SP179抗冲共聚聚丙烯性能评价

运用差示扫描量热仪(DSC)、动态热机械分析仪(DMA)、红外光谱(IR)和凝胶渗透色谱(GPC)等对SPi79抗冲共聚聚丙烯的相关性能参数进行了表征研究,评价了4个样品的乙烯含量、平均分子质量及其分布和热性能.实验证明,随着乙烯含量的增加,乙丙橡胶相增加,重均分子质量增大,样品的冲击强度升高,但弯曲模量下降,刚性降低...     

Phase morphology and impact toughness of impact polypropylene copolymer

Factors influencing the impact toughness of two impact polypropylene copolymers (IPC) with almost the same ethylene content, molecular weight and molecular weight distribution were studied by temperature gradient extraction fractionation (TGEF), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The results indicate that poor interfacial adhesion between the disperse phase and the continuous matrix, larger dimensions and non-uniform distribution of disperse phases are main reasons for the low impact toughness of IPC B that possesses of a low content of ethylene-propylene segmented copolymer with long crystallizable PE and PP sequences as a compatibilizer between the disperse phase and the matrix.     

Influence of polyfunctional monomer on melt strength and rheology of long‐chain branched polypropylene by reactive extrusion

Long chain branching (LCB) were added to linear polypropylene (PP) using reactive extrusion in the presence of selected polyfunctional monomers (PFMs) and a peroxide of dibenzoyl peroxide (BPO). Fourier Transformed Infrared spectra (FTIR) directly confirmed the grafting reaction occurred during the reactive extrusion process. Various rheological plots including viscosity curve, storage modulus, Cole‐Cole plot, and Van‐Gurp plots, confirmed that the LCB structure were introduced into modified PPs skeleton after modification. In comparison with linear PP, the branched samples exhibited higher melt strength, lower melt flow index, and the enhancement of crystallization temperature. The LCB level in modified PPs and their melt strength were affected by the type of PFM used and could be controlled by the PFM properties and structure. PFMs with lower boiling points, such as 1, 4‐butanediol diacrylate (BDDA), could not produce LCB structure in modified PP skeleton. The shorter molecular chain bifunctional monomers, such as 1,6‐hexanediol diacrylate (HDDA), favored the branching reaction if their boiling points were above the highest extrusion temperature. And some polar groups, such as hydroxyl, in the molecule of PFM were harmful to the branching reaction, which might be attributed to the harm of the polarity of groups to the dispersion of PFM in PP matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Extrusion film casting of long chain branched polypropylene

Extrusion film casting (EFC) is an important melt processing operation which is extensively used to make polypropylene (PP) films. Linear PP shows significant amount of necking and draw resonance during EFC. One of the ways to reduce necking is to introduce long chain branches (LCB) on the polymer backbone. The long branches impart extensional strain hardening behavior thereby stabilizing the melt flow. In this work, we investigate the influence of long chain branching in polypropylene on the extent of necking in the EFC process. Laboratory scale EFC experiments were performed on homopolymer PP of linear and long chain branched architectures. Simulations of the EFC process were carried out using the one‐dimensional flow model of Silagy et al., Polym. Eng. Sci., 36 , 2614 (1996) into which we incorporate two different multi‐mode molecular constitutive equations namely, the ‘eXtended Pom‐Pom’ equation (XPP, for long chain branched PP) and the ‘Rolie‐Poly’ equation (RP‐S, for linear PP). Our experimental data confirm that presence of long chain branching in PP reduces the extent of necking and our numerical predictions show qualitative agreement with experimental data, thereby elucidating the role of chain architecture on the extent of necking. POLYM. ENG. SCI., 55:1977–1987, 2015. © 2014 Society of Plastics Engineers     

抗冲共聚聚丙烯J842的开发

通过设计合理的生产控制方案,成功开发出高性能抗冲共聚聚丙烯J842产品,并分析了产品的力学性能.J842产品综合性能优良,抗冲击性能好,刚性稍有不足.建议通过改变催化剂体系、适当提高均聚聚丙烯粉料的熔体流动速率、优化改性剂添加配方等来改进J842产品的质量.     

