA6T/62) was synthesized by hexamethylene diamine-terminated 6T6-diamine and dibutyl oxalate via solution/solid state polycondensation. Random copolyamide (ran-PA6T/62) was also synthesized for comparison. The structure and properties of the copolymer were analyzed by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Wide-angle X-ray diffraction (WAXD) and the saturated water absorption test. The NMR results confirm the alternating structure of alt-PA6T/62. The DSC and TGA results demonstrate that the novel alternating copolyamide alt-PA6T/62 (T_m = 321°C, T₅ = 420°C) exhibited better thermal properties than those of ran-PA6T/62 (T_m = 294°C, T₅ = 412°C). The saturated water absorption of alt-PA6T/62 was found to be 3.2 wt%. These results revealed that the novel alt-PA6T/62 had an alternating sequence distribution, showed a high melting point as well as good processability and thermal stability, and possessed low saturated water absorption and excellent dimensional stability.     

Synthesis and thermal decomposition of poly(dodecamethylene terephthalamide)

A kind of semiaromatic polyamide, poly(dodecamethylene terephthalamide) (PA12T) was synthesized via a polycondensation reaction of terephthalic acid and 1,12‐dodecanediamine. The structure of prepared PA12T was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (¹H‐NMR), and elemental analysis. The mechanical properties of PA12T were also studied. The thermal behavior of PA12T was determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Pyrolysis products and thermal decomposition mechanism of PA12T were analyzed by pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS). Melting temperature (T_m), glass transition temperature (T_g), and decomposition temperature (T_d) of PA12T are 310°C, 144°C, and 429°C, respectively. The Py‐GC/MS results showed that the pyrolysis products were mainly composed of 32 kinds of compounds, such as benzonitrile, 1,4‐benzenedicarbonitrile, N‐methylbenzamide, N‐hexylbenzamide, and aromatic compounds. The major pyrolysis mechanisms were β‐CH hydrogen transfer process, main‐chain random scission, and hydrolytic decomposition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

High‐temperature copolyamides obtained by the efficient transamidation of crystalline–crystalline polyamide blends

High‐performance thermoplastic composites based on semiaromatic polyamides are prime candidates for metal replacement in lightweight structural applications. However, the low ductility and toughness of semiaromatic polyamides remain major obstacles to their wider industrial application. In this study, we showed that novel random copolymers were formed by the unexpectedly efficient transamidation during the melt compounding of semicrystalline semiaromatic and aliphatic polyamides. Thus, homogeneous materials with a single glass transition and a high degree of crystalline order were obtained from blends of the semiaromatic poly(hexamethylene terephthalamide‐co‐isophthalamide) (PA6TI) with poly(hexamethylene adipamide) (PA66) or poly(hexamethylene sebacoamide) (PA610). By contrast, phase segregation and a less efficient transamidation was observed for cocompounded PA6TI and polylaurolactam (PA12). We attributed this to differences in the hydrogen‐bonding patterns of the two polyamides. This study opened the way for the preparation of novel high‐performance thermoplastic polyamides and composites through simple melt compounding. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44349.     

New poly(arylene ether)s containing phthalimidine group in the main chain

Five new poly(arylene ether)s containing phthalimidine group in the main chain and pendent trifluoromethyl group have been prepared by the reaction of 4,4′‐(bis‐4‐fluoro‐3‐trifluoromethylphenyl)benzene (BTF) with bisphenols. Different molar ratios of N‐phenyl‐3,3‐bis(4‐hydroxyphenyl)phthalimidine (PA) and 4,4′‐isopropylidenediphenol (BPA) have been used to generate different copolymers. The polymers obtained by step growth polymerization exhibited weight‐average molecular weight upto 134,000 g/mol with a polydispersity index of 2.1–2.4. The homopolymer from BTF and PA showed very high glass transition temperature of 258°C and outstanding thermal stability upto 536°C for 5% weight loss under nitrogen. The polymers were soluble in a wide range of organic solvents. Transparent thin films of these polymers exhibited tensile strengths upto 65 MPa and elongation at break upto 45% depending on the exact repeat unit structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Improving the throwing power of acidic zinc sulfate electroplating baths

The effect of some plating parameters, such as Zn²⁺ ion concentration, pH, current density, temperature and duration on the throwing power, as well as on the throwing index of acidic zinc sulfate baths has been investigated. The addition of p‐anisidine (PA) and/or sodium dodecylbenzenesulfonate (DBS) has been examined as a possible means of improving the uniformity of deposit distribution. The additives cause a substantial increase in the overpotential for the reduction of Zn²⁺ ions and consequently improve the throwing power of the baths. The throwing power increases by a factor of four in the presence of DBS and a factor of one‐and‐a‐half in the presence of PA. The inhibition of zinc reduction was assumed to occur via adsorption of the PA or DBS molecules on the cathode surface and the adsorption followed the Langmuir adsorption isotherm. The surface morphology of the zinc plated with and without the additives was examined by using scanning electron microscopy (SEM). © 2000 Society of Chemical Industry     

