Low CaCO3 Research Articles

Germination and growth response of flax (Linum usitatissimum) to salinity stress by different salt types and concentrations

ABSTRACTThis investigation was conducted to explore the effects of salt types with different concentrations on germination and growth parameters of flax seeds. The experiment was set out as a factorial experiment based on a completely randomized design with three replications. We used six kinds of salts (NaCl, CaCl2, CaCO3, Na2SO4, Na2CO3 and KCl) with concentrations of 0, 50, 100 and 200 mM. According to the results, the inhibitory effects of the five salt types differed substantially, especially in the case of CaCO3, Na2CO3 and Na2SO4. Inhibitory effects of these salts were very strong compared to those of NaCl and CaCl2. Germination of flax seeds by various salts was in the order of NaCl > CaCl2 > KCl > Na2CO3 > Na2SO4 > CaCO3. The effect of salt concentration was obvious, too. Seeds of flax were able to germinate even in 200 mM NaCl, but they only germinated in distilled water or at very low CaCO3, Na2CO3 and Na2SO4 concentrations (50 mM).

Microstructural changes in alkali-activated slag mortars induced by accelerated carbonation

This study investigated microstructural changes in alkali-activated slag (AAS) mortars after carbonation using XRD, FTIR, DTG, 1H NMR and SEM examinations. The results showed that decalcification of C-S-H was the main reaction in carbonation of AAS. The C-S-H with a low Ca/Si was more vulnerable to decalcification in AAS samples activated by waterglass. Besides, AAS mortars demonstrated a lower CaCO3 formation compared to Portland cement mortars. Calcite and vaterite were the major CaCO3 polymorphs produced by carbonation of AAS precipitated mainly in gel pores and spaces in C-S-H interlayers. Meanwhile, the carbonation also caused a certain volume of contraction in AAS mortars.

Effects of foaming parameters on microstructure and compressive properties of aluminum foams produced by powder metallurgy method

Semi open-cell aluminum foams having channels between individual cells were produced using low cost CaCO3 foaming agent and applying the powder compact melting process. To this end, the aluminum and CaCO3 powder mixtures were cold compacted into dense cylindrical precursors for foaming at specific temperatures under air atmosphere. The effects of several parameters including precursor compaction pressure, foaming agent content as well as temperature and time of the foaming process on the cell microstructure, linear expansion, relative density and compressive properties were investigated. A uniform distribution of cells with sizes less than 100 μm, which form semi open-cell structures with relative densities in the range of 55.4%–84.4%, was obtained. The elevation of compaction pressure between 127–318 MPa and blowing agent up to 15% (mass fraction) led to an increase in the linear expansion, compressive strength and densification strain. By varying the foaming temperature from 800 to 1000 °C, all of the investigated parameters increased except compressive strength and relative density. The results indicated the optimal foaming temperature and time as 900 °C and 10–25 min, respectively.

Benthic foraminiferal paleoecology and depositional patterns during the Albian at DSDP Site 327 (Falkland Plateau)

The present paleoenvironmental study uses a spectrum of analytical methods, such as benthic foraminiferal assemblages, total organic carbon (TOC), calcium carbonate (CaCO3) contents and magnetic susceptibility (MS), to monitor variations in primary productivity, bottom-water oxygenation and depositional patterns within the Albian interval recovered at DSDP Site 327, Hole A, Falkland Plateau. Thirty-three benthic foraminiferal species were identified in the studied section and, based on the abundances of morphogroups (epifaunal and shallow infaunal), two distinct associations were identified. Stratigraphic intervals dominated by the epifaunal morphogroup can be interpreted as indicative of bottom-waters with low-oxygen content. However, these decreases in oxygenation were not vigorous enough to establish a dominance of deep-infaunal morphotypes, as supported by the low TOC values. Intervals dominated by the shallow infaunal morphogroup were interpreted as subjected to moderate to high nutrient flux to the ocean floor. These intervals are associated with high MS values and low CaCO3 content, suggesting that dissolution processes, rather than increased primary productivity, controlled CaCO3 accumulation in the studied section. Furthermore, faunal analysis points to deposition in an outer neritic to upper bathyal paleoenvironment.

