稻壳SiO_2/聚氨酯纳米复合材料的制备及性能研究

将酸处理后稻壳在600℃焚烧,得到比表面积为212 m2/g,纯度99.3%的稻壳SiO2纳米凝聚体,用偶联剂γ-氨丙基三乙氧基硅烷(KH550)改性后,SiO2纳米凝聚体在溶液中以纳米状态分散,大部分粒子尺寸约30~50 nm。将其与聚氨酯(PU)复合,探讨了不同SiO2含量复合材料的力学性能、热分解性能以及吸水性。研究结果表明:与纯PU相比,稻壳SiO2/PU纳米复合材料的力学性能有不同程度的提高,其耐热性能和耐水性明显增强。     

MC尼龙6/SiO2纳米复合材料的制备与表征

用原位聚合法制备了MC尼龙6／SiO2纳米复合材料。当纳米SiO2的加入量为1％时，复合材料的力学综合性能最优。与纯MC尼龙相比，拉伸强度提高21％，弯曲模量提高40．3％，简支梁冲击强度提高69．1％，断裂伸长率降低43％。随着纳米SiO2含量的增加，复合材料的力学性能呈现降低趋势。采用SEM、XRD和DSC对产物进行了表征，表明采用修饰后的纳米SiO2加入到产物中，粒子分布均匀，粒径分布窄，粒子的粒径在30nm左右。随着纳米SiO2加入量的增加，MC尼龙6／SiO2纳米复合材料的结晶度下降。复合材料的熔点比未改性的纯MC尼龙6提高了2～3℃左右。     

MC尼龙6/纳米SiO2复合材料的合成

用原位聚合法制备MC尼龙6／纳米SiO2复合材料。当纳米SiO2的加入量为1％时,力学综合性能最优。与纯MC尼龙相比,拉伸强度提高21％,弯曲模量提高40．3％,简支梁冲击强度提高69．1％,断裂伸长率降低43％。随着纳米SiO2含量的增加,复合材料的力学性能呈现减小趋势。采用SEM、XRD对产物进行了表征,表明采用修饰后的纳米SiO2加入到产物中,粒子分布均匀,粒径分布窄,粒子的粒径在30nm左右。随着纳米SiO2加入量的增加,MC尼龙6／纳米SiO2复合材料的结晶度下降。     

MC尼龙6/纳米SiO_2复合材料的合成

用原位聚合法制备MC尼龙6/纳米SiO2复合材料。当纳米SiO2的加入量为1%时,力学综合性能最优。与纯MC尼龙相比,拉伸强度提高21%,弯曲模量提高40.3%,简支梁冲击强度提高69.1%,断裂伸长率降低43%。随着纳米SiO2含量的增加,复合材料的力学性能呈现减小趋势。采用SEM、XRD对产物进行了表征,表明采用修饰后的纳米SiO2加入到产物中,粒子分布均匀,粒径分布窄,粒子的粒径在30 nm左右。随着纳米SiO2加入量的增加,MC尼龙6/纳米SiO2复合材料的结晶度下降。     

聚乳酸/蒙脱土纳米复合材料的制备及其性能研究

采用熔融共混法制备聚乳酸/蒙脱土（PLA/MMT）纳米复合材料。用X射线衍射仪、透射电子显微镜、差示扫描量热仪对材料的力学性能、微观结构和形貌进行表征。结果表明,PLA分子链插入MMT片层间,MMT层间距由1.801 nm增大到3.530 nm并呈纳米级均匀分散在PLA基体中,体系相容性良好;MMT的加入量为3 %（质量分数,下同）时,复合材料的力学性能得到最大改善,拉伸强度由纯PLA的53.1 MPa提高到62.8 MPa,冲击强度由纯PLA的18.00 kJ/m2提高到23.30kJ/m2,加入3 % MMT的复合材料结晶度为42.63 %,试样平均晶粒粒径尺寸为0.285 nm,而纯PLA的结晶度是24.52 %,平均晶粒粒径尺寸0.305 nm,MMT的加入明显提高了PLA的力学性能和结晶度。     

