Study on the viscosity of polypropylene composites filled with different size and size distribution CaCO3

Two kinds of different size calcium carbonates are blended and filled into polypropylene in 30 wt%. The melting viscosity of PP composites samples is measured by capillary extrusion rheometer at 230°C. The results show that the melt viscosity of PP composites evidently decreased when that was filled with the blending 325 and 1,500 mesh CaCO₃ and the 1,500 mesh proportion in fillers was from 20 to 60 wt%. The viscosity in the low shear velocity decreased more than that in the high shear velocity. The shear viscosity of single filler and filler samples with the size distribution at the different temperature was studied by capillary extrusion rheometer. The results show that the flow activation energy and the flow activation entropy of composites filled with the size distribution filler increased. The change of the flow activation entropy and the model of the efficient arrangement of the structure are used to explain the phenomenon in melting viscosity decrease of PP filled with the size distribution fillers. A structural model of composites that filled with the size distribution fillers was set up. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Processing characteristics of low‐density polyethylene filled with calcium carbonate of different size distributions

Low‐density polyethylene (LDPE) was filled with blends of different proportions of two sizes of calcium carbonate (CaCO₃; 600 and 2500 mesh). The torque of the LDPE/CaCO₃ samples was measured with a torque rheometer. The results showed that the process torque values of the LDPE/CaCO₃ samples obviously decreased when LDPE was filled with a blend of two sizes of CaCO₃ (600‐ and 2500‐mesh CaCO₃ blend) in comparison with samples filled with CaCO₃ of a single size (600 or 2500 mesh). When the ratio of 600‐mesh CaCO₃ to the total CaCO₃ was in the range of 40–60 wt %, the lowest torque value of the LDPE/CaCO₃ samples was achieved. When the content of CaCO₃ in a sample was 30 wt %, LDPE filled with CaCO₃ of different size distributions showed the largest decrease in the torque ratio in comparison with the samples filled with CaCO₃ of a single size. The torques of LDPE samples filled with CaCO₃ of a single size and those filled with CaCO₃ of different size distributions at different temperatures were also studied. The results showed that the flow activation energy and flow activation entropy of LDPE samples filled with CaCO₃ of different size distributions increased obviously. The increase in the flow activation entropy was used to explain the phenomenon of the process torque decreasing for LDPE samples filled with CaCO₃ of different size distributions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on the processability of UHMWPE filled with different size distribution calcium carbonate particles

Two kinds of different size distribution calcium carbonate (CaCO₃) particles were blended and filled into ultra‐high molecular weight polyethylene (UHMWPE). The torque of UHMWPE/CaCO₃ samples was measured with Haake torque rheometer. The results showed that the process torque of UHMWPE/CaCO₃ samples was decreased by filling two different size CaCO₃ particles (600 and 2500 mesh) into UHMWPE, compared with the samples filled with single size CaCO₃ particles (600 or 2500 mesh). When the content of CaCO₃ in the sample reaches 30 wt%, UHMWPE filled with different size distribution CaCO₃ particles showed the largest decrease in torque compared with the samples filled with single size CaCO₃ particles. We also studied the torque of UHMWPE samples at different temperatures. The results showed that flow activation energy and flow activation entropy of UHMWPE samples filled with different size distribution CaCO₃ particles increase significantly. The result where flow activation entropy increased was used to explain the phenomenon that the process torque decreases when UHMWPE filled with different size distribution CaCO₃ particles. POLYM. COMPOS., 36:1807–1812, 2015. © 2014 Society of Plastics Engineers     

Rheological and fusion behaviors of PVC micro‐ and nano‐composites evaluated from torque rheometer data

The effects of calcium carbonate (CaCO₃) particle size on the fusion and rheological behaviors of rigid poly(vinyl chloride) (PVC) composites prepared in a Haake torque rheometer were investigated by means of torque data recorded during processing. Increasing the number of particles in the same blend volume by decreasing the particle size resulted in increasing frictional forces. This increase led in turn to increased fusion torque and decreased fusion time and temperature. The power‐law‐index values of the composites increased with decreasing particle size except for 25‐nm CaCO₃. The viscosities of all composites were found to decrease with shear rate; therefore, high pseudoplasticity was observed. At a particular rotor speed, viscosity of the composites decreased with decreasing particle size except for 25‐nm CaCO₃. The overall results showed that the particle size of CaCO₃ altered the fusion characteristics and rheological behavior of PVC. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Effect of filler treatments on rheological behavior of calcium carbonate and talc‐filled polypropylene hybrid composites