TOC and CaCO3 content in Oligocene shelf deposits on Lemnos Island and their relation with depositional conditions

A series of seventy seven samples from outcrops of mudstones were analyzed in order to evaluate their total organic carbon (TOC) and calcium carbonate (CaCO3) concentrations. Results showed that TOC ranges between 0% to 1.15% (with a mean value of 0.34%) introducing that Oligocene shelf deposits on Lemnos island have fair to good conditions to be potential source rocks. Analysis of CaCO3 presented a range between 1.37% to 42.52% (with a mean value of 16.95%). The comparison of TOC and CaCO3 suggests that the two parameters are either inversely or positively related. The inversely related contents, high TOC and low CaCO3, may indicate anoxic conditions, whereas low TOC and high CaCO3 occur in oxic conditions due to the decomposition of TOC. The CO2 produced by decomposition of organic carbon and production of organic acids reduces the pH in pore water enough to dissolve any CaCO3 that reaches the sediment water interface. On the other hand, a positive relation, with both high TOC-CaCO3 contents, could be related with oxic conditions and high sedimentation rate or incidents of abrupt death and bury of great amounts of benthic organisms (TOC) increasing the maintenance of organic material in the sediment.

Metal mobility assessment for the application of an urban organic waste amendment in two degraded semiarid soils

Urban organic waste materials may find a potential use as amendments in agricultural or environmental fields. However, before being applied in field practices, urban organic wastes must meet some environmental and legal requirements. The objective of this work was to assess the metal (Cd, Cu, Mn, Pb and Zn) extractability in two amended degraded semiarid soils (a former agricultural soil and a mine tailings soil) employing an urban organic waste amendment. A seven-steps sequential extraction procedure was performed in order to determine the changes in metal (Cd, Cu, Mn, Pb and Zn) fractionation, after two weeks and after eight months of soil incubation in pots. The urban organic waste increased organic carbon at both soils but it did not affected pH. At both soils, the addition of the amendment increased the labile fractions of metals, especially Cu (up to 13% of total content). In the amended agricultural soil the incubation favoured the fractions associated to Mn oxides (for Mn and Zn) and organic matter (for Cu), probably due to the higher buffer capacity of the soil (pH~8, high CaCO3, loam texture). In the amended mine tailings soil, with lower buffer capacity (pH~7, low CaCO3, loamy sand texture), there was a redistribution into more labile fractions associated to carbonates (Mn, Pb and Zn). In low buffer capacity soils, such as the case of the mine tailings soil, the changes generated by the mineralisation of the organic matter may alter heavy metal fractionation promoting the increase of carbonate bound fractions, which could be easily mobilisable. The assessment of the long-term dynamics of organic matter mineralisation and its relation to metal geochemistry is necessary to provide a safe employment of this urban organic waste for restoring degraded soils.

Design of a multimodal (1H/23Na MR/CT) anthropomorphic thorax phantom

ObjectivesThis work proposes a modular, anthropomorphic MR and CT thorax phantom that enables the comparison of experimental studies for quantitative evaluation of deformable, multimodal image registration algorithms and realistic multi-nuclear MR imaging techniques. MethodsA human thorax phantom was developed with insertable modules representing lung, liver, ribs and additional tracking spheres. The quality of human tissue mimicking characteristics was evaluated for 1H and 23Na MR as well as CT imaging. The position of landmarks in the lung lobes was tracked during CT image acquisition at several positions during breathing cycles. 1H MR measurements of the liver were repeated after seven months to determine long term stability. ResultsThe modules possess HU, T1 and T2 values comparable to human tissues (lung module: −756±148HU, artificial ribs: 218±56HU (low CaCO3 concentration) and 339±121 (high CaCO3 concentration), liver module: T1=790±28ms, T2=65±1ms). Motion analysis showed that the landmarks in the lung lobes follow a 3D trajectory similar to human breathing motion. The tracking spheres are well detectable in both CT and MRI. The parameters of the tracking spheres can be adjusted in the following ranges to result in a distinct signal: HU values from 150 to 900HU, T1 relaxation time from 550ms to 2000ms, T2 relaxation time from 40ms to 200ms. ConclusionThe presented anthropomorphic multimodal thorax phantom fulfills the demands of a simple, inexpensive system with interchangeable components. In future, the modular design allows for complementing the present set up with additional modules focusing on specific research targets such as perfusion studies, 23Na MR quantification experiments and an increasing level of complexity for motion studies.

