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The thermal conductivity of hollow glass bead (HGB)-filled polypropylene (PP) composites was estimated using the thermal conductivity equation of inorganic hollow microsphere-filled polymer composites published in the previous paper. The estimations were compared with the measured data of the PP composites filled with two kinds of HGB with different size (the mean diameter was respectively 35 μm and 70 μm). The results showed that the predictions of the thermal conductivity were in good agreement with the measured data except to individual data points. Furthermore, both the estimated and measured thermal conductivity decreased roughly linearly with increasing the HGB volume fraction when the HGB volume fraction was less than 20%; the influence of the particle diameter on the thermal conductivity was insignificant.

The melt elongation flow properties of low-density polyethylene/nanoscale zinc oxide (nano-ZnO) composites were studied using a Rheotens rheometer (Gottfert Werkstoff-Prufmaschinen GmbH, Buchen, Germany). The die extrusion rate varied from 9 to 36 mm/s, the temperature ranged from 160°C to 200°C, and the nano-ZnO weight fraction range was from 0.2 to 4 weight percent (wt.%). The results showed that the melt elongation stress increased with the increasing elongation strain rate; the melt elongation viscosity decreased with the increasing temperature, and the temperature dependence obeyed the Arrhenius equation. The melt elongation viscosity of the composites with 0.4–0.8 wt.% nano-ZnO was lower in the whole composite system. Moreover, the melt elongation viscosity increased when the elongation strain rate was lower than 0.3 s−1 and then decreased with the increasing elongation strain rate; the melt elongation viscosity reached a maximum at an elongation strain rate around 0.3 s−1 and presented the stress hardening phenomenon.

Magnesium hydroxide [Mg(OH)2] with high flame retardant efficiency filled polypropylene (PP) composites were prepared using a twin-screw extruder. The impact fracture behavior of the composites was measured at room temperature. It was found that the toughening effect of the filler content on the PP resin was significant. The V-notched Izod impact strength of the PP/Mg(OH)2 composites showed a nonlinear increase with increase in filler weight fraction (ϕf), as ϕf was ϕf was 2 composite also increased nonlinearly, then it decreased slightly. The impact fracture surface was observed by means of a scanning electronic microscope, to understand the toughening mechanisms for the composite systems.

The polyphenylene sulfide (PPS) blended with polycarbonate (PC), reinforced glass fiber (GF) and nanometer calcium carbonate (nano-CaCO3) filled PPS ternary composite, as well as the PPS/PC/GF/nano-CaCO3 hybrid composite, were prepared by means of a twin-screw extruder, and the heat distortion temperature (Td) of these materials was measured to identify the influence of the PC and nano-CaCO3 content on the heatproof properties. The Td values for the PPS/PC blend were lower than that of the neat PPS, when the PC weight fraction (φPC) was less than 20%, and increased with increase in φPC. The Td values for the PPS/GF/nano-CaCO3 ternary composite, on which the particle surface was treated with a titanate coupler, were higher than that of the composite with the particle surface treated with a stearate coupler. When the nano-CaCO3 weight fraction (φf) was less than 6%, the Td values for the PPS/PC/GF/nano-CaCO3 hybrid composites increased with increasing φf; at greater than the maximum of 6%, Td decreased. There was a certain synergistic effect of the GF and nano-CaCO3 on the heatproof properties in the PPS/PC composite.

Understanding the reinforcing mechanisms should be meaningful for preparation of new polymer composites. The reinforcing mechanisms of the inorganic particulate-filled polymer composites were analyzed and discussed in the present paper, and concluded several reinforcing theories on the basis of the previous studies, such as interfacial adhesion reinforcing theory, filler inducing crystallization reinforcing theory, filler frame reinforcing theory, and synergistic reinforcing effect theory. The reinforcing effects should be related closely to the filler shape and size, in addition to the filler concentration and dispersion in the matrix. Consequently, to describe accurately the reinforcing mechanisms of the composites, two or more reinforcing theories should be used for the actual composite system, and one of among them should be usually as the major reinforcing mechanism. Finally, the quantitative characterization of the reinforcement was described.

