杉木光变色的FTIR光谱分析

暴露于室外环境的木材或木制品,由于受气候因子的作用其表面性状和品质发生劣化,主要表现为木材变色,大大降低其利用价值。以人工林杉木为研究对象,利用模拟太阳辐射的氙光衰减仪对木材表面进行光劣化处理,采用傅里叶变换红外(FTIR)光谱技术分析了木材光变色过程中化学成分的变化,建立了木材变色与化学成分变化之间的关系。试验结果表明:光照过程中,1 512,1 462,1 269和1 227 cm-1处与木质素有关的吸收峰强度明显降低,1 720～1 735 cm-1处非共轭羰基伸缩振动吸收明显增强,木材表面发生光氧化反应,木质素明显降解,同时不断有新的羰基化合物生成;光照80 h内,木质素的降解以及羰基化合物的生成速度较快,此后变化不显著;木材表面部分多糖物质(纤维素和半纤维素)被氧化降解。研究表明,木材光照过程中的颜色变化(ΔE*)与木质素的降解以及羰基官能团的生成密切相关。     

柠檬酸和乙二胺改性前后麦秸秆的红外光谱分析比较

对天然麦秸秆(NWS)、柠檬酸改性麦秸秆(CWS)、乙二胺改性麦秸秆(EWS)的红外光谱进行了比较分析.NWS的红外吸收光谱主要由碳水化合物如木质素、纤维素等吸收带组成.NWS表面的羟基吸收峰出现在3405.16cm-1、2916.81cm-1处的吸收峰来自亚甲基中C—H的伸缩振动.1736.02cm-1和1602.21cm-1处的吸收峰是由C=O的伸缩振动引起的;苯环的骨架伸缩振动峰出现在1511.33cm-1;1425.47cm-1处的吸收峰是来自羧基的C—O伸缩振动,1376.19cm-1处为CH2的弯曲振动峰.与NWS的红外光谱图相比,CWS的主要变化为1738.13cm-1和1592.06cm-1处C=O吸收峰强度显著增加;EWS的主要变化为3405.16cm-1处的吸收峰蓝移至3417.43cm-1,且强度增加,1736.02cm-1处的吸收峰消失,CH2的C—H伸缩振动峰(2903.49cm-1)和弯曲振动峰(1382.91cm-1)强度显著增加,结果说明改性后分别引入了羧基和胺基.     

水热法碱活化生物质乙醇木质素的化学结构变化

为了提高生物质乙醇木质素的反应活性,采用水热法在四种不同碱性条件下对生物质乙醇木质素进行催化活化处理。运用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、凝胶色谱(GPC)和有机元素分析手段研究了生物质乙醇木质素被四种碱(NaOH, KOH, K₂CO₃和Na₂CO₃)催化活化前后木质素的化学结构以及组分变化。FTIR结果表明生物质乙醇木质素碱经处理后,木质素的酚羟基特征吸收峰1 375 cm-1都有明显增大趋势,醚键振动吸收峰1 116 cm-1减弱,1 597和1 511 cm-1处苯环骨架振动吸收峰强度变化很小;1H-NMR分析结果表明酚羟基含量都有增大趋势,增加顺序为：KOH>NaOH>K₂CO₃>Na₂CO₃,其中KOH处理后的木质素酚羟基含量增加量为原木素的170%。这由于离子半径大的钾离子更容易与木质素β—O—4醚键上的氧形成加和物,进而发生醚键断裂反应,生成新的酚结构衍生物。GPC 表明生物质乙醇木质素碱处理后分子量分布向低分子区域扩展, 数均和重均分子量减小。元素分析结果显示木质素经过水热反应处理后,C含量都有所增加,而H和O含量则降低了,表明木质素经水热反应处理过程中有脱羧基作用,同时蛋白质的含量也有所降低,提高了木质素的纯度。这都有利于直接将木质素用于制备酚醛树脂胶黏剂。     

