Phase behavior,crystallization, and nanostructures in thermoset blends of epoxy resin and amphiphilic star‐shaped block copolymers

This article reports thermoset blends of bisphenol A‐type epoxy resin (ER) and two amphiphilic four‐arm star‐shaped diblock copolymers based on hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO). 4,4′‐Methylenedianiline (MDA) was used as a curing agent. The first star‐shaped diblock copolymer with 70 wt % ethylene oxide (EO), denoted as (PPO‐PEO)₄, consists of four PPO‐PEO diblock arms with PPO blocks attached on an ethylenediamine core; the second one with 40 wt % EO, denoted as (PEO‐PPO)₄, contains four PEO‐PPO diblock arms with PEO blocks attached on an ethylenediamine core. The phase behavior, crystallization, and nanoscale structures were investigated by differential scanning calorimetry, transmission electron microscopy, and small‐angle X‐ray scattering. It was found that the MDA‐cured ER/(PPO‐PEO)₄ blends are not macroscopically phase‐separated over the entire blend composition range. There exist, however, two microphases in the ER/(PPO‐PEO)₄ blends. The PPO blocks form a separated microphase, whereas the ER and the PEO blocks, which are miscible, form another microphase. The ER/(PPO‐PEO)₄ blends show composition‐dependent nanostructures on the order of 10?30 nm. The 80/20 ER/(PPO‐PEO)₄ blend displays spherical PPO micelles uniformly dispersed in a continuous ER‐rich matrix. The 60/40 ER/(PPO‐PEO)₄ blend displays a combined morphology of worm‐like micelles and spherical micelles with characteristic of a bicontinuous microphase structure. Macroscopic phase separation took place in the MDA‐cured ER/(PEO‐PPO)₄ blends. The MDA‐cured ER/(PEO‐PPO)₄ blends with (PEO‐PPO)₄ content up to 50 wt % exhibit phase‐separated structures on the order of 0.5–1 μm. This can be considered to be due to the different EO content and block sequence of the (PEO‐PPO)₄ copolymer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 975–985, 2006     

Eutectic crystallization and hydrogen bonding interactions in polymer/surfactant blends

The unusual eutectic crystallization behavior in the poly(ε‐caprolactone) (PCL) and 3‐pentadecylphonel (PDP) binary blends was investigated by differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy. A eutectic system was found with the eutectic composition at 60 wt % PDP and the eutectic melting temperature at 35 °C. The melting process of the blend at the eutectic composition was studied by in situ FTIR. The concurrence of the melting of PCL and PDP crystallites and the sequential formation of hydrogen bonding interaction between PDP molecules and PCL chains were traced. It was also found that a further increase in temperature above the eutectic melting temperature would impair the hydrogen bonding and increase the content of nonassociated phenol hydroxyl group. The semicrystalline morphology of blends affected by the composition was also investigated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1015–1023, 2009     

Copolymer architecture effects on the morphology and surface performance of epoxy thermosets containing fluorinated block copolymers

The architecture effects on phases and surface enrichment behaviors of epoxy nanocomposites containing fluorinated block copolymers are investigated by the incorporation of two novel copolymers composed of poly (2, 2, 2‐trifluoroethyl methacrylate) (PTFEMA) and poly (ε‐caprolactone) (PCL), PCL‐b‐PTFEMA and PTFEMA‐b‐PCL‐b‐PTFEMA, with identical molecular weight and composition. These fluorinated copolymers in epoxy display distinguished self‐assembled structures, as evidenced by dynamic laser scattering and scanning electron microscopy measurements. Static contact angle detection suggests that the nanocomposites display an obvious improvement in surface water repellency and a reduction in surface free energy. The enhancement in surface hydrophobicity is attributed to the enrichment of PTFEMA blocks at the nanocomposite surface and to the formation of the specific surface morphology, as confirmed by atomic force microscopy. The different architectures of the two block copolymers give rise to differences in phase‐structures, and the ultimate surface performances of composites. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1037–1045     