超声对不同粒径二氧化硅改性热塑性木薯淀粉影响

以木薯淀粉为研究对象,通过熔融共混模压法制得热塑性木薯淀粉（TPS）/二氧化硅（SiO2）复合材料。研究超声作用下不同粒径（0.02 μm、0.2 μm、23 μm）二氧化硅对热塑性木薯淀粉的回生熔融焓、回生速率、回生指数及球晶形态结构、接触角、热稳定性的影响规律。结果表明,与未超声样品相比,利用差示扫描量热仪（DSC）发现经过超声作用后TPS/SiO2复合材料的熔融焓增加,回生速率提高、回生指数降低,且添加20 nm SiO2制得产物回生速率提升幅度最大;偏光（PLM）和接触角测试发现,经过超声作用后,TPS/SiO2复合材料球晶都变得明显、水接触角提高。TG分析表明,超声作用使复合材料的水分容易挥发,甘油与淀粉的结合能力增强,淀粉的分子结构稳定性增加。SEM分析表明,超声作用下使得二氧化硅粒子在基体中聚集减少、分散更好;采用FTIR分析发现,复合材料的回生程度增加,双螺旋结构减少;XRD分析表明,复合材料呈现出A+V晶型,超声作用后使得V晶型增加、A晶型减少。     

PP/纳米SiO2/POE复合材料的研究

采用熔融共混法制备PP/纳米SiO2/POE复合材料,并通过力学性能测试、DSC分析以及材料断面形貌分析等手段,对增强增韧效果进行研究.结果表明纳米SiO2和POE微粒显现了比较明显的协同增韧效果,当PP/纳米SiO2/POE为100/4/15时,综合力学性能最优.纳米SiO2的成核作用提高了PP的结晶温度和结晶速率.两种微粒在PP基体中达到均匀分散,其中纳米SiO2粒子平均粒径为150nm,与其二次粒子直径相当,表明熔融过程并未造成纳米粒子的团聚.     

环氧树脂/镀银纳米石墨微片导热复合材料的制备与性能

以膨胀石墨为原料,采用超声分散法和化学镀法制得镀银纳米石墨微片,然后将其填充在环氧树脂基体中制备环氧树脂/镀银纳米石墨微片复合材料。结果表明,银粒子均匀镀覆在纳米石墨微片上,银层厚度为100 nm,有利于在环氧树脂基体中形成导热通路;与环氧树脂相比,环氧树脂/镀银纳米石墨微片复合材料的力学性能和热导率能都得到提高;当镀银纳米石墨微片含量为3 %时,复合材料的热导率为1.827 W/(m·K),比纯环氧树脂热导率提高了近5倍。     

BN填充PA6基导热绝缘复合材料导热性能研究

以聚酰胺6（PA6）为基体, 氮化硼（BN）作为导热填料,经双螺杆挤出机熔融共混,模压成型制得导热绝缘复合材料。研究了BN含量、粒径、形状和不同BN粒径复配对复合材料导热性能的影响,并研究了BN含量和粒径对复合材料绝缘性能的影响。结果表明,在各种粒径下,复合材料热导率均随BN填充量的增加而增大;在BN粒径为5 μm、填充量为25 %（体积分数,下同）时,复合材料热导率达到1.2187 W/(m·K);在BN填充量相同时,填料粒径对复合材料热导率的影响不是简单的单调规律,呈现50、100 μm时较小,1、5、15 μm时较大,150 μm时最大的规律;片状BN填料比球状BN填料更有利于提高复合材料的热导率;2种不同粒径填料复配所填充的复合材料的热导率大于单一粒径填充的复合材料;5 μm与150 μm粒径BN复配,在填充量为20 %,配比为1:3时,复合材料的热导率最大,达到1.3753 W/(m·K),为纯PA6的4.9倍;在不同BN含量和粒径下,复合材料体积电阻率均能达到10000000000000 Ω·cm以上,满足绝缘性能。     

