CaCO3/PEEK复合体系的力学行为和热行为研究

以聚醚醚酮和碳酸钙复合体系为研究对象,考察了偶联剂和填料添加量对复合材料力学行为和热行为的影响.发现磺化聚醚醚酮作为偶联剂能有效地改善材料的力学性能,提高基体树脂的玻璃化转变温度,降低基体树脂的熔点,有助于改善聚醚醚酮的加工条件     

ENR-25改性CaCO3填充LDPE的复合材料的研究

用环氧程度为25％的环氧化天然橡胶（ENR－25）改性轻质CaCO3。研究了改性方法，改性剂用量，CaCO3填充量对低密度聚乙烯（LDPE）材料与性能的影响。结果表明，7．5％的ENR－25湿法改性有效地改善了CaCO2在LDPE中的分散性及相容性，增强了界面作用强度，使材料在拉伸强度保持较高的情况下，拉伸弹性模量，撕裂强度和断裂伸长率得到有效的提高。     

原位固相接枝改性碳酸钙/聚丙烯复合材料的制备

用马来酸酐（MAH）在碳酸钙（CaCO3）表面引入双键,通过原位固相接枝法将聚丙烯蜡（PPW）化学键合在CaCO3表面,制得3种接枝率的CaCO3-MAH-PPW。 将这3种改性CaCO3填充聚丙烯（PP）制备复合材料,研究了PP/CaCO3界面作用对复合材料强度的影响。 结果表明,CaCO3表面经PPW接枝改性后在PP中的分散性提高,与PP相容性变好;随着改性CaCO3表面PPW接枝率的提高,CaCO3与PP之间界面作用逐渐增强。 当PPW接枝率为4.48 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用最强,复合材料拉伸强度下降最小,杨氏模量提升最大,当m(PP)∶m(CaCO3)=100∶50时,杨氏模量达0.86 GPa,是纯PP的1.63倍;而PPW化学接枝率为2.49 mg PPW/g CaCO3时,CaCO3与PP之间的界面作用适中,复合材料缺口冲击强度提升最大,且当m(PP)∶m(CaCO3)=100∶10时,缺口冲击强度达3.91 kJ/m2,是纯PP的1.35倍。     

ELECTRICAL RESISTIVITY,CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE/MULTI-WALLED CARBON NANOTUBE/CALCIUM CARBONATE COMPOSITES PREPARED BY MELT MIXING

Polypropylene(PP)/multi-walled carbon nanotube(MWCNT)/calcium carbonate(CaCO_3)composites are prepared by melt mixing using two types of CaCO_3 of different sizes.The electrical resistivities of the composites with the two types of CaCO_3 are all lower than those of the corresponding PP/MWCNT composites at various MWCNT loadings (1 wt%-5 wt%).The morphology of the composites is investigated by field emission scanning electron microscopy (FESEM).The crystallization behavior of PP in the composites is char...     

Preparation and properties of wheat gluten/rice protein composites plasticized with glycerol

Environment friendly thermosetting composites were prepared by blending wheat gluten(WG) and rice protein (RP) at different weight ratios with glycerol as plasticizer followed by compression molding the mixture at 120℃to crosslink the proteins.Reducing agent of sodium bisulfate and sodium sulfite and crosslinking agent formaldehyde were used to adjust the properties of the composites.Morphology,moisture absorption and tensile properties were evaluated.The results showed that formaldehyde could increase t...     

EFFECT OF PROCESSING METHOD ON THE IMPACT STRENGTH OF POM/TPU/CaCO3 TERNARY COMPOSITES

Polyoxymethylene （POM）/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane （TPU） and inorganic filler, namely, CaCO3, were used to achieve balanced mechanical properties of POM. The dispersion and phase morphology of POM/elastomer/filler composites were found to depend largely on processing method, CaCO3 content in masterbatch and the filler size. Two processing methods were employed to prepare POM/elastomer/filler ternary composites. One is called the one-step method, in which elastomer and the filler directly melt blended with POM matrix. The other is called the two-step method, in which the elastomer and the filler were mixed to get masterbatch first, which was then melt blended with pure POM of different content. The effect of phase morphology and processing method on impact strength was investigated. It was found that the two-step method results in an increase in impact strength but not for the one-step method. Additionally, the impact strength of POM ternary composites decreases with the increase in the size of CaCO3 particles.     

