聚苯乙烯光氧老化行为及其模型研究

研究了自然曝晒试验后的聚苯乙烯(PS)样品结构和性能的变化,同时对其拉伸强度保持率的变化进行回归拟合,并建立了光氧老化模型。结果表明:太阳辐照是影响PS光氧老化的主要因素,水分对其起促进作用;PS老化过程中有羰基基团生成;老化模型可以反映光、热、水综合作用的强弱。     

在模拟户内环境下聚苯乙烯颜色变化的老化模型及预估

采用棚下暴露、氙灯老化和荧光紫外灯老化这3种老化方法，研究聚苯乙烯在模拟户内环境下颜色随老化时间的变化。结果表明：聚苯乙烯颜色随老化时间的变化符合相关因数接近于1的线性回归方程：利用所获得的线性回归方程对聚苯乙烯的颜色变化进行预估，实测值包含在置信度为95％的预测区间之内。     

纳米氧化钛改性聚苯乙烯耐紫外光老化性能的研究

本文采用硅烷偶联剂对纳米TiO2进行表面改性,制备了不同含量纳米TiO2改性的聚苯乙烯材料,并对纳米TiO2/聚苯乙烯板材进行氙灯紫外加速老化处理。实验结果表明:纳米二氧化钛/聚苯乙烯复合板材在经过紫外老化处理后,其耐热性能、硬度、拉伸性能及冲击强度下降幅度不大。因此,适当配比的纳米二氧化钛能够减少紫外线对聚苯乙烯材料的降解作用,延缓材料的老化。     

聚苯乙烯海南自然气候暴露后的老化现象

采用直接气候暴露、玻璃板下暴露和百页窗下暴露三种自然老化方法研究了聚苯乙烯(PS)外观、力学性能和熔体流动速率在海南自然老化过程中的变化,考察了光、热、氧、水对PS老化的影响。结果表明,PS在海南的自然老化以断链反应为主,分子量的下降与太阳辐照强度密切相关;老化过程中,由于试样温度变化所产生的内应力是影响PS力学性能的重要因素;水对PS的各项性能不产生大的影响。     

自然环境老化对聚苯乙烯表观性能和形态的影响

开展聚苯乙烯在我国九个典型自然气候的自然大气暴露试验,研究不同自然环境老化对聚苯乙烯的表观性能(黄色指数、光泽、雾度)和表面形态的影响,分析自然环境下引起聚苯乙烯材料表观性能变化的主要环境因素。结果表明,辐照量是影响聚苯乙烯表观性能和形态的主要原因,温度与湿度起辅助作用。     

在模拟户内环境下聚苯乙烯颜色变化的老化模型及预估

采用棚下暴露、氙灯老化和荧光紫外灯老化这3种老化方法,研究聚苯乙烯在模拟户内环境下颜色随老化时间的变化。结果表明:聚苯乙烯颜色随老化时间的变化符合相关因数接近于1的线性回归方程;利用所获得的线性回归方程对聚苯乙烯的颜色变化进行预估,实测值包含在置信度为95%的预测区间之内。     

聚苯乙烯作为参考材料在氙灯老化试验中的应用

研究了在按ASTM D4459-1999进行的氙灯老化试验中,聚苯乙烯样板的色差和光泽保持率随辐照度的变化。结果表明：聚苯乙烯样板色差随辐照度的变化,符合相关系数接近于1的线性回归方程。在按ASTM D4459-1999进行的氙灯老化试验中,聚苯乙烯样板可作为参考材料,以色差为老化指标．监控老化设备的运转,保证在试样品在规定条件下老化。     

衰减全反射红外显微光谱法研究炭黑补强橡胶的老化

1前言 炭黑（CB）填充橡胶被认为是红外光谱（IR）极端困难表征的试样，因为橡胶对IR光有极强的吸收和散射。由于难以取得足够薄的试样，所以采用透射红外光谱对实际橡胶试样进行测试几乎不可能。然而。用溴化钾（KBr）稀释的CB填充二烯烃橡胶的透射试样是有用的，制成超薄切片就可以进行透射测试。     

不同对色方法对聚苯乙烯标准塑料片老化测试结果的影响

在氙灯暴露试验中可以用聚苯乙烯标准塑料片作为辐照剂量的校准物使用.该文主要是针对老化后的聚苯乙烯标准塑料片评价方法的摸索.通过聚苯乙烯标准塑料片在经受一定辐照剂量后,用透射法和反射法测得L、a、b值,通过比较L、a、b值数据,发现反射法更适于聚苯乙烯标准塑料片老化后的评价.     