Commercial stearic acid treated calcium carbonate (CaCO₃) was used to make a comparative study on rheological behavior of the CaCO₃ and talc‐filled polypropylene (PP) hybrid composites with nontreated filler. Apparent shear viscosity and extrudate swell were investigated with variation of filler ratio and temperature with 30% by weight total of filler was used in PP composite. The Shimadzu capillary rheometer was used to evaluate shear viscosity and shear rate of the composite. It was found that the shear viscosities decrease with increasing shear rate. The apparent shear viscosity of the composite containing the stearic acid treated is slightly lower than untreated filler. Shear thickening behavior at higher shear rate has also shown by 15/15 treated composites at higher temperature about 220°C and investigation by SEM has proved that filler being densely packed at that condition. Treated composites also exhibit lower swelling ratio value than untreated composite, and swelling ratio also decreases linearly with increasing temperature and the die length–diameter ratio. It is believed that dispersion of filler play an important role not only on shear viscosity but also on swelling ratio of PP composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5421–5426, 2006     

Melt flow behavior in capillary extrusion of nanosized calcium carbonate‐filled poly(L‐lactic acid) biocomposites

Nanosized calcium carbonate (nano‐CaCO₃)‐filled poly‐L ‐lactide (PLLA) biocomposites were compounded by using a twin‐screw extruder. The melt flow behavior of the composites, including their entry pressure drop, melt shear flow curves, and melt shear viscosity were measured through a capillary rheometer operated at a temperature range of 170–200°C and shear rates of 50–10³ s^?1. The entry pressure drop showed a nonlinear increase with increasing shear stress and reached a minimum for the filler weight fraction of 2% owing to the “bearing effect” of the nanometer particles in the polymer matrix melt. The melt shear flow roughly followed the power law, while the effect of temperature on the melt shear viscosity was estimated by using the Arrhenius equation. Hence, adding a small amount of nano‐CaCO₃ into the PLLA could improve the melt flow behavior of the composite. POLYM. ENG. SCI., 52:1839–1844, 2012. © 2012 Society of Plastics Engineers     

Rheology and Dispersion Behavior of Highly Filled Propylene-Ethylene Copolymer/Calcium Carbonate Composites

The rheology and dispersion behavior of commercial propylene-ethylene copolymer, highly filled propylene-ethylene copolymer/CaCO₃ composites and highly filled propylene-ethylene copolymer/HDPE/CaCO₃ composites prepared by melt-compounding were investigated. The pure propylene-ethylene copolymer exhibits pseudoplastic flow behavior obviously. The CaCO₃ particles in the composites have achieved a homogeneous dispersion and the increasing shear rate has almost no influence on the dispersion behavior of CaCO₃ particles. The high loading of CaCO₃ particles influences the rheology behavior of propylene-ethylene copolymer slightly. For the highly filled propylene-ethylene copolymer/CaCO₃ composites, the extensional viscosity only decreases slightly throughout the entire range of extension rates.     

Studies on crystal morphology and crystallization kinetics of polypropylene filled with CaCO3 of different size and size distribution

Changes in the crystal morphology, crystallinity, and the melting temperature of thermoplastics resulted in significant changes in the mechanical behavior of composites containing them. For this reason, the research of crystal morphology and crystallization kinetics in thermoplastic composites became an important requirement. The thermoplastic filled with the filler of different size gradation was a new method for improving processability of thermoplastic composites. We have previously reported that the melt viscosity of polypropylene (PP) composites, which were filled with 30 wt % CaCO₃ of effective size gradation, could be evidently declined. In this study, two sizes of CaCO₃, 325 meshes and 1500 meshes, were blended by different proportions and filled into PP matrix with 30 wt %. Crystal morphology and isothermal crystallization kinetics of a series of composites were characterized by differential scanning calorimeter (DSC) and polarizing microscope. The results showed that composites filled with CaCO₃ of effective size gradation leaded to a well‐crystalline order and a large crystal size, while their isothermal crystallization kinetics and crystallization rate constant (k) were declined, and their Avrami exponents (n) and crystallization half‐life (t_1/2) were increased compared with the composites filled with single size CaCO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2437–2444, 2006     

Processability,morphology, thermal,and mechanical properties of rigid PVC composites with liquid macromolecular modifier‐coated CaCO3