Crystallization, mechanical and thermal properties of sorbitol derivatives nucleated polypropylene/calcium carbonate composites

<正>The effect ofαphase nucleating agent(NA) 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol(DMDBS) on crystallization and physical properties of polypropylene/calcium carbonate(PP/CaCO_3) composites has been comparatively investigated.Compared with binary PP/CaCO_3 composites,in which CaCO_3 exhibits weak heterogeneous nucleation, inconspicuous reinforcement and toughening effects for PP,the introduction of a few amounts of DMDBS induces a great increase of the degree of crystallinity.Largely improved tensile properties,fracture toughness at relatively higher temperature and heat deformation temperature(HDT) are observed for DMDBS nucleated PP/CaCO_3 composites.     

超细CaCO_3的粒子尺寸对PP结晶行为的影响

The effects of CaCO3 on the crystallization behavior of polypropylene (PP) were studied by means of DSC and WAXD.The average sizes of the CaCO3 powders used were 0.1μm (UC) and 0.5μm (GC),respectively.The PP/CaCO3 composites at compositions of 1phr and 10 phr were investigated.The results showed that the addition of CaCO3 reduced the supercooling,the rate of nucleation and the overall rate of crystallization (except for the 10phr UC/PP sample).The crystallinity of PP was increased and the size distribution of the crystallites of α-PP was broadened.On the other hand,the crystallization rate of 10phr UC/PP is 1.5 times higher than that of neat PP.It has an overall rate of crystallization 2 times as much as that of the neat PP and has the maximum crystallinity.The sizes of crystallites and the unit cell parameters of α-PP were varied by the addition of CaCO3.β-PP was formed by addition of GC and was not detected by addition of UC.The differences of crystallization behaviors of PP might be attributed to the combined effects of the content and size of CaCO3 filled.     

Effects of calcium carbonate polymorph on the structure and properties of soy protein-based nanocomposites

Novel protein-based nanocomposites were well prepared by in vivo synthesis and co-precipitation of soy protein isolate (SPI) with calcium carbonate (CaCO3) in an aqueous solution. The resultant CaCO3 in the nanocomposites was identified as calcite- and aragonite-type, respectively. The morphology and structure of the CaCO3/SPI composites were investigated by means of wide-angle X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, and high-resolution transmission electron microscopy. The results revealed that the polymorph and the size of CaCO3 in the nanocomposites were dependent on its content, pH, and the conformation of soy protein. At the content of more than 5%, CaCO3 was changed into calcite crystal with the preference of growing along (104) plane. However, at lower content of less than 5%, CaCO3 preferred to form aragonite in the composite as a result of the modulation by soy protein. The aragonite nanocrystals were arrayed in the direction of (111) plane and self-assembled along beta-sheet planes of soy protein polypeptides. The mechanical properties, thermal stability, and water resistance of the CaCO3/SPI nanocomposites were significantly improved as a result of the nanosized effects. Interestingly, the aragonite/SPI nanocomposite exhibited higher tensile strength (about 50 MPa) than that of calcite/SPI, owing to a good compatibility and strong interaction between aragonite and soy protein polypeptides. This work provided a simple pathway to develop the soy protein-based bio-hybrid materials with high mechanical strength and valuable information on their structure-properties relationship.     

聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料的制备和表征

以聚乙二醇磷酸酯1000为表面处理剂, 采用碳化法合成了方解石型碳酸钙纳米粒子, 进一步制备了聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料. 采用透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR), 场发射扫描电子显微镜(FESEM)和热重分析(TGA)对样品进行了分析. 结果表明, 聚乙二醇磷酸酯1000成功地修饰到碳酸钙的表面, 并得到平均直径为60 nm, 形貌为立方体的纳米碳酸钙晶体. 与碳酸钙(空白)样品相比, 表面处理碳酸钙的复合材料表现出更好的分散性和热稳定性. 采用Friedman方法计算了复合材料热分解的活化能. 聚对苯二甲酸乙二醇酯、 聚对苯二甲酸乙二醇酯/空白碳酸钙和聚对苯二甲酸乙二醇酯/表面处理碳酸钙的活化能分别为200.58, 214.86和219.50 kJ/mol, 进一步说明了表面处理碳酸钙更好地改善了聚对苯二甲酸乙二醇酯的热稳定性.     

