3. Characterization of biopolymers

The most widely used characterization techniques of biopolymers include Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). In this section, we discuss the characterization of polysaccharides: cellulose, chitin, and chitosan using FTIR, XRD, TGA and SEM.

#### 3.1 Materials

Microcrystalline (MCC) was provided by FMC Biopolymer (Newark, DE). Chitosan (75–85% deacetylated) and chitin from shrimp shells were used as received from Sigma-Aldrich (Saint Louis, MO).

#### 3.2 Instrumentation

#### 3.2.1 X-ray diffraction (XRD) analysis

The wide-angle powder X-ray diffraction patterns of the samples were recorded on a SmartLab XRD system (Rigaku Corporation, ModelHD2711N) with CuK<sup>α</sup> radiation (λ = 1.541867 Å). The accelerating voltage and tube current used were 40 kV and 44 mA, respectively. A continuous scanning was performed at a scan speed of 2°/min and the 2θ ranged from 10° to 60°.

#### 3.2.2 Thermogravimetric analysis (TGA)

Thermogravimetric (TG) analyses of cellulose, chitin and chitosan samples were obtained using a PerkinElmer Pyris1TGA instrument (PerkinElmer, Waltham, MA) furnished with a 20-sample auto-sampler. TG profiles were recorded in an inert nitrogen atmosphere (20 ml/min) from 37 to 600°C with a constant a heating rate of 10°C/min using a high-resolution mode. All data were analyzed using Pyris Data Analysis software.

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization… DOI: http://dx.doi.org/10.5772/intechopen.80898

#### 3.2.3 Scanning electron microscopy (SEM)

2.4 Nanofibrillation/nanoparticles (nanocellulose, nanochitin, nanochitosan)

The term "nanocellulose"/"nanochitin"/"nanochitosan" encompasses various materials derived from respective biopolymers, which possess at least one dimension in the nanometer range [14, 47]. Nanoparticles from cellulose and chitin are usually prepared by destructing the native hierarchical structure of these biopolymers [48]. Cellulose and chitin nanofibers, in general, are obtained by subjecting purified cellulose and chitin substrates to multiple mechanical shearing actions, which disintegrate the native microfibril structure and release enmeshed individual or bundle of fibrils. Chitosan nanofibers are typically produced by

Highly crystalline elongated rod like (or needle-like) nanoparticles called nanocrystals can be obtained when cellulose and chitin substrates are subjected to a strong acid hydrolysis treatment due to preferential dissolution of amorphous domains. For acid hydrolysis to produce nanocrystals, sulfuric acid and

hydrochloric acid are usually employed [50, 51]. Biopolymer nanoparticles can be directly processed into films and aerogels by drying from the suspension or they can

The most widely used characterization techniques of biopolymers include Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). In this section, we discuss the characterization of polysaccharides: cellulose, chitin, and chitosan

Microcrystalline (MCC) was provided by FMC Biopolymer (Newark, DE). Chitosan (75–85% deacetylated) and chitin from shrimp shells were used as

The wide-angle powder X-ray diffraction patterns of the samples were recorded

Thermogravimetric (TG) analyses of cellulose, chitin and chitosan samples were obtained using a PerkinElmer Pyris1TGA instrument (PerkinElmer, Waltham, MA) furnished with a 20-sample auto-sampler. TG profiles were recorded in an inert nitrogen atmosphere (20 ml/min) from 37 to 600°C with a constant a heating rate of 10°C/min using a high-resolution mode. All data were analyzed using Pyris Data

on a SmartLab XRD system (Rigaku Corporation, ModelHD2711N) with CuK<sup>α</sup> radiation (λ = 1.541867 Å). The accelerating voltage and tube current used were 40 kV and 44 mA, respectively. A continuous scanning was performed at a scan

be utilized as reinforcement agents in other polymer matrices.

3. Characterization of biopolymers

received from Sigma-Aldrich (Saint Louis, MO).

speed of 2°/min and the 2θ ranged from 10° to 60°.

using FTIR, XRD, TGA and SEM.

3.2.1 X-ray diffraction (XRD) analysis

3.2.2 Thermogravimetric analysis (TGA)

3.1 Materials

3.2 Instrumentation

Analysis software.

8

electrospinning [49].

Advanced Sorption Process Applications

The morphology of cellulose, chitin and chitosan samples was studied on a Hitachi S-4700 field emission scanning electron microscope (TM-100, Hitachi, Japan) with an accelerating voltage of 15 kV.

#### 3.2.4 Fourier transform infrared (FTIR) spectroscopy

FTIR spectra of the cellulose, chitin and chitosan samples were recorded using a PerkinElmer Spectrum-400 FTIR spectrometer equipped with a universal attenuated total reflectance (UATR) accessory (PerkinElmer, Waltham, MA). All FTIR spectra were collected at a spectral resolution of 4 cm<sup>1</sup> , with 32 co-added scans in the wavenumber range of 4000 to 650 cm<sup>1</sup> . The spectra were analyzed using PerkinElmer Spectrum software.

All samples were conditioned in an environmentally-controlled laboratory maintained at a relative humidity of 65 2% and temperature of 21 1°C for at least 48 h prior to their characterization.

#### 4. Characterization of cellulose, chitin and chitosan

#### 4.1 X-ray diffraction (XRD) analysis

Wide-angle X-ray diffraction measurements were collected for raw cellulose, chitin, and chitosan powder samples. Figure 3 shows the X-ray diffraction curves for cellulose, chitin, and chitosan. The XRD pattern of cellulose exhibits five major diffraction peaks at 14.9 (101), 15.8 (10ī), 21.8 (021) 22.5 (002) and 34.6 (004) which are in agreement with the literature values reported for cellulose I<sup>β</sup> [52]. The XRD patterns of chitin showed two strong reflections at 9.2° (020) and 19.1° (110) and minor reflections at 12.6° (021), 22.9° (130) and 26.2° (013) corresponding to α-chitin [53]. Chitosan shows two distinct peaks at 10.67 (020) and 19.92° (110) [54]. Our results suggest that chitin has the highest crystallinity as compared

Figure 3. Wide angle X-ray diffraction curves for cellulose, chitin and chitosan powder.

to cellulose and chitosan. The low crystallinity of chitosan is the result of the deacetylation process.

4.3 TG and DTG analysis

DOI: http://dx.doi.org/10.5772/intechopen.80898

4.4 SEM studies

Figure 5.

Figure 6.

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High-resolution thermogravimetry (TG) profiles recorded in flowing nitrogen (N2) were used to investigate the thermal stability of cellulose, chitin and chitosan, see Figure 5(a). All samples display two main weight loss regions at 35–150 and 250–450°C. In the first region, approximately, 5.1–9.0% of the weight loss was observed, which is attributed to the removal of physically adsorbed water. The second region represents the largest weight loss of 90.4, 86.6 and 63.4% for cellulose (1), chitin (2) and chitosan (3), respectively, corresponding to the degradation of polysaccharide structure of the biopolymer. The differential thermogravimetric (DTG) profiles generated from TG data are shown in Figure 5(b). The DTG curves for cellulose, chitin, and chitosan exhibit the main decomposition peaks at 371, 391 and 300°C, respectively. These results suggest that among three biopolymers, chitin has the highest thermal stability while chitosan has the least thermal stability.

Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization…

The morphological characteristic of cellulose, chitin and chitosan was investigated and Figure 6 shows the comparison of typical surface morphologies for cellulose, chitin and chitosan. As it can be seen, all samples exhibited more irregu-

lar, flat, rough nanofiber surface with no porosity.

(a) TG and (b) DTG profiles of cellulose, chitin and chitosan.

SEM images of (a) microcrystalline cellulose, (b) chitin and (c) chitosan at 100 um magnification.