FTIR Spectroscopy Evidence for the Basicity Induced by Adsorption

Basicity of silanol oxygen atom increases after adsorption of ammonia or pyridine, as revealed by FTIR spectra of adsorbed CHF₃ and CO₂. The same effect of “induced basicity” was observed for the dangling hydroxyl groups of ice surface with coadsorbed ethylene and fluoroform. Possible role of the induced acidity and basicity in surface chemistry is discussed.     

Study of the Spatio-Chemical Heterogeneity of Tannin-Furanic Foams: From 1D FTIR Spectroscopy to 3D FTIR Micro-Computed Tomography

Tannin-furanic rigid foams are bio-based copolymers of tannin plant extract and furfuryl alcohol, promising candidates to replace synthetic insulation foams, as for example polyurethanes and phenolics, in eco-sustainable buildings thanks to their functional properties, such as lightness of the material and fire resistance. Despite their relevance as environmental-friendly alternatives to petroleum derivatives, many aspects of the polymerization chemistry still remain unclear. One of the open issues is on the spatial heterogeneity of the foam, i.e., whether the foam constituents prevalently polymerize in spatially segregated blocks or distribute almost homogenously in the foam volume. To address this matter, here we propose a multiscale FTIR study encompassing 1D FTIR spectroscopy, 2D FTIR imaging and 3D FTIR micro-tomography (FTIR-μCT) on tannin-furanic rigid foams obtained by varying the synthesis parameters in a controlled way. Thanks to the implementation of the acquisition and processing pipeline of FTIR-μCT, we were able for the first time to demonstrate that the polymer formulations influence the spatial organization of the foam at the microscale and, at the same time, prove the reliability of FTIR-μCT data by comparing 2D FTIR images and the projection of the 3D chemical images on the same plane.     

电导率法和红外光谱法分析硅烷试剂水解过程

1　前言　　金属表面的防腐研究已有多种防腐技术 ,例如 :电化学保护、电镀、化学镀、渗镀包镀、热喷涂及化学氧化膜法等。近期 ,国外学者提出了利用硅烷试剂(ＳｉｌａｎｅＡｇｅｎｔ,ＳＡ)与金属表面的氧化层形成化学键 ,来改变金属表面的性质[1],同时还具有无污染、处理件耐蚀性好、与涂层结合牢固等特点。一般ＳＡ首先水解反应生成硅醇 ,再起缩合脱水、缩合齐聚反应形成Ｓｉ-Ｏ -Ｍ (Ｍ为无机表面 )共价键和网状结构的膜覆盖在基材表面[2 ],这层膜具有抗外界酸、碱、盐等与金属反应的性质。不同ＳＡ的水解速度不同 ,因此溶剂及体系 ｐＨ…     

利用紫外加速老化试验分析聚苯乙烯老化的影响因素

通过荧光紫外人工加速老化试验对聚苯乙烯(PS)样条的老化行为进行了研究。利用力学性能和黄色指数测试、FTIR及TG分析对老化后的试样进行了表征。结果表明:PS的化学老化主要受光辐照的影响,温度对老化起促进作用而,水分对老化的影响不明显。     

FTIR and Raman Spectroscopy of Carbon Nanoparticles in SiO2, ZnO and NiO Matrices