Engineering superior toughness in commercially viable block copolymer modified epoxy resin

The microstructure and mechanical properties of a block copolymer modified commercial thermoset plastic formed from a bisphenol-A based epoxy and a bio-derived amine hardener (Cardolite^® NC-541LV) were investigated. A series of poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) diblock copolymers was synthesized at fixed composition (31 ± 1% by volume PEO) and varying molecular weight expanding on a commercially available PEO-PBO compound marketed by the Dow Chemical Company under the trade name FORTEGRA™ 100; direct application of any of these block copolymers resulted in little improvement of the poor fracture toughness of the cured material. Modification of the resin formulation and curing protocol led to the development of well-defined spherical and branched worm-like micelles containing a PBO core and PEO corona in the cross-linked products as evidenced by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) measurements. Maximum fracture toughness (K_1c) and a ninefold increase in the critical strain energy release rate (G_1c) over the unmodified neat epoxy was achieved at 5 wt % loading of intermediate molecular weight PEO-PBO, without measureable reductions in modulus, glass transition temperature or transparency. This study provides new strategies for engineering improved performance in thermoset materials using block copolymer additives that exhibit challenging mixing thermodynamic characteristics with the component monomers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 189–204     

Effect of block molecular weight distribution on the structure formation in block copolymer/homopolymer blends

The effect of homopolymer (hP) addition on the structure formation in lamellar amorphous block copolymers (BCP) with narrow‐ and broad‐molecular weight distribution (MWD) was studied using small‐angle X‐ray scattering and transmission electron microscopy. The systems in our study consist of blends of a poly(styrene‐b‐methyl acrylate) copolymer with block‐selective broad MWD of the poly(methyl acrylate) domain as well as polystyrene and poly(methyl acrylate) hPs with molecular weight less than the corresponding block of the copolymer. Homopolymer addition to the broad MWD domain of the BCP is found to induce structural changes similar to narrow MWD BCP/hP blend systems. Conversely, addition of hP to the narrow MWD domain is found to induce a more pronounced expansion of lamellar domains due to the segregation of the hP to the center region within the host copolymer domain. With increasing hP concentration, the formation of a stable two‐phase regime with coexisting lamellar/gyroid microphases is observed that is bounded by uniform lamellar phase regimes that differ in the distribution of hP within the corresponding narrow MWD block domain. The segregation of low‐molecular weight hP to the center region of the narrowdisperse domains of a broad MWD BCP is rationalized as a consequence of the more stretched chain conformations within the narrowdisperse block that are implied by the presence of a disperse adjacent copolymer domain. The increase of chain stretching reduces the capacity of the narrowdisperse block to solubilize hP additives and thus provides a driving force for the segregation of hP chains to the center of the host copolymer domain. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 106–116, 2012     

Miscibility and crystallization behavior of PBT/epoxy blends

The miscibility and the isothermal crystallization kinetics for PBT/Epoxy blends have been studied by using differential scanning calorimetry, and several kinetic analyses have been used to describe the crystallization process. The Avrami exponents n were obtained for PBT/Epoxy blends. An addition of small amount of epoxy resin (3%) leads to an increase in the number of effective nuclei, thus resulting in an increase in crystallization rate and a stronger trend of instantaneous three‐dimensional growth. For isothermal crystallization, crystallization parameter analysis showed that epoxy particles could act as effective nucleating agents, accelerating the crystallization of PBT component in the PBT/Epoxy blends. The Lauritzen–Hoffman equation for DSC isothermal crystallization data revealed that PBT/Epoxy 97/3 had lower nucleation constant K_g than 100/0, 93/7, and 90/10 PBT/Epoxy blends. Analysis of the crystallization data of PBT/Epoxy blends showed that crystallization occurs in regime II. The fold surface free energy, σ_e = 101.7–58.0 × 10^?3 J/m², and work of chain folding, q = 5.79–3.30 kcal/mol, were determined. The equilibrium melting point depressions of PBT/Epoxy blends were observed and the Flory–Huggins interaction parameters were obtained. It indicated that these blends were thermodynamically miscible in the melt. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1320–1330, 2006     

