Polypropylene/calcium carbonate nanocomposites

Polypropylene (PP) and calcium carbonate nanocomposites were prepared by melt mixing in a Haake mixer. The average primary particle size of the CaCO₃ nanoparticles was measured to be about 44 nm. The dispersion of the CaCO₃ nanoparticles in PP was good for filler content below 9.2 vol%. Differential scanning calorimetry (DSC) results indicated that the CaCO₃ nanoparticles are a very effective nucleating agent for PP. Tensile tests showed that the modulus of the nanocomposites increased by approximately 85%, while the ultimate stress and strain, as well as yield stress and strain were not much affected by the presence of CaCO₃ nanoparticles. The results of the tensile test can be explained by the presence of the two-counter balancing forces—the reinforcing effect of the CaCO₃ nanoparticles and the decrease in spherulite size of the PP. Izod impact tests suggested that the incorporation of CaCO₃ nanoparticles in PP has significantly increased its impact strength by approximately 300%. J-integral tests showed a dramatic 500% increase in the notched fracture toughness. Micrographs of scanning electron microscopy revealed the absence of spherulitic structure for the PP matrix. In addition, DSC results indicated the presence of a small amount of β phase PP after the addition of the calcium carbonate nanoparticles. We believe that the large number of CaCO₃ nanoparticles can act as stress concentration sites, which can promote cavitation at the particle-polymer boundaries during loading. The cavitation can release the plastic constraints and trigger mass plastic deformation of the matrix, leading to much improved fracture toughness.     

Mechanical properties of polypropylene filled with calcium carbonate

The tensile behavior of polypropylene (PP) filled with calcium carbonate particles has been studied using a tensile test. In particular, the effect of strain rate, filler content, and filler size upon the elastic modulus, yield stress, and strain of surface-modified and unmodified particles-filled PP were investigated. The results indicated that the elastic modulus and yield stress of an unmodified system were increased with an increase of strain rate and filler content, and with a decrease of filler size. The yield strain was decreased with an increase of filler content, and with a decrease of filler size, but did not depend on the strain rate. Although the dependence of elastic modulus on the filler size was maintained even by the surface-modified fillers, that dependence on the strain rate and filler content was decreased by such fillers. This may be because the modifier is present at the interface of filler and polymer matrix.     

微孔分散法制备超细CaCO3

引言 超细CaCO3的粒径范围通常为0.02～0.1μm[1],具有纳米尺度效应和特殊的性能,作为一种优质填料和白色颜料,广泛应用在橡胶、塑料、造纸、涂料、油墨、医药等众多行业.超细Ca-CO3的商业产品主要由湿化学沉淀法合成的,即用CO2气体和Ca(OH)2/H2O体系进行化学反应来制备.     

Crystallization behavior of polypropylene filled with surface-modified calcium carbonate

Polypropylene (PP) and calcium carbonate (CaCO₃) were mixed in a two-roll mill. The mixed compounds were molded on the plate by using a compression press heater. To improve the affinity of the relation between CaCO₃ and the PP matrix, we modified the CaCO₃ surface through chemical reaction with alkyl dihydrogen phosphates. The CaCO₃ content and size modification affected the crystallization behavior of the filled PP composites. The crystallization temperature in the nonisothermal crystallization process increased with the increase of CaCO₃ content and the decrease of CaCO₃ size. The crystallization temperature revealed the function of log (1 + T_s) (T_s, total surface area of CaCO₃) irrespective of CaCO₃ content and size for modified and unmodified systems, respectively. The shoulder or double crystallization peak of PP composites is recognized for the unmodified system (particle sizes: 1.0 and 4.5 μm).     

