Preparation and characterization of high MFR polypropylene and polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys

In this work, high melt flow rate (MFR) polypropylene (HF‐PP) and polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys (HF‐PP/EPR) with MFR ≈ 30 g/10 min were synthesized by spherical MgCl₂‐supported Ziegler–Natta catalyst with cyclohexylmethyldimethoxysilane (CHMDMS) or dicyclopentyldimethoxysilane (DCPDMS) as external donor (De). The effects of De on polymerization activity, chain structure, mechanical properties, and phase morphology of HF‐PP and HF‐PP/EPR were studied. Adding CHMDMS caused more sensitive change of the polymers MFR with H₂ than DCPDMS, and produced PP/EPR alloys containing more random ethylene‐propylene copolymer (r‐EP) and segmented ethylene‐propylene copolymer (s‐EP). CHMDMS also caused formation of s‐EP with higher level of blockiness than DCPDMS. HF‐PP/EPR alloy prepared in the presence of DCPDMS exhibited higher flexural properties but lower impact strength than that prepared with CHMDMS. Toughening efficiency of the rubber phase was nearly the same in the alloys prepared using CHMDMS or DCPDMS as De, but stiffness of the alloy can be improved by using DCPDMS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42984.     

Influence of cocatalyst on the structure and properties of polypropylene/poly (ethylene‐co‐propylene) in‐reactor alloys prepared by MgCl2/TiCl4/diester type Ziegler‐Natta catalyst

In this work, a series of polypropylene/poly(ethylene‐co‐propylene) (iPP/EPR) in‐reactor alloys were prepared by MgCl₂/TiCl₄/diester type Ziegler‐Natta catalyst with triethylaluminium/triisobutylaluminium (TEA/TIBA) mixture as cocatalyst. The influence of cocatalyst and external electron donor, e.g., diphenyldimethoxysilane (DDS) or dicyclopentyldimethoxysilane (D ‐donor), on the structure and mechanical properties of iPP/EPR in‐reactor alloys were studied and discussed. According to the characterization results, PP/EPR was mainly composed of random poly(ethylene‐co‐propylene), segmented poly(ethylene‐co‐propylene), and high isotactic PP. Using TEA/TIBA mixture as cocatalyst and DDS as external electron donor, as TEA/TIBA ratio increased, the impact strength of iPP/EPR in‐reactor alloys had an increasing trend. Using TEA/TIBA mixture as cocatalyst and D ‐donor as external electron donor, the impact strength of iPP/EPR in‐reactor alloy were dramatically improved. In this case, the iPP/EPR in‐reactor alloy prepared at TEA: TIBA = 4 : 1 was the toughest. The influence of cocatalyst and external electron donor on the flexural modulus and flexural strength could be ignored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of copolymerization conditions on the structure and properties of polyethylene/polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys synthesized in gas‐phase with spherical ziegler‐natta catalyst

A spherical TiCl₄/MgCl₂‐based catalyst was used in the synthesis of polyethylene/polypropylene/poly (ethylene‐co‐propylene) in‐reactor alloys by sequential homopolymerization of ethylene, homopolymerization of propylene, and copolymerization of ethylene and propylene in gas‐phase. Different conditions in the third stage, such as the pressure of ethylene–propylene mixture and the feed ratio of ethylene, were investigated, and their influences on the compositions, structural distribution and properties of the in‐reactor alloys were studied. Increasing the feed ratio of ethylene is favorable for forming random ethylene–propylene copolymer and segmented ethylene–propylene copolymer, however, slightly influences the formation of ethylene‐b‐propylene block copolymer and homopolyethylene. Raising the pressure of ethylene–propylene mixture results in the increment of segmented ethylene–propylene copolymer, ethylene‐b‐propylene block copolymer, and PE fractions, but exerts a slight influence on both the random copolymer and PP fractions. The impact strength of PE/PP/EPR in‐reactor alloys can be markedly improved by increasing the feed ratio of ethylene in the ethylene–propylene mixture or increasing the pressure of ethylene–propylene mixture. However, the flexural modulus decreases as the feed ratio of ethylene in the ethylene–propylene mixture or the pressure of ethylene–propylene mixture increases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2481–2487, 2006     