Correlation between crystallization kinetics and microdomain morphology in block copolymer blends exhibiting confined crystallization

The crystallization kinetics of poly(ethylene oxide) (PEO) blocks in poly(ethylene oxide)‐block‐poly(1,4‐butadiene) (PEO‐b‐PB)/poly(1,4‐butadiene) (PB) blends were previously found to display a one‐to‐one correlation with the microdomain morphology. The distinct correlation was postulated to stem from the homogeneous nucleation‐controlled crystallization in the cylindrical and spherical PEO microdomains, where there existed a direct proportionality between the nucleation rate and the individual domain volume. This criterion was valid for confined crystallization in which the crystallization was spatially restricted within the individual domains. However, it was possibly not applicable to PEO‐b‐PB/PB, in that the melt mesophase was strongly perturbed upon crystallization. Therefore, it may be speculated that the crystal growth front developed in a given microdomain could intrude into the nearby noncrystalline domains, yielding the condition of cooperative crystallization. To establish an unambiguous model system for verifying the existence of microdomain‐tailored kinetics in confined crystallization, we crosslinked amorphous PB blocks in PEO‐b‐PB/PB with a photoinitiated crosslinking reaction to effectively suppress the cooperative crystallization. Small‐angle X‐ray scattering revealed that, in contrast to the noncrosslinked systems, the pre‐existing domain morphology in the melt was retained upon crystallization. The crystallization kinetics in the crosslinked system also exhibited a parallel transition with the morphological transformation, thereby verifying the existence of microdomain‐tailored kinetics in the confined crystallization of block copolymers. Homogeneous nucleation‐controlled crystallizations in cylindrical and spherical morphologies were demonstrated in an isothermal crystallization study in which the corresponding crystallinity developments followed a simple exponential rule not prescribed by conventional spherulitic crystallization. Despite the effective confinement imposed by the crosslinked PB phase, crystallization in the lamellar phase still proceeded through a mechanism analogous to the spherulitic crystallization of homopolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 519–529, 2002; DOI 10.1002/polb.10121     

Morphology,thermo-mechanical properties and surface hydrophobicity of nanostructured epoxy thermosets modified with PEO-PPO-PEO triblock copolymer

In this paper, we report on the effect of amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer (TBCP) on the miscibility, phase separation, thermomechanical properties and surface hydrophobicity of diglycidyl ether of bisphenol-A (DGEBA)/4,4'-diaminodiphenylmethane (DDM) system. The blends were nanostructured. The phase separation occurred via self-assembly of PPO blocks followed by the reaction induced phase separation of PEO blocks. The surface roughness increased with increase in concentration of TBCP due to increased phase separation of PEO blocks at higher concentration. The phase separated PEO blocks formed the crystalline phase in the amorphous crosslinked epoxy matrix. The TBCP has a strong plasticizing effect on the matrix and decreased the glass transition temperature (T_g) and modulus of the thermoset. The incorporation of TBCP improved impact strength and tensile properties and 5 phr TBCP content was found to be optimum to achieve balanced mechanical performance. Moreover, the thermal stability of the epoxy system was retained while hydrophobicity was improved in the presence of TBCP.     

Miscibility and surface properties of fluorinated copolymer blends involving hydrogen‐bonding interactions

