微纳米SiO2/PP复合材料增强增韧的实验研究

为了研究无机刚性颗粒对通用塑料聚丙烯(PP)的力学性能的影响,采用熔融共混方法制备了经硅烷偶联剂A-151处理的SiO2/PP复合材料,并通过其缺口冲击、拉伸、弯曲试验和冲击断面的形貌观察,分析研究了微纳米SiO2颗粒大小、填充量、表面改性以及不同颗粒大小SiO2混合物对PP复合材料增韧、增强效果的影响.实验结果表明:纳米SiO2的加入可以同时改善其韧性、刚性和强度;填充量相同,颗粒越细,SiO2/PP复合材料的力学性能越好.SiO2经改性后填充到PP基体中,明显改善了颗粒在基体中的分散性及基体与颗粒之间界面结合性能,使复合材料的综合力学性能得到提高.不同颗粒大小的SiO2混合后填充到PP基体中,混合SiO2的协同效应使复合材料拉伸、弯曲性能进一步提高,对PP基体具有更好的增强效果,但其冲击性能下降.     

纳米Sb2O3增强聚丙烯基复合材料力学性能

通过球磨分散法和熔融共混法制得纳米Sb₂O₃/溴化环氧树脂-聚丙烯（BEO-PP）阻燃复合材料试样。采用XRD、DSC、拉伸和冲击性能测试,研究了纳米Sb₂O₃/BEO-PP阻燃复合材料的力学性能及其增强机制。研究结果表明：采用球磨法改性后的纳米Sb₂O₃颗粒在PP基体中的分散性和黏结性能得到明显改善;纳米Sb₂O₃颗粒的加入可改善PP基复合材料的强韧性;随着纳米Sb₂O₃质量分数的升高,纳米Sb₂O₃/BEO-PP复合材料的力学性能呈现出先升后降的趋势,PP基体的结晶度逐渐增高;当纳米Sb₂O₃颗粒添加量为2wt%时,纳米Sb₂O₃/BEO-PP复合材料表现出优异的综合性能。     

纳米SiO2/聚苯硫醚和SiO2-玻璃纤维/聚苯硫醚复合材料的性能

利用纳米SiO₂改性聚苯硫醚（PPS）树脂及玻璃纤维（GF）/PPS复合材料,探究纳米SiO₂对PPS树脂及GF/PPS复合材料性能的影响规律。采用熔融共混工艺制备纳米SiO₂/PPS树脂,并采用热压成型方法制备纳米SiO₂-GF/PPS复合材料,利用SEM、DSC、DMA和力学测试表征不同纳米SiO₂含量的SiO₂/PPS和SiO₂-GF/PPS复合材料。结果表明：纳米SiO₂通过熔融共混工艺能够均匀分散在PPS基体中,并提高PPS结晶度和弯曲性能。添加1wt%纳米SiO₂有效提高了GF/PPS复合材料的力学性能：层间剪切强度提高49.4%,弯曲强度提高30.6%,弯曲模量提高14.6%。纳米SiO₂的添加可以提高GF/PPS复合材料的玻璃化转变温度,同时纳米SiO₂能够改善树脂基体韧性并阻碍裂纹的扩展。     

纳米SiO2改性竹纤维/乙烯基树脂复合材料界面相容性

以乙烯基树脂(VE)为基体,竹纤维(BF)为增强材料,通过偶联剂KH602对纳米SiO₂进行改性处理,并利用改性后纳米SiO₂分别对竹纤维和树脂进行改性处理,采用真空辅助树脂传递模塑成型工艺(VARTM)制备了BF/VE复合材料。采用FTIR、SEM对改性后纤维和树脂的表面物理化学状态进行表征,结果表明:改性纳米SiO₂成功化学接枝到竹纤维表面且分散到树脂基体中,改性纳米SiO₂在BF1/VE0.5 (用1.0wt%改性纳米SiO₂改性纤维和0.5wt%改性纳米SiO₂改性树脂)复合材料中分散更为均匀;采用力学试验机和SEM对复合材料力学、断口和表面形貌进行分析,考察改性纳米SiO₂的添加量对BF/VE复合材料力学性能、界面性能的影响。结果表明:BF1/VE0.5复合材料的拉伸、弯曲及冲击强度分别达到最大值49.0 MPa、70.6 MPa和150.4 J/m,与未处理的复合材料相比分别提高了18.9%、26.1%、70.7%。此外,还初步探讨了改性纳米SiO₂的界面增强机制。      