Crystallization properties of polycaprolactone composites filled with nanometer calcium carbonate

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 (χ_c) of the composites increased with increasing particle weight fraction (?_f) when ?_f was more than 1%. When ?_f was 1%, χ_c 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     

Melt strength of calcium carbonate filled polypropylene melts

This paper investigates the extensional rheology (through melt strength measurement) of calcium carbonate (CaCO₃) filled polypropylene (PP) melts. Different concentrations of CaCO₃ filled PP were produced by mixing two master batches of pure PP and 70 wt% CaCO₃ filled PP in required proportions in a counter‐rotating twin‐screw extruder. It was found that the melt strength of the CaCO₃–PP melts was independent of CaCO₃ concentrations up to 25 vol%. Further increase in CaCO₃ concentration led to a severe reduction of melt strength. © 2002 Society of Chemical Industry     

Preparation of ultrafine calcium carbonate particles with micropore dispersion method

Ultrafine particles of CaCO₃ were synthesized by dispersing the mixture of CO₂ and N₂ into the Ca(OH)₂/H₂O slurry with a micropore-plate. Because the micropore is micrometers scale, process of momentum transfer, mass transfer and reaction was significantly enhanced. The carbonation process of Ca(OH)₂/H₂O system was monitored with pH and conductivity. Operation conditions were investigated on the specific surface area of particles, such as initial slurry concentration and volume, gas flowrate and concentration, and temperature. The crystal structure of particles was characterized with BET, IR, TEM, SEM, etc. Results showed ultrafine particles were calcite with general shape of cube, whose size was about 40 nm and specific surface area was more than 25 m²/g. This preparation method is easy to operate.     

Fire retardant properties of intumescent polypropylene composites filled with calcium carbonate

This study was aimed to investigate the influence of calcium carbonate (CaCO₃), a widely used filler, on the fire retardancy of intumescent polypropylene composites. Two intumescent systems based on (1) mixture of ammonium polyphosphate (APP) and pentaerythritol and (2) surface‐modified APP (m‐APP) were examined. In terms of steady heat release rate, total heat evolved, and fire growth index determined by mass loss calorimetry, m‐APP performed markedly superior to APP‐pentaerythritol. The presence of CaCO₃ in both intumescent formulations caused significant losses in fire retardant performance assessed by mass loss calorimetry, limiting oxygen index and UL‐94 tests. Peak rates of heat release and mass loss during combustion, and total heat evolved on combustion were increased, whereas time to ignition was decreased. Characterization of fire residues ascribed the mechanism of deterioration in fire retardancy to the formation of porous and nonexpanded crystalline calcium phosphate/CaCO₃ residues during combustion rather than the amorphous protective intumescent chars formed in the absence of CaCO₃. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Mechanical properties of polyethylene/ethylene vinyl acetate filled with calcium carbonate

The tensile behavior of polyethylene/ethylene vinyl acetate (PE/EVA) polymer blends filled with calcium carbonate (CaCO₃) was studied using tensile and viscoelastic tests. The relations between tensile properties (modulus, strength, etc) of oriented and unoriented PE/EVA-CaCO₃, and void volume of polymer/CaCO₃ interface, PE/EVA blend ratio, and CaCO₃ content were investigated. The results indicated that the tensile strength and elongation of PE/EVA-CaCO₃ decreased with CaCO₃ content and PE blend ratio for unoriented PE/EVA-CaCO₃ systems. In the case of oriented samples, the relative modulus (E/E, where E and E are the modulus of oriented composites and the modulus of oriented matrix, respectively) of PE/EVA-CaCO₃ is larger than that of PE/CaCO₃ by increasing the EVA content relative to PE and CaCO₃. The value of E/E can be simply expressed as the function of void volume and CaCO₃ modulus to polymer matrix modulus.     

Mechanical properties of polymers filled with alkyl dihydrogen phosphate treated calcium carbonate

Poly(ethylene) (PE) or poly(ethylene-co-vinyl acetate) (EVA) and alkyl dihydrogen phosphate ester (APEn, C_nH_2n+1OPO(OH)₂, n = 1, 4, 10, 12, 16) treated calcium carbonate (CaCO₃) were mixed on a two roll mill. In order to improve the affinity of polymer-CaCO₃ interface, the CaCO₃ surface was treated through chemical reaction with various APEn types. The effect of carbon number of APEn on the tensile elongation and the adhesion properties between CaCO₃ particles and polymer matrix was investigated. In the case of PE/CaCO₃ series, tensile elongation, modulus of oriented samples and adhesion of polymer-CaCO₃ interface increased with carbon number of APEn (n ≦ 12). In the EVA/CaCO₃ series, the dependence of the tensile elongation on the carbon number of APEn was not clearly recognized; the adhesion at the phase interface was improved with the decrease of carbon number of APEn (n ≦ 12).     