Evolution of Luyang Lake since the last 34,000 years: Climatic changes and anthropogenic impacts

A sediment section retrieved from Luyang Lake, Shaanxi province, China was employed for grain-size, total organic carbon content (TOC) and carbonates (CaCO3) analyses. Based on the Optically Stimulated Luminescence (OSL) chronology, the evolution of Luyang Lake since the last 34,000 years was reconstructed. Then the historical anthropogenic information like populations and arable lands obtained from literature were incorporated into the environmental sequence to demonstrate the linkage of lake evolution with both climatic and anthropogenic forcings. It indicated that the appearance of loessial sediment during ca. 33.4–10.7 ka exhibited a much lower lake level associated with a cold and dry climate setting. The sediment became finer with increasing TOC after ca. 10.7 ka implied the enhanced monsoon rainfall and relatively higher lake level until ca. 4.6 ka. Much higher TOC and lowest CaCO3 at 7.2–4.6 ka suggested the Holocene Climate Optimum in the region. The rising CaCO3 and declining TOC at ca. 4.6–2.0 ka revealed the enhanced evaporation/precipitation rate and depressed paleoproductivity, suggesting a drier climate. TOC reached its highest after ca. 2 ka, coinciding with the increasing population and the expanding arable lands since the last 600 years, would suggest the anthropogenic impacts like land reclamation and farming rather than climate forcing. Briefly, the evolution of Luyang Lake was controlled by the monsoon climate through geological times and the intensified anthropogenic interferences since the last 2 ka, especially the last 600 years, would account for the transformation of freshwater lake to a saline lake and wetland environment.

Structural-textural nature and sorption properties of limestones from the mesozoic-neogene contact zone in the Bełchatów deposit

Abstract Limestones of the Jurassic age are one of the most important minerals accompanying the Bełchatówlignite deposits. They are part of the Bełchatów and Szczerców rock subsoil complex and form natural hillsides of exploitation fields, which are gradually being exposed due to the progressive exploitation of coal. So far in Bełchatów Lignite Mine nearly 2 million tonnes of limestones have been extracted, which were used in the form of highway aggregate. For the extraction (mineral recovery) approx. 2 million tonnes remained in the Bełchatów field and from 20 to nearly 70 million tonnes in the Szczerców field. The limestones occurring in the deposit Bełchatów are differential qualitatively. Those situated in direct contact with Neogene deposits are characterized by strong karstification (karst formation), and even occur in the form of detrital minerals. Furthermore, they are covered by processes of secondary mineralization. These processes caused significant diversity of phase and chemical composition, and thereby have contributed to reducing the CaCO3 content. Despite this, limestones from the Mesozoic-Neogene contact zone possess excellent sorption properties in respect of SO2 in conditions of fluidised furnaces. These properties are determined firstly by their structural-textural nature, and above all with the presence of calcite sparite crystals in microcrystalline groundmass, of micropores, tectonic discontinuities, fracturings and compaction slits. With their presence, both decarbonatization and sorption processes proceed effectively. The CO2 particles are quickly removed from the structures of calcite crystals, and SO2 is able to penetrate into the interior of the sorbent grains where are absorbed on the inner surface of pores arising as a result of the decarbonatization process. These characteristic structural and textural properties of the surveyed limestones have been shaped at the diagenesis and epigenesis stage. This contributed to all chemical and mechanical compaction and cementation processes, as well as the dissolution and recrystallization processes. Despite the low CaCO3 content limestones from the Mesozoic-Neogene contact zone can be successfully used in the form of sorbents to reduce SO2 emissions in conditions of fluidised furnaces.

