不同改性蒙脱土对聚丙烯/蒙脱土纳米复合材料性能的影响

采用四种不同的改性剂对蒙脱土进行处理,在三单体固相接枝聚丙烯作用下,将聚丙烯与四种改性蒙脱土进行复合,制备聚丙烯/蒙脱土纳米复合材料,研究了四种复合材料的结构与力学性能.结果表明,经十六烷基三甲基氯化胺或自制的长碳链带有反应基团的不饱和季胺盐改性的蒙脱土与聚丙烯复合可制备性能优良的纳米复合材料,从力学性能来说,十六烷基三甲基氯化铵改性蒙脱土的效果最好.     

多壁碳纳米管-有机蒙脱土协同增韧环氧树脂

采用机械搅拌和离心分散的方法制备了多壁碳纳米管-有机蒙脱土/环氧树脂复合材料。X射线衍射分析表明,当有机蒙脱土含量为2 wt%时, 蒙脱土在树脂体系中能够形成离散性结构。断裂韧性测试结果表明,多壁碳纳米管和有机蒙脱土的混杂对环氧树脂具有协同增韧的作用。当有机蒙脱土含量为2 wt%,多壁碳纳米管含量为0.1 wt%时,所得复合材料的断裂韧性是纯环氧树脂的1.77倍,是2 wt%有机蒙脱土/环氧树脂复合材料的1.45倍,是0.1 wt%多壁碳纳米管/环氧树脂复合材料的1.39倍。扫描电镜分析表明,多壁碳纳米管在环氧树脂体系中分散均匀,并与有机蒙脱土片层形成了一定程度的相互穿插和咬合,多壁碳纳米管与有机蒙脱土协同增韧的主要原因是微裂纹增韧、剪切屈服与纤维拔出。      

低密度聚乙烯/蒙脱土复合材料的制备及隔声性能

以有机改性蒙脱土(OMMT)作为纳米隔声填料,分别通过熔融共混法和溶液共混法制备了LDPE/OMMT复合材料,研究了蒙脱土含量和制备方法对复合材料的隔声性能的影响。采用多级拉伸共挤出装置改善蒙脱土在基体中的分散,研究不同力场大小作用下蒙脱土分散形态及复合材料的隔声性能。结果表明,少量蒙脱土的加入可以大幅度改善LDPE的隔声性能,但是随着蒙脱土含量的增加,蒙脱土团聚严重,复合材料的隔声性能变差,与熔融共混相比,由于溶液共混法更能使蒙脱土在基体中分散,制备的复合材料的隔声性能更好。随着分割叠加单元个数的增加,蒙脱土在LDPE基体中分散改善,当分割-变形-叠加单元(LME)个数达到8个时,蒙脱土纳米级分散在基体中,复合材料的隔声性能最佳。     

咪唑基离子液体修饰蒙脱土/聚丙烯复合材料的耐热老化性能

研究了1-十八烷基-3-甲基氯化咪唑修饰的蒙脱土/聚丙烯复合材料耐热老化性能。结果表明,热老化前改性蒙脱土/聚丙烯复合材料的拉伸性能、弯曲性能与聚丙烯相比均有所改善,分别提高了7.3%和17.5%,冲击性能提高达54%。经以5d为一老化周期的热老化,研究了4个老化周期中改性蒙脱土/聚丙烯复合材料的力学性能保持率,质量变化率,以及颜色变化的情况。研究发现,在热老化过程中,复合材料的力学性能有很高的保持率,部分性能甚至得到改善,复合材料的质量变化很小,颜色无明显加深,说明该离子液体修饰的蒙脱土/聚丙烯纳米复合材料不仅有很好的力学性能,而且耐热老化性能优越。     

白炭黑/木质纤维素/蒙脱土/丁苯橡胶复合材料的制备及性能研究

对木质纤维素进行联合改性处理,制备了木质纤维素/蒙脱土补强剂,并部分替代白炭黑,制备了丁苯橡胶复合材料。研究了白炭黑、木质纤维素/蒙脱土补强剂配合比对丁苯橡胶复合材料性能的影响。结果表明:在白炭黑与木质纤维素/蒙脱土补强剂用量配合比为30∶10条件下,丁苯橡胶复合材料的力学性能最优,拉伸强度20.65MPa,断裂伸长率727.40%,邵氏A硬度74.00,撕裂强度35.60kN/m。木质纤维素/蒙脱土补强剂的加入,可以改善丁苯橡胶复合材料的力学性能和热氧老化性能。     

悬浮聚合法制备纳米蒙脱土/聚合物( 苯乙烯-共聚-二乙烯基苯) 复合材料及性能

采用悬浮聚合法制备了纳米蒙脱土/聚合物(苯乙烯-共聚-二乙烯基苯) 复合材料。钠基蒙脱土(SMMT) 经十六烷基三甲基溴化铵(CTAB) 离子交换后获得有机蒙脱土(OMMT) 。采用XRD 和FTIR 分析表征了有机蒙脱土的结构与性能。通过XRD、TEM、SEM、和FTIR 对复合材料微观结构进行了表征; 通过热重分析仪( TG) 对复合材料的热稳定性能进行了研究。讨论了蒙脱土含量和交联剂用量对复合材料热稳定性能的影响。结果表明, 钠基蒙脱土的层间距为1. 48 nm , 经有机改性蒙脱土的层间距为2. 85 nm , 纳米蒙脱土/聚合物复合材料的层间距约为4 nm; 纯聚苯乙烯最大质量损失温度为399 ℃, 当蒙脱土含量为5 %、交联剂用量为10 %时, 纳米蒙脱土/聚合物最大质量损失温度提高到437 ℃。在实验条件下, 纳米蒙脱土/聚合物复合材料具有更好的热稳定性能。      

