Preparation and properties of gluten/calcium carbonate composites

Environment friendly thermosetting composites were prepared by blending wheat gluten （WG） as matrix, calcium carbonate （CaCO3） as filler and glycerol as plasticizer followed by compression molding the mixture at 120 ℃ to crosslink the WG matrix. Morphology observation showed that the CaCO3 particles were finely dispersed in matrix. Incorporation of CaCO3 up to 10 wt% into the composites caused Young＇s modulus and tensile strength to increase markedly. On the other hand, the moisture absorption and elongation at break decreased slightly.

The Potential of Silane Coated Calcium Carbonate on Mechanical Properties of Rigid PVC Composites for Pipe Manufacturing

The inclusion of CaCO3 and kaolin in polyvinyl chloride (PVC) polymer matrices greatly enhances the physical and mechanical properties of the composite. In this study, the effects of kaolin and surface treatment of CaCO3 and kaolin particles on the microstructure and mechanical properties of PVC composites filled with kaolin particles via melt blending method were studied by means of SEM, tensile, Charpy impact testing, and FTIR. Treated and untreated kao-lin particles were dispersed in matrices of PVC resin at different concentrations up to 30 wt percentage. The tensile strength, elastic modulus, strain to failure and morphology of the resulting composites were measured for various filler loadings. Uniform dispersion of the fillers into the matrix proved to be a critical factor. SEM images revealed that small sized particles were more agglomerated than micron-sized particles and the amount of agglomerates increased with increasing particle content. Silane treated Kaolin-CaCO3/PVC composites had superior tensile and impact strengths to untreated kaolin-CaCO3/PVC composites. The Young’s modulus of all composites increased with increasing particle content up to maximum at 10% filler loading followed by gradually decreasing as content increased.

Engineering of Carbonate Apatite Bone Substitute Based on Composition-Transformation of Gypsum and Calcium Hydroxide

Even though a lot of research has been carried out concerning the preparation of carbonate apatite (CHA), they were related to CHA in the form of powder. In the present study, macroporous CHA bone substitutes were prepared through composition-transformation of gypsum and Ca-hydroxide. Here, we investigated the effect of added Ca-hydroxide to gypsum, carbonation periods, and hydrothermal temperatures for phosphatization to understand the basic principle of composition-transformation of gypsum added Ca-hydroxide to fabricate CHA bone substitutes. The specimens were characterized in terms of chemical and physical properties, such as extent of transformation of macroporous gypsum added Ca-hydroxide into CHA body, type and content of carbonate, and crystal morphology. It was observed that the transformation was faster with higher hydrothermal temperature. However, higher hydrothermal temperature caused de-carbonation phenomena which resulted in the lack of carbonate ions of the product. Moreover, the higher the percentage of Ca-hydroxide added to gypsum, caused the complete transformation of gypsum into CHA to be slower. These findings have been applied to the standard fabrication procedure of carbonate apatite, which in turn will allow scaling up process, and will be provided for biomedical purposes for the Indonesian community.

Surface modification of calcium carbonate:A review of theories,methods and applications

Calcium carbonate,which is widely employed as a filler added into the polymer matrix,has large numbers of applications owing to the excellent properties such as low cost,non-toxicity,high natural reserves and biocompatibility.Nevertheless,in order to obtain the good filling effect,calcium carbonate needs to be surface modified by organic molecules so as to enhance the dispersion and compatibility within the composites.This review paper systematically introduces the theory,methods,and applications progress of calcium carbonate with surface modification.Additionally,the key factors that affect the properties of the composites as well as the current difficulties and challenges are highlighted.The current research progress and potential application prospects of calcium carbonate in the fields of plastics,rubber,paper,medicine and environmental protection are discussed as well.Generally,this review can provide valuable reference for the modification and comprehensive utilization of calcium carbonate.

Synthesis of nano-CaCO_3 composite particles and their application

Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.

