Effects of titanate coupling agents on the rheological and mechanical properties of filled polyolefins

An experimental study was carried out to investigate the effects of titanate coupling agents on the rheological properties of p articulate-filled polyolefin melts. Inorganic fillers used were CaCO₃, talc, and fiberglass, and polyolefins used were high-density polyethylene (HOPE) and polypropylene (PP). It was found that the addition of the coupling agent TTS to the PP-CaCO₃ and PP-fiberglass systems reduced the melt viscosity considerably, whereas the addition of the coupling agent ETDS-201 to the PP-talc and HDPE-talc systems affected the melt viscosity very little. Also carried out was an injection molding study to investigate the effects of different inorganic fillers and the titanate coupling agents used on the mechanical properties of the injection molded specimens. It was found that addition of titanate coupling agents generally resulted in reduced modulus and tensile strength, and increased elongation and impact strength of the filled systems. The PP-CaCO₃-TTS and HDPE-talc-ETDS 201 systems were found to have impact strength improved by approximately 100 percent with the addition of a titanate coupling agent. The PP-CaCO₃-TTS samples have ultimate tensile elongation approaching that of virgin PP.     

Effects of coupling agent on the rheological behavior and processability of polypropylene

An investigation was made into the effect of coupling agents on the rheological behavior and processability of polypropylene. For the study, each of the following three commercially available coupling agents, a titanate coupling agent (Kenrich Petrochemicals, KR-TTS) and two silane coupling agents (Union Carbide, A1100 and Y9187), was melt-blended with polypropylene (PP). Melt blending was performed using a twin-screw compounding machine. It was found that the zero-shear viscosity of polypropylene was decreased by 1 order of magnitude after it had been extruded through the twin-screw compounding machine and that, when coupling agents were added to it, its viscosity was higher than that of the PP without the coupling agents, undergoing the same deformation history through the twin-screw compounding machine. Independent measurements of the molecular weight of the materials show that the weight-average molecular weight (M _W) of the extruded PP is 3.77 × 10⁵, whereas the M _W of the virgin PP (before extrusion) is 4.80 × 10⁵, indicating that considerable molecular degradation occurred during extrusion and the M _W of the PP extruded with coupling agent is greater than that of the PP extruded without coupling agent. In other words, the molecular weight measurement supports the viscosity measurements of the PP investigated with and without coupling agent. Also measured were the elongational viscosity of the PP with and without coupling agent, which was then correlated to the melt drawability of the materials investigated.     

Effects of coupling agents on the rheological behavior and physical/mechanical properties of filled nylon 6

An investigation was made on the rheological behavior and physical/mechanical properties of highly filled nylon 6 composites with and without a coupling agent. As fillers, calcium carbonate and calcium silicate were used, and, as coupling agent, two silanes (Union Carbide, A1100 and Y9187) and two titanates (Kenrich Petrochemicals, KR-44 and KR-138) were used. It was found that all the coupling agents used increased the viscosities of the nylon/CaCO₃ system. However, the effect of the coupling agents on the viscosity of the nylon/CaSiO₃ system seems quite complex; namely, the titanate KR-44 decreased the melt viscosity of the nylon/CaSiO₃ composite, whereas the titanate KR-138S and the silane Y9187 increased it. In general, the effectiveness of the coupling agents in improving the physical/mechanical properties of the nylon/CaCO₃ and nylon/CaSiO₃ composites was marginal. A considerable decrease in glass transition was observed upon exposure of all samples to water, regardless of the type of filler and coupling agent.     

Effects of coupling agents on the mechanical and rheologica properties and mica-reinforced polypropylene

Dimethylaminoethyl methacrylate (DMAEMA) was investigated as a prospective coupling agent for mica-reinforced polypropylene. Composites prepared with the widely-used silane coupling agent, N-(4-vinylphenyl) methyl-N′-(3-trimethoxysilylpropyl)ethylenediamine monohydroehloride (Z-6032), were compared with the amino-coupled composite. Improvements in the flexural properties at room temperature were observed with the two coupling agents: a 22 percent increase in the strength with the silane compared to a. 16 percent increase with DMAEMA. Cone-and-plate viscometry at 220°C showed that the addition of coupling agents greatly, reduces the viscosity of the composite: a 50 percent decease was obtained with the silane-treated composite and a 20 percent decrease with DMAEMA.     

Correlations between rheological and mechanical properties of mineral filled polypropylene compounds

A comparative study of rheological and mechanical properties of Polypropylene compounds with talc as a mineral filler is presented. It turns out that the main factors determining the mechanical behavior, namely (a) filler concentration, (b) filler particle size, and (c) degree of dispersion, influence the linear viscoelastic properties as well. Thus, a quick method for estimating compound properties from melt rheology is established. © 1994 John Wiley & Sons, Inc.     