In this study, the factors affecting the Young's modulus of inorganic fibrous particulate-reinforced polymer composites were analyzed, and a new expression of the Young's modulus was derived and was based on a simplified mechanical model. This equation was used to estimate the composite Young's modulus. The estimated relative Young's modulus increased nonlinearly with increasing filler volume fraction. Finally, we verified the equation preliminarily by quoting the measured Young's modulus values of poly(butylene terephthalate)/wollastonite, polypropylene/wollastonite, and nylon 6/wollastonite composites reported in the literature. Good agreement was shown between the predictions and the experimental data of the relative Young's modulus values for these three composite systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2957–2961, 2013

In the present article, an elongation viscosity equation of polymeric melts was derived based on the Moore dynamic model. The equation described the relationship between extensional viscosity and extension strain rate of polymer melts. The effects of the four parameters in this equation on the extension viscosity curves were analyzed in detail. The extensional viscosities of a low-density polyethylene (LDPE) and a linear LDPE as well as LDPE/glass bead composite melts at 170°C were estimated by applying this equation, and the predictions were compared with the measurement data under the same experimental conditions. The results showed that the estimations were in good agreement with the experimental data.

Microencapsulated red phosphorus (MRP)-filled polypropylene (PP) composites were prepared using a twin-screw extruder. The effects of load and temperature as well as the dispersion or distribution of the filler particles in the matrix on the melt volume flow rate (MVR) and melt density ( ρm) of the PP/MRP composites were investigated using a melt flow indexer and a scanning electron microscope. The temperatures and loads were varied from 180 to 205°C and from 2.16 to 12.5 kg, respectively. The results showed that the MVR of the composites increased nonlinearly with increase in temperature and load. The sensitivity of MVR of the composite melts to temperature was significant. The MVR of the composites also decreased slightly with an increase in the MRP weight fraction. However, the values of ρm of the composites varied slightly with increase in load, temperature, and MRP weight fraction. The findings can provide useful information for optimum processing of these composites.

The tensile properties of poly ( l -lactic acid) (PLLA) and polycaprolactone (PCL) composites filled with nanometer calcium carbonate (nano-CaCO3) were measured at room temperature and different tensile rates. With increase of the PCL weight fraction, the tensile elastic modulus, tensile strength and tensile strength at fracture for the PLLA/PCL/nano-CaCO3 composites decreased nonlinearly, and it increased slightly with increasing tensile rate. When the PCL weight fraction was less than 60%, the elongation at break for the composites increased slightly and then it increased sharply. This indicated that PCL was beneficial to improve the tensile fracture toughness of the composites.

The microencapsulated red phosphorus (MRP) filled polypropylene (PP) composites were prepared using a twin-screw extruder. The effects of load and temperature on the extrudate swell behavior of the PP/MRP composite melts were investigated by means of a melt flow indexer. The test temperatures and loads were varied from 180 to 205°C and from 2.16 to 12.5 kg, respectively. The results showed that the die-swell ratio (B) of the composite melts increased roughly linearly with increasing load while decreased slightly with a rise of test temperature. The sensitivity of the die-swell ratio of the composite melts to load was significant. When the test temperature or load was constant, the values of the B of the composite melts decreased slightly with increasing MRP weight fraction. The findings can provide useful information for processing of these composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polyformaldehyde (POM)/ethylene-vinyl acetate copolymer (EVA)/high-density polyethylene (HDPE) composites filled with nanometer calcium carbonate (nano-CaCO3) were prepared using a twin-screw extruder. The effects of load and temperature on the melt extrudate swell behavior of the composites were investigated, by using a melt flow rate instrument under experimental conditions, with temperatures ranging from 170°C to 220°C and loads varying from 1.2 kg to 12.5 kg. The results showed that the melt die-swell ratio (B) of the composites decreased linearly with a rise of temperature as the load was fixed, while it increased nonlinearly with increase in the melt volume flow rate (MVR) and load, when the test temperature was constant; they also showed that B is a quadratic function of shear rate or shear stress. The value of B increased nonlinearly with an increase of the HDPE weight fraction (ϕ) as the temperature was constant, and the temperature sensitivity of B to ϕ was insignificant, while the effect of load was significant. The correlation between B and ϕ obeyed a quadratic equation.