Enhanced adsorption and colorimetric detection of tetracycline antibiotics by using functional phosphate/carbonate composite with nanoporous network coverage

This work presents efficient tetracycline(TC) antibiotics adsorption using a functional porous phosphate/carbonate composite(PCC). The PCC was fabricated by anion-exchange of phosphate on the surface of vaterite-phase calcium carbonate particle scaffolds. The PCC,having dense nanoporous network coverage with large surface area and pore volume, exhibited excellent TC adsorption in solution. Its adsorption isotherm fitted well to the Freundlich model, with a maximum adsorption capacity of 118.72 mg/g. The adsorption process was spontaneous, endothermic, and followed pseudo-second-order kinetics. From the XPS analysis, the hydrogen bonding and surface complexation were the key interactions in the process. In addition, a colorimetric TC detection method was developed considering its complexation with phosphate ions, originating from PCC dissolution, during adsorption.The method was used to detect TC in mg/L concentrations in water samples. Thus, the multifunctional PCC exhibited potential for use in TC removal and environmental remediation.

复掺碳酸钙晶须增强轻质ECC材料力学性能研究

工程水泥基复合材料(ECC)由于其拉伸应变硬化行为和紧密多裂缝的独特特性能够满足混凝土基础设施韧性和耐久性的严格要求。使用粉煤灰漂珠代替细石英砂作为轻质细集料,使用国内高强高模量PVA和PE纤维,并复掺碳酸钙晶须对ECC进行多尺度增强,对轻质ECC的强度、单轴拉伸性能、薄板四点弯曲性能和孔隙率等进行试验研究。结果表明:碳酸钙晶须掺量为体积的1%时最佳,PVA-ECC抗压强度为57 MPa,极限拉伸强度为4.31 MPa,拉伸应变为3.44%;而PE-ECC抗压强度为60.4 MPa,极限拉伸强度为4.77 MPa,拉伸应变为8.16%。适量的晶须掺入,能够优化孔隙结构,提升强度,晶须微观桥接作用可延缓了微观裂纹发展,同时晶须可以增加界面粗糙度,提高摩擦结合强度,从而提高ECC拉伸应变能力。

淀粉的改性及其对淀粉/PBAT/碳酸钙复合材料结构和性能的影响

采用甘油、六偏磷酸钠(SHMP)和聚乙二醇(PEG)改性木薯淀粉并制备改性淀粉/聚己二酸对苯二甲酸丁二醇酯(PBAT)/碳酸钙复合材料,采用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、热失重分析仪(TG)等对改性淀粉和复合材料进行分析,研究改性淀粉对复合材料结构和性能的影响。结果表明,甘油的外增塑作用和PEG、SHMP的内增塑作用使淀粉化学结构改变、无定形成分增加,淀粉颗粒由饱满的圆球状变成了不规则的大颗粒,250℃前稳定性提高,250℃后稳定性降低,有利于使用加工和热分解,不同改性剂改性淀粉结晶熔融行为存在差异;复合不会改变PBAT、碳酸钙和淀粉的原有晶型,但相容性的差异导致复合材料热性能和力学性能的差异,改性淀粉增加了复合材料的韧性,甘油、SHMP和PEG的协同改性使淀粉与PBAT、碳酸钙的相容性最佳,复合材料的综合性能最好。

Heterogeneous reactions of gaseous methanesulfonic acid with calcium carbonate and kaolinite particles

Heterogeneous reactions of gaseous methanesulfonic acid (MSA) with calcium carbonate (CaCO3) and kaolinite particles at room temperature were investigated using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC).Methanesulfonate (MS-) was identified as the product in the condensed phase,in accordance with the product of the reaction of gaseous MSA with NaCl and sea salt particles.When the concentration of gaseous MSA was 1.34 × 10-13 molecules cm-3,the uptake coefficient was (1.21 ± 0.06) × 10-8 (1) for the reaction of gaseous MSA with CaCO3 and (4.10 ± 0.65) × 10 10 (1) for the reaction with kaolinite.Both uptake coefficients were significantly smaller than those of the reactions of gaseous MSA with NaCl and sea salt particles.

Effects of calcium carbonate on preparation and mechanical properties of wood/plastic composite

In order to reduce the cost and improve the performance of wood/plastic composite(WPC),the effects of additive amount of calcium carbonate on preparation and mechanical properties of high density polyethylene(HDPE)based WPC were studied.The results showed that the calcium carbonate can improve preparation and mechanical properties effectively.The 20%calcium carbonate additive could effectively improve the melt fluidity of the composites and reduce the energy consumption in the processing.The calcium carbonate had a favorable toughening effect on polymer and was effectively filled in WPC.For the best tensile,flexural and impact properties of WPC,the appropriate additive amounts of calcium carbonate were 25%,10%and 30%,respectively.The additive amount for preparation of WPC should be based on the processing requirements and the demands for different working conditions.