On the Frontline: Tracking Ocean Acidification in an Alaskan Shellfish Hatchery

The invasion of anthropogenic carbon dioxide (CO2) into the ocean is shifting the marine carbonate system such that saturation states of calcium carbonate (CaCO3) minerals are decreasing, and this is having a detrimental impact on early life stages of select shellfish species. The global, secular decrease in CaCO3 saturation states is occurring on top of a backdrop of large natural variability in coastal settings; progressively shifting the envelope of variability and leading to longer and more frequent exposure to adverse conditions. This is a great concern in the State of Alaska, a high-latitude setting vulnerable to rapid changes in the marine carbonate system, where an emerging shellfish industry plans major growth over the coming decades. Currently, the Alutiiq Pride Shellfish Hatchery (APSH) in Seward, Alaska is the only hatchery in the state, and produces many shellfish species with early life stages known to be sensitive to low CaCO3 saturation states. Here we present the first land-based OA measurements made in an Alaskan shellfish hatchery, and detail the trends in the saturation state of aragonite (Ωarag), the more soluble form of CaCO3, over a 10-month period in the APSH seawater supply. These data indicate the largest changes are on the seasonal time scale, with extended periods of sub-optimal Ωarag levels (Ωarag < 1.5) in winter and autumn associated with elevated water column respiration and short-lived runoff events, respectively. The data pinpoint a 5-month window of reprieve with favorable Ωarag conditions above the sub-optimal Ωarag threshold, which under predicted upper-bound CO2 emissions trajectories is estimated to close by 2040. To date, many species in production at APSH remain untested in their response to OA, and the data presented here establish the current conditions at APSH as well as provide a framework for hatchery-based measurements in Alaska. The current and expected conditions seen at APSH are essential to consider for this developing Alaskan industry.

Effect of calcium carbonate whisker content on the morphology, crystallization, and mechanical properties of poly(para-dioxanone)/Calcium carbonate whisker composites

In this work, poly(para-dioxanone) (PPDO) was mixed with 0, 1, 5, 10, 20, and 30 weight percent (wt%) calcium carbonate (CaCO3) whiskers by solution coprecipitation. Samples were compression molded into bars using a platen vulcanizing press. It has assessed the influence of the CaCO3 whisker content on the morphology, thermal, mechanical, and crystalline properties of the PPDO/CaCO3 whisker composites, using differential scanning calorimetry (DSC), polarized optical microscopy, scanning electron microscopy, and X-ray diffraction. DSC showed that the glass transition temperature (Tg) and crystallization temperature (Tc) of the composites increased with increasing CaCO3 whisker content. At low CaCO3 whisker content (1 wt%), the degree of crystallinity (Dc) of PPDO increased sharply. The addition of higher content of CaCO3 whisker would cause more agglomeration in PPDO matrix, so that the mechanical properties of PPDO/CaCO3 whisker composites would gradually decrease. The mechanical properties of PPDO were changed by the presence of CaCO3 whiskers; the optimal amount of CaCO3 whisker was 1 wt%, which sharply improved the tensile strength of PPDO by 54%. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Late Holocene continental shelf sediments, off Cuddalore, East coast, Bay of Bengal, India: Geochemical implications for source-area weathering and provenance

In the present study, a 60 cm sediment gravity core collected off the Cuddalore shore (11°42.419 N, 79°57.993 E) from a water depth of 150 m was radiocarbon dated and analysed for major elements (Si, Al, Na, K, Ca, Mg and P), trace elements (Fe, Cr, Mn, Co, Ni, Cu, Zn and Pb), calcium carbonate, and organic matter content to understand their behavior and probable sources and also to understand the monsoon variability. The sediment core has been radiocarbon dated from around 4100 to 3100 BP. High sand around 4000, 3700, 1500 BP with low CaCO3 content suggests high sediment flux coupled with higher precipitation corresponding to increased erosion during these periods, and more fresh water runoff from rivers in the late Holocene, thus reflecting intensification of the SW and NE monsoon. The results of the major elemental analyses show the fine-grained, detrital nature of sediments with high values of Si and lower values of Al and Fe. The present study clearly demarcates that the distribution patterns of Cr, Cu, Pb and Zn that are controlled by the distribution of the fine grained fractions. The increased Mn content towards the lower end of the sediment core denotes the allogenic supply of Mn from oxic to-sub-oxic recycling within the sediment column in fine grain sediments. The mean CIA values (56.47) reflect immature, moderately weathered sediments that are mostly derived from sandstone and clay.

Preparation and modification of nano calcium carbonate filler from waste marble dust and commercial limestone for papermaking wet end application

The objective of this work was to prepare low cost CaCO3 nanofillers for wet end papermaking application. CaCO3 nanofillers were successfully prepared from commercial limestone and white waste marble dust using wet carbonation technique. Anionic (sodium oleate) and cationic surfactants (CTAB) were used to modify the size, morphology and surface property of CaCO3. The prepared CaCO3 fillers were applied in paper handsheets and their effect on paper quality was systematically investigated. The results obtained from XRD and FTIR revealed that the prepared CaCO3 particles were typically calcite. The presence of surfactant during the preparation significantly reduced the particle size and changed the morphology from scalenohedral to rhombohedral as illustrated from TEM results. The surfactant modification of filler improved the retention and consequently all the paper optical properties significantly increased. However, the strength properties were practically unchanged despite the high retention values obtained compared with GCC, indicating improved affinity of the filler particles to the fibres. Oleate modified CaCO3 showed higher effect on retention, apparent density, opacity, and mechanical properties than the CTAB modified CaCO3.The SEM images of paper handsheets confirmed the results and indicated that the modified nano CaCO3 are highly retained and more effectively adhered and bonded to pulp fibre, in addition to their uniform distribution on paper surface.