聚乳酸/矿物填料复合材料的示差扫描量热研究

通过熔融共混法制备了一系列聚乳酸(PLA)/矿物填料复合材料.采用示差扫描量热(DSC)研究了含有碳酸钙(CaCO3)、蒙脱土(MMT)和凹凸棒土(AT)的聚乳酸复合材料在不同热历程中的结晶和熔融行为.研究发现,MMT和AT对PLA的慢速降温结晶无明显影响,而碳酸钙在慢速降温过程中能够有效促进PLA结晶;在2.5 K/min的降温速率下,结晶热焓随碳酸钙含量增加而增加;填料种类和含量会对复合材料升温过程的冷结晶和熔融产生较大影响,低含量矿物填料主要对PLA的冷结晶起成核作用,其中MMT成核效果最好.较高含量下不同填料会对PLA晶体形态产生影响,从而得到多样的DSC曲线变化.     

共沉淀法合成复合碳酸钙及其形貌和晶型的研究

以硬脂酸钠盐皂化液为介质，共沉淀法合成碳酸钙/硬脂酸钙复合物。SEM， XRD等测试手段表明：不同反应温度及有机物尝试条件下得到的复合物具有多变的 外观外形貌；其中碳酸钙以方妥石和球霰石的混晶形式存在，两者经例呈一定变化 规律，并对其进行了合理的解释，认为有机物的浓度和温度不同，使其在溶液中形 成的胶束结构及其亲水基团有不同排列，并以不同匹配方式影响碳酸钙结晶行为， 从而影响复合碳酸钙的形貌和晶型。     

填充增韧聚丙烯复合材料的断裂韧性及增韧机理

用表面处理的ＣａＣＯ３填充聚丙烯（均聚物ＰＰ），ＰＰ／ＣａＣＯ３复合材料的杨氏模量和缺口冲击强度同时得到增加，克服了通常填料填充聚合物降低韧性的缺点．用Ｊ积分研究其断裂韧性给出：裂纹扩展阻力ｄＪ／ｄ（△ａ）低是聚丙烯缺口脆性的主要原因，随着填料体积分数Ｖｆ的增加ＰＰ／ＣａＣＯ３的Ｊｃ出现一极大值，但其裂纹扩展阻力却不断增大；用裂纹引发点后的Ｊｃ＝Ｊｃ＋［ｄＪ／ｄ（△ａ）］·△ａ＝Ｊｅ（Ｊ积分弹性分量）＋Ｊｐ（Ｊ积分塑性分量）可全面表征韧性聚合物材料的断裂韧性；ＰＰ／ＣａＣＯ３的Ｊｐ明显增加，是裂纹扩展阻力和Ｊｔ增加的原因．ＳＥＭ分析结出，ＣａＣＯ３填料在裂尖损伤区内引起强烈的空洞化损伤，并增强了裂尖钝化破坏过程，这些细观损伤机制的变化，导致能量耗散增加，可用滞后分量Ｊｈ定量表征．由此给出聚合物材料被增韧的Ｊ积分判据为：复合材料的Ｊｈ＞基体的Ｊｈｍ．     

纳米级CaCO_3粒子与弹性体CPE微粒同时增韧PVC的研究

研究了平均粒径为 30nm的超细级纳米CaCO3 与氯化聚乙烯 (CPE)对聚氯乙烯 (PVC)共混体系二元协同增韧效应及机制 .结果表明 ,当共混体系中有一定量的CPE时 ,纳米CaCO3 的加入可以明显地提高共混物的韧性 ,而不降低共混物的强度和刚性 .纳米CaCO3 在PVC基体中达到了纳米级的分散 .当纳米CaCO3 的用量为 8份 (质量 )时 ,PVC CPE 纳米CaCO3 共混物的冲击断面产生了大量的有规则的网丝状结构 ,共混物的缺口冲击强度达到 81 1kJ m2 ,比不加纳米CaCO3 的共混体系高 7 3倍 .CPE的加入对共混体系的加工流动性能无影响 ,纳米CaCO3 的加入使共混体系的加工流动性能变差     

牛血清白蛋白对碳酸钙结晶的作用

The crystal CaCO₃ with specific shapes was prepared by the biomimetic synthesis , using BSA as the matrix. The products were characterized by scanning electron microscopy (SEM), FTIR spectroscopy and TG. The results show that BSA have the effect on the shapes of CaCO₃ in the crystallization process. The probable mechanism of the effect was discussed。     

Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique

Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite.     