Effect of viscosity ratio,rubber composition,and peroxide/coagent treatment in PP/EPR blends

Effect of Viscosity ratio (ηEPR/ηPP), propylene (C₃) content of (ethylene-propylene copolymer (EPR)), and peroxide/coagent treatment on polypropylene (PP)/EPR (80/20 by weight) melt blends were studied in terms of morphological, rheological, thermal, and mechanical properties. As the viscosity ratio increases from approximately 0.8 to 1.2, domain size increased (submicron-1.5 μm), and the degree of supercooling (ΔT) for crystallization increased (37.4–47.8°C) due to the decreased crystallization temperature (T_cc, 122.2–110.8°C). This resulted in larger spherulite size and increased hardness, modulus, and yield strength. With high C₃ EPR, total crystallinity (ΔH_f) of PP decreased, together with the mechanical properties, except the impact strength. With peroxide/coagent treatment, the spherulite size significantly decreased. The notched Izod impact strength decreased with increasing viscosity ratio, but significantly increased with high C₃ EPR and with peroxide/coagent treatments. The results were interpreted in terms of domain size and shape, chemical affinity between PP and EPR, copolymer formation, and main chain scission of PP. © 1996 John Wiley & Sons, Inc.     

Structure and morphology of polyethylene/polypropylene in‐reactor alloys synthesized by spherical high‐yield Ziegler–Natta catalyst

A series of spherical polyethylene/polypropylene (PE/PP) in‐reactor alloys were synthesized with spherical high‐yield Ziegler–Natta catalyst by sequential multistage polymerization in slurry. The morphology of PE/PP alloy granule was evaluated by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show PE/PP in‐reactor alloy with excellent morphology, high porosity, and narrow distribution of the particle size. The PE/PP in‐reactor alloys show excellent mechanical properties with good balance between toughness and rigidity. It was fractionated into five fractions by temperature‐gradient extraction fractionation, and every fractionation was analyzed by FTIR, ¹³C‐NMR, DSC, and WAXD. The PE/PP in‐reactor alloy was found to contain mainly five portions: PP, PE, segmented copolymer with PP and PE segment of different length, ethylene‐b‐propylene copolymer, and an ethylene–propylene random copolymer. The characteristic chain structure leads to good compatibility between the fractions of the alloy that shows a multiphase structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2075–2085, 2007     

New synthesis methods for polypropylene‐co‐ethylene‐propylene rubber

In this research, the reinforcement of polypropylene (PP) was studied using a new method that is more practical for synthesizing polypropylene‐block‐poly(ethylene‐propylene) copolymer (PP‐co‐EP), which can be used as a rubber toughening agent. This copolymer (PP‐co‐EP) could be synthesized by varying the feed condition and changing the feed gas in the batch reactor system using Ziegler–Natta catalysts system at a copolymerization temperature of 10°C. The ¹³C‐NMR tested by a 21.61‐ppm resonance peak indicated the incorporation of ethylene to propylene chains that could build up the microstructure of the block copolymer chain. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA) results also confirmed these conclusions. Under these conditions, the morphology of copolymer trapped in PP matrix could be observed and the copolymer T_g would decrease when the amount of PP‐co‐EP was increased. DMA study also showed that PP‐co‐EP is good for the polypropylene reinforcement at low temperature. Moreover, the PP‐co‐EP content has an effect on the crystallinity and morphology of polymer blend, i.e., the crystallinity of polymer decreased when the PP‐co‐EP content increased, but tougher mechanical properties at low temperature were observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3609–3616, 2007     

Influence of polymerization conditions on the structure and properties of polyethylene/polypropylene in‐reactor alloy synthesized in the gas phase with a spherical Ziegler–Natta catalyst

