Effect of 3‐aminopropyltriethoxysilane on properties of poly(butyl acrylate‐co‐maleic anhydride)/silica hybrid materials

The transparent poly(butyl acrylate‐co‐maleic anhydride)/silica [P(BA‐co‐MAn)/SiO₂] has been successfully prepared from butyl acrylate‐maleic anhydride copolymer P(BA‐co‐MAn) and tetraethoxysilane (TEOS) in the presence of 3‐aminopropyltriethoxysilane (APTES) by an in situ sol–gel process. Triethoxysilyl group can be readily incorporated into P(BA‐co‐MAn) as pendant side chains by the aminolysis of maleic anhydride unit of copolymer with APTES, and then organic polymer/silica hybrid materials with covalent bonds between two phases can be formed via the hydrolytic polycondensation of triethoxysilyl group‐functionalized polymer with TEOS. It was found that the amount of APTES could dramatically affect the gel time of sol–gel system, the sol fraction of resultant hybrid materials, and the thermal properties of hybrid materials obtained. The decomposition temperature of hybrid materials and the final residual weight of thermogravimetry of hybrid both increase with the increasing of APTES. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the morphology of hybrid materials prepared in the presence of APTES was a co‐continual phase structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 419–424, 1999     

Preparation of poly(methyl methacrylate‐co‐maleic anhydride)/SiO2?TiO2 hybrid materials and their thermo‐ and photodegradation behaviors

The optically transparent poly(methyl methacrylate‐co‐maleic anhydride) P(MMA‐co‐MA)/SiO₂? TiO₂ hybrid materials were prepared using 3‐aminopropyl triethoxysilane as a coupling agent for organic and inorganic components. Real‐time FTIR was used to monitor the curing process of hybrid sol, indicating that imide group formation decreased with increasing titania content. scanning electron microscopy, atomic force microscopy, and differential scanning calorimetry results confirmed their homogeneous inorganic/organic network structures. TGA analysis showed that incorporated titania greatly prohibits the thermodegradation of hybrid films, especially at the content of 5.3 wt %, showing an increase of about 32.6°C at 5% loss temperature in air. The UV degradation behavior of P(MMA‐co‐MA) studied by quasi‐real‐time FTIR showed that TiO₂ incorporated in the hybrid network provides a photocatalytic effect rather than a UV‐shielding effect. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1714–1724, 2005     

Effect of 3‐aminopropyltriethoxysilane and N,N‐ dimethyldodecylamine as modifiers of Na+‐montmorillonite on SBR/organoclay nanocomposites

In this study, styrene butadiene rubber (SBR)/organoclay nanocomposites were manufactured using the latex method with 3‐aminopropyltriethoxysilane (APTES) and N,N‐dimethyldodecylamine (DDA) as modifiers. The layer‐to‐layer distance of the silicates was observed according to each manufacturing process for APTES as the modifier using the X‐ray diffraction (XRD) method. From the XRD results and the TEM images, the dispersion of the silicates impoved for both APTES‐MMT and DDA‐MMT, and the dispersion of the silicates with the DDA modifier improved more than the APTES modifier. The SBR/DDA‐MMT compound exhibited the fastest scorch time, optimal vulcanization time, and cure rate. The dynamic viscoelastic properties of the SBR/APTES‐MMT compound were measured according to the change in the strain amplitude in order determine if a covalent bond was formed between APTES and bis(triethoxysilyl‐propyl)tetrasulfide (TESPT). The mechanical properties of the SBR/DDA‐MMT nanocomposite improved more than the SBR/APTES‐MMT composite because the vulcanization effects of alkylamine and the dispersion of silicates within the rubber matrix were relatively good. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Working mechanism of a high temperature (200°C) synthetic cement retarder and its interaction with an AMPS®‐based fluid loss polymer in oil well cement