The poly( L -lactic acid) (PLLA) filled with nanometer calcium carbonate (nano-CaCO3) composites were prepared by means of a twin-screw extruder in the present paper. The nano-CaCO3 surface was treated with stearate. The crystalline properties of PLLA/nano-CaCO3 composites were measured using a differential scanning calorimeter, to identify the influence of the nanometer particle content on the crystalline properties. The results showed that the crystallization onset temperature, crystallization temperature and crystallization end temperature as well as the crystalline degree of the composites were obvious higher than those of the unfilled PLLA resin when the particle weight fraction (ϕf) was 1%, then they varied slightly. While the crystallization temperature interval decreased slightly. The improvement of crystallinity degree might be attributed to the heterogeneous nucleation of the nano-CaCO3 in the matrix.

Elongation viscosity is an important characterization of flow properties for polymer melts. In the present article, a new extensional viscosity equation for polymer melts was established by introducing a relaxation time equation based on the Cross model. The elongation viscosities of a low-density polyethylene (LDPE) melt at 200 °C and a metallocene linear low-density polyethylene (mLLDPE) melt at 130 °C were estimated using this equation; then, the calculations of the melt elongation viscosity were compared with the measured data from the extension experiments of the LDPE melt and the mLLDPE melt reported in the reference. Good agreement was found between the predictions and the measured data from the LDPE and mLLDPE melts. In addition, this equation is easy to use for characterization of elongation viscosity during single shaft elongation flow for polymer melts.

The flexural properties of poly-L-lactide (PLLA) and polycaprolactone (PCL) shape memory composites filled with nanometer calcium carbonate (nano-CaCO3) were determined at room temperature. The results showed that with the increase of the nano-CaCO3 weight fraction the flexural moduli and strength of PCL/nano-CaCO3 composites increased roughly linearly and reached a maximum at the filler content of 2%, while the flexural strength of the composites decreased. The flexural moduli and strength of the composites decreased roughly linearly with increasing PLLA/PCL ratio for the PLLA/PCL/nano-CaCO3 composites.

Polypropylene (PP) composites filled with aluminum hydroxide (Al(OH)3) and magnesium hydroxide (Mg(OH)2) were prepared using a twin-screw extruder. The effective thermal conductivity (keff) of the composites was measured by means of a thermal conductivity instrument under different testing temperatures. The results showed that the values of keff increased quickly with an increase the volume fraction (ϕf) of Al(OH)3/Mg(OH)2 powder when ϕf was less than 7.1%, then keff increased slightly as ϕf was varying from 7.1% to 13.3%, while the values of keff increased obviously when ϕf was more than 13.3%. Under the same conditions, the values of keff increased nonlinearly with increasing the diameter (d) of the Al(OH)3/Mg(OH)2 powder. The values of keff of the composites increased somewhat with a rise of test temperature. On the basis of the experimental results, the thermal conduction mechanisms of the composite were analyzed and discussed.

The nanometer calcium carbonate (nano-CaCO3)-filled poly-L-lactide (PLLA) biocomposites were prepared using a twin-screw extruder. The first normal stress difference of the composites were measured by means of a capillary rheometer under experimental conditions with temperatures ranging from 170 to 200°C and shear rates varying from 50 to 103 s−1. The first normal stress difference (N1) increased roughly linearly with increasing shear stress (τw). The sensitivity of the N1 to τw increased with an increase of the die length–-diameter ratio, and the N1 value varied slightly with the filler weight fraction (ϕf) as test temperature was constant. When the shear stress was fixed, the N1 reached a minimum value for ϕf = 1%. The values of the N1 of the composite melts decreased roughly linearly with a rise of temperature when the shear rate was constant. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