The preparation and rheology characterization of long chain branching polypropylene

In order to study the rheological behavior of long chain branching (LCB) polypropylene (PP), linear polypropylene was modified by melt grafting reaction in the presence of 2,5-dimethyl-2,5(tert-butylperoxy) hexane peroxide and pentaerythritol triacrylate (PETA) in mixer. The transient torque curves and Fourier transformed infrared spectroscopy (FTIR) results indicated that macroradical recombination reactions took place and PETA had been grafted onto PP backbone. Various rheological plots including viscosity curve, storage modulus, loss angle, Han plot, Cole-Cole plot were used to distinguish LCB PP from linear PP. On the other hand, to quantify the LCB level in modified PPs, a new method was suggested on the basis of macromolecular dynamics models. The results showed that the level of LCB was in the range of 0.025-0.38/10⁴ C . Moreover, the length of the branched chains and the content of the branched component increase with PETA concentration. Furthermore, the LCB efficiency of monomer can also be calculated, less than 20% of grafting monomers was used to form branch structure.     

Fabrication of long chain branched polypropylene using click chemistry

This article presents a new method to produce LCBPP with well-defined structures via Huisgen’s 1,3-dipolar cycloaddition of azide and alkyne (click reaction). Azide-terminated isotactic polypropylene (iPP) (iPP-St-N₃) was synthesized via the hydrochlorination and subsequent substitution of the starting styryl-terminated i-PP (i-PP-t-St), which is the product of a metallocene-mediated isospecific propylene polymerization governed by a controlled chain transfer reaction. Alkyne-grafted iPP (iPP-g-≡) can be produced with high efficiency through one-pot esterification and the subsequent amidation of hydroxyl-functionalized iPP. Detailed analysis of the product by ¹H NMR, FTIR, DSC, and GPC reveals a clean and clear formation of LCBPP.     

Modeling the mechanical behavior and impact properties of polypropylene and copolymer polypropylene

We present a general internal state variable (ISV) elastic-viscoplastic constitutive model that was initially applied to amorphous polymers (Bouvard et al J Eng Mater Technol 131(4), 041206, 2013) but has been extended to apply to semi-crystalline polymers along with a fracture criterion. In this work, we experimentally calibrated and validated the mechanical behavior of two semi-crystalline polymers (a polypropylene (PP) and a copolymer polypropylene (co-PP)) under different stress states, temperatures, and nominal strain rates. The experiments included compression, tension, impact, and three point bending tests with the notion of capturing the time, temperature, stress state dependence, and failure mechanisms under large strains. The ISV model was integrated into a finite element (FE) code and the FE simulations agreed very well with the PP and co-PP mechanical behavior under compression, impact, and three point bending thus exercising the model under different nominal strain rates, temperatures, and stress states. Two failure criteria were determined from the numerical simulations to build failure criteria maps that distinguished brittle and ductile failure as validated by the experimental observations. This study illustrates the generality of the Bouvard et al. (J Eng Mater Technol 131(4), 041206, 2013), which was previously employed to analyze an amorphous polycarbonate polymer.     

Nanocomposites of polypropylene impact copolymer and organoclays: role of compatibilizers

Nanocomposites of polypropylene impact copolymer and organoclays were prepared using different compatibilizers (polypropylene‐graft‐(maleic anhydride) (PPMA), polyethylene‐graft‐(maleic anhydride) (PEMA) and their mixture) and varying percentages of clay (3 and 6%) in an attempt to obtain balanced mechanical properties. The nanocomposites were prepared by melt compounding and test specimens were prepared by injection molding. Mechanical properties such as tensile, flexural and Izod impact strength are reported. The clay dispersion was investigated using wide‐angle X‐ray diffraction while the phase morphology was characterized using scanning electron microscopy. It is shown that the mechanical properties of the system with mixed PPMA and PEMA compatibilizers showed the best balance of mechanical properties among the nanocomposites explored. Copyright © 2006 Society of Chemical Industry     