A spherical TiCl₄/MgCl₂‐based catalyst was used in the synthesis of in‐reactor polyethylene/polypropylene alloys by polyethylene homopolymerization and subsequent homopolymerization of propylene in the gas phase. Different conditions in the ethylene homopolymerization stage, such as monomer pressure and polymerization temperature, were investigated, and their influences on the structure and properties of in‐reactor alloys were studied. Raising the polymerization temperature is the most effective way of speeding up polymerization and regulating the ethylene content of polyethylene (PE)/polypropylene (PP) alloys, but it will cause a greater increase in the PE‐b‐PP block copolymer fraction (named fraction D) than in the fraction of PP‐block‐PE in which the PP segments have low or medium isotacticity (named fraction A). Although changing ethylene monomer pressure could influence the ethylene content of PE/PP alloys slightly, it is an effective way of regulating the structural distribution. Reducing the monomer pressure will evidently increase fractions A and D. The mechanical properties of the alloys, including impact strength and flexural modulus, can be regulated in a broad range with changes in polymerization conditions. These properties are highly dependent on the amount, distribution, and chain structure of fractions A and D. The impact strength is affected by both fraction A and fraction D in a complicated way, whereas the flexural modulus is mainly determined by the amount of fraction A. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2136–2143, 2006     

Fabrication of polypropylene blends with excellent low‐temperature toughness and balanced toughness‐rigidity by a combination of EPR and SEEPS

To overcome serious rigidity depression of rubber‐toughened plastics and fabricate a rigidity‐toughness balanced thermoplastic, a combination of styrene‐[ethylene‐(ethylene‐propylene)]‐styrene block copolymer (SEEPS) and ethylene‐propylene rubber (EPR) was used to toughen polypropylene. The dynamic mechanical properties, crystallization and melting behavior, and mechanical properties of polypropylene (PP)/EPR/SEEPS blends were studied in detail. The results show that the combination of SEEPS and EPR can achieve the tremendous improvement of low‐temperature toughness without significant strength and rigidity loss. Dynamic mechanical properties and phase morphology results demonstrate that there is a good interfacial strength and increased loss of compound rubber phase comprised of EPR component and EP domain of SEEPS. Compared with PP/EPR binary blends, although neither glass transition temperature (T_g) of the rubber phase nor T_g of PP matrix in PP/EPR/SEEPS blends decreases, the brittle‐tough transition temperature (T_bd) of PP/EPR/SEEPS blends decreases, indicating that the increased interfacial interaction between PP matrix and compound rubber phase is also an effective approach to decrease T_bd of the blends so as to improve low‐temperature toughness. The balance between rigidity and toughness of PP/EPR/SEEPS blends is ascribed to the synergistic effect of EPR and SEEPS on toughening PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45714.     

Phase structure and mechanical properties of PP/EPR/CaCO3 nanocomposites: Effect of particle's size and treatment

Calcium carbonate (CaCO₃) reinforced polypropylene/ethylene propylene rubber (PP/EPR) copolymer composites for automotive use were developed by means of extrusion and injection molding process. Three kinds of CaCO₃ (stearic acid treated and untreated) nanoparticles and microparticles were used as fillers. The influence of stearic acid, particle size, and filler content on the state distribution and morphology were investigated by SEM and rheological measurements. Two different morphologies were observed: EPR and CaCO₃ dispersed in the PP matrix and a core shell structure, depending on the interactions between EPR and CaCO₃. Toughening mechanisms and mechanical properties of the different systems were investigated. Significant improvement in tensile modulus is observed in all composites, depending on filler content. Elongation and notched impact strength were drastically decreased, especially for composites with nano CaCO₃. Better impact properties were obtained with low content of treated particles, showing the importance of filler treatment. POLYM. ENG. SCI., 55:2859–2868, 2015. © 2015 Society of Plastics Engineers     

Regulation of morphology and mechanical properties of polypropylene/poly(ethylene-co-propylene) in-reactor alloys by multi-stage sequential polymerization