硼氢化钠还原对褐腐木质素结构特征的影响

采用FTIR、UV-Visible、NMR和GPC分析手段研究了褐腐木质素被NaBH₄还原前后的化学结构变化。FTIR表明褐腐木质素还原后1 677 cm-1处与苯环共轭的羰基峰消失,1 715 cm-1处非共轭羰基峰强度减弱,1 509和1 603 cm-1处苯环骨架振动吸收峰强度变化很小;UV表明褐腐木质素还原后位于288 nm的最强吸收峰和300～400nm区域的吸收强度降低;1H NMR表明褐腐木质素还原后甲氧基和酚羟基数量减少,醇羟基数量增加,褐腐木质素芳香环和结构单元联接键上的氢质子数增加;GPC表明褐腐木质素还原后分子量分布向高分子区域扩展,数均和重均分子量增大,分子量分布明显变宽。NaBH₄在碱性环境中可以将褐腐木质素中的共轭羰基完全还原为羟基,非共轭羰基部分还原为羟基,其侧链结构部分被改变,苯环结构稳定,褐腐木质素在还原过程中发生了缩合反应。     

水性涂料施工过程中微观结构的FTIR研究

以市售立邦水性涂料作为研究对象,溶剂水作为变量因子。配制不同水料比的涂料系列样品,分别用FTIR/ATR、FTIR/漫反射光谱表征湿料、涂膜的微观结构特征,湿料抽滤得到的固型物用FTIR/漫反射光谱表征。分析其官能团变化情况,研究施工过程,溶剂对涂膜的影响。结果显示：随着加水量的增加,湿料的FTIR/ATR光谱中,1 727 cm-1对应的羰基吸收峰,逐渐转为肩峰,871 cm-1吸收峰发生蓝移,峰强度逐渐减弱;涂膜的漫反射红外图谱,3 400 cm-1的—OH吸收峰、3 030 cm-1不饱和—CH吸收峰强度逐渐变弱,2 962和2871 cm-1的甲基和亚甲基的吸收峰强度逐渐增强,2 516 cm-1吸收峰位移至2 603 cm-1形成肩峰,1 647 cm-1吸收峰逐渐位移至1 455 cm-1,1 107 cm-1对应的C—O伸缩振动吸收峰发生红移。在水性涂料施工过程中,溶剂水与涂料分子间存在相互作用,对涂层分子中电子云的密度分布有显著的影响,此结果对涂料的生产及施工有参考意义。     

UV辐射前后乙酰化木材的化学组分结构变化与微观构造表征

以杨木木粉为试样,进行不同时长的乙酰化处理,利用紫外光加速老化,探讨不同乙酰化度对木材耐光性能的影响,根据FTIR光谱分析试样化学组分特征吸收峰强度的变化规律,建立乙酰化处理时间与木材化学组分变化之间的关系。结果表明：UV辐射前,乙酰化木粉在1 739 cm-1处饱和酯化合物中CO和 1 385 cm-1处乙酸酯基中C—H的特征吸收峰强度均大于原木粉,处理40 min木粉的吸收峰强度最大,增重率最高,木粉的乙酰化效果显著;UV辐射后,乙酰化木粉在1 504 cm-1处木质素中苯环特征吸收峰强度明显大于原木粉,且乙酰化处理40 min木粉的吸收峰强度最大,表明乙酰化处理能够有效抑制木材化学组分的光降解反应,提高木材的耐光老化性能,其中处理40 min的效果最佳;SEM图片显示,乙酰化处理木粉的纤维状表面较原木粉更加均匀,材料粒径更小,乙酰化处理能有效提高木材的稳定性。     