The reinforcing mechanisms of inorganic plate-like particulate reinforced polymer composites were discussed based on the micro-mechanical model in this article, and a new expression of tensile strength was derived by introducing an interfacial strength factor. This equation was applied to estimate the tensile strength of inorganic plate-like particulate reinforced polymer composites. The results showed that the relative tensile strength increased nonlinearly with increasing filler volume fraction. Finally, the equation was verified preliminarily using the measured tensile strength of the mica reinforced poly (aryl ether ketone) composites and mica reinforced polydimethylsiloxane networks reported from literature, good agreement was found between the predictions of the relative tensile strength and the experimental data. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Nanosized calcium carbonate (nano-CaCO3) filled poly-l-lactide (PLLA)/polycaprolactone (PCL) bio-composites were prepared by using a twin-screw extruder. The melt flow behavior of the composites, including the 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 varying from 50 to 103 s−1. The melt shear flow roughly followed the power law, while the effect of temperature on the melt shear viscosity might be estimated by using the Arrhenius equation. Moreover, the relationship between the PCL weight fraction and the melt shear viscosity for the PLLA/PCL/nano-CaCO3 composite was described by a quadratic equation.

The variation of resistivity for high-density polyethylene (HDPE) conductive composites filled with carbon black (CB) with time was investigated under the excitation of different temperature field. The movement of CB particles in the HDPE matrix was not a momentary equilibrium process, but a relaxation process. The relaxation of resistivity of the composites was monotonic, and it could be described by an exponential form above melting temperature. However, the relaxation of resistivity was nonmonotonic below melting temperature, herein a parameter t0 which was the beginning time of the resistivity attenuation could be introduced into the exponential equation. The attenuation of resistivity at constant temperature was limited for the composites with certain content of CB. The resistivity of the composites would incline to a constant value with the prolongation of time no matter what the heat treatment temperature was. Heating rate had influence on the relaxation of resistivity of the composites, and the lower heating velocity resulted in less time to approach to the equilibrium resistivity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The thermal conductivity of polypropylene (PP) composites filled with Al(OH)3 and Mg(OH)2 was measured by means of the stable flat measuring instrument at different testing temperatures. The effective thermal conductivity of the composites was estimated by applying the thermal conductivity equation proposed previously, and the estimations were compared with the experimental measured data under the same experimental conditions. The results showed that the calculations and measurements of the effective thermal conductivity were close to each other when the volume fraction of the Al(OH)3/Mg(OH)2 powder was

The tensile stress and strain under small deformation for plastics/elastomer blends were analyzed, based on a geometric model and mechanical element model, and a Young’s modulus equation was derived based on the hypothesis with equal strain and Hooke’s law. The polypropylene (PP)/polyolefin elastomer (POE) blends were prepared by means of a twin screw extruder, and the Young’s modulus was measured at room temperature. It was found that the Young’s modulus decreased nonlinearly with increase in the POE volume fraction. The Young’s modulus of the PP/POE blends was estimated using the equation and was compared with the measured data. There was good agreement between them. Moreover, the Young’s modulus of PP/ethylene propylene diene monomer (EPDM) rubber EPDM blends at room temperature was estimated respectively using this equation and the mingling rule equation, as well as Liang’s equation published in the literature. The results showed that the calculations with this equation were closer to the experimental data reported in reference than those with the other two equations.

Polycaprolactone (PCL) composites filled with nanometer calcium carbonate (nano-CaCO3) were prepared by means of a twin-screw extruder in this study. The nano-CaCO3 surface treated with stearate. The crystalline properties of the PCL/nano-CaCO3 composites were measured with a differential scanning calorimeter to identify the influence of the nanometer filler content on the crystalline properties. The results show that the crystallization onset temperature, crystallization temperature, and crystallization end temperature of the composites were obviously higher than those of the unfilled PCL resin, and the crystallization degree (χc) of the composites increased with increasing particle weight fraction (ϕf) when ϕf was more than 1%. When ϕf was 1%, χc of the composite was less than that of the unfilled PCL resin. Moreover, the dispersion of the inclusions in the matrix was observed by means of scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polypropylene (PP) composites filled with hollow glass beads (HGB) were prepared by means of a twin-screw extruder. The extrudate swell ratio (B) of the PP/HGB composite melts was measured using a melt flow indexer under experimental conditions, with temperatures from 190°C to 230°C and loads varying from 1.20 kg to 7.50 kg, to identify the effects of the extrusion conditions and the particle size and content on the extrudate swell of composite melts. The results showed that the value of B of the composites increased nonlinearly with an increase of shear stress, while it decreased linearly with a rise of temperature. When the load and temperature were constant, the value of B increased nonlinearly with an increase of the HGB diameter, whereas it reduced nonlinearly with an increase of the HGB volume fraction. This should be attributed to the elastic deformation energy stored in the flow of the composite melts, which was decreased with an increase of the HGB number and content.