A series of polypropylene/poly(ethylene-co-propylene) (PP/EPR) in-reactor alloys were synthesized by the homopolymerization of propylene in the first stage, after that it switches to gas-phase ethylene-propylene copolymerization and gas-phase homopolymerization of propylene in a circular mode. The alloys were characterized by FTIR, DSC, PLM, TEM and SEM. Changing switch frequency had hardly any influence on the EPR content of the PP/EPR in-reactor alloys. However, as the switch frequency increased, the catalyst efficiency evidently increased. Measurement of mechanical properties shows that increasing the switch frequency has a positive effect on both the impact strength and flexural modulus. Although the content of EPR was almost similar to each other, as the switch frequency increased, the size of EPR phase decreases and the size distribution in the PP matrix trend to be more uniform that forms strong interfacial adhesion between PP phase and EPR phase. The simultaneous improvement of both impact strength and flexural modulus of the alloy can be mainly attributed to changes in its phase morphology as a result of fast circulation between homopolymerization and copolymerization.     

Effect of the structure on the morphology and spherulitic growth kinetics of polyolefin in‐reactor alloys

Four polyolefin in‐reactor alloys with different compositions and structures were prepared by sequential polymerization. All the alloys were fractionated into five fractions: a random copolymer of ethylene and propylene (25°C fraction), an ethylene–propylene segmented copolymer (90°C fraction), an ethylene homopolymer (110°C fraction), an ethylene–propylene block copolymer (120°C fraction), and a propylene homopolymer plus a minor ethylene homopolymer of high molecular weight (>120°C fraction). The effect of the structure on the morphology and spherulitic growth kinetics of the polypropylene (PP) component in the alloys was investigated. The polyolefin alloys containing a suitable block copolymer fraction and a larger amount of PP had a more homogeneous morphology, and the crystalline particles were smaller. Quenching the polyolefin alloys led to smaller crystallites and a more homogeneous morphology as well. Isothermal crystallization was carried out above the melting temperature of polyethylene, and the growth of PP spherulites was monitored with polarized optical microscopy with a hot stage. The alloys with higher propylene contents exhibited a faster spherulitic growth rate. The fold surface free energy was derived, and it was found that a large amount of block copolymer fractions and random copolymer fractions could reduce the fold surface free energy. The structure of the alloys also affected the crystallization regime of PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 632–638, 2005     

Effect of composition and component structure on thermal behavior and miscibility of polypropylene catalloys

The thermal behavior and the miscibility of an in‐situ polypropylene blend named polypropylene catalloys (PP‐cats) were investigated by using modulated differential scanning calorimeter (MDSC). It is found that all PP‐cats samples present two glass transitions, one of which is ascribed to the ethylene‐propylene random copolymer (EPR), and the other, to isotactic polypropylene (PP). However, no glass transition of ethylene‐propylene block copolymer (E‐b‐P) responsible for a third component in PP‐cats could be found. With the increase of EPR, the glass transition temperatures responding to PP and EPR components, T_g, _PP and T_g, _EPR, shift to low temperature, because of the enhancement of the interaction between PP and EPR component and the increase of ethylene content in EPR, respectively. Furthermore, the difference between T_g, _PP and T_g, _EPR remarkably decreases with the increase of the total ethylene content in PP‐cats, which indicates that the miscibility of PP‐cats is strongly dependent on the composition. Comparing the T_g, _PP and T_g, _EPR with T_g of fractionated PP and EPR, we ascribe the T_g change of PP fraction to the increase of EPR content; while that of EPR, to the increase of ethylene content in EPR. These experimental results suggest that the existence of E‐b‐P plays an important role in improving the miscibility between propylene homopolymer and EPR in PP‐cats. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effects of nanosilica filler surface modification and compatibilization on the mechanical,thermal and microstructure of PP/EPR blends