铜换热表面MgO颗粒与碳酸钙混合污垢沉积特性的分子动力学模拟

为探究MgO颗粒与碳酸钙混合污垢在换热表面沉积特性与机理,该文采用分子动力学模拟方法分析MgO颗粒和碳酸钙混合体系在铜换热表面的沉积过程,并通过改变碳酸钙浓度讨论浓度对混合污垢沉积特性的影响规律。结果表明,在混合污垢沉积过程中,碳酸钙团簇在颗粒与换热表面间起到连接作用,形成稳固的沉积状态。此外,MgO颗粒对离子缔合形成团簇过程中的动力学特性和结构特性有所影响。随着碳酸钙浓度由0.26 mol/L升至1.1 mol/L,换热表面直接吸附的碳酸钙团簇数量变多,MgO颗粒更容易通过碳酸钙团簇的相互作用沉积在换热表面。MgO颗粒促进了碳酸钙的缔合过程,碳酸钙促进了混合团簇的沉积,进而形成初始沉积阶段的混合污垢。

The synthesis of spherical calcium carbonate composite in amphiphilic PS-b-PAA solution and its thermal dynamic characteristic

Spherical calcium carbonate composite is synthesized in the solution of amphiphilic block copolymer of polystyrene(PS) and poly(acrylic acid)(PAA). SEM and XRD measurements show that the diameter of the particulates decreases with the augment of the PS-b-PAA concentration,crystalline in the composite is calcite and its morphology as well as the structure is changed too. TG-DTA together with IR analysis is applied to investigating the thermal dynamic behavior of the composite. The results show that the composite is mainly composed of two phases, that is, the nanocrystalline calcium carbonate and the PS-b-PA-Ca composites. PS phase decomposes first with a large heat release at about 330℃. However, the PAA chains have relatively high thermal stability, probably due to the structural Ca-O bond,and decomposes at above 400℃. Matching opinions are used to explain the possible reasons for the regular as well as the particular characteristics of the composite corresponding to a certain copolymer concentration.

碳酸钙晶须混杂聚乙烯纤维增强水泥基复合材料力学性能研究

为研究碳酸钙晶须掺量对聚乙烯纤维增强水泥基复合材料(PE-ECC)力学性能及微观结构的影响,设计了4组不同碳酸钙晶须掺量的PE-ECC试件,对其进行抗压性能试验、抗拉性能试验、三点弯曲断裂性能试验,并使用XRD、SEM、NMR技术对其微观结构进行研究。结果表明,碳酸钙晶须对PE-ECC有增强增韧作用,随着碳酸钙晶须掺量增加,这种增强增韧作用呈先增大后减小的趋势,当碳酸钙晶须掺量为1%(体积分数)时,PE-ECC的抗压性能、拉伸性能、断裂性能提升最佳。适量的碳酸钙晶须能填充基体,减少少害孔及多害孔数量,改善孔隙结构。

竹纤维粒径与比例对石竹塑复合材料的性能影响

【目的】阐明不同竹纤维粒径和原料配比对竹纤维/聚丙烯/碳酸钙复合材料物理力学性能的影响机理,为石竹塑复合材料的工业化生产与应用提供依据。【方法】以碳酸钙、竹纤维和聚丙烯为原料,在控制竹纤维粒径(40目、80目和120目)与原料配比的基础上,制备竹纤维/聚丙烯/碳酸钙复合材料,考察其物理力学性能,并采用扫描电子显微镜、热重分析仪和熔融指数仪对复合材料的微观结构、热稳定性和流动性进行表征。最后,综合考虑生产成本与相关性能要求,为竹纤维/聚丙烯/碳酸钙复合材料的生产与应用提出建议。【结果】随着碳酸钙添加量的增加,复合材料的拉伸强度、弯曲强度和弹性模量均逐渐下降,而密度则呈上升趋势。竹纤维粒径对复合材料物理力学性能的影响较为显著。当竹纤维粒径为80目,碳酸钙和竹纤维添加量分别为5%和45%时,复合材料的拉伸强度、弯曲强度和弹性模量最优,分别为36.09 MPa、62.6 MPa和4.30 GPa。碳酸钙添加量对复合材料冲击强度的影响不大。此外,随着碳酸钙添加量的增加,复合材料的热稳定性与熔体流动性均有所改善。当碳酸钙添加质量占比为20%时,复合材料的熔体流动速率为16.50 g/10 min,比未添加组提高了8.98%,加工性能得到改善。【结论】选用80目竹纤维的复合材料具有较优的物理力学性能,在添加碳酸钙后,复合材料的原料成本可降低1.63%~6.54%,且其相关指标仍远高于行业标准要求。