Two inorganic particle-filled polypropylene (PP) composites including PP/hollow glass bead (HGB) composite and PP/nanometer calcium carbonate (nano-CaCO3) composite were prepared by means of a twin-screw extruder in the present paper. The transmission loss was measured, to identify the effects of sound frequency and the filler content on the sound insulation properties of these filled systems. The results showed that the sound insulation effect of the PP/nano-CaCO3 obeyed roughly the law of mass, the transmission loss of the two composites increased nonlinearly with an increase of the filler volume fraction, and the value of the transmission loss for the PP/HGB system was higher than that of the PP/nano-CaCO3 system under the same level of sound frequency. The transmission loss increased roughly with an increase of sound frequency for the two composites except to individual sound frequency. The mechanisms of the sound insulation of these composites were discussed.

An expression of Young’s modulus of short inorganic fiber reinforced polymer composites was derived based on the tensile strength equation proposed in the previous paper, and the factor affecting the Young’s modulus was analyzed. This equation was applied to estimate the Young’s modulus of short inorganic fiber reinforced polymer composites. The results showed that the relative Young’s modulus increased nonlinearly with increasing fiber volume fraction, while increased linearly with an increase of fiber length-diameter ratio. Finally, the equation was verified preliminarily by using the measured Young’s modulus of the short glass fiber (SGF) reinforced polycarbonate/acrylnitrile–butadiene–styrene copolymer composites and the polypropylene reinforced respectively with SGF and short carbon fiber reported from literature, good agreement was found between the predictions and the experimental data.

The polypropylene (PP)/poly(ethylene-co-octene) (POE) blends was prepared by means of a twin screw extruder in a range of temperature from 185 to 195 °C. The mechanical properties including tensile, flexural and impact of the PP/POE blends were measured at room temperature to identify the effect of the POE content on the mechanical properties. It was found that the Young’s modulus, tensile strength and tensile elongation at break decreased nonlinearly with increasing the POE weight fraction. While the V-notched and unnotched impact fracture strength increased nonlinearly with an increase of the POE weight fraction. The flexural modulus and strength decreased roughly linearly with increasing the POE weight fraction. Furthermore, the impact fracture surface of the blends was observed by using a scanning electronic microscope and the toughening mechanisms were discussed.

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

The flame-retardant composites of polypropylene (PP) were prepared using a twin-screw extruder by compounding PP with either aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), zinc borate (ZB), polyolefin elastomer(POE) and nanometer calcium carbonate (nano-CaCO3). The flame retardant properties of these composites, including oxygen index (OI), horizontal burning speed (V), and smoke density rank (SDR) were measured. The results showed that the OI increased linearly, while the V and the SDR decreased nonlinearly with an increase of the filler weight fraction, and the effect of the specimen thickness on the V was significant. The reduction of the V of the flame-retardant PP composites decreased with increasing the specimen thickness. The addition of the nano-CaCO3 and POE could improve the flame-retardant properties of the composites.

The melt strength (MS) and extensional viscosity of low-density polyethylene/poly(butylene succinate) (LDPE/PBS) blends were measured using a melt-spinning technique to investigate the effects of extrusion conditions and mixing ratios on the extensional flow. The experimental results indicated that maximal extensional length and MS of the LDPE/PBS blends decreased with an increase of PBS content. The response of the MS to the extrusion rate depended on the components of the blends. The extensional viscosity of the LDPE/PBS blends decreased with the increases of PBS content, extrusion rate, and extensional strain rate. Extensional master curves were suitable for the LDPE/PBS blends, and the scaling factor decreased with the increase of extrusion rate according to a power law. When the PBS content was not more than 40%, with the further increase of the PBS content, the sensitivity of the scaling factor to the extrusion rate decreased. However, when the PBS content was 60%, the sensitivity of the scaling fac...