A copolymer comprising of 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS®) and itaconic acid (molar ratio 1 : 0.32) was synthesized by aqueous free radical polymerization and probed as high temperature retarder for oil well cement. Characteristic properties of the copolymer including molar masses (M_w and M_n), polydispersity index and anionic charge amount were determined. The copolymer possesses a M_w of ～ 2 × 10⁵ g/mol and is highly anionic. HT/HP consistometer tests confirmed effectiveness of the retarder at temperatures up to 200°C. The working mechanism of NaAMPS®‐co‐itaconic acid was found to rely exclusively on its huge calcium binding capacity (5 g calcium/g copolymer). It reduces the amount of freely dissolved, nonbound calcium ions present in cement pore solution and thus hinders the growth of cement hydrates because of lack of calcium. The value for the calcium binding capability is 46 times higher than the stoichiometric amount per ? COO^? functionality. Consequently, calcium also coordinates to other donor atoms present in the retarder. NaAMPS®‐co‐itaconic acid also adsorbs onto cement, as was evidenced by TOC analysis of cement filtrates, zeta potential measurement and decreased rheology of cement pastes. However, adsorption plays no role in the retarding mechanism of this copolymer. Combination of NaAMPS®‐co‐itaconic acid retarder with a common CaAMPS®‐co‐NNDMA fluid loss additive (FLA) revealed that competitive adsorption on cement between these two admixtures occurs. The retarder fills interstitial adsorption sites on cement located between those occupied by the larger FLA molecules. In consequence, fewer amounts of CaAMPS®‐co‐NNDMA can adsorb and its effectiveness is reduced. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of poly[(2‐oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether‐co‐N‐phenylmaleimide] and its miscibility in blends with styrene‐acrylonitrile or poly(vinyl chloride)

The aim of the study was to investigate the synthesis of a copolymer bearing cyclic carbonate and its miscibility with styrene/acrylonitrile copolymer (SAN) or poly(vinyl chloride) (PVC). (2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether (OVE) as a monomer was synthesized from glycidyl vinyl ether and CO₂ using quaternary ammonium chloride salts as catalysts. The highest reaction rate was observed when tetraoctylammonium chloride (TOAC) was used as a catalyst. Even at the atmospheric pressure of CO₂, the yield of OVE using TOAC was above 80% after 6 h of reaction at 80°C. The copolymer of OVE and N‐phenylmaleimide (NPM) was prepared by radical copolymerization and was characterized by FTIR and ¹H‐NMR spectroscopies and differential scanning calorimetry (DSC). The monomer reactivity ratios were given as r₁ (OVE) = 0.53–0.57 and r₂ (NPM) = 2.23–2.24 in the copolymerization of OVE and NPM. The films of poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were cast from N‐dimethylformamide. An optical clarity test and DSC analysis showed that poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were both miscible over the whole composition range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1809–1815, 2000     

Anhydrous proton conductivity and chemical oxidation stability of amphoteric N‐methyl‐5‐vinyltetrazole‐based copolymers

Poly(N‐methyl‐5‐vinyltetrazole‐co‐5‐vinyltetrazole) (P(MVT‐VT)) with different N‐methyl‐5‐vinyltetrazole (MVT) contents was synthesized via the method of click chemistry and the methylation thereafter. The chemical structure of the copolymers was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Compared with that of poly(5‐vinyltetrazole) (PVT), the solubility of P(MVT‐VT) is improved. The chemical oxidation stability of the copolymer increases with increasing substitution value of the methyl group on the tetrazole ring. H₃PO₄ and imidazole (Imi) blended PVT and P(MVT‐VT) composite membranes were prepared. The proton conductivity of P(MVT‐VT)/H₃PO₄ and P(MVT‐VT)/Imi composite membranes decreases with increasing MVT content. After the methylation of the tetrazole ring, the amphoteric properties of P(MVT‐VT) is improved, which means either acid or base blended P(MVT‐VT) can exhibit suitable proton conductivity. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Optimization and effect of 3‐aminopropyltriethoxysilane content on the properties of bentonite‐filled ethylene propylene diene monomer composites