Effects of carbonation on mechanical properties of CAC-GGBFS blended strain hardening cementitious composites

Calcium aluminate cement(CAC)—based strain hardening cementitious composites(SHCC)has been developed and used for the rehabilitation of sewerage pipelines.In addition to well-known microbiologically induced corrosion,CO_(2)concentration in the sewerage environment is high,which may cause significant carbonation of pipelines.Thus,this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based SHCC.Two types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were prepared.The accelerated carbonation test was conducted in a carbonation chamber with a 5%CO_(2)concentration.The compressive and tensile behaviour of SHCC was tested first,and microstructure analysis,e.g.,X-ray diffraction and scanning electron microscopy,was then performed.The results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging effect.Also,the compressive and tensile strength was significantly improved as well as achieving a higher tensile strain capacity after carbonation when compared with OPC-based SHCC.Microstructure analysis revealed that the metastable phases in carbonated CAC-based SHCC were converted into stable phases and calcium carbonate polymorphs,densifying the binder matrix.The obtained results of this paper may provide new insight into utilizing carbonation to avoid the unstable conversion of hydrates in calcium aluminate cement.

Effect of wastewater composition on the calcium carbonate precipitation in upflow anaerobic sludge blanket reactors

Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content.The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket(UASB)reactors.Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate,respectively.There was an obvious accumulation of inorganic precipitate observed in the biogranules.Observations via scanning electron microscope(SEM)and energy dispersive spectroscopy(EDS)showed that the acclimated biogranules in the two reactors differed in microstructure.Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules,but precipitated at the core of the carbohydrate-degrading biogranules.The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge,which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates.Moreover,the location of calcium carbonate precipitation substantially affected the specific methanogenic activity(SMA)of the granular sludge.The SMA of the acetate-degrading biogranules dropped from 1.96 gCODCH4·gVSS^(–1)·d^(–1)to 0.61 gCODCH4·gVSS^(–1)·d^(–1)after 180-d of operation in the reactor.However,the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation.

电石渣对复合胶凝材料力学性能和微观结构的影响

电石渣作为一种Ca(OH)_(2)含量较高的工业副产品,可协同Na_(2)CO_(3)加速碱激发复合胶凝材料的水化过程。本文采用粉煤灰和矿粉作为复合胶凝材料的前驱体,探究不同电石渣(CCR)和Na_(2)CO_(3)质量比对复合胶凝材料的孔溶液pH值和力学性能影响。此外,通过水化热、X射线衍射、热重分析和扫描电子显微镜,探讨了CCR和Na_(2)CO_(3)协同激发作用对复合胶凝材料的水化过程和微观结构的影响。研究结果表明,随着CCR掺量的增加,复合胶凝材料的孔溶液pH值和力学性能均呈先增加后递减的趋势。当CCR和Na_(2)CO_(3)的掺量分别为6%和9%(质量分数)时,碱激发复合胶凝材料的3 d孔溶液pH值和28 d抗压强度分别达到最大值12.95和26.8 MPa。微观结构分析表明,在CCR和Na_(2)CO_(3)的协同激发作用下,碱激发复合材料能够生成更多的水化硅(铝)酸钙(C-(A)-S-H)凝胶,使得结构更加密实。

机械活化重质碳酸钙制备复合碳酸钙及其对溶液中的Cu^(2+)吸附性能

利用机械活化法对重质碳酸钙进行了纳米化表面改性,以聚丙烯酸钠和纳米碳酸钙为改性原料与重质碳酸钙进行混合研磨,成功制备了纳米碳酸钙包覆重质碳酸钙的复合钙,并考察了复合钙对溶液中的Cu^(2+)的吸附性能。研究结果如下:扫描电子显微镜和X射线衍射仪分析证实了纳米碳酸钙包覆在重质碳酸钙表面,傅里叶变换红外光谱分析表明复合碳酸钙表面羟基明显增加,比表面积分析表明复合碳酸钙的比表面积为20.5m^(2)/g,具有介孔结构。复合碳酸钙对Cu^(2+)的最大吸附量为65.5mg/g,去除率可达98%。吸附性能研究表明,复合碳酸钙对Cu^(2+)吸附动力学符合伪二阶动力学模型,等温吸附过程符合Langmuir-Freundich模型,证明吸附过程以离子交换反应为主,该过程为吸热反应。