Polypropylene/ethylene-propylene rubber/nanosilica (PP/EPR/nano-SiO₂) composites were prepared by a melt blending masterbatch process using a Brabender mixer. In order to improve the interfacial adhesion and achieve diverse desired properties of the composites, nanosilica surface silylation by means of two silane coupling agents: N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (AEAPTMS) and 3-methacryloxypropyltrimethoxysilane (MPTMS) was explored. The composites were also compatibilized using three compatibilizers: methyl methacrylate grafted PP (MMA-g-PP), glycidylmethacrylate grafted PP (GMA-g-PP) and maleic anhydride grafted PP (MAH-g-PP). The properties of the blends and the composites were examined using tensile and Izod impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (ATG) and scanning electron microscopy (SEM). According to the mechanical property evaluations, the incorporation of nano-SiO₂ particles into PP/EPR blend improved the tensile strength and Young’s modulus of the composites. The elongation and Izod impact strength were adversely affected. A significant improvement in the mechanical properties was obtained for the composites with AEAPTMS-SiO₂ and MAH-g-PP. The DSC results indicated that the incorporation of the modified silica and MAH-g-PP increased the crystallinity of the composites. However, no significant variation in the crystallinity was observed as a result of the addition of MMA-g-PP and GMA-g-PP. The TGA results revealed that the composites exhibit a higher thermal stability than that of the neat matrix. SEM micrographs of the fractured surfaces revealed a two-phase morphology with EPR nodules being dispersed in the PP matrix. SEM also indicated that the incorporation of MAH-g-PP into PP/EPR composites contributes to a better dispersion of the EPR phase and nano-SiO₂ particles in the polymer matrix.     

Study of the modification of the properties of (PP/EPR) blends with a view to preserving natural resources when elaborating new formulation and recycling polymers

The aim of the present work is to study how CaCO₃, very abundant on earth, can be blended with polypropylene/ethylene propylene rubber (PP/EPR) either to preserve natural resources when elaborating virgin formulations or to simulate mixtures of waste made of CaCO₃ filled PP with PP/EPR which could result from end-of-life-vehicles (ELV). The article focuses on the studies of PP/EPR blends, used in the manufacture of automobile fenders, in the presence of nano-CaCO₃ and compatibilizers. Blends of various compositions (with and without compatibilizer and nanoparticles) were prepared using a corotating twin-screw extruder. The results were compared with the ones presented by a commercial (PP/EPR) blend. The experiments included mechanical tests, differential scanning calorimetry, scanning electron microscopy, and dynamic mechanical analysis experiments. The presence of the compatibilizers in the (PP/EPR) blends decreases the size of elastomer particles, improves the adherence to the interface and improves the mechanical properties. The nano-CaCO₃ would also seem to act as a nucleating agent in the PP/EPR matrix; it increases the cristallinity and the Young modulus of the blends. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Characterization and properties of polypropylene‐block‐poly(ethylene‐co‐propylene) synthesized by short‐period polymerization

The morphology and mechanical properties of novel block copolymers consisting of isotactic polypropylene (PP) and ethylene–propylene rubber (EPR) synthesized by a short‐period polymerization method were examined using differential scanning calorimetry, atomic force microscopy, dynamic mechanical analysis, and a rheooptical technique. It was found that the novel block copolymers show a single glass transition and EPR segments are trapped into the amorphous region of PP. Furthermore, the rheooptical analysis demonstrates that a drawing process of the EPR‐rich block copolymer induces orientation of the PP lamellae in the EPR matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 958–964, 1999     

Mechanical properties and structural characteristics of dynamically photocrosslinked PP/EPDM blends

The mechanical properties and crystal morphological structures of dynamically photocrosslinked polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends have been studied by mechanical tests, wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Dynamically photocrosslinking of PP/EPDM blends can improve the mechanical propertiess considerably, especially the notched Izod impact strength at low temperature. Data obtained from mechanical tests show that the notched Izod impact strength of a dynamically photocrosslinked sample with 30% EPDM at ?20°C is about six times that of an uncrosslinked sample with the same EPDM component. The results from the WAXD, SEM, and DSC measurements reveal the enhanced mechanism of impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (i) the β‐type crystal structure of PP is formed and the interplanar distance of β‐type crystal increases slightly with an increase in the EPDM component; (ii) the droplet size of the EPDM phase in the photocrosslinked PP/EPDM blends is obviously reduced and the droplet number is increased with an increase in the EPDM component during the dynamical photocrosslinking process; (iii) the graft copolymer of PP‐g‐EPDM is formed at the interface between PP and EPDM components. All the above changes from the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of PP/EPDM blends at low temperatures.     