Effect of titanate coupling agents on mechanical properties of mica-filled polypropylene

The application of titanate coupling agents for the surface modification of mica filler and its reinforcement in polypropylene (PP) has been directed towards improvement in mechanical properties. Four titanate coupling agents, namely neoalkoxy tri(dioctylpyrophosphato) titanate (C₁), neoalkoxy trineodecanoyl titanate (C₂); bis-(acetylacetonato)distearato titanate (C₃), and bis-(acetylacetonato)dipalmitato titanate (C₄) were used in the present investigation. Mica powder (10 μm particle size) was coated with these coupling agents of varying concentration (0.5 to 1 % on the weight of filler) and then blended with polypropylene powder of 10 melt flow index. The mica (10 to 50 wt. %) filled polypropylene samples with and without coupling agents, were injection molded and the mechanical properties of the specimens tested. There is an improvement in the tensile, flexural, and impact strength of PP/mica samples coupled with titanates. The best performance in terms of yield stress and flexural strength was observed in PP/mica samples having 0.7% C₁, titanate coupling agent. The fracture behavior of mica filled PP has also been studied using a scanning electron microscope.     

Melt rheological properties of nickel powder filled polypropylene composites

The melt rheological properties of nickel powder filled polypropylene composites were investigated. The effect of filler concentration on shear stress-shear rate data, melt viscosity and melt elasticity parameters were determined by using a capillary rheometer. The study shows that the materials follow a power law in viscous behavior over the entire range of shear rates investigated and that the viscosity increases and elasticity decreases as filler concentration is increased up to a critical value. However, beyond the critical filler content melt viscosity decreases while melt elasticity increases. The effect of temperature on the viscoelastic properties of filled polypropylene was also investigated.     

Effect of titanate coupling agent on the mechanical,thermal, dielectric,rheological, and morphological properties of filled nylon 6

Fillers are used along with various commodity as well as engineering polymers to improve the properties of polymers. The performance of filled polymers is generally decided on the basis of the interface attraction of filler and polymers. Fillers of widely varying particle size and surface characteristics are responsive to the interfacial interactions with polymers. The present study deals with the effect of a coupling agent, tetra isopropyl titanate (TPT), on the properties of flyash filled nylon 6. It is observed that tensile strength, impact strength, and heat distortion temperature improved with the addition of TPT as compared to without the coupling agent filled nylon 6. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 266–272, 2006     

Effects of lubricants on the rheological and mechanical properties of wood flour/polypropylene composites

The lubricant is an indispensable agent used in wood plastic composites (WPCs) to improve the processing flowability, especially with high wood content. Here, the effects of different lubricating systems on the rheological and mechanical properties of wood flour/polypropylene (WF/PP) composites are investigated. Additionally, several theoretical models are used to describe the rheological behavior. The results show that stearic acid (SA), semirefined paraffin wax (Wax), and zinc stearate (ZnSt) can decrease the equilibrium torque, complex viscosity, relaxation time, and flow activation energy of the composite melts. Compared to a single lubricant, the combination of Wax and SA lubricants exhibits lower values and the composite with 3 wt % SA and 1 wt % Wax has the best lubricating effect. The synergistic effect of the combined SA and Wax lubricants further decreases the interactive force between the molecules, indicating that multifunctional lubricating systems play a predominant role in WPCs and improve the overall processing properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47667.     

Optical,rheological, and thermal properties of hollow glass bead filled isotactic polypropylene

Hollow glass beads (HGB) were mixed into isotactic polypropylene (iPP) by an internal mixer and the effect of HGB concentration on optical, rheological, and thermal properties of iPP/HGB composites was studied. The dispersion of treated and nontreated HGB in the iPP matrix and the crystal habit of iPP in the composites were examined by phase contrast microscopy. Dynamic rheological measurements were carried out in the melt state in the oscillatory shear mode. The data were analyzed to yield the variations of rheological properties of the composites when the HGB were added. The influence of HGB concentration on the thermal properties including the crystallization and melting behaviors of the composites was studied by means of differential scanning calorimeter and wide angle X‐ray diffraction. It was found that the addition of HGB had effect on the crystallization and melting behaviors of the composites, including that HGB had a weak nucleating effect in the matrix and promoting the formation of β‐crystals of iPP. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Effects of calcium carbonate and its purity on crystallization and melting behavior,mechanical properties,and processability of syndiotactic polypropylene