纺锤状磁性碳酸钙复合材料的制备及其表征

为了探索制备磁性碳酸钙复合材料的新途径,以Ca(OH)_(2)和CO_(2)为原料,乙二胺四乙酸二钠(EDTA-2Na)为晶型控制剂,通过在高压反应釜中添加Fe_(3)O_(4)纳米粒子,碳化制备了分散均匀、形貌为中空纺锤状的磁性碳酸钙复合材料CaCO_(3)Fe_(3)O_(4),采用SEM、XRD、VSM、XPS、TEM等表征方法探究了反应温度、EDTA-2Na添加量等对CaCO_(3)Fe_(3)O_(4)形貌和性能的影响。结果表明:纺锤状磁性CaCO_(3)Fe_(3)O_(4)的最佳制备条件为反应温度为120℃、Ca(OH)_(2)的质量分数为2%、EDTA-2Na用量为Ca(OH)_(2)质量的8%、反应时间为2 h、Fe_(3)O_(4)与CaCO 3的物质的量比为1∶10,所制备的CaCO_(3)Fe_(3)O_(4)的平均直径约400 nm,长度约为1μm,饱和磁化强度为9.78 emu/g。

外源碳酸钙和温度对黄壤活性有机碳组分及微生物群落组成的影响

为探究不同温度条件下添加碳酸钙对活性有机碳组分及微生物群落组成的影响,以贵州典型黄壤土为研究对象,采用同位素标记法,设置6个处理(培养温度分别为15,25,35℃下添加碳酸钙和不添加碳酸钙),通过分析不同温度下碳酸钙添加对土壤活性有机碳、微生物群落组成的影响,揭示外源碳在土壤活性碳库中的分配规律,以期为贵州典型黄壤有机碳固存和改良提供理论依据。结果表明:各温度下添加碳酸钙显著增加土壤DOC和MBC含量(p<0.01),添加碳酸钙各处理土壤DOC含量在培养第5天均达到最大值,相较于不添加碳酸钙处理,添加碳酸钙处理土壤DOC含量在15,25,35℃下分别显著提高83.41%,80.37%,90.41%;添加碳酸钙处理温度对土壤DOC、MBC具有显著影响(p<0.05),在培养的第15,60天,土壤DOC和MBC含量均在不同温度下达到显著性差异,土壤DOC含量大小依次为35,15,25℃,土壤MBC含量多少依次为15,25,35℃。同位素标记发现,在培养第1和第5天,^(13)C-DOC,^(13)C-MBC含量在15,25,35℃下达到峰值,且^(13)C-DOC对土壤总DOC贡献率分别为16.85%,21.20%和15.22%,^(13)C-MBC对土壤总MBC的贡献率分别11.95%,10.49%和17.18%。添加碳酸钙各处理均显著提高土壤pH。高通量测序发现,在培养第60天,外源碳酸钙输入对细菌群落组成相对丰度及群落结构具有显著影响,但对真菌群落组成影响较小。添加碳酸钙处理提高变形菌门相对丰度,降低绿弯菌门相对丰度。相关分析表明,土壤pH与优势菌门变形菌门(Proteobacteria)、担子菌门(Basidiomycota)呈显著正相关,与绿弯菌门(Chloroflexi)、子囊菌门(Ascomycota)呈显著负相关;绿弯菌门与土壤DOC呈显著负相关,放线菌门与土壤MBC、^(13)C-DOC及担子菌门与DOC、^(13)C-MBC、^(13)C-DOC呈显著正相关。综上表明,外源碳酸钙对土壤活性有机碳的影响大于温度,外源碳酸钙增加土壤pH、DOC和MBC含量,改变土壤微生物群落组成丰度。因此,碳酸钙添加是黄壤有机碳固存和改良的有效措施。