Experimentos de disolución de CaCO&lt;sub&gt;3&lt;/sub&gt; en foraminíferos bentónicos aglutinados del Paleoceno-Eoceno en Zumaya (Cuenca Vasco-Cantábrica, España)

The largest extinction of deep-sea benthic foraminifera in the Cenozoic occurred during the Paleocene-Eocene Thermal Maximum event (PETM, ~55.8 Ma). Much has been speculated about the causes of such extinction, and proposed mechanisms include changes in productivity and/or oxygenation of bottom waters, metabolic changes and in the composition of the food supply to the seafloor, or the ocean acidification related to the massive input of isotopically light carbon into the ocean-atmosphere system, among others. Here we analyse ocean acidification as a potential triggering mechanism of the extinctions. The early Eocene at the Zumaya section (Basque-Cantabrian Basin) is marked by a 4 m-thick interval with a very low CaCO 3 content. In order to analyse whether CaCO 3 dissolution had a direct effect on the extinctions across the PETM, we car-ried out dissolution experiments on various species of agglutinated benthic foraminifera from Zumaya. In general, agglutinated species that do not disappear in the interval of most intense dissolution at Zumaya were not -or only slightly- affected by our dissolution experiments, since they do not have calcareous particles or cement. However, some species that went extinct or locally disappeared during the early Eocene, such as Dorothia cylindracea, Spiroplectammina spectabilis and Haplophragmoides cf. walteri , are resistant to dissolution. These results sug-gest that, in addition to ocean acidification, other factors must have contributed to the destabilization of benthic foraminiferal assemblages.

Occurrence of aragonite corrosive water in the North Yellow Sea, near the Yalu River estuary, during a summer flood

To understand seawater CaCO3 saturation state (Ωarag for aragonite and Ωcal for calcite) dynamics in river-dominated ocean margins, we investigated the carbonate system and ancillary parameters in the North Yellow Sea, near the Yalu River estuary, during and after a summer flood (August and September 2013, respectively). During the flood period, nearshore Ωarag ranged from 0.76 to 1.61 and Ωcal ranged from 1.22 to 2.53. Aragonite undersaturation values were associated with quite low salinity of 14.58–25.18 and a broad dissolved oxygen saturation range from 58% to 102%. A week after the flood period, aragonite undersaturated waters together with the estuarine plumes disappeared. Based on field data analyses and simplified model simulation, we suggest that net community respiration/remineralization and the dilution of riverine water discharge both contributed to the low CaCO3 saturation states.

Community calcification in Lizard Island, Great Barrier Reef: A 33 year perspective

Measurements of community calcification (Gnet) were made during September 2008 and October 2009 on a reef flat in Lizard Island, Great Barrier Reef, Australia, 33years after the first measurements were made there by the LIMER expedition in 1975. In 2008 and 2009 we measured Gnet=61±12 and 54±13mmolCaCO3m−2·day−1, respectively. These rates are 27–49% lower than those measured during the same season in 1975–76. These rates agree well with those estimated from the measured temperature and degree of aragonite saturation using a reef calcification rate equation developed from observations in a Red Sea coral reef. Community structure surveys across the Lizard Island reef flat during our study using the same methods employed in 1978 showed that live coral coverage had not changed significantly (∼8%). However, it should be noted that the uncertainty in the live coral coverage estimates in this study and in 1978 were fairly large and inherent to this methodology. Using the reef calcification rate equation while assuming that seawater above the reef was at equilibrium with atmospheric PCO2 and given that live coral cover had not changed Gnet should have declined by 30±8% since the LIMER study as indeed observed. We note, however, that the error in estimated Gnet decrease relative to the 1970’s could be much larger due to the uncertainties in the coral coverage measurements. Nonetheless, the similarity between the predicted and the measured decrease in Gnet suggests that ocean acidification may be the primary cause for the lower CaCO3 precipitation rate on the Lizard Island reef flat.

