纳米白炭黑核-壳型木塑复合材料抗紫外老化研究

以高密度聚乙烯(HDPE)和木粉为原料,辅以少量化学助剂,采用共挤出生产工艺,以芯层木塑比为6∶4,壳层添加不同含量纳米白炭黑制备出核-壳结构木塑复合材料(WPC)。将其放入老化箱进行紫外光加速老化试验,并对表面颜色、表面形貌、抗弯性能及化学成分进行了测试和表征。结果表明,紫外老化2 500 h后,较之空白样,加入2%纳米白炭黑的ΔE下降了32.7%,试样表面更加完整,裂纹与粉尘较少;弯曲强度保留率提高了9.9%,弹性模量保留率提高了13.2%,且均优于1%纳米白炭黑试样;所有材料表面的氧(O)/碳(C)含量比(n_O/n_C)与老化后木塑表面氧化的碳(C_(ox))/未氧化的碳(C_(unox))的含量比(n_(C_(ox))/n_(C_(unox)))均增大,表面氧化程度加深;其中添加2%纳米白炭黑的WPC表面氧化程度最低,n_O/n_C增长幅度为15.5%,n_(C_(ox))/n_(C_(unox))增加了16.5%,均低于空白样与1%纳米白炭黑试样。说明纳米白炭黑能够提高核-壳WPC抗紫外老化性能并降低其光氧化降解程度,并且适当提高添加量效果更佳。     

北京化工大学开发出一种碳包覆白炭黑新方法

北京化工大学研究人员采用淀粉、低聚糖、甘油、聚乙二醇为原料,对白炭黑进行改性,在二氧化硅表面均匀包覆一层碳层,再经惰性气体或绝氧氛围中高温碳化得到一种以二氧化硅为核、碳为壳的核壳结构纳米粉末。与传统白炭黑相比,碳包覆白炭黑表面拥有独特的碳包覆层,赋予了白炭黑导电性,提高了白炭黑的结构性,改善了白炭黑与橡胶的相容性,且应用在轮胎中提高了轮胎的抗湿滑性能,摩擦生热小等特点。     

核-壳结构木塑复合材料的抗静电及热力学性能研究

为了减弱核-壳结构木塑复合材料(WPC)壳层因高密度聚乙烯(HDPE)的非极性结构而产生的静电效应,降低其表面电阻率,在WPC壳层添加炭黑(CB),运用超高电阻测量仪、万能力学试验机、扫描电子显微镜以及差式扫描量热仪对样品进行检测分析,研究其电学性能、力学性能、微观结构和热力学性质。结果表明,改性处理前,核-壳结构木塑复合材料的表面电阻率约为10~(14)Ω,使用炭黑改性可以有效降低表面电阻率。壳层添加20%的炭黑后,表面电阻率降为10~6Ω。弯曲强度和弯曲模量分别增加21.56%和10.77%,冲击强度也增加26.11%。扫描电子显微镜图表明炭黑的加入会使得HDPE形成一定的片状结构,有助于电子的移动。炭黑的加入可作为HDPE成核剂,降低其熔融状态起始温度和熔融温度,并降低其结晶度。     

熔融沉积成型PLA/麦秸粉复合材料的抗老化性能

采用木塑复合材料与熔融沉积成型技术相结合制备了聚乳酸(PLA)/麦秸粉复合材料,利用扫描电子显微镜、傅里叶变换红外光谱、X射线光电子能谱对复合材料进行测试,分析了紫外光吸收剂UV531对复合材料抗老化性能的影响。结果表明:老化使复合材料变白褪色,添加UV531可改善颜色变化;老化使复合材料的力学性能下降,适量的UV531可提高复合材料的力学强度保持率,w(UV531)为0.6%时,弯曲强度保持率、冲击强度保持率达最大,分别为96.11%,89.03%;老化使复合材料的表面出现裂纹,UV531可以减小裂纹的长度与宽度;老化使复合材料表面被氧化,O原子与C原子个数的百分比增加,UV531可以降低材料被氧化的程度;老化使复合材料的表面官能团发生变化,UV531可以适当抑制该变化。     