Rigid poly(vinyl chloride) (PVC)/CaCO₃ and PVC/liquid macromolecular modifier (LMM) coated CaCO₃ (PVC/LCC) composites were both fabricated by melt mixing. The processability, micro‐structure, dynamic mechanical behavior and mechanical properties of PVC/CaCO₃ and PVC/LCC composites were studied by using torque rheometer, scanning electron microscope (SEM), dynamic mechanical analysis (DMA), and universal mechanical testing machine. The results showed that the synergistic effect of LMM and CaCO₃ particles accelerated the plasticization of PVC resins. The processability of PVC/LCC composites was improved. The dispersion of LCC in PVC matrix was improved by the modification of CaCO₃ particles with LMM. The T_gs of PVC/LCC composites were enhanced by filling with LCC. Because of the synergistic toughening of LMM and CaCO₃ particles, the PVC/LCC composites exhibited excellent notched impact properties at the optimum value of LCC particles content. POLYM. COMPOS., 36:1286–1292, 2015. © 2014 Society of Plastics Engineers     

Photo polymerization of acrylamide onto calcium carbonate particle surfaces and filled nylon‐6

The polymerization of acrylamide (AAM) onto calcium carbonate (CaCO₃) particle surfaces induced by ultraviolet light and the properties of polyamide‐6 (PA6) filled with the surface‐treated CaCO₃ were studied. Electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), particle size distribution, impact strength and degree of polymerization measurements were determined. After AAM polymerization, a PAAM layer was formed on the CaCO₃ surface. This layer tightly banded the CaCO₃ particle and could not be washed away by acetone. A N_1s peak was observed in the ESCA spectra of the treated CaCO₃ particles. The average particle size of the treated CaCO₃ increased compared to that of the original CaCO₃. The interfacial interaction and impact strength of the treated CaCO₃–filled PA6 were enhanced compared to those of the untreated CaCO₃–filled PA6. Polym. Eng. Sci. 44:1277–1282, 2004. © 2004 Society of Plastics Engineers.     

Rheology of poly(n‐butyl methacrylate) and its composites with calcium carbonate

Poly(n‐butyl methacrylate) (PBMA) composites with calcium carbonate (CaCO₃) were prepared by in situ radical copolymerization of butyl methacrylate (BMA) and methacrylic acid (MA) with precipitated calcium carbonate. To compare the different rheological behaviors of the monomer mixtures with CaCO₃ and the composites, the steady and dynamic viscosities of BMA/MA/CaCO₃ and poly(BMA/MA/CaCO₃) were measured by means of steady and oscillatory shear flows. The viscosity of the mixture BMA/MA/CaCO₃ was found to increase evidently with the increasing of CaCO₃%. The influence of MA% on viscosity of BMA/MA/CaCO₃ was slight. During the in situ polymerization, the viscosity of the reacting system was measured to be enhanced by a factor of about 10⁴ from the monomer/CaCO₃ mixture to composites. The dependency of zero‐shear viscosity on molar mass of PBMA was also investigated. The relation between the zero‐shear viscosity and molar mass is η₀ = 10^?15 M_w^3.5. The evolution of the viscosity with the temperature for both PBMA and its composites was obtained and time–temperature superposition was used to build master curves for the dynamic moduli. The flow activation energies were found to be 115.0, 148.6, and 178.7 kJ/mol for PBMA, composite PBMA/CaCO₃ (90/10), and PBMA/MA/CaCO₃ (89/1/10), respectively. The viscosity of the composites containing less than 10% CaCO₃ was lower than that of pure PBMA with the same molar mass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1376–1383, 2003     

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     

Preparation and characterization of nano/micro‐calcium carbonate particles/polypropylene composites

A new kind of polypropylene (PP)/CaCO₃ composites was prepared on a twin screw extruder with the nanoparticle content of 5 wt % and the 2500 mesh microparticle content of 15 wt %. The mechanical property of four different samples [pure PP (1) , PP filled with 15 wt % microCaCO₃ particle composites (2) , PP filled with 5 wt % nanoCaCO₃ particle composites (3) and PP filled with micro/nano‐CaCO₃ complex size particle composites (4) ] was investigated through tensile tests, notched Izod impact tests and SEM. The results indicated that the sample 4 had the best mechanical property. The proofs of SEM showed that the high impact energy could lead to debonding and creating microcavitation between the nanoparticle and polymer interface if the polymer was filled with the nanoparticles. This process could absorb a lot of mechanical failure energy, but too much mechanical failure energy would lead to the enlargement of microcavitation and the destruction of the composites in sample 3 . In sample 4 , the microparticle could be used to prevent the enlargement of microcavitation in the matrix polymer under the higher impact failure energy. In this article, the model of the impacting failure process of micro/nanoCaCO₃/PP composites was established. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,characterization, and properties of polyethylene composites highly filled with calcium carbonate through co‐rotating conical twin‐screw extrusion