On the SO2 problem of solid fuel combustion

Many companies use two-phase absorbents (CaCO3 suspension) for waste gases purification from SO2. A qualitative theoretical analysis of the absorption kinetics in the cases of two-phase absorbent, using the convection-diffusion type of model, is presented. It is shown that the low CaCO3 concentration lead to very small chemical reaction rate and as a result the absorption rate is limited by the physical absorption of SO2 in water, i.e. the process efficiency is very small. An average concentration model for quantitative analysis of the absorption process and an iterative numerical algorithm for the model equations solution is proposed.

Cumulative influences of a small city and former mining activities on the sediment quality of a subtropical estuarine protected area.

This study aimed to evaluate the sediment quality in the estuarine protected area known as Cananéia-Iguape-Peruíbe (CIP-PA), located on the southeastern coast of Brazil. The study was designed considering possible negative effects induced by the city of Cananéia on the sediment quality of surrounding areas. This evaluation was performed using chemical and ecotoxicological analyses. Sediments were predominantly sandy, with low CaCO3 contents. Amounts of organic matter varied, but higher contents occurred closer to the city, as well as did Fe and Total Recoverable Oils and Greases (TROGs) concentrations. Contamination by Cd and Cu was revealed in some samples, while concentrations of Zn were considered low. Chronic toxicity was detected in all tested sediments and acute toxicity occurred only in sediments collected near the city. The principal component analysis (PCA) revealed an association among Cd, Cu, Fe, TROG, fines, organic matter, CaCO3, and chronic toxicity, whereas acute toxicity was found to be associated with Zn and mud. However, because Zn levels were low, acute toxicity was likely due to a contaminant that was not measured. Results show that there is a broad area within the CIP-PA that is under the influence of mining activities (chronic toxicity, moderate contamination by metals), whereas poorer conditions occur closer to Cananéia (acute toxicity); thus, the urban area seems to constitute a relevant source of contaminants for the estuarine complex. These results show that contamination is already capable of producing risks for the local aquatic biota, which suggests that the CIP-PA effectiveness in protecting estuarine biota may be threatened.

Early- to late-Holocene contrast in productivity, OMZ intensity and calcite dissolution in the eastern Arabian Sea

The Oxygen Minimum Zone (OMZ) is a potential source of CO2 to the atmosphere, and the extensive OMZ spread to 1.37 × 106 km2 in the Northern Arabian Sea would be an important contributor to the CO2 budget. In this perspective, we report here that the Eastern Arabian Sea experienced coeval increase in productivity and denitrification from ~7 to 0 kyr, which coincides with minimum dissolved oxygen levels in bottom waters. In addition, during the same period, an increased calcium carbonate dissolution occurred as evidenced by low CaCO3 content, decreasing shell weights of planktonic foraminifer species Globigerinoides ruber with well-marked dissolution features on their shells. Therefore, this study has implications on the role of OMZ in governing CaCO3 dissolution and contributing to an increase in atmospheric CO2.

Influence of High-Density Polyethylene and Nano-Calcium Carbonate of Various Content Ratios on the Crystallization of Polypropylene

The influence of high-density polyethylene (HDPE) and nano-CaCO3 of various content ratios on the crystallization of polypropylene (PP) was investigated by differential scanning calorimetry, dynamic rheology, wide angle X-ray diffraction (WAXD), and Izod impact strength measurements. The results showed that HDPE and PP were phase separated in their blends and the additive CaCO3 filler mainly dispersed in the PP phase, acting as a nucleation agent to promote the crystallization of PP. For the samples HDPE/ nano-CaCO3 30/0 and 25/5, the β crystals content was much higher than the other samples. The reason is that the viscosity difference between HDPE and PP led to a velocity difference, which could induce shear stress at the interfaces of HDPE and PP during injection molding. The intensive shear stress at their phase interfaces is advantageous for orientation of the chains, inducing the formation of β crystals. However, with the increment of CaCO3 content, there were dual effects of CaCO3 on the crystallization of PP: at low CaCO3 content, it would hamper the orientation of PP chains, thus leading to a decrease of β crystals; at high CaCO3 content, it would induce β crystals by itself.