The steady shear viscosity (ηs), the steady first normal stress coefficient (Ψ1), the steady second normal stress coefficient (Ψ2), and extensional viscosity (ηe) are four important parameters for polymer melts during polymer processing. In this article, we propose a stress and rate-dependent function to describe creation and destruction of polymer junctions. Moreover, we also introduce a movement expression to describe nonaffine movement of network junctions. Based on network theory, a nonaffine single-mode rheological model is presented for the steady flow of polymeric melts, and the equations of ηs, Ψ1, Ψ2, and ηe are derived from the model accordingly. Furthermore the dependences of ηs and ηe on model parameters are discussed for the model. Without a complex statistical simulation, the single-mode model with four parameters yields good quantitative predictions of the steady shear and extensional flows for two low density polyethylene melts reported from previous literature in very wide range of deformation rates. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The extensional rheological properties of a low density polyethylene (LDPE) melt were studied by using melt spinning technique. Based on the extension properties of the LDPE melt under experimental condi- tions, the melt spinning master-curves were plotted by introducing scaling factor b and the draw ratio k. The scal- ing factor b shows the combination effects on the preorien- tation before extension, the unwrapping and orientation of molecular chains during extension. Several linear relation- ships between b and temperature, log b and the logarithm of extrusion flow rate v0 (log v0) have been investigated. By using the values of b and the reference curve, the extension viscosity curves with different temperature and extrusion flow rate could be calculated, thus the measure- ment range of melt spinning technique would be extended effectively. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: 2202-2206, 2012

The sound insulation behavior of inorganic particulate-filled polymer composites was analyzed by means of acoustics theory in this article to reveal the mechanisms of sound insulation. On the basis of it, a physical model of the sound wave transfer in the composite system was established, and a relevant transmission loss equation was derived. The transmission loss of the glass bead-filled polyethylene composites was estimated by using this equation. The results showed that the calculated transmission loss of the composites increased linearly with an increase of the glass bead volume fraction, and it increased nonlinearly with increasing sound frequency. The sensitivity of the transmission loss to the sound frequency was significant at low sound frequency. The transmission loss decreased nonlinearly with the size of added glass bead when the volume fraction was constant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A new extensional viscosity model based on the Cross model is introduced. The proposed model can correctly describe the relation between extensional viscosity and extension rate. Effect of the four parameters in the new model is analyzed in detail. Compare the predictive curves to the measurement results reported in the references. It shows that the model calculation gives a good fit to the experiment data. This simple model has only a few parameters and is easy to use.

The particle surface of nanometer calcium carbonate (nano-CaCO3) was treated by fatty acid and titanate coupling agent, and polypropylene (PP) composites filled with nano-CaCO3 with the volume fraction range from 0 to 3.0% were prepared by means of melt blending in a twin-screw extruder. The V-notched impact strength of the nanocomposites was measured at room temperature. The V-notched impact fracture surface fractal dimensions of PP/nano-CaCO3 composites were measured by means of projective-covering method, and the relationship between the fracture surface fractal dimension and the impact strength of these composites was investigated. The results showed that the fracture surface fractal dimension ranges from 2.367 to 2.412, all of the correlation coefficients were higher than 0.96, the strong correlation indicated that the fracture surface of the composites was fractal obviously, and the relationship between the impact strength and fractal dimension of the composites obeyed roughly exponential function. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 31: 71–81, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20237

Ternary composites of glass fiber-reinforced poly(p-phenylene sulfide) (PPS/GF) filled with nanometric calcium carbonate (nano-CaCO3) were prepared by means of a twin-screw extruder. The nano-CaCO3 surface was treated with stearate and treated with titanate, the composites being called SI composite system and SII composite system, respectively. The crystallization and heatproof properties of the PPS/GF/nano-CaCO3 composites were measured using a differential scanning calorimeter, to investigate the influence of the nanometric filler content on the crystallinity. The results show that the variation of the starting crystallization temperature, crystallization temperature and crystallinity with an increase of the particle weigh fraction (ϕf) of SI composite system is different from that of SII composite system. When ϕf is less than 4 wt%, the crystallinity of the two composite systems increases and then decreases slightly with increasing ϕf. Moreover, the crystallization behavior and mechanisms are discussed. Copyright © 2011 Society of Chemical Industry