The effect of silane coupling agent, 3‐aminopropyltriethoxysilane (APTES) content on the curing, tensile, swelling, and morphological properties of bentonite (Bt)‐filled ethylene‐propylene‐diene monomer (EPDM) composite was studied. The EPDM composites containing constant Bt composition of 30 phr and various APTES content (0, 1, 3, and 5 phr) were prepared using a laboratory scale two‐roll mill. The result showed that the cure time (t₉₀) and scorch time (t_S2) were shortened, whilst, the cure rate index (CRI), the maximum (M_H) and minimum (M_L) torque increased with increasing APTES content. The experimental results revealed that the optimum APTES content that led to the highest tensile and swelling properties was 3 phr. The presence of APTES greatly improved the dispersion of Bt in EPDM matrix and enhanced the interfacial interaction between EPDM and Bt. Morphological study through scanning electron microscopy revealed the enhanced adhesion between EPDM and Bt in the presence of 3 phr APTES. POLYM. COMPOS., 33:1993–2000, 2012. © 2012 Society of Plastics Engineers     

Phase‐separation prevention and performance improvement of poly(vinyl acetate)/TEOS hybrid using modified sol‐gel process

The formation of covalent bonds between silanols in copolymer and those in silica prevents organic–inorganic phase separation. Two series of hybrid composite materials, poly(vinyl acetate‐co‐vinyl trimethoxysilane)/TEOS and poly[vinyl acetate‐co‐3‐(trimethoxysilyl)propyl methacrylate]/TEOS, were fabricated using a modified sol‐gel process. The hybrids were transparent. Two kinds of silane coupling agents, vinyl trimethoxysilane (VTS) and 3‐(trimethoxysilyl)propyl methacrylate (γ‐MPS), were used to prevent macrophase separation through formation of covalent bonds. Thermal analysis showed that γ‐MPS was more effective than VTS for the formation of covalent bonds. Enhancement of thermal stability of the hybrids was investigated by thermogravimetric analysis. Photomicrographs of scanning electron microscopy and images of atomic force microscopy indicated that inorganic silica particles were homogeneously dispersed in less than 50 nm in organic matrix. The morphological properties of hybrids were strongly dependent on the organic–inorganic composition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2310–2318, 2001     

Studies on damping properties of P(MMA‐AN)/P(EA‐nBA) LIPNs

Using a two‐stage emulsion polymerization method, a series of poly(methyl methacrylate‐acrylonitrile)/poly(ethyl acrylate‐n‐butyl acrylate) [P(MMA‐AN)/P(EA‐nBA)] latex interpenetrating polymer networks (LIPNs) were synthesized by varying AN content, ratio of network I/network II, crosslinker content, and introducing chain transfer agent. The damping properties of the LIPNs were investigated using a Rheovibron Viscoelastometer. The results indicates that a suitable content of AN can improve the damping properties of the LIPNs. Three kinds of fillers were incorporated into the LPINs, respectively, to measure the change in the damping properties. Mica and TiO₂ both increased the damping properties of the LIPNs over the wide temperature range. For TiO₂‐filled LIPNs, it was observed that the tan δ values exceeded 0.4 over 112.6°C temperature range from −50 to 72.6°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 722–727, 2000     

Effect of polyethylene glycol on the properties of styrene‐butadiene rubber/organoclay nanocomposites filled with silica and carbon black

Polyethyene glycol (PEG) is widely used as a dispersing agent and can also be used to prevent the adsorption of ingredients on the surface of silica. From the XRD results, PEG that was used as the dispersing agent on the SBR/organoclay compound filled with silica and carbon black (CB) was intercalated between the organoclay layer. Additionally, the interactions with the PEG differed depending on whether 3‐aminopropyltriethoxysilane (APTES) or N,N‐dimethyldodecylamine (DDA) were used as clay modifiers. When PEG was added, the T_g of the SBR/silica/APTES‐MMT compound increased through the formation of hydrogen bonds between the ether linkages of PEG and the hydroxyl groups of APTES. For the SBR/silica/DDA‐MMT compound with PEG, slippage occurred between the silicate, and DDA because of the alkyl chain of DDA. The SBR/silica/APTES‐MMT/CB compound with PEG exhibited the highest T_g value and the highest bound rubber content, with high modulus values at 100 and 300%. The SBR/silica/DDA‐MMT/CB compound had the best properties in terms of the wet skid resistance and the rolling resistance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Grafting of sulfonated monomer onto an amino‐silane functionalized 2‐aminoterephthalate metal − organic framework via surface‐initiated redox polymerization: proton‐conducting solid electrolytes