Crystal structure of uniaxially stretched bio-based polyamide 510 films

The crystal structure changes of PA510 films during uniaxially stretching at 80°C, 110°C, 140°C and 170°C had been investigated as a function of stretching ratio and stretching rate. The stress–strain relationship curves showed that the stress of the PA510 films gradually increased when the stretching ratio increased. The wide-angle X-ray diffraction results verified that only one distinct equator reflection of stretched films was clearly identified at 80°C, 110°C and 140°C, namely γ(100) at 2θ = 20.6°. However, when the stretching temperature reached 170°C, the γ(004), γ(006) and γ(008) crystal form appeared in the meridional direction at λ = 12. Combined with differential scanning calorimeter analysis, it was found that the Xc increased from 7% to 40% as a result of the strain induced crystallization phenomenon and the stretching promoted the appearance of γ crystal form. In addition, the increase in the crystallinity and the molecular chain orientation increased the strength of the PA510 films in the tensile direction. And it also found that the microcracks occurred in the stretched films at high stretching ratio (λ = 12).     

Crosslinking reaction and properties of two‐component waterborne polyurethane from terpene‐maleic ester type epoxy resin

A two‐component waterborne polyurethane (2K‐WPU) is prepared with the terpene‐maleic ester type epoxy resin‐based polyol dispersion and a hydrophilically modified hexamethylene diisocyanate tripolymer. Laser particle size analyzer and transmission electron microscopy are used to characterize the particle size distribution and the micromorphology of the 2K‐WPU. Crosslinking reaction kinetics of the 2K‐WPU is examined by fourier transform infrared spectrometry (FTIR) spectra. In the preliminary stage of the crosslinking reaction, it shows a very good fit with a second order reaction kinetics, and the apparent activation energy is 94.61 kJ mol^?1. It is also shown from the FTIR spectra that the complete crosslinking reaction of the 2K‐WPU needs 7 h at 70°C. The crosslinked products of the 2K‐WPU have good thermal resistant properties, with glass‐transition temperatures (T_g) in the range of 35–40°C and 10% weight loss temperatures (T_d) in the range of 275–287°C. The films obtained from the crosslinked products have good water‐resistance, antifouling, blocking resistance properties and impact strength of >50 cm, flexibility of 0.5 mm, adhesion of 1 grade, pencil hardness of HB‐2H. The pencil hardness and thermal‐resistant properties of the crosslinked products increase with the molar ratio of isocyanate (? NCO) group to hydroxyl (? OH) group. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Ultrathin Films from Fluorine Containing Polymers: Fabrication and Characterization

Monolayers and ultrathin films of some fluorine containing polymers were prepared by the Langmuir‐Blodgett (LB) technique. The polymers were obtained using two main synthetic approaches: firstly, polyamide (PA‐1) and polyimide (PI‐1) were prepared from direct polycondensation of 4,4′‐hexafluoroisopropylidenediphthalic anhydride and 4,4′‐hexafluoroisopropylidenedianiline in N‐methyl‐2‐pyrrolidone (NMP). The thermogravimetric analysis (TGA) for PI‐1 yielded 580°C by 1% weight loss. They formed stable monolayers with a collapse pressure of 62 mN/m and a collapse area of 0.20 nm² per repeat unit (R.U.) in the case of PA‐1, for PI‐1 the collapse pressure was 60 mN/m associated with a collapse area of 0.23 nm² per R.U. Secondly, poly[(maleic acid perfluorooctylamide‐imide)‐co‐ethylene] (PAPE) with fluorinated side chains was synthesized from poly[(maleic anhydride)‐co‐ethylene]. They formed stable monolayers too. Multilayer depositions onto various substrates were possible for all the synthesized polymers. LB films were characterized by ultra‐violet/visible spectroscopy (UV‐Vis), surface plasmon resonance (SPR), dielectric spectroscopy and atomic force microscopy (AFM). Gas phase polymerization of tetrafluoropropyl methacrylate (TFPM) was carried out in the presence of macroinitiator, poly[octadecene‐co‐(maleic anhydride)] modified with tert‐butyl hydroperoxide. Film thickness could be controlled on different hydrophobic substrates varying the reaction time.     