Fractal analysis of polypropylene composite filled with nano‐calcium carbonate

Polypropylene (PP) and nano‐calcium carbonate (CaCO₃) composites were prepared by melt mixing in a corotating twin‐screw extruder. Transmission electron microscopy study and particle size analysis revealed the dispersion and the size distribution of CaCO₃ in PP. With the increase of loading of filler, CaCO₃ nanoparticles densely aggregated together and the dispersion of filler became bad. The fractal dimensions of the composites were determined using fractal concept. The fractal dimensions of D and D_k described the irregularities of the shape of an object and the distributions of particle populations, respectively. The D and D_k values were influenced by the content of filler, i.e., the D values increased, and the D_k values decreased with the increase of loading of filler. When the loading of filler was low, the values of D and D_k of PP composites differ slightly than the counterparts of PP/PP‐g‐MA (50 wt %) blend. For 20 wt %, they were almost identical. This fact showed that the fractal dimension was correlated with the dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Crystallization kinetics of polypropylene composites filled with nano calcium carbonate modified with maleic anhydride

The subject of this study was the crystallization behavior and thermal properties of polypropylene (PP)/maleic anhydride (MAH) modified nano calcium carbonate (nano‐CaCO₃) composites. In this study, 5 wt % nano‐CaCO₃ modified with different contents of MAH was filled into a PP matrix. X‐ray diffraction and differential scanning calorimetry were used to characterize the crystal morphology and crystallization kinetics of a series of composites. The results demonstrate that the nano‐CaCO₃ modified with MAH had an important effect on the thermal and morphological properties of the nanocomposites. The Avrami exponent of the pure PP was an integer, but those of the composites were not integers, but the crystallization rate constant decreased as the content of MAH in the nano‐CaCO₃ filler increased in isothermal crystallization. In nonisothermal crystallization, the kinetic parameter F(T) and the degree of crystallinity of pure PP were compared with those of the PP composites filled with nano‐CaCO₃. We suggest that heterogeneous nucleation existed in the PP composites and that the transformation and retention of the β‐form crystal into the α‐form crystal took place in the composite system and the β‐form crystal had a higher nucleation rate and growth process than the α‐form crystal in the PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The performance of calcium carbonate filled,random fiber composites

This paper describes an investigation into the performance of calcium carbonate filled, random fiber reinforced composites. A series of composite plaques were fabricated by resin transfer molding (RTM) a calcium carbonate filled, unsaturated polyester resin with either an A-glass continuous strand mat (CSM) or an E-glass CSM preform. The influence of fiber type and calcium carbonate filler loading level were then evaluated through a combination of experiments and micro-mechanics based modeling. The results of these studies indicate that the use of the E-glass reinforcement led to better mechanical properties relative to their A-glass counterpart. In addition, the composite moduli increased as the calcium carbonate filler level increased; however, the composite strengths were insensitive to filler loading level. Finally, a previously developed micro-mechanics based model was extended to consider the presence of the filler within the resin matrix. This model was used to predict the tensile moduli and strength as well as the overall shape of the stress-strain curves. Good agreement was found between the model predictions and the experimental results which suggests that this model could be used as a preliminary design tool to examine the effect of constituent composition on structural performance.     

Rheological and optical properties of polypropylene filled with synthetic silicates and calcium carbonate

The rheology of PP filled with three different types of fillers, namely synthetic sodium aluminium silicate (SSAS), aluminium silicate (AS) and calcium carbonate (CaCO₃), at concentrations up to 40% was studied. Variation of shear and extensional viscosity was evaluated for all the compositions. When filler loading was less than 20%, the shear viscosity at low shear rates was less than that of virgin PP. Flow curves are described by the Ellis model. The onset of non-Newtonian shear thinning behaviour is related to parameter η₁₀/τ_1/2. Although fillers are white, they imparted a yellowish tone at lower loadings. At higher loadings, this yellowing effect was masked, yielding a lower yellowness index.     