块菌的傅里叶变换红外光谱研究

块菌是珍稀野生食用菌,其蛋白质和糖类含量较高,块菌多糖具有潜在的药用价值。文章利用傅里叶变换红外光谱技术(FTIR)对五种云南野生块菌作了研究。结果表明,块菌属真菌有其独特的光谱特征,全谱最强峰为出现在1 042和1 077 cm-1附近的强双峰。在脂分子的羰基峰1 742 cm-1及糖类异构体的指纹区1 200～750 cm-1,不同种类、不同产地块菌的光谱有明显差异,另外,正常块菌和霉变块菌的光谱亦有明显差异,主要体现在谱峰吸收强度的变化上,部分谱峰吸收强度比的变化表明,块菌样品变质前后,其蛋白质和糖类物质的含量发生了变化。FTIR光谱提供了块菌成分的有关化学信息,为鉴别块菌和区分块菌的种类、质量提供了简便快捷的手段。     

采用FTIR技术研究高压处理对冻干大豆分离蛋白构象的影响

采用傅里叶转换红外光谱技术(FTIR)研究了高压(HP)处理对冷冻干燥的大豆分离蛋白(SPI)构象的影响。在SPI的去卷积FTIR光谱的酰胺Ⅰ′区域(1 600～1 700 cm-1),观察到12个与蛋白构象相关的红外吸收峰,分别对应于CO键伸缩振动与肽键的C—N伸缩振动。通过对该区域的峰强度与波数分析显示,压力为200～400 MPa的HP处理导致SPI在该区域的峰发生明显的“红移”(约2 cm-1),强度也显著增加。更高的HP处理进一步增强了SPI的酰胺Ⅰ′区域的峰强度。对酰胺Ⅱ峰分析显示,HP处理导致酰胺Ⅱ峰(如1 560～1 500 cm-1)的强度、面积逐渐增加(与压力呈正相关)。以上分析显示,HP处理导致SPI的二级与三级结构逐渐打开,然而变性蛋白的结构在高压释放后经历一个“重构过程”。     

太空育种中药材防风的FTIR分析与表征

采用傅里叶变换红外光谱法（FTIR）对第四代太空防风与地面组防风和对照品防风进行了对比分析。三种防风主要吸收峰的峰形峰位相近,说明太空防风的主要化学成分和基本结构并未发生明显变化, 但1 640 cm-1处酮的CO吸收峰明显增强,表明色原酮类含量明显增加;2 927和2 856 cm-1处亚甲基的CH吸收峰和1 054 cm-1处C—O吸收峰明显增强,表 明色原酮苷类、多糖类含量明显增加;1 743 cm-1处内酯的CO吸收峰强于地面组,低于对照品,说明香豆素类含量较地面组增加,少于对照品。整体来看,太空防风成分得到优化,其有效 成分含量明显提升。     

马尾松木材褐腐降解的红外光谱研究

用傅立叶变换红外光谱(FTIR)研究了马尾松木材被茯苓褐腐菌降解过程中化学成分的变化。测量了木质素和综纤维素的相关红外吸收峰的峰高比值,用湿化学方法测定了未褐腐和不同褐腐时间木材的Klason木质素含量和综纤维素含量,分析了红外吸收峰峰高比值与Klason木质素含量和综纤维素含量的相关性。褐腐15周内,1736和1372cm-1处归属于综纤维素的吸收峰强度逐渐减弱,1510和1225cm-1处归属于木质素的吸收峰强度逐渐增强;但褐腐15周后,1736和1372cm-1处的吸收强度却开始略微增强,1510和1225cm-1处吸收强度略微下降。I1510/I1736,I1510/I1372,I1225/I1736和I1225/I1372与Klason木质素和综纤维素含量之间均存在非常好的线性相关,R2为0.96～0.99。I1736/I1510和I1372/I1510与综纤维素含量之间存在高度线性相关,R2=0.96。结果说明用红外光谱技术可以对木材褐腐过程中的综纤维素含量和Klason木质素含量进行准确分析。     