聚乙烯醇/葡萄糖酸蒙脱土纳米复合材料的制备及表征

为了改善聚乙烯醇的力学强度、耐水性及耐热性,采用纳米葡萄糖酸蒙脱土对聚乙烯醇进行了物理复合改性,制备了聚乙烯醇/葡萄糖酸蒙脱土纳米复合材料.在机械搅拌与超声波震荡协同作用下,把纳米葡萄糖酸蒙脱土均匀预分散在甘油中,然后加入到聚乙烯醇乳液中,得到了聚乙烯醇/葡萄糖酸蒙脱土纳米复合薄膜.实验结果表明,当甘油用量为聚乙烯醇的...     

LLDPE/HDPE/MMT纳米复合材料的制备及性能研究

以线性低密度聚乙烯(LLDPE)、高密度聚乙烯(HDPE)、有机改性的蒙脱土(MMT)为主要原料,选用乙烯-醋酸乙烯酯接枝马来酸酐(EVA-g-MAH)作为增容剂,采用熔融插层法制备了线性低密度聚乙烯/高密度聚乙烯/蒙脱土(LLDPE/HDPE/MMT)纳米复合材料。通过X射线衍射(XRD)分析蒙脱土在聚乙烯基体中的分散情况,并研究蒙脱土的含量对其在基体中分散效果的影响。TG实验结果表明,蒙脱土的加入使LLDPE/HDPE/MMT纳米复合材料的热稳定性得到很大的提高。由DSC曲线可以得出,加入蒙脱土的复合材料相比于纯聚合物,其熔点和热分解温度都有很大的提高,提高程度与蒙脱土的含量有关。     

聚丙烯/蒙脱土纳米复合包装材料的制备与力学性能研究

采用熔融插层法在双螺杆挤出机中制备了聚丙烯(PP)/蒙脱土(MMT)纳米复合材料,纳米复合材料机械性能测试结果表明,当有机蒙脱土(MMT)质量比为2%时,复合材料的综合力学性能明显优于聚丙烯(PP).扫描电镜观测不到纳米复合材料中明显的有机-无机相畴,表明蒙脱土(MMT)片层分散均匀,分散尺度已基本达到纳米级.     

蒙脱土对聚丙烯酸基纳米复合材料性能的影响

对聚丙烯酣蒙脱土纳米复合材料的制备方法及其吸水、何水性能进行了研究。利用高温快速反应法成功制备了聚丙烯酣蒙脱土高吸水性纳米复合材料，考察了蒙脱土质量分数对复合材料吸水倍率的影响规律，当蒙脱土用量为5％时，可获得较好的结果，所得纳米复合材料吸水倍率为511ml／g对纳米复合材料的保水性能研究的结果表明，聚丙烯酸，蒙脱土高吸水性纳米复合材料在高温条件下具有优异的保水性能。     

层状PPGr/PP复合材料的结构和电磁屏蔽性能

利用共挤出设备,制备了导电层(石墨填充聚丙烯PPGr)和绝缘层(聚丙烯PP)叠合的层状复合物,同时制备了PPGr普通共混物。比较了层状材料与普通共混材料在结构形态、电学性能、力学性能和电磁屏蔽性能方面的差异。研究发现,普通共混物电阻率为2.04×103Ω.cm时,在低频区(500 MHz~2 GHz)和中间频段区(2 GHz~18 GHz)内的最大屏蔽值都为34dB,而层状材料电阻率为2.79×105Ω.cm时,在上述频率区间的屏蔽效果分别达到49dB和56dB。力学性能测试表明层状材料的断裂伸长率和拉伸强度也优于普通共混材料。文中提出了层状复合物中电磁波的内部多重反射机理来解释这一实验现象。     

PP/POE/高岭土三元复合材料的力学及热性能

研究了高岭土和乙烯-辛烯共聚物弹性体(POE)填充聚丙烯(PP)制备的PP/POE/高岭土三元复合材料的力学和热力学性能。结果表明,POE和高岭土不能提高PP的拉伸强度,但高岭土可以显著提高PP/POE的杨氏模量。POE降低了PP的弯曲强度和弯曲模量,但PP/POE/高岭土三元复合材料的弯曲强度和弯曲模量显著高于PP/POE和PP。POE和高岭土可以显著提高PP的冲击强度,当高岭土和POE的填充份数分别为10份和5份时,PP/POE/高岭土复合材料的冲击强度最大。高岭土的添加可以提高PP的结晶温度,加快PP的结晶速率,促进PP的异相成核。合适含量的高岭土可以提高PP的熔融温度,改善PP的耐热性能。     

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.     