Polypropylene filled with kaolinite-based conductive powders

Antimony doped tin oxide nanoparticles (Sb–SnO₂) were uniformly coated on the surfaces of rod-/flake-like kaolinites (Kaol) to synthesize kaolinite-based conductive powders (Sb–SnO₂)Kaol, which was then added into polypropylene (PP) matrix to produce conductive (Sb–SnO₂)Kaol–PP nanocomposites. The effects of (Sb–SnO₂)Kaol characteristics on the volume resistivity and mechanical properties of (Sb–SnO₂)Kaol–PP were in detail investigated. The results indicated that surface-modified (Sb–SnO₂)Kaol could improve the dispersion in PP matrix, and the as-synthesized nanocomposites showed better electrical property than that without surface modification. The volume resistivity of (Sb–SnO₂)Kaol–PP reached 7.3 × 10⁸ Ω·cm at the (Sb–SnO₂)Kaol concentration of 40%, 6–7 order of magnitude lower than that of pure PP. The as-synthesized (Sb–SnO₂)Kaol–PP nanocomposites could show potential applications in the conductive fields.     

Porosity formation by biaxial stretching in polyolefin films filled with calcium carbonate particles

Porous polymer films were generated by biaxial stretching of polypropylene (PP) and high‐density polyethylene (HDPE) filled with various amounts of calcium carbonate particles. The porosity of the films was measured by mercury porosimetry, and the obtained results were related to the processing conditions and to the morphology development during the biaxial stretching. The results showed that increasing the calcium carbonate (CaCO₃) concentration and the draw ratio resulted in porosity increase for PP‐based composite films and in a decreased porosity in HDPE‐based composite films. Such peculiar behavior was connected to interfacial specific interactions between the matrix and the dispersed particles as well as to the crystallinity of the films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The evaluation of extensional viscosity of highly filled polyolefins composites films with calcium carbonate

This article reports the results of the extensional viscosity ( ) of polyolefins composites films. The test material was composed of ternary MDPE/iPP/CaCO₃ composites with a calcium carbonate content of 48–72% by mass. The concentrations of the composites and reference materials that were PE‐MD/iPP mixtures are summarized in Table 1. For all materials the viscosity curves (rotational rheometer) and the change in mass flow rate were determined. Two types of investigated films were produced: cast films and blow films. The extensional viscosity of films (thickness ≈ 80 μm) was performed on a SER‐2 Universal Testing Platform. The influence of the addition of calcium carbonate, extrusion techniques and the direction of sample cut (MD and TD) to change the extensional viscosity were discussed. The extensional viscosity measurements ( ) were taken at a temperature of 140°C and for a strain rate (Hencky strain rate) of = 0.1, 0.2 and 0.5 s^?1. POLYM. ENG. SCI., 59:E155–E163, 2019. © 2018 Society of Plastics Engineers     

Synthesis of transparent oil dispersion of monodispersed calcium carbonate nanoparticles with high concentration

The preparation of monodispersed inorganic nanoparticles is of great interest for many applications. In this article, transparent oil dispersion of monodispersed amorphous CaCO₃ nanoparticles with high concentration and long‐term stability were controllably prepared by a reverse microemulsion method. The effects of the addition amount of extra minute water and (NH₄)₂CO₃ as novel assistant promoter, reaction temperature, Ca(OH)₂/CaO mole ratio were explored. The optimum synthesis conditions were achieved. The as‐prepared transparent oil nanodispersion had a good monodispersity, a uniform particle size of 8–10 nm, a high stability of over 12 months, a high solid content of 38 wt% (Ca content of about 15.5 wt%) and a high total base number of 416 mgKOH/g. The preparation process was further investigated by polarized optical microscope and Fourier transform infrared. This nanodispersion will find a promising applicability as an excellent nanodetergent in the fields of automobile and marine lubricants. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3663–3669, 2017     

轻质碳酸钙表面改性及填充丁苯橡胶

采用干法表面化学改性,用脂肪酸类表面活性剂（JZ）或钛酸酯类偶联剂（TZ）对轻质碳酸钙进行了表面改性,并将改性轻质碳酸钙填充到丁苯橡胶中制备硫化胶。结果表明,轻质碳酸钙试样的最佳改性条件为：改性剂为JZ时,改性温度为100℃,用量为1．4％;改性剂为TZ时,其相应值依次为110℃,2．2％,与未改性轻质碳酸钙相比,JZ改性轻质碳酸钙填充丁苯硫化胶的拉伸强度及扯断伸长率有较明显的提高。     

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