Morphology, microstructure and compatibility of impact polypropylene copolymer

The morphology of impact polypropylene copolymer (IPC) was studied through scanning electron microscope (SEM) and transmission electron microscope (TEM) observation, and a modified dispersed phase model of IPC with core-shell structure was proposed. Through fractionation of IPC, the glass transitions of the ethylene-propylene random copolymer (EPR) fraction, ethylene-propylene block copolymer (EbP) fraction and propylene homopolymer (iPP) fraction were detected, respectively. Moreover, the glass transitions and crystallization behaviors of EbP/iPP and EPR/EbP fraction blends were systemically investigated and several reasonable chain structures of EbP component were confirmed. The results reveal that the EbP component presents three glass transition peaks, and the glass transition temperature of ethylene-propylene random copolymer in IPC sample is remarkably lower than that of pure EPR fraction due to the existence of special structure of EbP component in IPC. In addition, co-crystallization occurring between the polypropylene chains in EbP fraction and in iPP fraction was found for solution-mixed EbP/iPP blends, and it is believed that there exists a dilute effect of EPR on the crystallization of EbP fraction for the solution-mixed EPR/EbP blends. Accordingly, it can be inferred that EbP fraction has good compatibility with both EPR and iPP fraction, and indeed it confirms that the compatibilization effect of EbP fraction in IPC was good.     

可控流变抗冲共聚聚丙烯的相分离及增长模型

研究了抗冲共聚聚丙烯(ICPP)和可控流变抗冲共聚聚丙烯(CRICPP)的流变行为以及亚微观形态.结果表明:CRICPP在加工流动性大幅度提高的同时,经注塑加工,相分离后的形态与ICPP明显不同; ICPP的分散相由较大的颗粒组成;而CRICPP则由多个小颗粒聚集而成,且随着过氧化物含量的提高,组成分散相的颗粒尺寸明显变小.为直观描述ICPP及CRICPP的相分离过程,建立了相应的分散相增长模型.     

抗冲击聚丙烯合金结构与性能的研究进展

综述了抗冲击聚丙烯合金(IPC)组成、微观形态的分析测试方法,以及IPC的组成和微观形态对其性能的影响。采用交互式高效液相色谱法可以快速分析出IPC中的化学组成。通过分析IPC中各组分的微观结构发现,含少量乙烯的聚丙烯链可以增加IPC的拉伸强度,而含少量丙烯的聚乙烯链可以增加合金的冲击强度,乙烯-丙烯嵌段共聚物含量高的IPC具有很好的低温抗冲击性能。IPC的刚性和韧性可以通过控制相对分子质量和等规指数来调节。熔融退火会极大地影响IPC的结晶形态和结晶行为。     

汽车保险杠用抗冲共聚聚丙烯发展概况

介绍了汽车保险杠系统结构特点、保险杠材料的发展状况、聚丙烯在保险杠上的应用以及国内外保险杠用抗冲共聚聚丙烯的开发现状和发展趋势.     

长链支化聚丙烯的制备及其流变性能研究

设计合成了3种不同结构的非对称双烯单体,作为制备长链支化聚丙烯的接枝单体。并通过旋转流变仪研究了所制备样品的流变性能,研究发现对烯丁基苯乙烯、对烯丁氧基甲基苯乙烯、丙烯酸烯丁酯抑制聚丙烯降解的能力依次减弱,其中对烯丁基苯乙烯和对烯丁氧基甲基苯乙烯适合用作制备长链支化聚丙烯的接枝单体。     

Effect of chain structure on the melt rheology of modified polypropylene

The effect of molecular structure of polypropylene (PP) on the melt rheological properties were investigated for electron irradiated polymer and di-2-ethylhexyl peroxy dicarbonate (EHPC)-treated polymer. The modifications were examined in terms of the rheological behaviors, molecular weight distribution, and the degree of branching. The high melt strength PP was obtained by irradiating with 50 and 80 kGy and adding EHPC. The modified PPs showed the strain hardening in the uniaxial elongational viscosity, though the linear elongational viscosity was lower than that of the unmodified PP. Low angle laser light-scattering measurements of the modified PPs showed the interesting results; high irradiation doses such as 50 and 80 kGy caused higher molecular weight chains branching. Nevertheless, the long branching chains were not detected for the EHPC modified PP, which also showed the strain hardening in uniaxial elongational flow. In this article, the relation between chain structure and rheological properties is discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1493–1500, 1999     

Toughening effects of nucleating agent on impact polypropylene copolymer

In this study, the impact polypropylene copolymer (IPC) blended with the sorbitol‐based nucleating agent (NA) NX8000 was prepared and then characterized using a wide range of instrumentations. The results showed that the NA formed a fibril network which resulted in the increased viscosity of system and the decreased size of ethylene–propylene random copolymer (EPR) phase. The results of mechanical tests revealed “the brittle–ductile transition (BDT)” occurred while the ethylene content was between 3.5 wt % and 6 wt % and indicated that the impact strength of IPC was greatly improved by the addition of NX8000 when the EPR content was right over the critical value of BDT. The investigations provided valuable information for the further development of IPC materials and boarded its potential industrial applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40705.     