环氧树脂/稻壳SiO2纳米复合材料的热性能及拉伸性能研究

将稻壳用酸处理后在600 ℃焚烧得到纯度为99.3%、比表面积为212 m2/g的SiO2。经硅烷偶联剂γ-氨丙基三乙氧基硅烷（KH550）改性后的SiO2为无定形态,尺寸在30~50 nm之间。将改性后的稻壳SiO2与环氧树脂复合,利用热分析方法考察了纳米复合材料在N2气氛中的热性能,并采用万能材料试验机测试其拉伸性能。结果表明：稻壳SiO2的加入能有效增加环氧树脂/稻壳SiO2纳米复合材料的热稳定性,复合材料的起始分解温度（Ti）、分解速率最大时的温度（Tmax）以及失重50 %的分解温度（T50 %）均高于纯环氧树脂,并随稻壳SiO2含量的增加而增加。当环氧树脂/稻壳SiO2纳米复合材料的组成相同时,KH550改性的复合材料的Ti、Tmax和T50 %均比未经过KH550改性的高。随KH550用量增加,复合材料T50 %向高温方向移动。此外,复合材料的拉伸强度、断裂伸长率和模量也高于纯环氧树脂。     

Mechanical and flame-resistance properties of polyurethane-imide foams with different-sized expandable graphite

Polyurethane-imide (PUI) composite foams with expandable graphite (EG) of different sizes were prepared by a polyimide prepolymer method. EG particles were treated with a silane coupling agent to improve compatibility with the foam. The effect of EG particle size on cell morphology, thermal degradation, flame-resistance and mechanical properties of PUI foams was investigated. Results showed that the mean cellular diameter of foams with EG particle was much higher than that of foams with surface-modified EG particle at the same filler loading. When filler particle diameter increased from 20 to 90 μm, the compressive strength, density and closed-cell ratio of foams increased, and then decreased when filler particle diameter further increased from 90 to 150 μm. Thermal stability of foams increased with the increasing filler particle diameter from 20 to 50 μm, and decreased with the increasing filler particle diameter from 50 to 90 μm. The limited oxygen index (LOI) value of foams with surface-modified EG increased from 24.8% to 32.1% when EG particle diameter was below 90 μm. Foams with surface-modified EG exhibited enhanced mechanical properties, thermal stability and flame resistance than foams with neat EG at the same loading.     

The role of nanofillers on (natural rubber)/(ethylene vinyl acetate)/clay nanocomposite in blending and foaming

Nanocomposite foams were fabricated from 60/40 wt% ethylene vinyl acetate (EVA)/natural rubber (NR) blends by using azodicarbonamide as a blowing agent. Two different nanofillers (sodium montmorillonite and organoclay) were employed to study their effects on foam properties. The results were also compared with conventional (china clay)‐filled foams. Transmission electron microscopy, X‐ray diffraction, scanning electron microscopy, and three‐dimensional Microfocus X‐ray computed tomography scanning analysis were performed to characterize the EVA/NR blend morphology and foam structures. The results revealed that the nanofiller acted as a blend compatibilizer. Sodium montmorillonite was more effective in compatibilization, generating better phase‐separated EVA/NR blend morphology and improving foam structure. Higher filler loading increased the specific tensile strength of rubber foams. The rubber nanocomposite foam showed superior specific tensile strength to the conventional rubber composite foam. The elastic recovery and compressive strength of the nanocomposite foams decreased with increasing filler content, whereas the opposite trend was observed for the conventional composite foams with china clay. The thermal conductivity measurement indicated that the nanofiller had better beneficial effect on thermal insulation over china clay filler. From the present study, the nanofillers played an important role in obtaining better blend morphology as compatibilizer, rather than the nucleating agent and the nanofiller content of 5 phr (parts by weight per hundred parts of rubber) was recommended for the production of EVA/NR nanocomposite foams. J. VINYL ADDIT. TECHNOL., 21:134–146, 2015. © 2014 Society of Plastics Engineers     