反相微乳液体系制备SiO2包覆的ZnO NPs及其作为防晒材料的应用

通过AEO9/环己烷/正己醇/水反相微乳体系制备二氧化硅透明壳层包封的纳米氧化锌紫外屏蔽器以降低纳米氧化锌的光催化性,提高纳米氧化锌防晒剂的使用安全性。TEM图像与傅里叶红外光谱图表明SiO₂包覆在纳米氧化锌表面,ZnO@SiO₂纳米颗粒具有核壳结构。亚甲基蓝降解实验证明SiO₂降低了纳米氧化锌的光催化活性。紫外屏蔽测试结果表明ZnO@SiO₂纳米颗粒防晒效果好,SiO₂壳层提高了纳米氧化锌在可见光区的透明度。TEOS与纳米氧化锌质量比为0.4时,制备的ZnO@SiO₂纳米颗粒防晒效果最好,光催化活性最低。     

阻燃功能核壳结构木塑复合材料制备及性能研究

通过在表层添加有机改性蒙脱土(OMMT)与聚磷酸铵(APP)以及纳米氢氧化镁[Mg(OH)_2]与APP制备具有阻燃功能的核壳型木塑复合材料,并利用力学性能测试、锥形量热测试和热重分析,研究了阻燃剂对核壳型木塑复合材料的力学性能、燃烧性能和热稳定性能的影响。结果表明,OMMT与APP有更好的协同效果和阻燃效果,其热释放总量以及热释放速率都呈下降趋势,但是复配之后的产烟量却增多。热失重分析结果表明,APP与OMMT的复配和APP与Mg(OH)_2的复配相比较,前者残炭率更高,达到了55.2%。两种阻燃剂复配后弯曲强度和弹性模量呈现下降趋势,力学强度下降。综合比较,APP与OMMT复配阻燃性能更好。     

SDBS对核壳结构木塑复合材料抗静电及热力学性能的影响

以十二烷基苯磺酸钠(SDBS)为抗静电剂,将其加入到具有核壳结构的高密度聚乙烯(HDPE)木塑复合材料中,以减小壳层HDPE的静电效应。采用超高电阻测量仪、万能力学试验机、表面接触角测试仪以及差示扫描量热仪对样品进行电学、力学、表面润湿性以及热力学分析。结果表明:未添加SDBS的核壳结构木塑复合材料的表面电阻率为10~(15)Ω;添加18%的SDBS后,木塑复合材料的表面电阻率降至10~8Ω。添加SDBS后,木塑复合材料的力学性能先上升后下降,弯曲强度较最高值下降约3.67%,弯曲模量较最高值下降约9.92%,冲击强度较最高值下降约10.20%。复合材料表面润湿性随着壳层SDBS含量的增加而降低,壳层结构HDPE基体结晶度则先降低后提高。     

不饱和聚酯玻璃钢与环氧乙烯基酯玻璃钢耐久性能试验研究

采用湿热老化、冻融循环及紫外老化等加速试验方法,通过质量变化率、弯曲强度保留率及SEM分析,对189不饱和聚酯玻璃钢及MFE-2环氧乙烯基酯玻璃钢在海洋环境中的腐蚀机理和耐久性进行了详细研究。试验结果表明,湿热老化150d后,189不饱和聚酯玻璃钢及MFE-2环氧乙烯基酯玻璃钢的质量变化率分别为-6.03%和0.31%,弯曲强度保留率分别为26.2%和47%;紫外老化300h后,弯曲强度保留率分别为84%和94%;1000次冻融循环后,弯曲强度保留率分别为30%和65%。基体树脂分子链上酯基的密度是影响玻璃钢在海洋环境中耐久性的关键因素,MFE-2环氧乙烯基酯树脂分子链上酯基的密度约为189不饱和聚酯树脂分子链上酯基密的1/3,所以MFE-2环氧乙烯基酯玻璃钢在海洋环境中具有更好的耐久性。     

聚丙烯基木塑复合材料的老化性能研究

以聚丙烯(PP)作为基体,以木粉作为填料,并分别加入炭黑、钛白粉、氧化铁红等,用注射成型法制备了PP基木塑复合材料(WPC),用烘箱热氧老化法和氙灯老化法研究了颜料对WPC老化性能的影响。结果表明,随着老化时间的增加,无论是否加入颜料,均出现了WPC的拉伸强度和氧化诱导时间减小,熔体流动速率和色差增大的现象;烘箱老化前后,添加钛白粉和氧化铁红的WPC的拉伸强度、氧化诱导时间和色差均较小,熔体流动速率均较大;在氙灯老化条件下,添加颜料的WPC老化后拉伸强度、熔体流动速率、颜色和氧化诱导时间的变化速度均较小。     