Preparation of core-shell CaCO3 capsules via Pickering emulsion templates

Micron size and food grade pristine CaCO(3) particles were used to stabilize an oil in water Pickering emulsion. The particles also acted as nucleation sites for the subsequent crystallization of CaCO(3) with the addition of CaCl(2) and CO(2) gas as precursors. After the controllable crystallization process, a dense CaCO(3) shell with a few microns in thickness was formed. The CaCO(3) shell was proven to be calcite without the presence of crystallization modifiers. The crystallization speed and the shell integrity were controlled by manipulating the addition of CaCl(2) amount during the different crystallization stages; therefore, the homogeneous nucleation in the bulk was almost inhibited, and the heterogeneous nucleation at the oil-water interface on pristine CaCO(3) particles was the main contribution to the growth of the shell. The encapsulated limonene flavor in CaCO(3) capsules showed a prolonged release in neutral water at 85°C, while a burst release at pH 2 water as expected. The method is a simple and scalable process for creating inorganic core-shell capsules and can be used for producing food grade capsules for controlling the flavor release or masking undesirable taste in mouth.     

Biomimetic approach to forming chitin/aragonite composites

Biomimetic materials which display the complexity of biominerals like nacre are synthetically difficult to prepare. The formation of chitin/calcium carbonate composites, where CaCO(3) is present as aragonite, was achieved via reacetylation of preformed chitosan scaffolds followed by the combination of presoaking of chitin templates with mineral solutions in the presence of poly(acrylic acid). The as-synthesised composites are comprised of well-ordered ribbons of aragonite crystals held within an organic matrix, mimicking the structure of nacre.     

Buffering dissociation/formation reaction of biogenic calcium carbonate

The oscillating stability of coral reef seawater pH has been maintained at around physiological pH values over the past 300 years (Pelejero et al., 2005). The stability mechanism of its pH has been interpreted in terms of the buffering dissolution/formation reaction of CaCO(3) as well as the proton consumption/generation reaction in CaCO(3)-saturated water. Here the pH-dependent solubility product [HCO(3)(-)][Ca(2+)] has been derived on the basis of the actual pH-dependent reactions for the atmospheric CO(2)/CO(2 (aq.))/HCO(3)(-)/CO(3)(2-)/Ca(2+)/CaCO(3) system. Overbasic pH peaks appeared between pH approximately 8 and approximately 9.5 during sodium hydroxide titration, as a result of simultaneous CaCO(3) formation and proton generation. The spontaneous and prompt water pH recovery from the acidic to the physiological range has been confirmed by the observation of acid/base time evolution, because of simultaneous CaCO(3) dissolution and proton consumption. The dissolution/formation of CaCO(3) in water at pH 7.5-9 does not take place without a proton consumption/generation reaction, or a buffering chemical reaction of HCO(3)(-)+Ca(2+)right arrow over left arrowCaCO(3)+H(+). SEM images of the CaCO(3) fragments showed that the acid water ate away at the CaCO(3) formed at physiological pH values. Natural coral reefs can thus recover the physiological pH levels of seawater from the acidic range through partial dissolution of their own skeletons.     

Influence of Glycerol Content on Properties of Wheat Gluten/Hydroxyethyl Cellulose Biocomposites

Environmentally friendly biocomposites were prepared by blending wheat gluten（WG）as a matrix, hydroxyethyl cellulose（HEC）as a filler,and glycerol as a plasticizer,followed by thermo-molding of the mixture at 120°C for crosslinking the matrix.Moisture absorption,tensile properties,dynamic mechanical analysis,and dynamic rheology were evaluated in relation to the glycerol content.Tensile strength and modulus drop dramatically with increasing glycerol content,which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.