PF泡沫塑料对PF/EPS复合泡沫塑料性能的影响

研究出一种具有较好稳定性、保温性能、力学性能和阻燃性能的酚醛树脂(PF)/可发性聚苯乙烯(EPS)复合泡沫塑料。在PF泡沫塑料颗粒基体中加入EPS发泡颗粒,充分混合固化,使PF泡沫塑料颗粒与EPS发泡颗粒紧密结合,EPS发泡颗粒被PF泡沫塑料颗粒包围并相互隔离,再用模具发泡成型得到该复合泡沫塑料。实验结果表明,PF的含量越高,稳定性、力学性能和阻燃性能越好,保温性能呈现先升高后下降的趋势,当PF的含量为80%时,PF/EPS复合泡沫塑料的表观密度为38.4 kg/m3,热导率为0.024 W/(m·K),弯曲强度为0.134 k Pa,压缩强度为323 k Pa,极限氧指数为47.9%,烟密度等级小于15,热释放速率峰值小于250 k W/m2,综合性能最好。     

Nanoclay filled soy‐based polyurethane foam

Polyurethane foam was fabricated from polymeric diphenylmethane diisocyanate (pMDI) and soy‐based polyol. Nanoclay Cloisite 30B was incorporated into the foam systems to improve their thermal stabilities and mechanical properties. Neat polyurethane was used as a control. Soy‐based polyurethane foams with 0.5–3 parts per hundred of polyols by weight (php) of nanoclay were prepared. The distribution of nanoclay in the composites was analyzed by X‐ray diffraction (XRD), and the morphology of the composites was analyzed through scanning electron microscopy (SEM). The thermal properties were evaluated through dynamic mechanical thermal analysis (DMTA). Compression and three‐point bending tests were conducted on the composites. The densities of nanoclay soy‐based polyurethane foams were higher than that of the neat soy‐based polyurethane foam. At a loading of 0.5 php nanoclay, the compressive, flexural strength, and modulus of the soy‐based polyurethane foam were increased by 98%, 26%, 22%, and 65%, respectively, as compared to those of the neat soy‐based polyurethane foam. The storage modulus of the soy‐based polyurethane foam was improved by the incorporation of nanoclay. The glass transition temperature of the foam was increased as the nanoclay loading was increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical and thermal properties of modified red mud‐reinforced phenolic foams

A new type of composite based on phenolic foams reinforced with red mud microparticles was prepared using a thermal foaming method. Red mud was ground into ultrafine particles with grain diameters ranging from 1 to 1.5 μm. Silane coupling agent γ‐ureidopropyltriethoxysilane was used to modify the red mud microparticles to improve particle dispersion and adhesion between the particles and the phenolic matrix. The effects of the modified red mud microparticles on the mechanical and thermal properties of the composite were investigated at weight ratios ranging from 0 to 21%. The phenolic foams incorporating 15 wt% of the filler exhibited the best integrated performance. In comparison with native phenolic foams, tensile strength and impact strength were increased by 81.8 and 82.3%, respectively. Furthermore, the addition of modified red mud microparticles to the phenolic foam significantly decreased its thermal conductivity while increasing its limiting oxygen index. A morphological analysis using scanning electron microscopy indicated that incorporation of the modified red mud microparticles into the foam produced relatively small and uniformly sized cells within the material, which indicated that the observed improvements in mechanical and thermal properties were primarily due to the chemical adhesion between the particles and the matrix and good dispersion of particles in the matrix. The reinforced foams described in this study can be used in a variety of applications in the field of heat insulation. © 2018 Society of Chemical Industry     

Preparation of phenolic-based carbon foam with controllable pore structure and high compressive strength

Phenolic-based carbon foams with controllable pore structure and high compressive strength were prepared by foaming of resin solution under the pressure of 4 MPa and then carbonizing. Results showed that the average pore size of carbon foam ranging from 20 to 180 nm can be controlled by changing the resin concentration. The nanometer pore structure resulted in significant improvement of compressive strength and thermal insulation properties of the carbon foams. Carbon foam with bulk density of 0.73 g/cm³, average pore size of 20 nm, compressive strength of 98.3 MPa and thermal conductivity of 0.24 W/mK was obtained.     