Flexible all‐aromatic polyesterimide films with high glass transition temperatures

A series all‐aromatic poly(esterimide)s with different molar ratios of N‐(3′‐hydroxyphenyl)‐trimellitimide (IM) and 4‐hydroxybenzoic acid (HBA) (IM/HBA = 0.3/0.7 and 0.7/0.3) was prepared with the aim to design flexible high T_g films. Melt‐pressed films, either from high molecular weight polymer or cured phenylethynyl precursor oligomers, exhibit T_gs in the range of 200 °C to 242 °C and are brittle. After a thermal stretching procedure, the films became remarkably flexible and very easy to handle. In addition, the thermally stretched 3‐IM/7‐HBA and 7‐IM/3‐HBA films show tensile strengths of 108 MPa and 169 MPa, respectively. Thermal treatment increased the T_g of 3‐IM/7‐HBA from 205 °C to 248 °C, whereas the T_g of 7‐IM/3‐HBA increased from 230 °C to 260 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 133, 44774.     

Synthesis and characterization of new cardo poly(ether imide)s derived from 9,9‐bis [4‐(4‐aminophenoxy)phenyl]xanthene

A series of new cardo poly(ether imide)s bearing flexible ether and bulky xanthene pendant groups was prepared from 9,9‐bis[4‐(4‐aminophenoxy)phenyl]xanthene with six commercially available aromatic tetracarboxylic dianhydrides in N,N‐dimethylacetamide (DMAc) via the poly(amic acid) precursors and subsequent thermal or chemical imidization. The intermediate poly(amic acid)s had inherent viscosities between 0.83 and 1.28 dL/g, could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough poly(ether imide) films which were further characterized by X‐ray and mechanical analysis. All of the poly(ether imide)s were amorphous and their films exhibited tensile strengths of 89–108 MPa, elongations at break of 7–9%, and initial moduli of 2.12–2.65 GPa. Three poly(ether imide)s derived from 4,4′‐oxydiphthalic anhydride, 4,4′‐sulfonyldiphthalic anhydride, and 2,2‐bis(3,4‐dicarboxyphenyl))hexafluoropropane anhydride, respectively, exhibited excellent solubility in various solvents such as DMAc, N,N‐dimethylformamide, N‐methyl‐2‐pyrrolidinone, pyridine, and even in tetrahydrofuran at room temperature. The resulting poly(ether imide)s with glass transition temperatures between 286 and 335°C had initial decomposition temperatures above 500°C, 10% weight loss temperatures ranging from 551 to 575°C in nitrogen and 547 to 570°C in air, and char yields of 53–64% at 800°C in nitrogen. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Silver nanoparticle deposition on hydrophilic multilayer film surface and its effect on antimicrobial activity

Silver nanoparticles were deposited on the surface of the external polyamide 6 (PA6) layer of a multilayer film, by spraying and ultrasound‐assisted methods. The effect of silver nanoparticles content and deposition method on the mechanical and optical properties of the multilayered films as well as the efficiency of silver ion release and their fungicidal characteristics were evaluated. Itaconic (IA) and Maleic anhydride (MA) were used as adhesion promoter agents for preventing the agglomeration of the silver nanoparticles and for improving the adhesion to the PA6 polymer surface. With IA, a homogeneous distribution of silver nanoparticles on the PA6 surface was achieved. The silver ion release and biocide effect of the multilayered films was found to be dependent on the anhydride type and on the deposition method used. The multilayer films with a layer of PA6‐silver nanocomposite demonstrated good fungicidal activity, specifically against fungus Aspergillius niger. The observed results could be applied in the design of industrial films for packaging. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Solid‐state polymerization and characterization of a copolyamide based on adipic acid, 1,4‐butanediamine,and 2,5‐furandicarboxylic acid

2,5‐Furandicarboxylic acid (FDCA) is a promising biobased alternative material to terephthalic acid. In this study, three types of poly(butylene adipamide) (PA‐4,6) containing 10, 20, and 30 mol % of poly(butylene‐2,5‐furandicarboxylamide) (PA‐4,F) were synthesized through consecutive prepolymerization and solid‐state polymerization (SSP). The incorporation of a 10 mol % PA‐4,F component into PA‐4,6 resulted in slight increases in the intrinsic viscosity (IV) and glass‐transition temperature (T_g) after 12 h of SSP at 220 °C. When the SSP temperature and reaction time increased, IV increased proportionally. The highest IV value of 0.75 was obtained by 48 h of SSP at 240 °C, whereas increases in the PA‐4,F content to 20 and 30 mol % gave rise to decreases in IV, T_g, and melting temperature; this interrupted the increase in SSP temperature. The thermal decomposition temperature of the PA‐4,F‐incorporated polyamide was lower than that with PA‐4,6 because of the lower thermal stability of the FDCA component. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43391.     

