**2.1. Materials selection**

All samples were fabricated using poly (D-glucosamine) deacetylated chitosan ((C<sup>6</sup> H11O<sup>4</sup> N)n, 75% deacetylation, Sigma Aldrich), cellulose powder (cotton linens, Sigma Aldrich) and strontium titanium oxide ((SrTiO3 ), 99 + %, Fisher). A chitosan solution was dissolved in acetic acid solution (CH3 CO<sup>2</sup> H, 99.7 + %, Alfa Aesar) while 4-methylmorpholine N-oxide solvent (CH3 CO<sup>2</sup> H, 99.7 + %, Alfa Aesar) was needed to dissolve the cellulose powder. The fabrication of the composites consisted of two subsequent stages: (1) fabrication of chitosan-cellulose films, and (2) synthesis of chitosan-cellulose composites containing SrTiO<sup>3</sup> nanoparticles.

we could reduce the particle size to the smallest possible, the particle size was determined at different milling times using the Scherrer equation [12, 13]. Afterwards, the particle size was computed at different milling times to select the most time-efficient operation, i.e., maximum size reduction at minimal time. The overall technique had been successfully implemented to

On the Mechanical and Dielectric Properties of Biocomposites Containing Strontium Titanate Particles

http://dx.doi.org/10.5772/intechopen.76858

All samples were characterized with a Rigaku ULTIMA III diffractometer operated at 40 kV and 44 mA. The characterization of the composites was conducted at 25°C with a 2θ step of 0.02° and a 1 s dwelling time. The target used was copper with a Kα wavelength of 0.154178 nm.

To measure the capacitance of the composites, we utilized a QuadTech 2200 automatic transformer system (with an AC supply). The frequency range was set from 1 to 10 kHz. Once the capacitance readings as a function of the frequency were recorded, the dielectric constant was

*A*.*ε*<sup>0</sup>

, the permittivity of vacuum [16].

where K is the dielectric constant; C, the capacitance of the dielectric material; A, the area of

To study dielectric breakdown in the composite, a GW INSTEK GPS-3303 DC power supply provided the current passing through the material when the applied voltage changed from 5 to 60 V. A GW-INSTEK GDM-8246 power meter connected in series was used to register the current values by following the guidelines of the ASTM D-149 standard [17]. According to this standard, the current flow must be recorded at equal increments of voltage and after a specific time. For our research, 5 V increments were applied to the dielectric material and then, after 10 s, the current flow was recorded at each of those increments. The current allowed us to

To construct the capacitor, an AJA ATC Orion magnetron sputtering unit permitted to apply a titanium coating on both sides of the biocomposite film for 20 min at 200 W. All these capacitors were characterized using a Caframo™ stirrer clamp made of cast zinc-aluminum alloy and coated with epoxy as shown in **Figure 1**. The stirrer clamp also included a hold chuck key to ensure a close circuit between the capacitor and the copper electrodes. One electrode was placed at the base of the chuck key while another electrode was placed at the base of the Calframo™ stirrer clamp. In addition, a small weight of 1.27 N was placed on top of the chuck key to ensure proper contact between the capacitor and the electrodes. The ASTM D-150 standard provided guidelines to select the dimensions of the capacitors, i.e., 10 mm in length and

(1)

77

reduce the size of compound particles in previously published works [14, 15].

**2.3. Characterization**

*2.3.1. Structure analysis*

*2.3.2. Electrical analysis*

10 mm in width [18, 19].

determined for the biocomposites using Eq. (1).

*K* = \_\_\_\_ *<sup>C</sup>*.*<sup>d</sup>*

the plates; d, the distance between the plates; and ε<sup>o</sup>

determine the conductivity of the dielectric material.

## **2.2. Sample preparation**

To prepare the specimens, one must considered their adequate size for the ensuing characterization. In particular, special care was taken to better the uniform distribution of the particles in the matrix.