The miscibility and underlying hydrogen‐bonding interactions of blends of a fluorinated copolymer containing pyridine and a nonfluorinated copolymer containing methacrylic acid were studied with differential scanning calorimetry (DSC), transmission Fourier transform infrared (TX‐FTIR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS), whereas the surface properties of the blends were investigated with contact‐angle measurements, time‐of‐flight secondary‐ion mass spectroscopy, XPS, and attenuated total reflectance Fourier transform infrared spectroscopy. DSC studies showed that the presence of a sufficient amount of 4‐vinylpyridine units in the fluorinated copolymer produced miscible blends with the nonfluorinated copolymer containing methacrylic acid. TX‐FTIR and XPS showed the existence of pyridine–acid interpolymer hydrogen‐bonding interactions. Even though the anchoring effect of hydrogen bonding hindered the migration of the fluorinated component to the blend surface, it could not completely eliminate the surface enrichment of the fluorinated component and the surface rearrangement of the fluorinated pendant chain. The air–blend interface was mainly occupied by the fluorinated pendant chain, and the surface energies of the blends were extremely low, even with only 1.5 wt % of the fluorinated component in the blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1145–1154, 2004     

Nanostructured thermoset epoxy resin templated by an amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) diblock copolymer

An amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) (PEO–PDMS) diblock copolymer was used to template a bisphenol A type epoxy resin (ER); nanostructured thermoset blends of ER and PEO–PDMS were prepared with 4,4′‐methylenedianiline (MDA) as the curing agent. The phase behavior, crystallization, hydrogen‐bonding interactions, and nanoscale structures were investigated with differential scanning calorimetry, Fourier transform infrared spectroscopy, transmission electron microscopy, and small‐angle X‐ray scattering. The uncured ER was miscible with the poly(ethylene oxide) block of PEO–PDMS, and the uncured blends were not macroscopically phase‐separated. Macroscopic phase separation took place in the MDA‐cured ER/PEO–PDMS blends containing 60–80 wt % PEO–PDMS diblock copolymer. However, the composition‐dependent nanostructures were formed in the cured blends with 10–50 wt % PEO–PDMS, which did not show macroscopic phase separation. The poly(dimethylsiloxane) microdomains with sizes of 10–20 nm were dispersed in a continuous ER‐rich phase; the average distance between the neighboring microdomains was in the range of 20–50 nm. The miscibility between the cured ER and the poly(ethylene oxide) block of PEO–PDMS was ascribed to the favorable hydrogen‐bonding interaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3042–3052, 2006     

环氧树脂在热塑性树脂改性中的应用

本文综述了国内外有关利用环氧树脂改性热塑性树脂共混体系研究的最新进展。着重阐述了环氧树脂在热塑性树脂之间的增容作用,如尼龙6(PA6)合金体系,改性聚苯乙烯塑料(ABS)合金体系,以及聚对苯二甲酸丙二醇酯(PTT)合金体系等。同时,介绍了利用环氧树脂的反应活性提高无机填料在聚合物中分散性研究的情况,如二氧化硅纳米粒子在聚醚砜(PES)中,以及滑石粉在聚丙烯(PP)中分散性的提高。最后,简介了环氧树脂改性热塑性树脂提高热塑性树脂物理机械性能方面的研究方向和成果并展望了环氧树脂在热塑性树脂改性研究中的前景。     

Reactive compatibilization of epoxy/polyorganosiloxane blends

A new thermoset material based on DGEBA with polyaminosiloxane curing agents is presented. The system shows reaction-induced compatibilization which prevents coalescence of polysiloxane and DGEBA rich domains, leading to gradient structured morphologies. The influence of curing temperature and/or chemical nature of the siloxane on the morphology and surface microhardness were examined. When siloxane is pre-reacted with epoxypropylphenylether (EPPE), a more homogeneous material is obtained. Microhardness profiles on the material are strongly influenced by the extension of the compositional gradients.     

Compatibilizing effect of polyarylate-polystyrene block copolymer in polyarylate/polystyrene blends

The compatibilizing effect of polyarylate-polystyrene (PAR-PS) block copolymer prepared from macroazo initiator was examined in polyarylate/polystyrene blends from the view-points of morphology, density, and thermal, mechanical, and rheological properties. PARPS block copolymer enhanced the mutual dissolution of the homopolymers. Reduced dispersed-domain size and increased density showed the efficiency of the block copolymer as a compatibilizing agent. Results from mechanical and rheological properties could also be explained by the compatibilizing effect of PAR-PS block copolymer in the blends. © 1994 John Wiley & Sons, Inc.     

