Effect of polymeric additives on the rheological properties of talc-filled polypropylene

The effect of small amounts of low molecular weight polypropylene oxide on the rheological properties of talc-filled polypropylene composites was studied experimentally using a capillary viscometer. The elastic behavior of the system was investigated by exit pressure and die swell methods. Initial studies showed that the talc filler does not influence the viscosity of the polypropylene but decreases the elasticity of the polymer system. Addition of oligomer concentration in a 40 wt percent talc-filled polypropylene not only decreases the viscosity but also further decreases considerably the elasticity of the filled polymer composite. In both cases about 3 wt percent oligomer cone entration appears to be optimal, and further addition of oligomer does not significantly influence the rheological characteristics of the talc-filled polypropylene composite.     

Mechanical properties and morphology of polypropylene composites II. Effect of polar components in talc-filled polypropylene

Using the concept of filler coating, a study has been made of the morphology and mechanical properties of polypropylene/talc/elastomer composites with a series of polar components as added elastomers. Both impact strength and stiffness of the blends were better than those of polypropylene homopolymer. Most of the polar components showed a considerable amount of filler coating, as evidenced by morphological studies. However, the impact strength of the composites was generally lower than that of similar blends with non-polar elastomers, probably owing to (a) the high glass transition temperatures of the polar components, (b) the poor dispersion of some of the elastomeric phases, and (c) a reduced affinity of the elastomers for polypropylene.     

Photodegradation of talc-filled polypropylene

Injection-molded talc-filled polypropylene (PP) composites have been exposed to ultraviolet (UV) radiation in the laboratory for periods up to 26 weeks. The extent of chemical degradation has been assessed by means of Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC), and the results correlated with the mechanical properties. In the early stages of exposure, the photo-oxidation is faster in the talc-filled composites than in the unfilled polymer, but this trend is reversed for exposures longer than ∼12 weeks. Scanning electron microscopy (SEM) inspection has revealed that surface cracks caused by photodegradation in the filled PP occur in the surface exposed to the UV source only, resulting in much less deterioration in tensile properties when compared with the unfilled polymer which degrades significantly at the unexposed surface also. Measurements of melting temperatures by differential scanning calorimetry (DSC) gave a consistent picture of degradation with that obtained by FTIR and GPC studies. DSC analyses have also shown that an increase in the melting enthalpy for both the unfilled and filled grades occurs during exposure.     

Structure and properties of talc-filled polyethylene and nylon 6 films

Water vapor transmission rates can be reduced by as much as 50% in polyethylene by using talc as a filler. The oxygen permeability as well as water vapor transmission rates are similarly reduced by talc in nylon 6 films. The films show low elongation at break and reduced breaking strenth in the presence of talc. The yield strength and the modulus increase with the amount of talc, whereas the elongation at yield decreases. The mechanical and the barrier properties change with the size of the filler, the smaller size being more favorable. Talc probably acts as a nucleating agent and increases the crystallinity in polyethylene and nylon. Polyethylene unit cells in talc-filled films are oriented with the (110) planes parallel to the (001) planes of talc. Nylon 6 crystals, which are in the α form in the presence of talc, are oriented with the hydrogen bonded sheets, the (002) planes, parallel to the (001) planes of talc. In both polyethylene and nylon 6, talc is oriented with the c-axis normal to the plane of the film, i.e., with the broad faces of talc flakes in the plane of the film. Lattice matching between the polymer and talc suggests epitaxy to be a contributing factor for the observed orientation of polyethylene and nylon 6 crystals.     