紫外光下毛竹的自由基与光电子能谱分析

分析了紫外光照射下毛竹自由基的变化规律和表面化学组成及结构的变化.利用电子自旋共振波谱和X射线光电子能谱技术,分别测量紫外光辐照后毛竹颗粒的自由基波谱和X射线光电子能谱.结果表明:毛竹自由基的光谱分裂因子g=2.003 3,自由基的强度随着辐照时间按Y=1-e-b,Pt规律增加;紫外光照60 min后毛竹表面O/C原子比稍有增加,C-C和C-H含量增加,C-O和C=O含量减少,-O-C=O含量增加为原来的3倍左右,说明毛竹表面生成了一些含氧官能团或碳的氧化态增高.     

紫外光下毛竹的自由基与光电子能谱分析

分析了紫外光照射下毛竹自由基的变化规律和表面化学组成及结构的变化.利用电子自旋共振波谱和X射线光电子能谱技术,分别测量紫外光辐照后毛竹颗粒的自由基波谱和X射线光电子能谱.结果表明:毛竹自由基的光谱分裂因子g=2.003 3,自由基的强度随着辐照时间按Y=1-e^-b_iPt规律增加;紫外光照60 min后毛竹表面O/C原子比稍有增加,C-C和C-H含量增加,C-O和C=O含量减少,-O-C=O含量增加为原来的3倍左右,说明毛竹表面生成了一些含氧官能团或碳的氧化态增高.     

Comparative study of the photo-discoloration of moso bamboo (Phyllostachys pubescens Mazel) and two wood species

Bamboo or bamboo products undergo surface degradation during outdoor exposure resulting in lower quality in service. In this study, the effect of UV-vis light irradiation on changes in color and surface chemistry of moso bamboo (Phyllostachys pubescens Mazel) was investigated. For comparison purpose, two wood species (a soft and a hardwood) were also studied to present their differences in degradation performance. Color characterization was performed by measuring CIELab parameters (L*, a*, b* and ΔE*), and Fourier transform infrared (FTIR) spectroscopy was used to analyze the chemical changes induced by irradiation. The results showed that the surface color of bamboo changed rapidly during the irradiation process. Compared with the wood species, bamboo was less influenced by photo-irradiation. Chemical analysis indicated that irradiation altered the chemical structures of bamboo surfaces. Lignin was the most sensitive component to photo-degradation and the intensities of its characteristics bands decreased significantly during the irradiation process. This was accompanied by formation of new carbonyl groups at 1735 cm⁻¹. The rate of lignin degradation and carbonyl formation in bamboo was relatively lower compared with the wood species. The color changes (ΔE*) was well correlated with lignin degradation and carbonyl formation regardless bamboo or the wood species.     

Effects of atomic oxygen irradiation on the surface properties of phenolphthalein poly(ether sulfone)

To study the effects of low earth orbit environment on the surface properties of polymers, phenolphthalein poly(ether sulfone) (PES-C) blocks were irradiated by atomic oxygen in a ground-based simulation system. The surface properties of the pristine and irradiated blocks were studied by attenuated total-reflection FTIR (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM). It was found that atomic oxygen irradiation induced the destruction of PES-C molecular chains, including the scission and oxidation of PES-C molecular chains, as evidenced by FTIR and XPS results. The scission of PES-C molecular chains decreased the relative concentration of C in the surface, while the oxidation increased the relative concentration of O in the surface. The changes in surface chemical structure and composition also changed the surface morphology of the block, which shifted from smooth structure before irradiation to “carpet-like” structure after irradiation.     