Mechanical analysis was made based on the micro-mechanical model of short inorganic fibre reinforced polymer composites, and an expression for tensile strength was derived by introducing an interfacial strength factor. This equation was applied to estimate the tensile strength of short inorganic fibre reinforced polymer composites. The results showed that the relative tensile strength increased nonlinearly with increasing fibre volume fraction. Finally, the equation was preliminarily verified by using the measured tensile strength of both short glass fibre reinforced polycarbonate/acrylnitrile-butadiene-styrene copolymer composites and short carbon fibre reinforced polyamide composites reported in literature. Good agreement was found between the predictions and the experimental data.

The nanometer calcium carbonate (nano-CaCO 3 ) filled Poly- dl -lactide (PDLLA) bio-composites were prepared with a twin-screw extruder. The melt volume flow rates (MVRs) and melt densities of the composites were measured by means of a melt flow rate instrument under experimental conditions at a temperature range from 180 to 230 °C and a load range varying from 2.16 to 10 kg. The result showed that the MVRs of the composites increased nonlinearly with a rise in temperature and an increase of load, but decreased linearly with increasing the filler weight fraction. The melt densities of the composites decreased nonlinearly with a rise of temperature, but increased nonlinearly with increasing the load and increased linearly with an addition of the filler weight fraction.

The nanometer calcium carbonate filled Polyformaldehyde/ethylene-vinyl acetate copolymer/high-density polyethylene (HDPE) composites were prepared using a twin-screw extruder. The effects of load and temperature on the melt volume flow rate (MVR) and melt density (ρ m ) of the composites were investigated by using a melt flow rate instrument under experimental conditions with temperatures range from 170 to 220°C and loads varying from 1.2 to 12.5 kg. The results showed that the MVR of the composites increased with an increase of temperature and load, while reduced with an increase of the weight fraction (φ) of the HDPE, and the relationship between the MVR and φ was almost consistent with a linear law function. The melt density of the composites increased nonlinearly with an increase of load, while decreased with a rise of temperature. Moreover, the ρ m of the composites decreased with increases in φ.

The interfacial stress and its distribution during impact of inorganic particulate-filled polymer composites were analyzed in the present paper by means of a three-dimensional (3D) finite element method, and the software used was the ANSYS/LS-DYNA (ANSYS Inc., Canonsburg, PA, USA). The simulation results showed that the normal stress, the shear stress, and the equivalent stress reached the maximum at the particle equator, and then they reduced quickly toward the direction of the particle pole along the interface between the particle and the matrix and achieved the minimum from about 0.5 to 2.0 µm from the equator. Finally, they tended to gently or somewhat increase. Furthermore, the ways and mechanisms of the major fail or fracture of the polyphenylene sulfide (PPS)/calcium carbonate (CaCO3) composites under impact load were discussed. The mechanism of impact fracture or failure of inorganic particle-filled PPS composites might be that the matrix around the neighboring inclusions will first yield owing to the stress concentration in the interface between the inclusion and the matrix to induce crazes and extend quickly. Copyright © 2011 John Wiley & Sons, Ltd.

In this paper, a comparison between the Liang model and the Cogswell model is made by using them to simulate numerically the boundary streamline and the region length during the entrance converging flow of polymer melts. The results show that both of them can properly describe the flow conditions. Furthermore, the Liang model can accurately describe the geometry effect on the boundary streamline, and by introducing the Bagley correction factor e and the slip factor ξ, it can also describe the changes of the region length more precisely.

The correlation between the entry pressure drop and elongation viscosity during entry converging flow of polymer melts was discussed in this article. The entry pressure drop during extrusion of a low density polyethylene (LDPE) melt and a linear low density polyethylene (LLDPE) melt was measured by means of a capillary rheometer under test conditions with temperature of 170 °C and shear rate varying from 10 to 300 s−1. The results showed that the entry pressure drop increased nonlinearly with an increase of the shear stain rate, and the variation of entry pressure drop of the two melts was close to each other. The melt elongation viscosity of the two resins was estimated using Cogswell equation from the measured entry pressure drop data, and the predictions were compared with the melt extension viscosity measured by using a melt spinning technique published in literature. It was found that the melt extension viscosity from entry converging flow was slightly lower than that from melt spinning technique under the same temperature and extension strain rate.