三种增强填料对交联POE强度的影响

研究了纳米碳酸钙、白炭黑、纳米高岭土作为交联POE的填料的补强效果。结果表明:白炭黑补强效果最好;纳米高岭土极易在表面改性,经含量为2%的铝酸酯偶联剂表面改性的纳米高岭土填料对交联POE有较强的补强作用,可完全取代纳米CaCO3,或部分替代白炭黑。     

消防水带用聚氨酯胶黏剂的研制

采用具有较高结晶性的聚酯多元醇,以及合适的扩链剂和异氰酸酯为原料制备高初粘强度的消防水带用聚氨酯胶黏剂,并且分析了聚酯多元醇种类及数均相对分子质量(n)、扩链剂种类及用量、异氰酸酯指数(R)、纳米白炭黑及水解稳定剂对聚氨酯胶黏剂性能的影响。实验结果表明,采用n为3000左右的聚己二酸1,4-丁二醇酯,扩链剂采用1,4-丁二醇,R取1.02～1.03,并且加入经过表面改性的纳米白炭黑TS-720,加入0.5%～0.7%(与聚酯的质量比)的水解稳定剂,反应后得到的聚氨酯胶黏剂具有较高的初粘强度、较好的耐水解性能和耐老化性能。     

Weathering performance of waterborne acrylic coating systems on flat-pressed wood–plastic composites

This study applied coating systems containing two different waterborne acrylic resins with an ultraviolet (UV) absorber on the surfaces of polyvinyl chloride-based flat-pressed wood–plastic composites (WPCs) evaluated and the effects of waterborne acrylic coating on the performance of WPCs in outdoor conditions. The results showed that waterborne acrylic coating systems enhanced the surface quality of WPC. The decrease in flexural strength was found to reach up to 22%, while it was about 25% for modulus. The color changes on the surface decreased by 55% as a result of the UV absorbability of the coating systems. Moreover, the chemical changes in the composites were found to be almost nonexistent in the attenuated total reflection–Fourier transform infrared spectroscopy for WPCs coated with both formulations. The light microscopy images revealed that the coating systems minimized deformation on the surface. In comparison to the control samples, it was seen that the surface roughness of the WPC was also improved by using waterborne acrylic coating systems. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48518.     

外墙乳胶漆耐候性研究

采用天然曝晒和人工老化方法研究了各种纯丙乳液和硅丙乳液的耐候性,由该类乳液制备的不同PVC白色乳胶漆的耐候性,以及白色乳胶漆与各色色浆配制的浅色乳胶漆的耐候性。结果表明:硅丙乳液和核壳型纯丙乳液具有较好的耐候性,高PVC乳胶漆容易变色,炭黑和氧化铁系色浆适合于配制浅色外墙乳胶漆,有机颜料色浆应用在外墙时应谨慎。     

Effects of weathering aging on mechanical and thermal properties of injection molded glass fiber reinforced polypropylene composites

The effect of weathering aging on the degradation behavior of injection molded short glass fiber reinforced polypropylene composites (GFPP) is studied. First, the effect of outdoor weathering on mechanical properties of GFPP composite was investigated by tensile, flexural, and impact tests. Furthermore, to clarify the degradation behavior under natural weathering environments, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements were carried out to analyze the structural and molecular changes during weathering aging. The results show that weathering aging has a significant influence on changes in mechanical properties, melting temperature and the degree of crystallinity of PG6N1 without added carbon black and UV absorbing agent. Those degradations not only occurred on the surface of GFPP but also proceeded to the inner matrix and interface. However, GFPP GWH42 with added carbon black and UV absorbing agent shows excellent weathering stability.     