Efficient micromachining of poly(vinylidene fluoride) using a laser-plasma EUV source

In this paper an efficient micromachining of poly(vinylidene fluoride) (PVDF) by direct photo-etching with a laser-plasma EUV (extreme ultraviolet) source was demonstrated for the first time. Mass spectroscopy was employed to investigate the ablation products and revealed emission of numerous molecular species of C-containing fragments of the polymer chain. Chemical surface changes after irradiation were investigated using X-ray photoelectron spectroscopy (XPS). The XPS spectra obtained for PVDF samples, irradiated with low and high EUV fluence, indicate significant differences between chemical structures in near-surface layers. It was shown that irradiation with low fluence results in defluorination and thus carbon enrichment of the polymer in near-surface layer. In contrary, irradiation with high fluence leads to intense material ablation and hardly modifies the chemical structure of the remaining material.     

The influence of UV irradiation on surface composition of collagen/PVP blended films

The surface chemical composition and surface properties of collagen/poly(vinyl pyrrolidone) (PVP) blended films before and after UV irradiation (λ = 254 nm) were investigated using X-ray Photoelectron Spectroscopy (XPS), FTIR-ATR spectroscopy and Atomic Force Microscopy (AFM).The XPS results showed that collagen is enriched on the surface of the collagen/PVP blend. The surface composition of the collagen film was changed more by UV irradiation than the surface composition of the collagen/PVP blend.FTIR-ATR spectra showed that the positions of the amide bands in collagen are more altered after UV irradiation than those for the collagen/PVP blends.AFM images showed that the collagen surface is ordered contrary to PVP. The blend surface was similar to the pure collagen surface and confirms that there is more collagen present at the surface (higher concentration of collagen at the surface compared to PVP). UV irradiation caused only the small changes in the surface morphology of the collagen/PVP films. All of the results confirm that the surface of the collagen/PVP blend is more photoresistant than collagen.     

γ射线辐照处理竹材化学组分及结晶度变化研究

利用核磁共振波谱仪和X射线衍射仪,对γ射线辐照处理前后的竹材进行CP/MAS13C-NMR图谱、XRD光谱分析,得出竹材细胞壁主要化学组分在辐照过程中结构和性质的变化规律.随着辐照剂量升高,竹材纤维素结晶度呈现先升高后降低的趋势,半纤维素发生降解,木质素由非酚型向酚型转变.     

γ射线辐照处理竹材化学组分及结晶度变化研究

利用核磁共振波谱仪和X射线衍射仪,对γ射线辐照处理前后的竹材进行CP/MAS 13C-NMR图谱、XRD光谱分析,得出竹材细胞壁主要化学组分在辐照过程中结构和性质的变化规律。随着辐照剂量升高,竹材纤维素结晶度呈现先升高后降低的趋势,半纤维素发生降解,木质素由非酚型向酚型转变。     

Wettability characteristic of PTFE and glass surface irradiated by keV ions

Commercial PTFE and soda lime glass were irradiated by keV O³⁺ and F⁴⁺. After irradiation, in contrast to the decrease of contact angle on PTFE, contact angle on glass increased apparently. SEM observation revealed that irradiation did not cause noticeable change in surface topological structure. XPS was used to investigate chemical structure changes on the surface. Defluorination effect and formation of oxygen containing group caused by irradiation were considered to the reason of more hydrophilic PTFE surface. On the surface of irradiated glass, more carbon contaminations were observed. The differences of underlying physical and chemical processes between the two kinds of samples are discussed.     

Study on the surface performance of carbon fibres irradiated by γ-ray under different irradiation dose

The technology of high-energy irradiation is widely used in the field of material interface modification because of its high efficiency, energy conservation and environment friendliness. In this paper, γ-ray irradiation graft technology was used in order to enhance the surface performance of the carbon fibre (CF). The surface chemical elements and functional groups of untreated and irradiated CF were observed by photoelectron spectroscopy (XPS). The results show that the value of O/C and the quantity of oxygen functional groups on CF surface were enhanced efficiently after treatment by γ-ray irradiation graft technology. The morphology of CF was characterized by scanning electron microscopy (SEM) and atom forced microscopy (AFM), respectively. The surface roughness of CF was greatly increased compared with the untreated CF. Moreover, the interface performance was clearly improved after irradiation.