纳米SiO2/低密度聚乙烯复合材料的陷阱特性与电击穿机制

以低密度聚乙烯（LDPE）为聚合物基体,通过熔融共混的方式填充不同粒径的纳米SiO₂无机颗粒,制备纳米SiO₂/LDPE复合材料,研究提高聚乙烯电绝缘性能的纳米改性方法和机制。利用SEM表征纳米SiO₂在LDPE基体中的微观形态和分散程度,采用DSC和偏光显微镜（PLM）分析纳米SiO₂对LDPE基体结晶度和结晶形态的影响,通过热刺激电流法（TSC）分析纳米SiO₂/LDPE复合材料的陷阱密度和陷阱能级,并结合电击穿的Weibull分布研究纳米复合材料的击穿机制。研究结果表明:纳米SiO₂填充可以改变复合材料结晶度,进而增加LDPE基体本征结构缺陷和陷阱密度,同时填充纳米SiO₂颗粒可引入比LDPE基体本征陷阱更深的陷阱能级,纳米SiO₂填充颗粒引入的陷阱能级深度随着复合材料结晶度的增加而先增大后减小,填充浓度3wt%时可最有效地通过俘获载流子而抑制电击穿过程,纳米SiO₂/LDPE复合材料的击穿场强达到最高值。与60 nm SiO₂颗粒相比,30 nm SiO₂填充颗粒具有更高的比表面积,界面电极化导致更高的介电常数,更高密度的纳米界面深陷阱态对于提高电击穿场强更有效。当填充浓度为5wt%时,纳米颗粒的团聚作用导致纳米复合材料的击穿强度降低。基于电双层理论提出了电子捕捉模型和界面结构模型,合理阐释了纳米SiO₂/LDPE复合材料的微观陷阱特性及宏观电击穿机制。      

深度混炼对纳米SiO2/低密度聚乙烯复合材料分散性与直流电性能影响

利用同向平行双螺杆挤出机对纳米SiO₂/低密度聚乙烯（LDPE）复合材料进行深度混炼,采用SEM、直流击穿强度试验及变温空间电荷试验研究了该工艺对纳米SiO₂/LDPE复合体系中纳米SiO₂颗粒分散性、直流击穿强度和空间电荷特性的影响,综合评估了纳米SiO₂颗粒分散性改善和纳米SiO₂/LDPE复合材料熔融状态下机械剪切降解对电性能的影响。结果表明,随着混炼次数的增加,纳米SiO₂颗粒在LDPE中分散的更加均匀;深度混炼与单次混炼相比,SiO₂/低密度聚乙烯复合材料直流击穿强度上升,室温下达到433.1 kV/mm;随着混炼次数的增加,SiO₂/低密度聚乙烯复合材料低温时抑制空间电荷能力变强,但60℃以上高温时抑制能力变差。混炼次数的增加改善了纳米SiO₂颗粒的分散性,使其与LDPE基体的界面增多,同时,纳米SiO₂颗粒还使SiO₂/低密度聚乙烯复合材料的片晶厚度增大,结晶度升高,界面区和力学性能都随着分散性改善而增加和增强,两者共同促进了SiO₂/低密度聚乙烯复合材料电学性能的改善。但是由于深度混炼引发了材料降解,结构缺陷的增多影响了纳米SiO₂/LDPE复合材料高温区的空间电荷抑制性能。     

纳米SiO2分散性对SiO2/LDPE纳米复合材料直流介电性能的影响

SiO₂/低密度聚乙烯(LDPE)复合材料的介电性能与纳米SiO₂在LDPE基体中的分散性密切相关。为研究室温下拉伸处理对纳米SiO₂颗粒在LDPE基体中分散性的作用机制,本文选取7 nm粒径的疏水型纳米SiO₂与LDPE熔融共混制备SiO₂/LDPE纳米复合材料。将制备好的纳米复合材料经过三次拉伸处理,利用SEM、DSC表征纳米粒子的分散性及复合材料的结晶度,利用热刺激电流法(TSC)测试分析复合材料的陷阱能级和陷阱密度。通过对纳米复合材料的空间电荷,电导电流,直流击穿强度进行实验测试,研究了拉伸对纳米粒子分散性的影响及其所导致的直流介电性能的改变。结果表明室温下拉伸有助于纳米粒子的分散,使纳米SiO₂粒子的团聚尺寸从200 nm左右缩减到100 nm左右;但拉伸会破坏LDPE的结晶结构,劣化其性能;通过掺杂纳米SiO₂引入深陷阱能级可以改善LDPE的直流介电性能。经过拉伸的SiO₂/LDPE的空间电荷积累得到...     