Calcium carbonate‐filled syndiotactic poly(propylene) (CaCO₃‐filled s‐PP) was prepared in a self‐wiping, co‐rotating twin‐screw extruder. The effects of CaCO₃ of varying particle size (1.9, 2.8 and 10.5 μm), content (0–40 wt %), and type of surface modification (uncoated, stearic acid‐coated, and paraffin‐coated) on the crystallization and melting behavior, mechanical properties, and processability of CaCO₃‐filled s‐PP were investigated. Non‐isothermal crystallization studies indicate that CaCO₃ acts as a good nucleating agent for s‐PP. The nucleating efficiency of CaCO₃ for s‐PP was found to depend strongly on its purity, type of surface treatment, and average particle size. Tensile strength was found to decrease, while Young's modulus increased, with increasing CaCO₃ content. Both types of surface treatment on CaCO₃ particles reduced tensile strength and Young's modulus, but improved impact resistance. Scanning electron microscopy (SEM) observations of the fracture surfaces for selected CaCO₃‐filled s‐PP samples revealed an improvement in CaCO₃ dispersion as a result of surface treatment. Finally, steady‐state shear viscosity of CaCO₃‐filled s‐PP was found to increase with increasing CaCO₃ content and decreasing particle size. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 201–212, 2004     

Effects of nucleating agents on crystallization behavior and mechanical properties of high-fluid polypropylene

The effects of organic aluminum phosphate (NA-21) and rare earth organic coordination compounds (WBG), serving as ??, ?? nucleating agents, on crystallization and mechanical properties of high-fluid polypropylene (PP) have been investigated. As determined by differential scanning calorimetry, the isothermal crystallization temperature of PP increased from 126.5 to 137.7?°C and 133.6?°C with NA-21 and WBG, respectively. The two endothermal melting peaks of PP blending with WBG indicated the transformation of ??-crystal. The wide-angle X-ray diffraction pattern and melting behavior of PP blending with WBG testified that a high proportion of ??-crystal, which was more than 70%, was induced, while the crystal-phase of PP modified with NA-21 had little change. The mechanical properties of nucleated PP were tested by tensile testing machine and izod pendulum impact tester. A dramatic increment of impact strength, as high as 191%, was obtained for PP with the introduction of WBG, comparing to 132% by NA-21 addition. The impact fracture surfaces were observed by scanning electron microscope; the resistance of crack growth of nucleated PP was better than that of pure PP. Although flexural strength of PP improved in both scenarios, the influence of nucleators on yield strength of PP differed. Yield strength of PP increased by 8.5% when using 0.2?wt% NA-21, but decreased by 6% when using WBG at the same content. Therefore, WBG, a novel ??-nucleator, played an essential role in enhancing impact strength of PP.     

A study on the rheological properties and processability of polycarbonate

The transport theory for the solids conveying zone in a single‐screw extruder was applied to calculate the pressure distributions along the screw channel for several bisphenol A polycarbonate resins based on the screw revolution speed and the flow rate. The pressure distributions and the flow rates of the resins were related to the structural and rheological properties. When polymers have the same chemical structure and number‐average molecular weight and the same mechanical properties, the polymer having a broader molecular weight distribution showed a lower glass transition temperature. For the polymer with broader MWD a relatively low pressure was developed along the screw channel, and an increased flow rate was observed. A relatively short melting length was also observed for this polymer and, accordingly, it was concluded that the polymer with a broader MWD has a better processability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2921–2929, 2002     

Influence of grafted polypropylene on the mechanical properties of mineral‐filled polypropylene composites

The purpose of this work was to study how mineral fillers would behave in a polypropylene (PP) matrix when PP modified with maleic anhydride (MA) and/or itaconic acid (IA) was used as a coupling agent in the preparation of mineral‐filled PP composites. The composites were characterized with tensile mechanical measurements and morphological analysis. The optimum amount of the coupling agent to be used to obtain composites with improved mechanical properties was established. The results indicated that these coupling agents enhanced the tensile strength of the composites significantly, and the extent of the coupling effect depended on the nature of the interface that formed. The incorporation of coupling agents enhanced the resistance to deformation of the composite. The behavior of IA‐modified PP as a coupling agent was similar to that of a commercial MA‐modified PP for the filled PP composites. Evidence of improved interfacial bonding was revealed by scanning electron microscopy studies, which examined the surfaces of fractured tensile test specimens; their microstructures confirmed the mechanical results with respect to the observed homogeneous or optimized dispersion of the mineral‐filler phase in these composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2343–2350, 2007     

Effect of molecular weight distribution on the rheological and mechanical properties of polypropylene

The effect of molecular weight distribution on the Theological and mechanical properties of a series of polypropylenes is evaluated. The polypropylenes tested were produced by controlled chemical degradation in a single-screw plasticating extruder. Measured properties include shear, extensional and intrinsic viscosity, melt flow index, extrudate swell, melting and crystallization temperatures, impact strength, flexural modulus, and tensile stress.     