Coatings of carbon nanoparticles dispersed in SiO₂, ZnO and NiO matrices on aluminium substrates have been fabricated by a sol–gel technique. Spectrophotometry was used to determine the solar absorptance and the thermal emittance of the composite coatings with a view to apply these as selective solar absorber surfaces in solar thermal collectors. Cross-sectional high resolution transmission electron microscopy (X-HRTEM) was used to study the fine structure of the samples. Raman spectroscopy was used to estimate the grain size and crystallite size of the carbon clusters of the composite coatings. X-HRTEM studies revealed a nanometric grain size for all types of samples. The C–SiO₂, C–ZnO and C–NiO coatings contained amorphous carbon nanoparticles embedded in nanocrystalline SiO₂, ZnO and NiO matrices, respectively. Selected area electron diffraction (SAED) showed that a small amount of Ni grains of 30 nm diameter also existed in the NiO matrix. The thermal emittances of the samples were 10% for C–SiO₂, 6% for the C–ZnO and 4% for the C–NiO samples. The solar absorptances were 95%, 71% and 84% for the C–SiO₂, C–ZnO and C–NiO samples, respectively. Based on these results, C–NiO samples proved to have the best solar selectivity behaviour followed by the C–ZnO, and last were the C–SiO₂ samples. Raman spectroscopy studies revealed that both the C–ZnO and C–NiO samples have grain sizes for the carbon clusters in the range 55–62 nm and a crystallite size of 6 nm.     

红外光谱技术的进展及其应用

对漫反射、衰减全反射傅里叶变换红外光谱和差谱等技术及其应用进行了简单介绍     

A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy

Second derivative and Fourier self-deconvolution (FSD) are two commonly used techniques to resolve the overlapped component peaks from the often featureless amide I band in Fourier transform infrared (FTIR) curve-fitting approach for protein secondary structural analysis. Yet, the reliability of these two techniques is greatly affected by the omnipresent water vapor in the atmosphere. Several criteria are currently in use as quality controls to ensure the protein absorption spectrum is negligibly affected by water vapor interference. In this study, through a second derivative study of liquid water, we first argue that the previously established criteria cannot guarantee a reliable evaluation of water vapor interference due to a phenomenon that we refer to as sample’s absorbance-dependent water vapor interference. Then, through a comparative study of protein and liquid water, we show that a protein absorption spectrum can still be significantly affected by water vapor interference even though it satisfies the established criteria. At last, we propose to use the comparison between the second derivative spectra of protein and liquid water as a new criterion to better evaluate water vapor interference for more reliable second derivative and FSD treatments on the protein amide I band.     

Mechanical and Hygrothermal Aging Study on Polystyrene/Organo-montmorillonite Nanocomposites

Melt intercalation blending of polystyrene (PS)/organo-montmorillonite (OMMT) was prepared using the extrusion technique followed by compression molding. The loading of OMMT ranged from 2–10 wt.%. Maleic-anhydride grafted poly(styrene-block-(ethylene-co-butadiene)-block-styrene) (SEBSgMAH) was added to PS/OMMT composites in order to improve the impact strength of the composites. The concentration of SEBSgMAH ranged from 5–15%. The mechanical properties of PS/OMMT were characterized using flexural and impact tests. The morphological properties of the composites were studied using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Intercalation of the OMMT layered silicates in the PS matrix was conformed by the XRD spectra. The incorporation of SEBSgMAH improved the flexural strength, flexural displacement, and impact strength of PS/OMMT significantly. The percentage of retention and recovery in impact strength of PS/OMMT nanocomposites after being subjected to hygrothermal aging were increased by the addition of SEBSgMAH.     

Characterization of the deformation behavior of dynamic vulcanizates by FTIR spectroscopy

To clarify the deformation mechanisms and to improve the mechanical properties of dynamic vulcanizates, we studied their deformation behavior by Fourier‐transform infrared (FTIR) spectroscopy. It was found that the orientation in the dispersed phase (EPDM phase) is higher than in the matrix (PP phase) upon loading. The orientation of the rubber phase increases continuously. In the thermoplastic phase, a change of the deformation mechanism takes place. With respect to the total strain of the material, the orientation in the thermoplastic phase of the dynamic vulcanizates is lower, and in the elastic phase, it is higher than the corresponding orientation of the pure components. During stress relaxation, there is an increase of the orientation in the crystalline PP phase. Simultaneously, a decrease of the orientation in the EPDM phase is observed. Upon unloading, the orientation recovery in the EPDM phase is always complete, while the orientation recovery in the PP phase is reversible only at low strains. The critical point, where the elastic deformation gets lost, corresponds to the minimum in the orientation function curve. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 148–158, 2001