改性纳米SiO2/硅橡胶复合材料的制备及性能

为提高纳米SiO₂在硅橡胶（SR）基体中的分散性及两相间的界面结合力,设计以羟基硅油（HSO）和γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）为纳米SiO₂的表面封端改性剂,并将改性SiO₂与双组份加成型液体SR复合得到改性纳米SiO₂/SR复合材料。通过一系列表征手段对改性纳米SiO₂的形貌结构及其在乙醇中的分散性等进行分析,研究了改性纳米SiO₂对纳米SiO₂/SR复合材料的断面形貌、力学性能及热稳定性的影响。结果表明:KH570成功接枝到纳米SiO₂表面并与SR基体间形成化学键。当HSO协同KH570改性纳米SiO₂时,可有效改善纳米SiO₂在SR基体中的分散性能及纳米SiO₂与SR两相间的界面结合性能,并显著提高纳米SiO₂/SR复合材料的力学性能和热稳定性。将SiO₂∶HSO∶KH570以质量比为2.0∶0.2∶0.6处理的改性纳米SiO₂粒子,得到的改性纳米SiO₂/SR复合材料起始热分解温度提高了230℃。当SiO₂∶HSO∶KH570质量比为2.0∶0.2∶0.45时,改性纳米SiO₂/SR复合材料的拉伸强度和断裂伸长率分别提高了约1倍。      

聚多巴胺改性纳米二氧化硅增强反式-1,4-聚异戊二烯形状记忆聚合物的制备与性能

由于形状记忆聚合物(SMP)较低的力学强度，不足以满足现今大多数商用复合材料的使用标准，严重限制了其在许多高级应用中的使用。因此，为制备高性能SMP复合材料，利用聚多巴胺(PDA)对纳米SiO₂进行表面改性，制备了一种新型纳米填料SiO₂@PDA，并通过SEM、XPS和FTIR对其结构和性能进行了表征。将SiO₂和SiO₂@PDA作为纳米填料填充到反式-1,4-聚异戊二烯(TPI)中，制备了TPI形状记忆复合材料，系统的研究了TPI/SiO₂和TPI/SiO₂@PDA复合材料的热稳定性、力学性能和形状记忆性能。结果表明：PDA修饰增强了SiO₂在TPI基体中的分散性和界面相互作用，从而使TPI/SiO₂@PDA复合材料的热稳定性、力学性能得到提升的同时仍能够保持良好的形状记忆性能。当SiO₂@PDA含量为1.5%(以TPI的质量为基准，下同)时，TPI复合材料的冲击强度和拉伸强度达到最大值，...     

微米和纳米SiO2改性聚四氟乙烯的摩擦磨损性能

使用超细及纳米SiO₂颗粒填充改性聚四氟乙烯塑料。测量其摩擦系数、磨损系数、结晶度,得到了填加量与复合材料摩擦系数、磨损系数和结晶度的关系曲线,并使用扫描电镜(SEM)对其表面形貌进行了分析。结果表明,无论微米或纳米SiO₂、表面处理后的纳米SiO₂,均使PTFE的摩擦系数有所提高,而耐磨损性能也有大幅度的提高。填充量小于6%时,填加未经偶联剂处理的纳米SiO₂的SiO₂/PTFE复合材料的磨损率降低98.5%;填充量大于6%以后,磨损率趋于稳定;填充量为6%时,摩擦系数仅从未加填料时的0.1提高为0.12。而偶联剂表面处理的纳米SiO₂复合材料的摩擦系数提高幅度最小。      