Partial replacement of EPR by GTR in highly flowable PP/EPR blends: Effects on morphology and mechanical properties

This research analyzes the effect of ground tire rubber (GTR) and a novel metallocene‐based ethylene–propylene copolymer (EPR), with high propylene content, on the morphology and mechanical behavior of ternary polymer blends based on a highly flowable polypropylene homopolymer (PP). The PP/EPR blends morphology, with very small domains of EPR dispersed in the PP matrix, indicates a good compatibility among these materials, which leads to a significant improvement on elongation at break and impact strength. The incorporation of EPR on the rubber phase of thermoplastic elastomeric blends (TPE) based on GTR and PP (TPE^GTR) has a positive effect on their mechanical performance, attributed to the toughness enhancement of the PP matrix and to the establishment of shell‐core morphology between the rubber phases. The mechanical properties of the ternary blends reveal that TPE^GTR blends allow the upcycling of this GTR material by injection molding technologies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42011.     

Structural parameters in relation to the rheological behavior and properties of PP/EPR in‐reactor alloy synthesized by multi‐stage sequential polymerization

The morphology and molecular structure of an in‐reactor polypropylene/ethylene propylene rubber alloy, synthesized by multi‐stage sequential polymerization, were studied with respect to the rheological behavior and final properties of the alloy. The polymer alloys, based on different structural morphologies, were characterized by SEM, GPC, ¹³C NMR, DSC, rheological analysis, and mechanical testing. The scanning electron microscopy of samples showed that the size of the dispersed phase particles is decreased as the switch frequency of copolymerization timing is increased. The GPC results showed that switch frequency slightly altered the molecular weight distribution of the copolymer although it had no effect on PP homopolymer. ¹³C NMR results were used for the evaluation of compatibility between the two phases with changes in switch frequency. DSC results showed that T_m and T_c were almost independent of switch frequency, even though the size of dispersed phase was decreased and the blend crystal content increased with ΔH of about 13%. The small amplitude oscillation rheometry showed that storage modulus and viscosity shifted to higher values when switch frequency increased. In studying the mechanical properties it was revealed that, especially the impact strength increased by about 62% when the size of the dispersed particles was decreased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Facile synthesis of ethylene–propylene fully alternating copolymer and comparison with random copolymer of similar composition

A precisely sequenced ethylene–propylene (EP) fully alternating copolymer was synthesized via trans‐1,4‐polymerization of isoprene catalyzed by Ziegler–Natta catalyst followed by hydrogenation. This EP copolymer was used as model polymer for studying structure–property relationship. An ethylene–propylene random copolymer (ethylene–propylene rubber [EPR]) with similar ethylene content was also prepared for comparison, and the effect of comonomer sequence distribution on properties was investigated. The copolymer chain structures were monitored by ¹H and ¹³C NMR and Fourier translation infrared. Differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile tests were employed to determine the thermal and mechanical properties. The fully alternating copolymer EP gives a more precise glass transition comparing than EPR. Further understanding on thermal properties and aggregation behavior of ethylene–propylene copolymers is made possible by this comparative study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45816.     

聚丙烯结构形态对性能的影响

用红外光谱、动态粘弹谱、透射电镜、X光衍射仪、DSC、偏光显微镜和机械力学性能测试仪等手段对均聚、嵌段共聚、无规共聚PP进行了结构、形态与性能关系的研究。结果表明,嵌段共聚物中乙烯在红外谱图中显示两个特征峰,而无规共聚物中乙烯只出现—个特征峰。研究还证明,PP嵌段共聚物是PP、PE、EPR多元组分的共混物。PE包含在EPR中以球形无规地分散在PP基体中。EPR的含量是提高PP共聚物冲击性能的决定因素。无规共聚物形态接近均相体系,其冲击强度小于嵌段共聚物而大于均聚物。