Temperature‐dependent location of a weakly segregated block copolymer in binary blends of block copolymers

The phase behaviors of binary blends of poly(styrene‐b‐butadiene) block copolymers were investigated by a small‐angle X‐ray scattering technique. The blends were composed of weakly segregated one in a random micellar phase and the other in a cylindrical phase with similar molecular weights and complementary volume fractions. Morphologies, domain spacings, and order–disorder transition temperatures of the blends indicated that the junctions of the constituent block copolymers share the interface at low temperatures. The domain spacing decreased as temperature increased in a blend with a small amount of the weakly segregated block copolymer. In the cases of the blends with a large amount of the weakly segregated constituent, domain spacing increased with increasing temperature. These results implied that some of the weakly segregated block copolymer moved from the interface to one microdomain at higher temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 470–476     

Shear induced orientation of phase segregated block copolymer/epoxy blends

In this work a phase segregated blend system consisting of a block copolymer (BCP) and epoxy matrix with cylindrical morphology is considered. Transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) investigations reveal that long-ranged ordered nanostructures can be obtained under certain preparation conditions. The pre-shearing conditions are the most important factors in order to obtain regular structures.     

Cocrystallization of ethylene/1‐octene copolymer blends during crystallization analysis fractionation and crystallization elution fractionation

Blending of ethylene/1‐octene copolymers can be used to achieve a well‐controlled broad chemical composition distribution (CCD) required in several polyolefin applications. The CCD of copolymer blends can be estimated using crystallization analysis fractionation (CRYSTAF) or crystallization elution fractionation (CEF). Unfortunately, both techniques may be affected by the cocrystallization of chains with different compositions, leading to profiles that do not truly reflect the actual CCD of the polymer. Therefore, understanding how the polymer microstructure and the analytical conditions influence copolymer cocrystallization is critical for the proper interpretation of CRYSTAF and CEF curves. In this investigation, we studied the effect of chain crystallizabilities, blend compositions, and cooling rates on cocrystallization during CEF and CRYSTAF analysis. Cocrystallization is more prevalent when the copolymer blend has components with similar crystallizabilities, one of the components is present in much higher amount, and fast cooling rates are used. CEF was found to provide better CCD estimates than CRYSTAF in a much shorter analysis time. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Phase behavior in mixtures of a homopolymer and a block copolymer. 4. SALS and SAXS studies

Phase behavior of blends of poly(vinyl methyl ether) (PVME) with four styrene-butadiene-styrene (SBS) triblock copolymers, being of various molecular weights, architecture, and compositions, was investigated by small-angle light scattering. Small-angle X-ray scattering investigation was accomplished for one blend. Low critical solution temperature (LCST) and a unique phase behavior, resembling upper critical solution temperature (UCST), were observed. It was found that the architecture of the copolymer greatly influenced the phase behavior of the blends. Random phase approximation theory was used to calculate the spinodal phase transition curves of the ABA/C and BAB/C systems; LCST and resembling UCST phase behavior were observed as the parameters of the system changed. Qualitatively, the experimental and the theoretical results are consistent with each other. © 1996 John Wiley & Sons, Inc.     

Phase behavior and crystallization analysis in binary crystalline blends of syndiotactic polypropylene and ethylene—Propylene random copolymer