表面改性对聚丙烯/纳米氢氧化镁复合材料性能的影响

研究了表面处理剂(钛酸酯和硅烷偶联剂)对聚丙烯/纳米氢氧化镁(MH)阻燃复合材料性能的影响。通过高压毛细管流变仪、LO I、力学测试、DSC和SEM对PP/纳米MH复合体系的结构与性能进行了研究。结果表明,所选偶联剂能有效地降低复合体系的表观黏度,改善体系的流动性。未改性的纳米MH对PP基体有异相成核作用;而表面改性剂能削弱填料对基体的异相成核作用。改性后的纳米MH粒子以独立形式均匀分散在基体中,PP与纳米MH界面的粘接力得到了加强,复合材料的拉伸性能和冲击强度有较大幅度的提高,阻燃性能也得到了改善。     

包覆混料对镀铜混合尺寸SiCp/Fe力学性能的影响

为探索提高SiCp/Fe力学性能的途径,采用包覆混料工艺,研究了该工艺对镀铜SiCp/Fe力学性能的影响,以及该工艺下增强粒子混合尺寸的影响.结果表明:包覆混料相比于普通混料,可显著改善SiC粒子在基体中分散的均匀性,而镀铜的作用是显著消除界面缺陷;性能的改善是包覆混料改善粒子分散性和镀铜改善界面结合的综合结果.对于体积分数30%SiCp/Fe的抗拉强度,通过包覆改善均匀性的贡献可提高7.2%,通过镀铜消除界面缺陷的贡献可提高12.5%,因此减少界面缺陷对颗粒增强复合材料力学性能的提高更重要.混合尺寸粒子对力学性能的增强效果明显高于其对应单一尺寸,这是由于小尺寸粒子能有效地提高基体的强度,而大尺寸颗粒更有效地承担载荷传递的作用.     

Anomalous behavior of thermal conductivity and diffusivity in polymeric materials filled with metallic particles

Thermal properties of two composites prepared by using a polypropylene matrix filled with aluminum (slightly oxidized) and copper fillers were investigated. For each of these fillers two different particle sizes were used. We have shown an anomalous thermal behavior when these metallic fillers are slightly oxidized, i.e. higher thermal transport is obtained for PP/Al composites when using the largest particles. So, the PP/Al composites thermal behavior is not consistent with the PP/Cu ones and with the literature results reported for dielectric or conducting filler particles in a polymeric matrix. Thus, these PP/Al composites exhibit higher thermal transport properties than the homopolymer matrix where as electrical insulating properties of PP are preserved. This kind of composite structure might be of great interest in some technological applications where both good electrical insulation and high thermal conduction are required.     

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.     

聚丙烯接枝马来酸酐改性纳米ZnO/聚丙烯复合材料的成核结晶行为及力学性能

采用熔融共混法制备了nano-ZnO/聚丙烯(PP)复合材料,研究了相容剂聚丙烯接枝马来酸酐(PP-gMAH)的加入对nano-ZnO/PP复合材料的成核结晶行为、晶体结构、结晶形态以及力学性能的影响。结果表明,低添加量(质量分数小于5%)的nano-ZnO对PP有较好的β晶成核效应,而当其质量分数大于5%时,nano-ZnO对PP结晶有明显的异相成核作用,使PP结晶温度大幅度提高,PP结晶在(040)晶面呈现生长择优性;PP-gMAH的加入增强了nano-ZnO粒子与PP基体之间的界面相互作用,改善了纳米粒子的分散性,促进了PP基体的异相成核,提高了nano-ZnO/PP复合材料的拉伸强度和冲击强度,但却抑制了nano-ZnO诱导PP生成β晶。nano-ZnO/PP复合材料体系中因界面相互作用改善所致的韧性提高明显强于nano-ZnO诱导PP形成β晶的增韧效应。     

Physico-mechanical properties of chemically treated coir reinforced polypropylene composites

The physico-mechanical properties of coir reinforced polypropylene (PP) composites been investigated. In order to attain improved mechanical properties of the composites coir was chemically treated with o-hydroxybenzene diazonium salt. Both raw and treated coir samples were utilized for the fabrication of the composites. The mechanical properties of the composites prepared from chemically treated coir are found to be much better compared to those of untreated ones. Tensile strengths of the composites of both raw and chemically treated coir-PP composites showed a decreasing trend with increasing filler content. However, the values for the chemically treated coir-PP composites at all mixing ratios are found to be higher than that of neat PP. The surface morphologies of the fractured surfaces of the composites were recorded using scanning electron microscopy (SEM) to gain information about the fiber–matrix interfacial adhesion in the composites.     