硅烷偶联剂对ZnO/PA6复合材料力学性能的影响

以硅烷偶联剂KH550和KH560为改性剂对ZnO粉体进行表面改性,KH550带有氨基团,KH560带有环氧基团,通过HAAKE双螺杆混合机制备ZnO/PA6复合材料。红外光谱证实改性后两种偶联剂均与ZnO表面发生了化学键和;结果表明经偶联剂改性的氧化锌比未改性的氧化锌能更好的提高PA6的拉伸强度,而且在ZnO的添加量为2%～3%时对PA6力学性能的改善达到一个最佳效果。     

Dynamic mechanical properties of polypropylene composites filled with ultrafine particles

The dynamic moduli of isotactic polypropylene (PP) filled with ultrafine SiO₂ and micron sized glass particles are measured in the temperature range 30–130°C at frequency 10 Hz. The storage moduli of PP composites, E′_c, increase with filler content and decreasing filler size in the whole range of temperature. The loss moduli of PP composites, E″_c, increase with filler content and decreasing filler size above 40°C. The intensity of the broad despersion which appears at ca. 60°C increases with filler content and decreasing filler size. By assuming that the energy is not dissipated in the effective volume, namely, filler volume plus that of immobilized interfacial region, the effective volume fraction is evaluated from the relative loss modulus, E″_cE″₀ at 60°C. The effective volume fraction increases with filler content and decreasing filler size. The effect of addition of ultrafine particles on the broad dispersion at ca. 60°C resembles the effect of increasing crystallinity of pure PP. It is concluded that the broad dispersion which appeared at ca. 60°C seemed to be assigned to the grain boundary of PP composities or crystalline boundary of pure PP.     

Physical,mechanical, and thermal properties of polypropylene composites filled with walnut shell flour

Injection molded specimens were prepared from the walnut shell flour and polypropylene with and without maleic anhydride-grafted polypropylene at 40, 50, and 60% (weight) contents of the walnut shell. The bending and tensile modulus of the composites significantly increased with increasing the filler content while the bending and tensile strengths significantly decreased. Water absorption and thickness swelling of the composites increased with increasing filler content. The MAPP improved the interfacial adhesion between walnut shell flour and polymer matrix. A 40/57/3 formulation of the walnut shell flour/polypropylene/MAPP can be used in outdoor applications requiring a high dimensional stability.     

Effects of compatibilizers and testing speeds on the mechanical properties of organophilic montmorillonite filled polyamide 6/polypropylene nanocomposites

In the present study, the fracture properties of different types of organophilic montmorillonite (OMMT) filled polyamide 6/polypropylene nanocomposites was investigated. Two types of compatibilizers, i.e., maleic anhydride grafted polypropylene (PP‐g‐MA) and maleic anhydride grafted styrene‐ethylene/butylene‐styrene (SEBS‐g‐MA) were used to compatibilize these systems. The tensile properties were studied through tensile test at two different testing speeds; 50 and 500 mm/min whereas the fracture properties were determined using single‐edge‐notch‐3 point‐bending (SEN‐3PB) specimens at three different testing speeds; 1, 100, and 500 mm/min. The presence of both PP‐g‐MA and SEBS‐g‐MA compatibilizers improved the tensile and fracture properties of nanocomposites due to the compatibilizing effect of both compatibilizers. SEBS‐g‐MA compatibilizer seemed to be more effective in improving the fracture toughness of nanocomposites than PP‐g‐MA especially at high testing speed. This was due to the elastomeric nature of SEBS‐g‐MA, which can provide a better toughening effect than the relatively harder PP‐g‐MA. POLYM. ENG. SCI., 50:1493–1504, 2010. © 2010 Society of Plastics Engineers     

The rheological modification of talc‐filled polypropylene by epoxy‐polyester hybrid resin and its effect on morphology,crystallinity, and mechanical properties

Reactive mixing of polypropylene (PP) and talc with epoxy‐polyester resin was preformed using a corotating twin screw extruder, and the rheology, morphology, crystallization behavior, and mechanical properties of composites were evaluated. The melts of composites mixed with resin exhibited yield stress and the variation of viscosity against frequency can be approximated in two lines with various slopes. The measurement of the suspension viscosity can be used to characterize the microstructural state of dispersion. Empirical formula was used to relate viscosity with particle concentration, and the analysis showed that the maximum volume fraction increases by using small amount of epoxy resin in the formulations. The morphological study of composites by scanning electron microscopy revealed that the use of resin improved the dispersion of talc in PP, which leads to the arrangement of talc platelets in the direction of flow even close to wall of the mold. The differential scanning calorimetry showed that the epoxy resin suppressed the nucleation effect of talc on PP while the degree and rate of crystallization increased. The compatibilization by maleic anhydride‐grafted polypropylene showed a noticeable increase in tensile strength of composites reactively mixed with epoxy resin. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers