scholarly journals Some Applications of Vibrational Spectroscopy for the Analysis of Polymers and Polymer Composites

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1159 ◽  
Author(s):  
Liliane Bokobza
Keyword(s):  
Polymer Composites ◽  
Vibrational Spectroscopy ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Polymeric Materials ◽  
Molecular Structures ◽  
Hydroxyl Groups ◽  
Inorganic Particles ◽  
Reinforcing Fillers

Vibrational spectroscopies, including infrared and Raman techniques, are important tools for the characterization of chemical composition, molecular structures, and chain orientation under mechanical deformation of polymeric materials. The development of fiber-optic-based spectrometers has broadened the use of vibrational spectroscopy for process monitoring in various fields including polymerization, curing, and manufacturing processes. Combined with chemometrics, near-infrared (NIR) spectroscopy is now recognized as one of the most important techniques for polymer analyses. Infrared and Raman studies also offer invaluable means for the analysis of inorganic particles used as reinforcing fillers for polymers. The characterization of surface species and the nature of interfacial bonding between the organic and inorganic phases are important issues for the understanding of composite properties. Infrared spectroscopy is particularly convenient for the detection and analysis of hydroxyl groups on filler surfaces, and Raman spectroscopy is particularly well suited for the study of carbon-based materials. In both techniques, polymer-filler interactions can be evidenced through frequency shifts or width changes of bands associated with vibrational modes of functional groups of either macromolecular chains or filler particles. Selected examples of application of infrared and Raman spectroscopies illustrate their potential for monitoring polymer processes, measuring polymer orientation, and characterizing polymer composites.

Optical Absorption Spectroscopy of DNA-Wrapped HiPco Carbon Nanotubes

2019 ◽  
Vol 943 ◽  
pp. 95-99
Author(s):  
Li Jun Wang ◽  
Kazuo Umemura
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Optical Characterization ◽  
Optical Absorption Spectroscopy ◽  
Double Stranded Dna

Optical absorption spectroscopy provides evidence for individually dispersed carbon nanotubes. A common method to disperse SWCNTs into aqueous solution is to sonicate the mixture in the presence of a double-stranded DNA (dsDNA). In this paper, optical characterization of dsDNA-wrapped HiPco carbon nanotubes (dsDNA-SWCNT) was carried out using near infrared (NIR) spectroscopy and photoluminescence (PL) experiments. The findings suggest that SWCNT dispersion is very good in the environment of DNA existing. Additionally, its dispersion depends on dsDNA concentration.

Study of the Infrared Spectral Features of an Epoxy Curing Mechanism

2008 ◽  
Vol 62 (10) ◽  
pp. 1129-1136 ◽  
Author(s):  
Liang Li ◽  
Qili Wu ◽  
Shanjun Li ◽  
Peiyi Wu
Keyword(s):  
Correlation Analysis ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Diglycidyl Ether ◽  
Hydroxyl Groups ◽  
Spectral Correlation ◽  
Derivative Analysis ◽  
Curing Mechanism ◽  
Infrared Spectral ◽  
Epoxy Groups

In this work, the isothermal curing process of diglycidyl ether of bisphenol A(DGEBA) cured with 4,4′-diaminodiphenylmethane (DDM) was monitored in situ by mid-infrared (MIR) and near-infrared (NIR) spectroscopy. With the help of generalized two-dimensional (2D) correlation analysis, the results obtained showed that, during curing, the change of amine and epoxy groups was simultaneous, taking place prior to the change of hydroxyl groups, followed by the change of CH2/CH groups, resulting from the ring-opening reaction of epoxy groups. In addition, 2D MIR×NIR hetero-spectral correlation analysis and second-derivative analysis were also employed, by means of which direct evidence of the curing mechanism could be obtained and obscure NIR band assignments in the overlapped CH combination region could be made.

scholarly journals Quantitative Characterization of Arnicae flos by RP-HPLC-UV and NIR Spectroscopy

Foods ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Daniela Ivanova ◽  
Vera Deneva ◽  
Dimitrina Zheleva-Dimitrova ◽  
Vesela Balabanova-Bozushka ◽  
Daniela Nedeltcheva ◽  
...  
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Sesquiterpene Lactones ◽  
Nir Spectroscopy ◽  
Spectral Distortion ◽  
Active Components ◽  
Quantitative Characterization ◽  
Convolution Window ◽  
Spectra Processing

The possibility of applying near-infrared (NIR) spectroscopy to monitor 13 active components (phenolic acids, flavonoids, and sesquiterpene lactones) in Arnicae flos was studied. The preprocessing of the spectra were performed by using the conventional Golay-Savitzky procedure and the newly developed step-by-step filter. The results obtained show that the step-by-step filter derivatives provide a better signal-to-noise ratio at a lower convolution window. Better calibration for the content of protocatechuic acid, chlorogenic acid, caffeic acid, p-cumaric acid, ferulic acid, isoquercitrin, and quercetin were obtained by step-by-step filter derivatives, compared to the direct raw spectra processing and the Golay-Savitzky approach. Although the step-by-step filter substantially reduces the spectral distortion, the convolution procedure leads to loss of spectral points in the red end of the spectral curve. Probably for this reason this approach shows better calibration only in seven of the monitored 13 active components.

Quantitative Analysis of Hydrogen Bonding in Poly(4-Vinylphenol) Blends Using near Infrared Spectroscopy

2003 ◽  
Vol 11 (3) ◽  
pp. 183-191 ◽  
Author(s):  
Haijun Cai ◽  
Josée Brisson
Keyword(s):  
Hydrogen Bonding ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Weight Fraction ◽  
Hydroxyl Groups ◽  
Absorption Coefficients ◽  
Oh Groups ◽  
Refinement Method ◽  
Poly Ethylene ◽  
Vinyl Phenol

Quantitative evaluation of hydrogen bonding of poly(4-vinyl phenol)/poly(ethylene oxide) PVPh/PEO blends was conducted using Fourier transform near infrared (FT-NIR) spectroscopy. Absorption coefficients of the free ( aF), intra- (PVPh–PVPh) ( aA) and inter-associated (PVPh–PEO) hydroxyl groups ( aI) were estimated. Two sets of approximations were tested, including adopting a least-squares refinement method to calculate absorption coefficients from all NIR spectra or using a literature value for aF. Each set of absorption coefficients thus estimated were used to determine hydroxyl concentration for the free and hydrogen-bonded hydroxyl overtone bands in the blends. A comparison is made among the resultant concentrations of the free, intra- and inter-associated hydroxyl groups. The concentration of free hydroxyl groups markedly decreases with PEO percentage, and that of intra-associated hydroxyl remains almost constant. Concentration for the inter-associated hydroxyl groups in the blends increases very slowly above 0.2 PEO weight fraction. When concentration of OH groups is reported per PVPh chain, FT-NIR measurements show a broad maximum in the number of interchain hydrogen bonds. This result can be used to explain partially previous orientation behaviour observed for PVPh/PEO blends.

Near Infrared Spectroscopy for Polymer Research, Quality Control and Reaction Monitoring

2007 ◽  
Vol 15 (5) ◽  
pp. 269-282 ◽  
Author(s):  
N. Heigl ◽  
C.H. Petter ◽  
M. Rainer ◽  
M. Najam-ul-Haq ◽  
R.M. Vallant ◽  
...  
Keyword(s):  
Near Infrared ◽  
Structural Parameters ◽  
Nir Spectroscopy ◽  
Physical And Mechanical Properties ◽  
Polymeric Materials ◽  
Kinetic Studies ◽  
Research Quality ◽  
Morphological Properties ◽  
Natural Substances ◽  
Infrared Measurements

This review covers recent applications of near infrared (NIR) spectroscopy in the determination of physico-chemical and morphological parameters of polymeric materials. Near infrared measurements in the diffuse reflection mode are highlighted, which analyse the structural parameters such as porosity, surface area and particle size. Fundamentals and applications of the technique are discussed and examples of quantitative and qualitative analysis are explained. Various approaches like on- and in-line techniques, bulk measurements and kinetic studies for recording spectra are discussed. Furthermore, this review addresses the development of calibrations, which allow for the differentiation and quantification of materials with varying physical and morphological properties. Parameters like constitution, composition and crystallinity have a strong affect on the material characteristics. Therefore, chemical, physical and mechanical properties of synthetic as well as natural substances, such as polymeric composites and cotton or wool, need to be studied in-depth. To sum up, NIR spectroscopy has been developed as a flexible, robust and high-throughput analytical method that can be combined with chemometric and multivariate data analysis for fast and reliable screening in material science.

Non Destructive Characterization of Wooden Members Using near Infrared Spectroscopy

2013 ◽  
Vol 778 ◽  
pp. 328-334 ◽  
Author(s):  
Anna Sandak ◽  
Mariapaola Riggio ◽  
Jakub Sandak
Keyword(s):  
Near Infrared ◽  
Species Recognition ◽  
Nir Spectroscopy ◽  
Visual Assessment ◽  
Additional Information ◽  
Drilling Resistance ◽  
Non Destructive ◽  
Non Destructive Characterization ◽  
Routine Assessment

On site characterization of wood members is a very challenging task, after considering all the variables affecting the whole structure itself and material used for construction. The up-to-data procedures are limited to few characterizations, and in general based on visual assessment supported by local drilling resistance analysis, stress-wave time of flight measurement and/or moisture content estimation. The goal of this work was to promote near infrared (NIR) spectroscopy as a supplementary tool providing additional information for the expert assessing timber structures. The paper presents several examples of successful NIR application in species recognition, physical properties prediction, evaluation of wood weathering and/or fungal degradation level. However, it must be stated that implementation of NIR in routine assessment protocols requires prior preparation of a dedicated databases of high precision reference values to build reliable, flexible and sufficiently generalized models.

Fire Retardancy of Polymeric Materials Incorporated With Nanoscale Inclusions

2013 ◽  
Author(s):  
A. Ghazinezami ◽  
A. Jabbarnia ◽  
R. Asmatulu
Keyword(s):  
Flame Retardant ◽  
Flame Retardancy ◽  
Surface Characterization ◽  
Polymeric Materials ◽  
Cost Effective ◽  
Industrial Applications ◽  
Molecular Structures ◽  
Chemical Compositions ◽  
Test Results

Polymeric materials have a wide variety of applications in many manufacturing industries. However, because of the molecular structures and chemical compositions of polymeric materials, they have considerably low resistances against the fire/heat. Although these materials are highly flammable, their flame retardancy can be improved significantly by incorporating with flame retardant nanomaterials. Nanoclay and nanotalc are some of the examples of the flame retardant nanomaterials which are highly cost effective and environmentally friendly for these applications. Thus, these inclusions have a great potential to improve thermal, electrical, and mechanical properties of the new materials. This study is mainly focused on the effects of nanoparticle additions in the polyvinyl chloride (PVC) in terms of the flame retardancy. Five sets of nanocomposite materials were prepared using the solvent casting method at different weight percentages of the nanomaterials. The flame retardancy values of the resultant nanocomposite samples were determined using the ASTM UL 94 standard tests. The test results were also supported with the thermogravimetric analysis (TGA) tests. Surface characterization of the resultant materials was carried out using scanning electron microscopy (SEM). Test results showed that the flame retardancy values of the new nanostructured materials were significantly enhanced in the presence of nanoscale inclusions, which may be useful for various industrial applications.

scholarly journals Characterization of Biochar Properties Affected by Different Pyrolysis Temperatures Using Visible-Near-Infrared Spectroscopy

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Haiqing Yang ◽  
Kuichuan Sheng
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Calorific Value ◽  
Volatile Matter ◽  
Coefficient Of Determination ◽  
Single Type ◽  
Good Prediction ◽  
Cotton Stalk ◽  
Fixed Carbon

Rapid characterization of biochar for energy and ecological purpose utilization is fundamental. In this work, visible and near-infrared (vis-NIR) spectroscopy was used to measure ash, volatile matter, fixed carbon contents, and calorific value of three types of biochar produced from pine wood, cedar wood, and cotton stalk, respectively. The vis-NIR spectroscopy was also used to discriminate biochar feedstock types and pyrolysis temperature. Prediction result shows that partial least squares (PLS) regression calibrating the spectra to the values of biochar properties achieved very good or excellent performance with coefficient of determination (R2) of 0.86~0.91 and residual prediction deviation (RPD) of 2.58~3.32 for ash, volatile matter, and fixed carbon, and good prediction with R2 of 0.81 and RPD of 2.30 for calorific value. Linear discrimination analysis (LDA) of the principal components (PCs) produced from PCA of wavelength matrix shows that three types of biochar can be successfully discriminated with 95.2% accuracy. The classification of biochar with different pyrolysis temperatures can be conducted with 69% accuracy for all three types and 100% accuracy for single type of cotton stalk. This experiment suggests that the vis-NIR spectroscopy is promising as an alternative of traditionally quantitative and qualitative analysis of biochar properties.

Near-Infrared Spectroscopy for Monitoring the p-Diethylbenzene Separation Process

2000 ◽  
Vol 54 (5) ◽  
pp. 715-720 ◽  
Author(s):  
Hoeil Chung ◽  
Min-Sik Ku ◽  
Jaebum Lee ◽  
Jaebum Choo
Keyword(s):  
Aromatic Hydrocarbons ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Separation Process ◽  
Molecular Structures ◽  
Calibration Model ◽  
Spectral Features ◽  
Excellent Correlation ◽  
Absorption Bands ◽  
Combination Bands

Near-infrared (NIR) spectroscopy has been successfully used for the monitoring of important components in the p-diethylbenzene (PDEB) separation process. The process is composed of mostly diethylbenzene isomers ( ortho, meta, and para) and extractant ( p-xylene), as well as other C9–C11 aromatic hydrocarbons. Therefore, the major concern in using NIR spectroscopy in this process was the spectral resolution of NIR spectra among diethylbenzene isomers, since the molecular structures of each isomer were very similar. NIR spectral features of o-diethylbenzene (ODEB), m-diethylbenzene (MDEB), and PDEB showed considerable spectral differences in the 2100–2220 nm range. These combination bands originated from the combination of the =C–H stretch at 3100–3000 cm−1 and C=C ring stretch at 1600–1450 cm−1. Characteristic C=C ring stretches of each isomers in the IR region result in selective and identifiable spectral features in the NIR region. Partial least-squares (PLS) regression was used to build each calibration model for ODEB, MDEB, PDEB, and p-xylene (PX). PLS calibration results of the four components showed excellent correlation with gas chromatography data. The combination region (2100–2500 nm) provided the important isomeric spectral information for PLS calibration since the absorption bands in this region were the most sensitive and selective.

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