CNT基木塑复合材料的力学性能、电磁屏蔽性能

采用碳纤维(CF)和碳纳米管(CNT)通过模压工艺制备出具有电磁屏蔽功能的丙烯酸酯木塑复合材料。借助材料试验机、动态热机械分析仪、微欧计和电磁屏蔽测量仪等详细研究CNT质量分数对丙烯酸酯木塑复合材料弯曲性能、动态力学性能、电阻率和电磁屏蔽效能的影响。结果表明,添加质量分数为2%的CNT,使得复合材料的弯曲强度和弯曲弹性模量分别增加了10%和16%。复合材料的储能模量也在CNT质量分数为2%时达到最大值,之后储能模量随着CNT的增加而逐渐下降,损耗因子在CNT质量分数多于2%时也逐渐增加。复合材料的吸水率和导电性能随着CNT含量的增加而增加。同时复合材料的电磁屏蔽效能也随着CNT含量增加而递增。在30~1 500 MHz范围内,电磁屏蔽效能从27 d B增加到40 d B。结果证明,当CNT质量分数在2%时,丙烯酸酯木塑复合材料具有较佳的力学性能和较好的电磁屏蔽效能(30 d B),能满足商业要求。     

保险杠自然曝露后虎皮纹缺陷的研究

针对自然曝露后出现的虎皮纹缺陷现象设计了保险杠自然曝露试验,并对缺陷的发生的原因进行了研究分析.结果发现,保险杠经自然曝露试验后出现了黑白相间虎皮纹缺陷;相比于虎皮纹的黑段,白段的色差值更大且存在大量微裂纹,表面O元素含量急剧上升,表现出明显的老化现象;保险杠材料中的橡胶增韧相发生了不平衡剪切取向,白段的取向程度明显高...     

Effects of ultraviolet aging on the surface properties and tribological performance of polyformaldehyde

Ultraviolet aging restricts the outdoor application of polyformaldehyde as the friction material. In this work, ultraviolet aging processes were applied to polyformaldehyde specimens and effects of the processes on their surface properties and tribological performance were evaluated. Surface morphology results show that a thin layer of white powder and micro‐cracks with further ramifications in other directions were observed on the surfaces after 400 h of ultraviolet exposure, while it is not detectable for the unaged specimens. Analysis of aging surface indicates that ultraviolet leads to the increase of micro‐cracks and the degree of crystallinity. All the tribological test results demonstrate that with the extension of ultraviolet aging time, (i) the process of damage on polyformaldehyde surface induced by ultraviolet aging is first slowly and faster afterward; (ii) the fluctuation of the friction coefficients of polyformaldehyde/GCr15 rubbing pairs increases; and (iii) the wear rate of polyformaldehyde markedly increase after aging test 400 h. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44684.     

Efficacy of hindered amines in woodflour‐polypropylene composites compatibilized with vinyltrimethoxysilane after accelerated weathering and moisture absorption

In this work, the aim was to analyze the efficacy of hindered amine light stabilizers (HALS) in woodflour‐polypropylene composites compatibilized with vinyltrimethoxysilane after moisture absorption and accelerated weathering. Moisture uptake of materials decreased with incorporation of silane due to diminished accessibility of water molecules to reactive regions. In dynamic mechanical experiments performed on wet samples, a marked reduction in the storage modulus in the glassy and rubbery zone was observed, since water has a plasticizing effect. After sample weathering, in a xenon‐arc apparatus, the changes in chemical structure and physical properties after exposure were analyzed by attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, color measurement, flexural properties, and morphological analysis by scanning electron microscopy (SEM). The data showed that HALS maintain the brightness of the materials after aging and prevent sample whitening. They also reduced color loss after aging and the SEM micrographs revealed that they inhibit surface cracking during weathering. Although a slight decline in the mechanical properties was not completely avoided, the combination of the additives studied (UV absorbers and HALS) successfully prevented the deterioration of surface materials by UV radiation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

炭黑对丁苯橡胶耐热氧和紫外老化性能的影响

研究了填充不同量炭黑对丁苯橡胶耐热氧和紫外老化性能的影响,测试了各试样的交联密度及物理机械性能,并用扫描电镜观察了其表面形貌.结果表明,丁苯橡胶在热氧老化开始时内部发生了以交联为主的反应,表面氧化缓慢;而在紫外老化开始时表面的变化较大,在老化过程中交联密度出现峰值;热氧和紫外老化120 h后,橡胶的硬度增加,表面变得致密,使热氧和紫外线侵入至橡胶内部变得困难,邵尔A硬度等物理机械性能的变化趋势减缓;炭黑填充量大于20份(质量)时SBR的耐紫外老化性能得到改善,老化360 h后物理机械性能保持率仍然较高,这是因为炭黑对紫外线有很好的屏蔽作用,而炭黑对SBR耐热氧老化性能的影响却相反.