Preparation of heat‐resistant branched poly(styrene‐alt‐NPMI) by ATRP with divinylbenzene as the branching agent

Heat‐resistant branched poly(styrene‐alt‐NPMI) has been prepared via atom transfer radical polymerization (ATRP) of styrene (St) and N‐phenyl maleimide (NPMI) with divinylbenzene (DVB) as the branching agent in anisole at 80°C. Gas chromatography (GC) was used to determine the conversion of the reactants. Triple detection gel permeation chromatography (TD‐GPC) was used to analyze the copolymers. The results show that the polymerization yields primary chains predominately in the early stages and the formation of branched molecules occurs mainly when conversion is higher than 50%. As expected, higher dosage of DVB in our investigation range favors the formation of polymers with higher degree of branching. All the resulting branched poly(styrene‐alt‐NPMI)s have glass transition temperature (T_g) above 175°C, extrapolated initial weight loss temperature (T_i) above 410°C and statistic heat‐resistant index above 200°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Semiaromatic polyamide poly(hexamethylene terephthalamide)‐co‐polycaprolactam: Thermal and flame‐retardant properties

The poly(hexamethylene terephthalamide)‐co‐polycaprolactam (PA6T/6; 50:50) copolymer was synthesized with a reactive extrusion method and subsequently mixed with a certain content of glass fibers (GFs) and different ratios of flame‐retardant aluminum diethyl phosphinate (AlPi) to fabricate a series of composites. These resulting composites were found to have excellent mechanical (tensile strength = 119–154 MPa) and thermal properties (heat‐deflection temperature = 263–293 °C). It is particularly worth mentioning that the value of the limiting oxygen index reached 29.5% and a UL‐94 V‐0 rating (1.6 mm) was achieved with the addition of 20 portions of AlPi. Also, the values of the peak heat‐release rate and total heat release in cone calorimetry were found to decrease with the addition of the flame‐retardant AlPi, which acted mainly as a flame inhibitor in the gas phase. Through visual observation, scanning electron microscopy after cone calorimetry testing, and thermogravimetric analysis, the condensed‐phase flame‐retardant mechanism of the PA6T/6–GF–AlPi system was confirmed to have a synergetic role. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46451.     

Potential in situ preparation of aliphatic polyamide‐based nanocomposites: The organoclay‐polyamide salt interaction

In situ intercalative polycondensation is applied for the preparation of polyamide (PA) n,6–clay nanocomposites, namely poly(ethylene adipamide) (PA 2,6), poly(hexamethylene adipamide) (PA 6,6), and poly(dodecamethylene adipamide) (PA 12,6). For this purpose, two different polymerization routes are considered; a low‐temperature melt polymerization technique and the conventional solution‐melt one. Under the specific experimental conditions, lack of clay exfoliation is detected through XRD measurements, which is proved irreversible even when twin‐screw extrusion is attempted as an additional step. The resulting PA n,6–clay structures are found dependent on the diamine moiety length; more specifically, an intrinsic interaction between the polyamide monomer and the organoclay surfactant is indicated. An ion exchange occurs between the two competitive species, that is, diamine and surfactant cations, leading to flocculated clay structures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of biodegradable poly(ester‐urethanes) based on bacterial poly(R‐3‐hydroxybutyrate)

A series of poly(R‐3‐hydroxybutyrate)/poly(ε‐caprolactone)/1,6‐hexamethylene diisocyanate‐segmented poly(ester‐urethanes), having different compositions and different block lengths, were synthesized by one‐step solution polymerization. The molecular weight of poly(R‐3‐hydroxybutyrate)‐diol, PHB‐diol, hard segments was in the range of 2100–4400 and poly(ε‐caprolactone)‐diol, PCL‐diol, soft segments in the range of 1080–5800. The materials obtained were investigated by using differential scanning calorimetry, wide angle X‐ray diffraction and mechanical measurements. All poly(ester‐urethanes) investigated were semicrystalline with T_m varying within 126–148°C. DSC results showed that T_g are shifted to higher temperature with increasing content of PHB hard segments and decreasing molecular weight of PCL soft segments. This indicates partial compatibility of the two phases. In poly(ester‐urethanes) made from PCL soft segments of molecular weight (M_n ≥ 2200), a PCL crystalline phase, in addition to the PHB crystalline phase, was observed. As for the mechanical tensile properties of poly(ester‐urethane) cast films, it was found that the ultimate strength and the elongation at the breakpoint decrease with increasing PHB hard segment content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 703–718, 2002