Study on thermal behavior of impact polypropylene copolymer and its fractions

An impact polypropylene copolymer (IPC) was fractionated into three fractions using n‐octane as solvent by means of temperature‐gradient extraction fractionation. The glass transitions, melting, and crystallization behavior of these three fractions were studied by modulated differential scanning calorimeter (MDSC) and wide‐angle X‐ray diffraction (WAXD). In addition, successive self‐nucleation and annealing (SSA) technique was adopted to further examine the heterogeneity and the structure of its fractions. The results reveal that the 50°C fraction (F₅₀) mainly consists of ethylene‐propylene random copolymer and the molecular chains may contain a few of short but crystallizable propylene and/or ethylene unit sequences; moreover, the lamellae thicknesses of the resulting crystals are extremely low. Furthermore, 100°C fraction (F₁₀₀) mainly consist of some branched polyethylene and various ethylene‐propylene block copolymers in which some ethylene and propylene units also randomly arrange in certain segments, and some polypropylene segments can form crystals with various lamellae thickness. An obvious thermal fractionation effect for F₁₀₀ samples after being treated by SSA process is ascribed to the irregular and nonuniform arrangement of ethylene and propylene segments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microstructure of two polypropylene homopolymers with improved impact properties

Two polypropylene homopolymers, samples A and B, synthesized with heterogeneous Ziegler-Natta catalysts, are studied in this work. Both samples show improved impact properties at low temperature than isotactic PP. Particularly, sample B exhibits better toughness, higher molecular weight and slight lower flexural properties than sample A. Then, these two samples were fractionated into six fractions via temperature rising dissolution fractionation, respectively. Both samples are mainly composed of fractions 4, 5 and 6, which were collected above 100 °C and have high isotacticity. On the one hand, the fractions of sample B have higher molecular weight than the corresponding fractions of sample A collected at the same temperatures. On the other hand, ¹³C NMR and DSC analyses of the fractions indicate clearly that fractions of sample B have lower isotacticity and crystallinity than the corresponding fractions of sample A. The above difference in microstructure between samples A and B should be the key factors resulting in their difference in mechanical properties finally. Both polypropylene homopolymers possibly become new type of impact PP.     

Role of crystalline ethylene‐propylene copolymer on mechanical properties of impact polypropylene copolymer

Impact polypropylene copolymer (IPC) has been known as a multiphase material in which an ethylene‐propylene (EP) random copolymer, serves as toughening component, is dispersed in the homo‐polypropylene hPP matrix. The crystalline EP copolymer (cEP) is another component whose role and microstructural effect on the IPC properties has not been well understood. This work reveals the relationship between the microstructure of cEP and the mechanical properties, that is, impact and tensile resistance, of IPC. We clarify that IPC comprising high contents of cEP with long homo‐PP segment can extend the elongation at break while cEP with high content of homo‐PE segment contributes to high impact strength. Mechanisms for both of these processes have been proposed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structure and melt rheology of long‐chain branching polypropylene/clay nanocomposites

Long‐chain branching polypropylene (LCB‐PP)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder. The microstructure and melt rheology of these nanocomposites were investigated using x‐ray diffraction, transmission electron microscopy, oscillatory shear rheology, and melt elongation testing. The results show that, the clay layers are intercalated by polymer molecular chains and exfoliate well in LCB‐PP matrix in the presence of maleic anhydride grafted PP. Rheological characteristics, such as higher storage modulus at low‐frequency and solid‐like plateau in tan‐ω curve, indicate that a compact and stable filler network structure is formed when clay is loaded at 4 phr (parts per hundred parts of) or higher. The response of the nanocomposite under melt extension reveals an initial decrease in the melt strength and elongational viscosity with increasing clay concentration up to 6 phr. Later, the melt strength and elongational viscosity show slight increases with further increasing clay concentration. These results might be caused by a reduction in the molecular weight of the LCB‐PP matrix and by the intercalation of LCB‐PP molecular chains into the clay layers. Increases in the melt strength and elongational viscosity for the nanocomposites with decreasing extrusion temperature are also observed, which is due to flow‐induced crystallization under lower extrusion temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011