Jute/polypropylene composites I. Effect of matrix modification

Natural fibre-reinforced polymers can exhibit very different mechanical performances and environmental aging resistances depending on their interphase properties, but most studies have been focused on fibre surface treatment. Here, investigations of the effect of maleic anhydride grafted polypropylene (MAHgPP) coupling agents on the properties of jute fibre/polypropylene (PP) composites have been considered with two kinds of matrices (PP1 and PP2). Both mechanical behaviour of random short fibre composites and micro-mechanical properties of single fibre model composites were examined. Taking into account interfacial properties, a modified rule of mixture (ROM) theory is formulated which fits well to the experimental results. The addition of 2 wt% MAHgPP to polypropylene matrices can significantly improve the adhesion strength with jute fibres and in turn the mechanical properties of composites. We found that the intrinsic tensile properties of jute fibre are proportional to the fibre’s cross-sectional area, which is associated with its perfect circle shape, suggesting the jute fibre’s special statistical tensile properties. We also characterised the hydrophilic character of natural fibres and, moreover, humidity environmental aging effects. The theoretical results are found to coincide fairly well with the experimental data and the major reason of composite tensile strength increase in humidity aging conditions can be attributed to both improved polymer–matrix and interfacial adhesion strength.     

纳米SiO2/聚丙烯复合材料的微观结构

利用原子力显微镜和透射电镜分析了聚苯乙烯辐射接枝纳米二氧化硅粒子( SiO₂-g-PS) 填充聚丙烯( PP) 的微观结构, 并与该复合材料的拉伸和冲击强度相关联, 为探讨纳米粒子的增强增韧作用机制提供了直观证据。利用原子力显微镜进行的微划痕和纳米压痕实验, 通过与显微硬度和动态力学性能测试结果的比较, 证实了接枝改性后的纳米粒子团聚体具有承载能力, 而这些团聚体对复合材料的局部和整体力学响应不同, 揭示了团聚体增强效应的内在原因, 即在纳米粒子团聚体内部以及团聚体之间形成了特定的应力双逾渗结构。     

Effects of chemical modification of wood particles with glutaraldehyde and 1,3-dimethylol-4,5-dihydroxyethyleneurea on properties of the resulting polypropylene composites

Both glutaraldehyde (GA) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) can crosslink the cell wall polymers and dimensionally stabilize wood particles and the treated wood particles are thus expected to enhance the properties of the resulting wood particle/polypropylene composites. Compared to the composites filled with untreated particles, treatments of wood particles with both GA and DMDHEU showed a great reduction in water uptake and dimensional swelling of the resulting composites up to 39% and 46%, respectively. Both the flexural and tensile moduli increased due to wood particles treatments with GA and DMDHEU. Treatments of wood particles improved the tensile strength but moderately weakened the flexural strength and Charpy impact strength of the composites. Dynamic mechanical analysis and microscopy suggested an improved interfacial compatibility between wood particles and matrix due to GA and DMDHEU treatments. Chemical treatment resulted in smaller particle sizes and altered microscopic fracture appearance after composite production as compared to untreated particles. Morphological changes were attributed to embrittlement of wood particles, which may negatively influence the mechanical properties of the resulting composites.     

聚丙烯/改性煤系高岭土复合材料的制备与性能

煤系高岭土经过硅烷偶联剂表面改性后,与聚丙烯(PP)树脂熔融共混制备出聚丙烯/改性煤系高岭土复合材料。通过X射线衍射、红外光谱、力学性能和扫描电镜分析,研究了改性煤系高岭土的填充量对复合材料力学性能的影响。结果表明,利用硅烷偶联剂可以实现煤系高岭土的表面改性。改性煤系高岭土填充量为3%时,复合材料具有最佳的冲击韧性。填充量为5%时,复合材料的断裂伸长率达到最大值。随着改性煤系高岭土填充量的增加,复合材料的弯曲强度和弯曲模量逐渐增大,填充量为10%时,二者比纯PP分别提高14.5%和27.5%。