A series of highly filled polyethylene (PE) composites in which the calcium carbonate content was as high as 50–75 wt% was prepared by co‐rotating conical twin‐screw extrusion (Co‐RCE). The effects of Co‐RCE processing and CaCO₃ content on the morphology, structure, and properties were investigated in detail. The results indicated that the Co‐RCE processing improved the filler dispersion and thereby enhanced the melt processability of the blends. Observation by polarized light microscopy and analysis by differential scanning calorimetry and wide‐angle X‐ray diffraction showed that the crystallinity of PE decreased with the increase of CaCO₃ content. In comparison with neat PE, an increase of up to 20^oC in onset weight loss temperature was observed in the CaCO₃‐filled PE composites, as confirmed by thermogravimetric analysis. Tensile tests indicated that the elongation at break of the highly CaCO₃‐filled PE composites was much higher than that of the neat PE. Meanwhile, the highly filled composites still exhibited superior tensile strength. J. VINYL ADDIT. TECHNOL., 20:108–115, 2014. © 2014 Society of Plastics Engineers     

The effect of alginate on the mechanical,thermal, and rheological properties of nano calcium carbonate‐filled polylactic acid composites

Traditional plasticizers to modify polylactic acid (PLA) usually leads to limited biodegradation, due to its inherent non‐biodegradability of additives. In this work, we report a melt blending method to modify PLA using the alginic acid and two different alginates combined with nano CaCO₃, a fully sustainable and biodegradable component. And, the mechanical, thermal, and rheological properties of the composites are investigated. We demonstrated that the filled samples show a lower tensile strength and higher impact strength which means a toughening effect occurs. Dynamic mechanical analysis experiments showed that the calcium alginate‐filled samples show higher performances than other filled samples not only in static mechanical but also dynamic mechanical properties. The fracture morphology of the samples shows that a better interfacial reaction has been constituted for gel calcium alginate between CaCO₃ and PLA. Nevertheless, the thermogravimetric analysis results indicate that a lower thermal stability has been achieved in alginate filled samples. Chemorheological study indicated the alginate‐filled samples also show a lower modulus and viscosity than neat PLA. It was found that the complex viscosity decrease with the addition of alginates, in comparison with PLA/CaCO₃ composites, and the samples filled with calcium alginate show a higher viscosity than those of sodium alginate and alginic acid. The alginate derivatives showed interesting potential as new green plastic additives attributed to origin from the biodegradable natural resources with a polymeric matrix. POLYM. ENG. SCI., 59:1882–1888, 2019. © 2019 Society of Plastics Engineers     

Structure‐rheology responses of polylactide/calcium carbonate composites

Polylactide (PLA) and calcium carbonate (CaCO₃) were melt blended using a twin‐screw extruder. The morphology of PLA/CaCO₃ composites was observed by scanning electronic microscopy. The linear and nonlinear shear rheological behaviors of PLA/CaCO₃ melts were investigated by an advanced rheology expended system. The results show that the CaCO₃ particles are evenly dispersed in the PLA matrix. The incorporation of low CaCO₃ content (<20%) causes the reduction of the storage moduli, loss moduli, and dynamic viscosities whereas high CaCO₃ content (>30%) leads to the increase of the storage moduli, loss moduli, and dynamic viscosities. The composites with high CaCO₃ content show pseudo‐solid‐like behaviors at low frequency. High CaCO₃ content also results in a significant increase of flow activation energy and a dramatic decrease of flow index n, which is in consistent with the more serious shear‐thinning tendency of high‐filled PLA composites melts. The particular rheological responses might be attributed to the formation and destruction of the percolating network. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheological behaviour of copoly(ethylene/octene) elastomer compunds: Effect of blowing agent and precipitated CaCO3 filler

Abstract

An experimental study of the rheological behaviour of ethylene/octene copolymer compounds in extrusion containing blowing agent has been carried out. The cell morphology development was studied using scanning electron microscopy. Rheological properties of unfilled and precipitated CaCO₃ filled systems with various blowing agents, extrusion temperatures, and shear rates were studied using a capillary rheometer. The total extrusion pressure, apparent shear stress, apparent viscosity, and die swell of the unfilled and CaCO₃ filled compounds were also determined and the effect of blowing agent on the rheological properties of the compounds studied. It was observed that there is reduction of stress and viscosity with blowing agent loading. Incorporation of blowing agent led to decreased shear thinning behaviour resulting in an increase in the power law index. The viscosity reduction factor of the unfilled compound was found to be dependent on the concentration of blowing agent, the shear rate, and the temperature.     