聚丙烯塑料涂料的制备与性能研究

利用接枝共聚反应合成了在聚丙稀塑料表面具有优异附着力的氯化聚丙烯改性树脂,对该树脂的结构、性能进行了讨论,同时对该树脂在聚两烯表面的附着机理进行了探讨。利用该氯化聚丙烯改性树脂配制的底面合一涂料,具有较好的综合性能,适合汽车等聚丙烯塑料件的涂装。     

Mechanical properties and impact toughness of talc-filled β-crystalline phase polypropylene composites

Injection molded β-crystalline phase polypropylene (PP) composites containing 5, 10, 20, 30 and 40% (by weight) of talc filler were studied by X-ray diffraction, scanning electron microscopy, static tensile and falling drop weight impact tests. The X-ray diffraction analysis showed that the talc filler suppresses the formation of β-form PP dramatically. As a result, the β-PP composites containing talc content ≥20 wt% consisted mainly of the α-form PP phase. The tensile test showed that the addition of talc filler up to 40 wt% leads to an increase in Young's modulus whereas little effect is observed on the yield strength of composites with the addition of talc up to 30%. This behavior can be attributed to the load bearing effect of talc particles with a platelike structure and to good interfacial bonding exists between the matrix and filler. The impact tests revealed that the critical stain energy release rate (G_c) of the β-PP polymers appears to increase initially with the addition of 5 wt% talc; thereafter it decreases significantly with increasing talc content.     

Mechanical properties of talc-filled polypropylene. Influence of filler content,filler particle size and quality of dispersion

Mechanical properties of polypropylene-talc composites are measured as a function of talc concentration up to 40 wt.-%, Young's modulus of filled polypropylene shows linear increase with talc concentration up to double the value of unfilled polymer. Yield stress and Charpy notch toughness decrease with increasing talc content below matrix level at the highest filler content. Composite ultimate tensile elongation and tensile impact strength decrease sharply beginning at the lowest filler concentration. The influence of the talc particle size on the mechanical properties, especially composite toughness, mentioned above, is investigated. Four type of talc were used. Notch toughness decreases according to a linear dependence with mean size of talc particles. Evaluating impact strength possible content of agglomerates of filler and other additions is necessary to be included: tensile impact strength gives slow linear dependence with increasing content of filler particles and/or agglomerates above about 10 μm. The influence of talc particle size on the toughness of filled polypropylene becomes strong if the rubber particles are present.     

高抗冲共聚聚丙烯的结构与性能

采用核磁共振仪、差示扫描量热仪、扫描电子显微镜等表征了两种高抗冲共聚聚丙烯(HIPP)和汽车保险杠专用聚丙烯(PP)树脂SP179,研究了HIPP和SP179的动态流变行为.由于HIPP中橡胶相的含量较高,导致HIPP与SP179相比在低温下具有较高的悬臂梁缺口冲击强度和弹性.在-30℃时,两种HIPP的悬臂梁缺口冲击...     

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...     

Structure and properties of MDO stretched polypropylene

Two polypropylene cast films of different crystalline structures (one with coexisting small rows of lamellae and spherulites and the other with only a spherulitic structure) were prepared by extrusion. The produced cast films were uniaxially hot drawn at T = 120 °C using a machine direction orientation (MDO) unit and the changes in structure and morphology were examined and related to barrier as well as tear and puncture properties. Structural changes in terms of the degree of crystallinity and crystal size distribution, orientation of the amorphous and crystalline phases, and the deformation behavior at the crystal lattice and lamellae scales were investigated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), wide angle X-ray diffraction (WAXD), and small angle X-ray scattering (SAXS), respectively. A significant effect of the original crystal morphology on the alignment of the amorphous and crystalline phases was observed from FTIR and WAXD. The results also revealed that the deformation behavior of the crystal structure was dependent on the draw ratio (DR). Our findings showed that by increasing DR the crystal lamellae first broke up and oriented along the drawing direction and then, at large DR, they were deformed and created a fibrillar structure. Morphological pictograms illustrating the effects of original morphology and draw ratio on the stretched film microstructure are proposed. The tear resistance along the machine direction (MD) decreased significantly with increasing DR whereas the puncture resistance increased drastically. Finally, the oxygen transmission rate (OTR) of the MDO stretched films could be correlated with the orientation parameters as well as the β-relaxation peak magnitude of the amorphous tie chains.     

Effect of corn‐zein coating on the mechanical properties of polypropylene packaging films

In this study, a novel film structure of corn zein coated on polypropylene (PP) synthetic films for food packaging applications was developed, and the mechanical properties of the resulting coated film, as affected by the coating formulation, were investigated. Composite structures of PP films coated with corn zein were obtained through a simple solvent casting method. Different amounts of corn zein (5 and 15%) were dissolved in 70 and 95% aqueous ethanol solution at 50°C. Solutions of corn zein plasticized with poly(ethylene glycol) and glycerol (GLY) at various levels (20 and 50%) were applied on corona‐discharge‐treated PP. A statistical analysis based on full factorial design was performed to examine the influence of the coating formulation on the final properties of the corn‐zein‐coated PP films. A significant (p < 0.05) improvement in the coated film's mechanical properties was observed compared to those of the uncoated PP. The effect of the plasticization of the coating solutions was also quite significant. In general, GLY provided better improvements in the mechanical properties of the corn‐zein‐coated PP films. The statistical analysis of the results showed that the corn‐zein and plasticizer concentrations and plasticizer type used in the coating formulations were more effective parameters and had significant effects on the mechanical behavior of the coated PP films. In conclusion, corn‐zein coatings could have potential as alternatives to conventional synthetic polymers used in composite multilayer structures for food packaging applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

挤出涂层级LDPE树脂1C7A-1的结构与性能

研究了涂层级低密度聚乙烯1C7A-1的相对分子质量及其分布,甲基支化度及羧基、碳碳双键含量,熔胀比及加工性能。结果表明:1C7A-1的相对分子质量及其分布为15～17、熔胀比为1.71,均与国外试样相当;甲基支化度、双键数、羰基含量适中;具有优良的高速加工性能。     

Structure and properties of polypropylene/hydrotalcite nanocomposites

This article presents the study of the modification of the particle/matrix interface region and its effects on the structure and dynamic mechanical behavior of polypropylene (PP)/hydrotalcite nanocomposites prepared by melt extrusion. The interface modification was promoted by combinying the organophillization of the hydrotalcite particles with blending the PP with a maleic anhydride‐grafted‐PP (PP‐g‐MAH) or a maleic anhydride‐grafted‐poly(styrene‐co‐ethylenebutylene‐co‐styrene) (SEBS‐g‐MAH). Sodium dodecyl sulphate was used to promote the organophillization of the hydrotalcite particles. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) showed a partially exfoliated hydrotalcite structure, with an increasing exfoliation being achieved by adding a compatibilizer and organo‐modifying the particles. Values of the Young's modulus (E), storage modulus (E′), maximum tensile strength (σ_max), neck propagation strength (σ_neck), and elongation at break (ε_b) were found to depend both on the nature of the particle matrix interface as well as on the type of compatibilizer. Also, nanocomposites prepared with the organophillized particles showed lower T_g and loss factor values. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

芳纶浆粕增强聚丙烯复合材料的结构与性能

利用双螺杆挤出机制备了聚丙烯(PP) /芳纶浆粕(PPTA-pulp)以及聚丙烯(PP)/芳纶浆粕(PPTA-pulp)/马来酸酐接枝聚丙烯(MAH-g-PP)复合材料。采用力学性能测试、差示扫描量热仪（DSC）、扫描电子显微镜(SEM)、平板流变仪,研究了PP/ PPTA-pulp复合材料的力学性能、结晶行为、断面形态结构及流变行为。结果表明：随着PPTA-pulp含量的增加,复合材料的拉伸强度和弯曲模量增加,缺口冲击强度和断裂伸长率下降,芳纶浆粕对聚丙烯结晶起了成核剂的作用。马来酸酐接枝聚丙烯(MAH-g-PP)作为相容剂,改善了PPTA-pulp与基体PP分子之间的亲和性,提高了界面作用力,并使复合材料的储存模量、损耗模量和力学性能进一步改善。     

Structure and properties of rubber-modified polypropylene impact blends

The state of dispersion of poly(ethylene-co-propylene) (PEP) rubber and high-density polyethylene (HDPE) in polypropylene (PP) blends was investigated using scanning electron microscopy to examine solvent-etched microtomed surfaces cut at low temperatures. The validity of the method was established by comparing the areal fraction of dispersed particles in micrographs with the volume fraction of PEP and HDPE in PP-rich blends. When small amounts of PEP and HDPE were added to PP, they combined to form composite PEP–HDPE particles with characteristic internal structures in a PP matrix. Changes in impact strength and flexural modulus with changes in mixing conditions and blend composition were determined and interpreted in terms of the size, composition, and internal structure of the dispersed particles. Particle growth in the melt limited the impact strength level achieved in molded articles. A simple model proposed for screening rubbers for toughening of brittle plastics successfully predicts that PEP rubber should be an excellent impact modifier for PP.     

Structure and properties of polyethylene–polypropylene blend

The structure and mechanical properties of blends of low-density polyethylene and isotactic polypropylene were studied. The blends behaved like a simple composite obeying the rule of mixture for the modulus dependence on composition. Tensile strength of the LDPE was enhanced with the addition of PP but elongation at break was drastically reduced for all blend compositions. Studies with WAXD, hot-stage microscope, and DSC indicated lack of interaction between the LDPE and the PP. The crystallographic structure of LDPE and PP remained unchanged. However, the spherulite size of the PP was found to be reduced in the presence of LDPE, possibly due to an increase in nucleation density.     

Structure and properties of AlSi/polyester coating

Powder coatings, which are formed by plasma spray technique, are being used in industrial applications. Resistance of plastics and their based composite materials to chemicals, solvents, atmospheric conditions, and high impact strength even at low service temperature increases the importance of plastic and plastic based coating applications. In this study, aluminum silicon based polyester (AlSi/polyester) coating was applied by plasma spraying technique with and without intermediate bond layer coat (NiAl). The effect of coating thickness, intermediate bond layer coat, and plasma spraying parameters on bond strength of coating were studied experimentally. The bond strengths of the coatings were determined according to the ASTM C‐633–79. Microstructures of the coating were examined by optic microscopy and scanning electron microscopy (SEM), respectively. Obtained results indicated that plasma spraying current rate, coating thickness, and spraying distance were important factors on bond strength of coating. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2437–2444, 2004     

Structure and properties of polypropylene alloy in situ blends

A series of polypropylene (PP) alloys containing different ethylene contents have been prepared by the in situ sequential polymerization technique, using Ziegler–Natta catalyst (MgCl₂/TiCl₄/BMF; BMF is 9,9‐bis(methoxymethyl)fluorine, as an internal donor) without any external donor. The structure and properties of PP alloys obtained have been investigated by nuclear magnetic resonance, Fourier transform infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy (SEM). The results have suggested that PP alloys are the complex mixtures containing PP, the copolymer with long sequence ethylene chain, ethylene‐propylene rubber (EPR), and block copolymer etc. In the alloys, PP, EPR, and the copolymer with long sequence ethylene chain are partially compatible. The investigation of the mechanical properties indicates that notched Izod impact strength of PP alloy greatly increases at 16°C/?20°C in comparison with that of pure PP. The noticeable plastic deformation is observed in SEM photograph. The increase in the toughness, the mechanical strength of PP alloy decreases to a certain extent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4804–4810, 2006     

高熔体强度聚丙烯树脂的结构与性能

采用差示扫描量热法、傅里叶变换红外光谱、毛细管流变、熔体拉伸等方法,从结晶性、黏弹性及物理机械性能等方面对高熔体强度聚丙烯(HMSPP)树脂进行结构表征与性能分析。结果表明:HMSPP树脂具备较高的弯曲模量,同时具备优异的抗熔垂能力和更宽的加工温度;拉伸黏度随拉伸速率的增大而增大,呈现出HMSPP应变硬化这一明显行为,使得熔体在热成型过程中具有均匀变形的自我调节能力,从而克服普通聚丙烯在热成型加工中的严重熔垂问题;含有较长接枝链段的HMSPP树脂在刚性、熔体强度、结晶性能等方面均优于普通聚丙烯。