木质素基PF泡沫的发泡工艺与性能

利用低廉的木质素部分取代苯酚制备木质素基酚醛树脂(PF)泡沫,采用正交试验对木质素基PF发泡工艺进行了研究,研究了表面活性剂(吐温–80)用量、发泡剂(正戊烷)用量、发泡温度三个因素对木质素基PF泡沫性能的影响,从而优化发泡工艺。实验结果表明,对木质素基PF泡沫的极限氧指数(LOI)和导热系数影响最大的是发泡温度,而对于压缩强度影响最大的是表面活性剂用量。木质素基PF泡沫的最佳发泡工艺为:表面活性剂(吐温–80)用量为8%、发泡剂(正戊烷)用量为12%,发泡温度为90℃,所得泡沫具有较好的热稳定性,其LOI为39%,压缩强度为0.32 MPa,导热系数为0.025 W/(m·K)。     

Poly(vinyl alcohol) foams reinforced with carbon nanotubes for stapedial annular ligament applications

This study aims to develop carbon nanotubes (CNTs) reinforced poly(vinyl alcohol) (PVA) foams as a possible material for stapedial annular ligament (SAL) application. As-grown (AG) and purified CNTs are used as reinforcing fillers for PVA foams. Uniaxial and cyclic compression tests reveal that specific modulus and energy dissipation behavior improve after reinforcing foam with CNTs. A relatively higher improvement in specific modulus is recorded for purified CNTs as they tend to produce stiffer cell walls. Thermogravimetric analysis shows thermal stability improves after addition of CNTs in PVA foams. The 50 wt % degradation temperature is higher for PVA_AG foam in comparison to neat PVA foam. Under dynamic loading storage, modulus is found to be higher for CNT doped foams with higher relative improvement with purified CNTs than AG CNTs. It is shown that reinforcing PVA foams with purified CNTs is a feasible strategy to improve their average mechanical properties and microstructure for SAL application. While the specific elastic modulus of neat PVA foam found to be in range of 0.05–0.06 MPa gcc⁻¹ with almost zero porosity. The addition of CNTs provides a wide range of specific elastic modulus 0.1–1.3 MPa gcc⁻¹ with an average pores size of about 300 μm. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48736.     

Carbon foams with high compressive strength derived from mixtures of mesocarbon microbeads and mesophase pitch

Carbon foam with relatively high compressive strength and suitable thermal conductivity was prepared from mixtures of mesocarbon microbeads (MCMBs) and mesophase pitch, followed by foaming, carbonization and graphitization. The influence of addition amount of MCMB on the properties of as-prepared carbon foams was investigated in detail. Results showed that addition of MCMBs into mesophase pitch could significantly reduce the amount and length of cracks in carbon foams, which results in increase of compressive strength of carbon foams. Carbon foam with high compressive strength of 23.7 MPa and suitable thermal conductivity of 43.7 W/mK, was obtained by adding 50% MCMBs into mesophase pitch, followed by foaming, carbonization and graphitization.     

酚醛泡沫的制备

本文介绍两种酚醛泡沫的制备,一种是用加热方法制备的普通酚醛泡沫,另一种是用尿素改性的酚醛泡沫的制备。前者的压缩强度较常温发泡提高一倍左右,吸水率降至原来的一半,导热系数由原来的0．033W／m·k降至0．028W／m·k,后者性能介于前者和常温发泡两种酚醛泡沫之间,但可降低成本。