The extensional rheological properties of three grades of polyethylene melts, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE) were measured using a melt spinning technique under the test conditions with temperature ranging from 150 to 210°C and extrusion rate varying from 11.25 to 22.50 mm s−1. The results showed that the melt strength decreased with a rise of temperature while increased with an increase of extensional rate. With the rise of extensional strain rate and temperature, the melt extensional viscosity decreased. The extensional stress and viscosity reduced with increasing extrusion velocity when the temperature and extensional rate were constant. Moreover, the melt strength and extensional viscosity of the LDPE resin was the highest and the LLDPE was the lowest under the same experimental conditions. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

The parameters characterizing the interfacial adhesion strength, such as interaction parameter (B) and interfacial adhesion angle (θ), of inorganic particulate-filled polymer composites were analyzed in this paper. On the basis of the previous studies and the research work reported in literature, several expressions for predicting these parameters and the determination methods of these parameters were proposed, and the relationship between the interaction parameter and interfacial adhesion angle was discussed. Then the parameters B and θ were estimated from the experimental measured tensile strength of the several inorganic particulate-filled polypropylene (PP) composites including nanometer calcium carbonate, glass bead and diatomite particles. The results showed that the value of θ was about from 44 to 75 degrees while the value of B was varying from 1.12 to 2.42 of these filled systems under the experimental conditions. Moreover, the value of B decreased roughly linearly with increasing θ for these particulate-filled PP composites.POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

The extensional rheology of low density polyethylene (LDPE) is studied bymelt spinning technique. Melt spinning mastercurves for LDPE are plotted for the measurement results of various temperatures and extrusion velocities. Linear relations between scaling factor b and T, Logb and Logv0 have been found. The analysis indicates that b can be regarded as a useful index of combination effects on the pre-orientation before extension, and on the unwrapping and orientation of macromolecular chains during extension. By using the values of b and the data from reference curve, extension viscosity curves of any setting temperature and extrusion velocity can be calculated, which will effectively enlarge the measurement range of melt spinning technique.

Extensional flow is one of the common flow patterns in polymer processing, such as melt spinning and entry contraction flow. Extensional viscosity is an important characterization of flow properties for polymeric materials. In this article, temperature T was introduced into H function which represents the destruction rate of network junctions and a new viscosity equation was derived based on Phan-Thien—Tanner model. The elongation viscosities of a high-density polyethylene (HDPE) and a low-density polyethylene (LDPE) melts were estimated using this equation at 150°C, and the calculations were compared with the measured data from the extension experiments of the HDPE and LDPE melts reported in reference. Good agreement was showed between the predictions and the measured data. Furthermore, the parameters in this equation were easy to be determined.

A modified model of electrical conduction for carbon black-polymer composites is proposed based on the general effective media theory and the number of carbon black particles per aggregate to describe their nonlinear conductive behavior. In order to consider the interactions between carbon black particles, a simple self-consistent approach is used to improve the model. Expressions of electrical conductivity and percolation threshold are derived from the modified model. The predicted results of electrical conductivity and percolation threshold are in good agreement with experimental data reported in previous literature. Moreover, the dependences of electrical conductivity and percolation threshold on the number of carbon black particles per aggregate are discussed. Copyright © 2010 Society of Chemical Industry

Extensional rheological properties of HDPE was measured and investigated by melt spinning techniques. It was observed that the melt strength of HDPE decreased with the rise of temperature. According to the slope of Arrhennius plots, melt strength activation energy was calculated. The curves of extensional stress and viscosity were plotted. Analysis of the results under different conditions indicated that with the rise of strain rate, the stress increased and the viscosity decreased, whereas higher temperatures yielded lower stress and viscosity. In addition, it was found that faster extrusion velocity caused lower level of extensional stress and viscosity during the experiment.