Microstructure and rheologic development of polypropylene/nano‐CaCO3 composites along twin‐screw extruder

Polypropylene/nano‐calcium carbonate (PP/nano‐CaCO₃) composites were prepared by using an intermeshing, co‐rotating twin‐screw extruder. Two different screw configurations, denoted by screws A and B, respectively, were employed. The former provided high dispersive mixing and the later provided high dispersive and distributive mixing. Effect of mixing type on microstructure and rheologic development of nanocomposites was investigated by taking samples from four locations along screws A and B. Transmission electron microscopy results show that in the sample at the exit of extruder, the percentage of nano‐CaCO₃ particles with the equivalent diameter lower than 100 nm along screws A and B is 66.5 and 79.0%. respectively. Moreover, for screw B, the number‐averaged diameter at four sampling locations is smaller than that for screw A. This means that the distributive mixing, provided by screw B, favors the size decrease of nano‐CaCO₃ in the PP matrix. In addition, rheologic results show that the decrease of complex viscosity for the nanocomposites is deeply related to turbine mixing elements, which provides distributive mixing. The online melt shear viscosity of the nanocomposite at the exit of extruder prepared by screw B is lower than that of pure PP. This is related to the dispersion of nano‐CaCO₃ in PP matrix. Finally, the relationship between rheologic properties and microstructure was analyzed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties and morphology of polypropylene‐calcium carbonate nanocomposites prepared by dynamic packing injection molding

In this article, dynamic packing injection molding (DPIM) technology was used to prepare injection samples of Polypropylene‐Calcium Carbonate (PP/CaCO₃) nanocomposites. Through DPIM, the mechanical properties of PP/nano‐CaCO₃ samples were improved significantly. Compared with conventional injection molding (CIM), the enhancement of the tensile strength and impact strength of the samples molded by DPIM was 39 and 144%, respectively. In addition, the tensile strength and impact strength of the PP/nano‐CaCO₃ composites molded by DPIM increase by 21 and 514%, respectively compared with those of pure PP through CIM. According to the SEM, WAXD, DSC measurement, it could be found that a much better dispersion of nano‐CaCO₃ in samples was achieved by DPIM. Moreover, γcrystal is found in the shear layer of the DPIM samples. The crystallinity of PP matrix in DPIM sample increases by 22.76% compared with that of conventional sample. The improvement of mechanical properties of PP/nano‐CaCO₃ composites prepared by DPIM attributes to the even distribution of nano‐CaCO₃ particles and the morphology change of PP matrix under the influence of dynamic shear stress. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects on the melt rheology of systems of Nd‐Fe‐B particles suspended in a poly(phenylene sulfide) and liquid crystalline polymer blend

The melt rheology of blends of a liquid crystalline polymer (LCP) and poly(phenylene sulfide) (PPS) and their composites with ferromagnetic Nd‐Fe‐B particles (MQP) was studied. We investigated the effects of LCP concentration, Nd‐Fe‐B particle volume fraction and size, distribution, and shear rate on the rheological properties of these composites. Enthalpy of fusion changes that were observed resulted from the addition of the LCP and Nd‐Fe‐B particles to the polymer blends/composites. The shear rate and frequency dependencies of the materials revealed a viscosity reduction at low (1–3 wt%) and moderate (10–15 wt%) LCP concentrations, and strong effects on the shear‐thinning characteristics of the melt. The suspensions of polydispersed Nd‐Fe‐B particle configurations in PPS that were of lower size ratios gave better processability, which is contradictory to previously reported behavior of suspensions containing spherical particles. Specifically, the compositions with unimodal and a bimodal distribution of Nd‐Fe‐B particles gave the lowest viscosities. The experimental data were correlated with semi‐empirical viscosity model equations of Maron‐Pierce, Krieger‐Dougherty, Eilers, and Thomas and were found to be consistent with the data. The maximum packing fraction, ϕ_m, of the MQP particles was estimated to be within the range of 0.78 ϕ ≤_m ≤ 1.0 through graphical and parametric evaluation methods.