A post‐polymerization method for metal–organic frameworks (MOFs) has been developed to produce super‐acidic solid nanoparticles. Thus, the NH₂MIL‐53(Al) MOF was functionalized with (3‐aminopropyl)triethoxysilane (APTES) from amine groups to yield active site anchored MOF nanoparticles. Then, sulfonated polymer/MOF hybrid nanoparticles were prepared by redox polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (MOF‐g‐PAMPS), initiated onto the surfaces of aminopropyl‐functionalized NH₂MIL‐53(Al) nanoparticles. The synthesis and modification of NH₂MIL‐53(Al) nanoparticles were characterized by Fourier transform infrared (FTIR) spectroscopy and TGA. FTIR and TGA results indicated that APTES modifier agent and AMPS monomer were successfully grafted onto the MOF nanoparticles. The grafting efficiency of PAMPS polymer onto the MOF nanoparticles was estimated from TGA thermograms to be 33%. Also, sulfonated polymer/MOF hybrid nanoparticles showed a proton conductivity as high as 4.9 × 10^?5 S cm^?1. Nitrogen adsorption of modified NH₂MIL‐53(Al) showed also a decrease in pore volume. The morphology and crystalline structure of MOF nanoparticles before and after the modification processes were studied by SEM and XRD, respectively. © 2015 Society of Chemical Industry     

Synthesis and characterization of alkali‐modified styrene‐maleic anhydride copolymer for dispersion of TiO2

A copolymer of styrene and maleic anhydride was synthesized by free radical polymerization at 80°C using N,N‐dimethylformamide (DMF) as solvent and benzoylperoxide as initiator. The monomer feed ratio of styrene to maleic anhydride was varied in the range of 1 : 1 : to 3 : 1. The polymer yield was found to decrease with increase in styrene in the feed. The molecular weight of copolymers which were formed by taking styrene to maleic anhydride ratio of 1 : 1, 2 : 1, and 3 : 1, as determined by Ostwald Viscometery were about 1862, 2015, and 2276 respectively. The acid values of abovementioned three copolymers were found to be 480, 357, and 295, respectively. The typical viscosity values of 20% solids in ammonical solution of copolymers formed by taking feed ratios of Sty : MAn as 1 : 1 and 2 : 1 were 26 and 136 cp, respectively. For the feed ratio 3 : 1, a gel was formed. The synthesized copolymers were hydrolyzed by alkalis, namely, NaOH, KOH, and NH₄OH. The dispersing ability of hydrolyzed styrene‐maleic anhydride (SMA) copolymers for dispersion of titanium dioxide was studied. The modified SMA copolymers were found to be effective dispersants for TiO₂. Among the three alkalis studied, the Sodium salts of SMA were found to give better dispersion. The copolymer having a 1 : 1 feed ratio showed the best dispersing ability for TiO₂ particles among the three ratios studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3194–3205, 2007     

Variations of the glass‐transition temperature in the imidization of poly(styrene‐co‐maleic anhydride)

The imidization of poly(styrene‐co‐maleic anhydride) (SMA) was conducted, and the glass‐transition temperatures (T_g's) of the resulting products were measured with differential scanning calorimetry. The contributions from functional groups of maleic anhydride, N‐phenylmaleamic acid, and N‐phenylmaleimide to T_g were examined. T_g increased in the order of SMA < styrene–N‐phenyl maleimide copolymer < styrene–N‐phenyl maleamic acid copolymer and followed the Fox equation. T_g of the imidized products of SMA could be controlled by the conversions of both ring‐opening and ring‐closing reactions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2418–2422, 2007     

Preparation and self‐assembly of poly(diglycidyl maleate‐co‐stearyl methacrylate)

Poly(diglycidyl maleate‐co‐stearyl methacrylate) (P(DGMA‐co‐SMA)) with reactive epoxy groups was synthesized by reaction of poly(maleic anhydride‐co‐stearyl methacrylate) (P(MA‐co‐SMA)) and epichlorohydrin. The effect of precipitant on self‐assembly behaviors of the resultant copolymer was investigated. It was found that vesicles and nanotubule liked aggregates can be obtained through self‐assembly of P(DGMA‐co‐SMA) in THF solution using CH₃CH₂OH (EtOH) as precipitant while spheral aggregates can be obtained using H₂O as precipitant. The mechanism of the self‐assembly behavior was discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis,characterization, and properties of polystyrene/SiO2 hybrid materials via sol–gel process

Isocyanate‐functionalized polystyrene (P(St‐co‐TMI)) was successfully synthesized by solution free radical polymerization, which was then used to react with (3‐aminopropyl) triethoxysilane (APTES) to prepare a precursor of polystyrene/inorganic composites (PS/SiO₂). To obtain PS/SiO₂ composites with chemical bond, the precursor was mixed with triethoxysilane (TEOS) under the sol–gel reaction condition. The chemical bond between the PS and SiO₂ particles made the crosslink network more stable and avoided aggregation compared with the physical connection and barely mechanical mixing. The Fourier transform infrared (FT‐IR) results indicate that the isocyanate group ( NCO) was completely reacted with APTES. The field‐emission scanning electron microscopy results show that the morphology of composites and the distribution of the particles, which exhibit good compatibility between organic and inorganic phases, and the inorganic particles show good spatial uniformity. The differential scanning calorimetry shows that the glass transition temperature (T_g) of the PS/SiO₂ composites was shifted to high temperature when the amount of APTES increased. The thermal degradation temperature of the PS/SiO₂ composites increases with the increasing of APTES content. Master curves at 200°C are constructed for the storage and loss modulus as well as complex viscosity. POLYM. COMPOS. 36:482–488, 2015. © 2014 Society of Plastics Engineers     

Combination of double‐modified clay and polypropylene‐graft‐maleic anhydride for the simultaneously improved thermal and mechanical properties of polypropylene

Double‐modified montmorillonite (MMT) was first prepared by covalent modification of MMT with 3‐aminopropyltriethoxysilane and then intercalation modification by tributyl tetradecyl phosphonium ions. The obtained double‐modified MMT was melt compounded with polypropylene (PP) to obtain nanocomposites. The dispersion of the double‐modified MMT in PP was found to be greatly improved by the addition of PP‐graft‐maleic anhydride (PP‐g‐MA) as a “compatibilizer,” whose anhydride groups can react with the amino groups on the surface of the double‐modified MMT platelets and thus improve the dispersion of MMT in PP. Fourier transform infrared, X‐ray diffraction, transmission electron microscopy, thermogravimetric analysis, scanning electron microscopy, and tensile test were used to characterize the structure of the double‐modified MMT, morphology, and the thermal and mechanical properties of the nanocomposites. The results show that PP‐g‐MA promotes the formation of exfoliated/intercalated morphology and obviously increases the thermal properties, tensile strength, and Young's modulus of the PP/double‐modified MMT nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Sol‐Gel Materials, 1. Synthesis and Hydrolytic Condensation of New Cross‐Linking Alkoxysilane Methacrylates and Light‐Curing Composites Based upon the Condensates

New methacryloyloxyalkylaminoalkylalkoxysilanes have been synthesised by Michael addition of the corresponding acryloyloxyalkyl methacrylates with (3‐aminopropyl)triethoxysilane (APTES). Low‐viscosity polycondensates have been formed by hydrolysis and condensation of these silanes in the presence of ammonium fluoride (NH₄F). The reaction of APTES with the addition product of succinic or glutaric anhydride with glycerol dimethacrylate results in the formation of new dimethacrylate‐functionalised 3‐amidopropyltriethoxysilanes. The hydrolytic condensation of these silanes was carried out in the presence of 0.5 M HCl. The hydrolysis and condensation of the silanes have been studied by ²⁹Si NMR spectroscopy. Cross‐linked inorganic‐organic materials have been obtained by free‐radical photopolymerisation of the polycondensates and their mixtures in the presence of camphorquinone and ethyl 4‐(dimethylamino)benzoate with visible light (VL). The synthesised polycondensates enable the preparation of diluent‐free composites. The mechanical properties of VL‐cured polycondensates and composites have been investigated.     