Role of micro/nano fillers on mechanical and tribological properties of polyamide66/polypropylene composites

The objectives of this research article is to evaluate the mechanical and tribological properties of polyamide66/polypropylene (PA66/PP) blend, graphite (Gr) filled PA66/PP, nanoclay (NC) filled PA66/PP and NC plus short carbon fiber (NC + SCF) filled PA66/PP composites. All composites were fabricated using a twin screw extruder followed by injection molding. The mechanical properties such as tensile, flexure, and impact strengths were investigated in accordance with ASTM standards. The friction and sliding wear behaviour was studied under dry sliding conditions against hard steel on a pin-on-disc apparatus. Scanning electron micrographs were used to analyze the fracture morphologies. From the experimental investigation, it was found that the presence of NC and SCF fillers improved the hardness of PA66/PP blend. Further, the study reveals that the tensile and flexural strength of NC + SCF filled PA66/PP was higher than that of PA66/PP blend. Inclusion of micro and nanofillers reduced the wear rate of PA66/PP blend. The wear loss of the composites increased with increasing sliding velocity. The lowest wear rate was observed for the blend with nanoclay and SCF fillers. The wear rates of the blends with micro/nanofillers vary from 30–81% and lower than that of PA66/PP blend. The wear resistance of the PA66/PP composites was found to be related to the stability of the transfer film on the counterface. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.     

Electromagnetic absorption efficiency of polypropylene/montmorillonite/polypyrrole nanocomposites

Electrical conductivity and dielectric properties have been studied for two types of polypropylene composites containing conducting phase. One type comprised conducting polymer–polypyrrole while the second employed montmorillonite particles coated with conducting polymer–polypyrrole. Composites’ shielding properties were estimated based on their previously determined electromagnetic characteristics. Unlike a basic binary polypropylene/polypyrrole composite, the ternary sample with multicomponent montmorillonite particles exhibits higher dielectric losses and consequently a significant rise in shielding efficiency in the radio-frequency range of 0.1–1.5 GHz. This stems from the presence of highly polarizable multicomponent montmorillonite anisotropic lamellar particles with polypyrrole conducting layer, which considerably increases the complex permittivity of the composite.     

Influence of fiber-like nanofillers on the rheological,mechanical, thermal and fire properties of polypropylene: An application to multifilament yarn

Polypropylene and polypropylene grafted maleic anhydride based composites with modified and non-modified carbon nanotubes and sepiolite were prepared by melt extrusion. Their thermal, rheological, and dynamic mechanical properties were evaluated. Multifilament yarns were obtained from the composites by spin-drawing process and their mechanical properties were measured. Knitted fabrics from the multifilament yarns were characterized by cone calorimetry. The best interaction was obtained for polypropylene/carbon nanotubes and polypropylene/polypropylene grafted maleic anhydride/sepiolite composites, as was confirmed by the increasing on the elastic modulus and thermal resistance. Nanofillers changed the thermal decomposition profiles compared to bare polypropylene. Knitted structures containing sepiolite decrease the maximum of heat release rate in comparison with unfilled samples.     

Biocomposites from Musa textilis and polypropylene: Evaluation of flexural properties and impact strength

Abaca (Musa textilis)-reinforced polypropylene composites have been prepared and their flexural mechanical properties studied. Due to their characteristic properties, M. textilis has a great economic importance and its fibers are used for specialty papers. Due to its high price and despite possessing very distinctive mechanical properties, to date abaca fibers had not been tested in fiber-reinforced composites. Analysis of materials prepared showed that, in spite of reduced interface adhesion, flexural properties of the PP composites increased linearly with fiber content up to 50 wt.%. Addition of a maleated polypropylene coupling agent still enhanced the stress transfer from the matrix to the reinforcement fiber. As a result, composites with improved flexural properties were obtained. The mechanical properties of matrix and reinforcing fiber were evaluated and used for modelling both the flexural strength and modulus of its composites. In addition, the impact strength of materials was evaluated. Comparison with mechanical properties of composites reinforced with fiberglass points out the potentiality of abaca-reinforced polypropylene composites as suitable substitutes in applications with low impact strength demands.     

Effect of material and process parameters on the mechanical properties of unidirectional and multidirectional flax/polypropylene composites

Unidirectional (UD) and multidirectional (MD) flax/polypropylene composites were studied. Flax with varying retting degree and boiled flax was used as reinforcement for the UD composites and unmodified and maleic acid anhydride modified polypropylene (MAA-PP) was used as matrix. Multidirectional flax/polypropylene composites were manufactured on laboratory scale and on pilot scale. They were made from needle-punched hybrid flax/PP non-wovens. Normally retted flax as well as boiled flax was used. For the specimens made on pilot scale, a third kind of flax, namely bleached flax was also studied. The influence of different process times and temperatures on the mechanical properties of the composites was analysed. Generally, the composites have adequate good mechanical properties. The unidirectional composites of boiled flax combined with MAA-PP show the best mechanical properties. Contrary to the UD composites, flax treatment did not lead to the expected property improvements for MD composites.