The effects of liquid–liquid (L–L) phase separation on the crystallization behavior of binary syndiotactic polypropylene (sPP) and ethylene–propylene random copolymer (PEP) mixtures are examined by phase‐contrast microscopy (PCM), differential scanning calorimetry (DSC), and cloud point measurements. The PCM experiments reveal that blends of sPP and PEP exhibit a lower critical solution temperature behavior in the melt. The L–L phase diagram, constructed in terms of temperature (T) and composition by cloud point measurements, follows the prediction of the Flory–Huggins theory with the interaction parameter between sPP and PEP [χ(T) = 0.01153 ? 4.5738/T (K)]. When the blends are melted within the two liquid‐phase (α and β) regions, because of the fact that each phase domain reaches the equilibrium concentration ? and ? as well as the phase volume fraction ν^α and ν^β, the crystallinity of each component obeys the equation X_C,I = ν^α X + ν^β X, I = PEP, sPP. Also, the equilibrium melting temperatures of both components remain constants, slightly lower than those of neat polymers. For the sPP/PEP blends crystallized from one homogeneous phase in the melt, we observe that the crystallizability of the major component is not greatly affected upon blending. However, the crystallization behavior of the minority component in the presence of the major component is strongly dependent on the crystallization temperature (T_c). When T_c is high, because the decreasing degree of the minority mobility is much greater than the increasing degree of the formed nuclei, the crystallizability of the minor component is depressed significantly. On the other hand, the promotion of the minority crystallizability in the intermediate regime of T_c is mainly because of the large increase of the heterogeneous nuclei upon blending with a major component. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2995–3005, 2004     

Crystallization behavior of dynamically cured polypropylene/epoxy blends

Dynamically cured polypropylene (PP)/epoxy blends compatibilized with maleic anhydride grafted PP were prepared by the curing of an epoxy resin during melt mixing with molten PP. The morphology and crystallization behavior of dynamically cured PP/epoxy blends were studied with scanning electron microscopy, differential scanning calorimetry, and polarized optical microscopy. Dynamically cured PP/epoxy blends, with the structure of epoxy particles finely dispersed in the PP matrix, were obtained, and the average diameter of the particles slightly increased with increasing epoxy resin content. In a study of the nonisothermal crystallization of PP and PP/epoxy blends, crystallization parameter analysis showed that epoxy particles could act as effective nucleating agents, accelerating the crystallization of the PP component in the PP/epoxy blends. The isothermal crystallization kinetics of PP and dynamically cured PP/epoxy blends were described by the Avrami equation. The results showed that the Avrami exponent of PP in the blends was higher than that of PP, and the crystallization rate was faster than that of PP. However, the crystallization rate decreased when the epoxy resin content was greater than 20 wt %. The crystallization thermodynamics of PP and dynamically cured PP/epoxy blends were studied according to the Hoffman theory. The chain folding energy for PP crystallization in dynamically cured PP/epoxy blends decreased with increasing epoxy resin content, and the minimum of the chain folding energy was observed at a 20 wt % epoxy resin content. The size of the PP spherulites in the blends was obviously smaller than that of PP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1181–1191, 2004     

Microstructure, morphology, crystallization and rheological behavior of impact polypropylene copolymer

Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and microstructure. In the present article, recent progress in the studies on microstructure, morphology, crystallization and rheological behavior of IPC is summarized, and findings of the authors and their collaborators are reported. In general, IPC is divided into three components, i.e., ethylene-propylene random copolymer (EPR), a series of different segment lengths ethylene-propylene copolymer (EbP) and propylene homopolymer. The reasonable macromolecular structures of EbP and a multilayered core-shell model of dispersed phase structure in IPC were proposed, in which the dispersed phase consists of an outer EbP shell, an inner EPR layer and an EbP core. It is found that the annealing at melt-state may lead to an abnormal phase inversion, and the phase inversion disappears when temperature cools down to room temperature. The cause of phase inversion is ascribed to the existence of EbP component, which results in the stronger activity of the dispersed phase. The crystalline structure and morphologic results confirm the formation of β-iPP in IPC. Furthermore, it is found that the ethylene content in IPC and cooling rate of the samples have an important influence on the formation of β-iPP. Based on the crystallization kinetics analyzed by Lauritzen-Hoffman theory, crystallization behavior of different IPC samples is discussed and it is proposed that the dilution effect of ethylene propylene copolymer has a more remarkable influence on surface nucleation than on crystal growth. In addition, annealing at high temperature can result in the changes of chain structure for IPC, and this instability is ascribed to the oxidative degradation and crosslink reaction mainly in iPP component.