Crystallization behavior and mechanical strength of poly(butylene succinate‐co‐ethylene glycol)‐based nanocomposites using functionalized multiwalled carbon nanotubes

Biodegradable poly(butylene succinate‐co‐ethylene glycol) (PBSG)/multiwalled carbon nanotube (MWCNT) nanocomposites were successfully prepared through physical blending and silication between PBSG and acyl aminopropyltriethoxysilane functionalized multiwalled carbon nanotube (MWCNT‐APTES). Nuclear magnetic resonance (NMR) spectra observations revealed that the PBSG chains were covalently attached to the MWCNT‐APTES by hydrolysis. PBSG/MWCNT‐APTES nanocomposites after hydrolysis showed excellent interfacial compatibility between PBSG and MWCNT‐APTES, which was helpful for the dispersion of MWCNT in the PBSG matrix. The incorporation of MWCNT‐APTES accelerated the crystallization of PBSG in the nanocomposites for both approaches of physical blending and hydrolysis due to the heterogeneous nucleation effect of MWCNT while the crystal structure of PBSG was remained. Furthermore, the crystallization rate of PBSG in PBSG/MWCNT‐APTES nanocomposites after hydrolysis was slower than that in the nanocomposite by physical blend. The tensile strength and modulus of the nanocomposites increased about 6% and 11% with the addition of only 1 wt% MWCNT‐APTES compared with that of neat PBSG, and was larger for the PBSG/MWCNT‐APTES nanocomposites after hydrolysis. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Synthesis and characterization of conducting copolymer of Trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene with EDOT

Ferrocene‐substituted conducting polymer namely poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene‐co‐3,4‐ethylenedioxythiophene) [P(MTFE‐co‐EDOT)] was synthesized and its electrochromic properties were studied. Monomer, MTFE, was obtained using 2‐(ferrocenyl)ethene and 3‐methyl‐4‐bromothiophene. The structure of monomer was determined via Fourier transform infrared spectroscopy (FTIR), ¹H‐NMR, and ¹³C‐NMR techniques. The copolymer was synthesized using this monomer and EDOT. The resulting copolymer P(MTFE‐co‐EDOT) was characterized by cyclic voltammetry, FTIR, scanning electron microscopy, atomic force microscopy, and UV–vis spectroscopy. The conductivity measurements of copolymer and PEDOT were accomplished by the four‐probe technique. Although poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene) [P(MTFE)] reveals no electrochromic activity, its copolymer with EDOT has two different colors (violet and gray). Band gap (E_g) and λ_max of P(MTFE‐co‐EDOT) were determined. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Miscibility and crystallization kinetics of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ poly(methyl methacrylate) blends

The miscibility and crystallization kinetics of the blends of random poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐co‐HV)] copolymer and poly(methyl methacrylate) (PMMA) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that P(HB‐co‐HV)/PMMA blends were miscible in the melt. Thus the single glass‐transition temperature (T_g) of the blends within the whole composition range suggests that P(HB‐co‐HV) and PMMA were totally miscible for the miscible blends. The equilibrium melting point (T°_m) of P(HB‐co‐HV) in the P(HB‐co‐HV)/PMMA blends decreased with increasing PMMA. The T°_m depression supports the miscibility of the blends. With respect to the results of crystallization kinetics, it was found that both the spherulitic growth rate and the overall crystallization rate decreased with the addition of PMMA. The kinetics retardation was attributed to the decrease in P(HB‐co‐HV) molecular mobility and dilution of P(HB‐co‐HV) concentration resulting from the addition of PMMA, which has a higher T_g. According to secondary nucleation theory, the kinetics of spherulitic crystallization of P(HB‐co‐HV) in the blends was analyzed in the studied temperature range. The crystallizations of P(HB‐co‐HV) in P(HB‐co‐HV)/PMMA blends were assigned to n = 4, regime III growth process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3595–3603, 2004