**2.1 Materials**

*Use of Gamma Radiation Techniques in Peaceful Applications*

cost-effective or technically impossible [9–15].

well in hygiene packing [22, 23].

along with the development in urbanization. The development of biodegradable polymers generally catches the attention of researchers due to environmental

Poly(butylene adipate-*co*-terephthalate) (PBAT) is an aliphatic-aromatic random co-polyester, fully biodegradable, and prepared from 1,4–butanediol, adipic acid, and terephthalic acid: a synthetic polymer based on fossil resources, 100% biodegradable, with high elongation at break, and very flexible [16]. PBAT is an elastomeric polymer intended to improve mechanical properties; it can be used in several applications, such as, packaging materials, hygiene products, biomedical fields, and industrial composting, among others [17–21]; nevertheless, PBAT has poor thermal and mechanical properties, which can be overcome through the addition of fillers; in addition, it is a versatile polymer that allows the manufacturing from films up to shaped devices, and it can be used in food and dairy industries as

Polylactide or poly(lactic acid) (PLA) is the front-runner in the emerging bioplastics market with the best availability and the most attractive cost structure: PLA is a linear, aliphatic thermoplastic polyester, used for different applications ranging from medical to packaging, resorbable, and biodegradable under industrial composting conditions [24]. Therefore, its rheological properties, especially its shear viscosity, have important effects on thermal processes. Despite all its advantages, some properties of PLA such as inherent brittleness, low toughness, slow crystallization, poor melt strength, narrow processing window, and low thermal stability, besides high cost, pose considerable scientific challenges that limit their large-scale

applications (film blowing, injection molding, and foaming) [25–27].

So, combining the high toughness of PBAT and the relatively low price of PLA can result in a novel blend. PLA was blended with PBAT flexible polymer, considering its high toughness and biodegradability. Poly(lactic acid) (PLA) and poly(butylene adipate-*co*-terephthalate) (PBAT), both biodegradable aliphatic polyesters, semicrystalline, and thermoplastic, can be processed by conventional methods. Their resulting blends provide interesting materials for industrial and hygiene packaging applications, due to their increased ductility in function of

PLA and PBAT binary blends exhibited improved properties concerned with higher elongation at break but lower tensile strength and modulus than pure PLA. Therefore, the addition of filler to PLA/PBAT blends led to a modulus

In this paper bio-calcium carbonate from avian egg shells was used. Daily, tons of chicken eggshells are discarded, generating commercially devalued waste from restaurants, food industry, and homes. Currently, egg production throughout the world is 65.5 million metric tons per year, with Asia as a key contributor to global egg output growth [28]. The eggshell is rich in calcium carbonate, a natural bioceramic composite with a unique chemical composition of high inorganic (95% of calcium carbonate in the form of calcite) and 5% of organic (type X collagen,

The depletion of petroleum resource led to considerable research efforts on the development of biodegradable polymeric materials. Biodegradable polymers offer a great variety of advantages to environmental conservation; based on their nonharmful effects, they can be classified into two major categories: natural polymers and synthetic polymers; polymers obtained basically from renewable sources are a new generation of material capable to significantly reduce the environmental impact in order to achieve certain technical requirements besides being fully biodegradable. In addition, natural polymer-based materials offer a feasible alternative to the traditional polymeric materials when recycling of synthetic polymer is not

problems associated with the disposal of petroleum-based polymers.

**140**

PBAT content.

approaching that of pure PLA.

PLA and PBAT polymers, with main characteristics described in **Table 1**. Both PLA and PBAT were dried at 70°C for 12 h before processing.

PLA, irradiated in a Cobalt-60 source, 150 kGy, 10.5 kGY h<sup>−</sup><sup>1</sup> dose ratio, at multipurpose reactor, in CTR/IPEN, Instituto de Pesquisas Energéticas e Nucleares, São Paulo.

Carbon dioxide (CO2): physical blowing agent, selected according to good diffusion in PLA foaming [42].

Calcium carbonate (CaCO3) from avian eggshells: white chicken eggshells were subjected to a thorough cleaning using tap water for removing of internal membranes. Afterward, clean eggshells were kept for 4 h in a 100°C water bath


#### **Table 1.**

*Main characteristics of used polymers.*


**Table 2.**

*Material designation and composition for PBAT/PLA/CaCO3/PLA 150 kGy gamma-irradiated.*

and finally dried at 100 ± 2°C for 2 h in an air-circulating oven. Eggshells were size reduced to fine powder, particle size equal or lower than 125 μm, by using ball mills and granulometric sieve, respectively. Then they were dried again at 100 ± 2°C, for 24 h, in order to reduce its moisture content to less than 2%.

#### **2.2 Preparation and processing**

Composite materials were prepared according to **Table 2**; they were first homogenized by melting extrusion process, using a corotating twin-screw extruder (HAAKE Rheomex 332p, 3.1 L/D, 19/33 compression ratio), by using a 120–145°C temperature profile and 50 rpm.

Homogenized samples (pellets) were further subjected to extrusion under pressure, by expansion physical method using carbon dioxide (CO2) as blowing agent, at 10 bar (approximately 10 kgf cm<sup>−</sup><sup>2</sup> ). A mono-screw specific for foaming was used, maintaining the same temperature profile: 130–145°C.

## **3. Characterization**

#### **3.1 Differential scanning calorimetric analyses (DSC)**

Thermal behavior was examined in a DSC Mettler Toledo apparatus, according to ASTM D3418-08. A set of heating/cooling ramps was carried out following a three-step process; the samples were firstly heated to 200°C and kept in the molten state for 10 min to erase the thermal history of the material. They were then cooled

**143**

*Study of Bio-Based Foams Prepared from PBAT/PLA Reinforced with Bio-Calcium Carbonate…*

positions listed in **Table 2** to crystallize upon cooling. After cooling treatment, the

where ΔHm is the measured heat of fusion, w is the weight fraction of PLA or

Thermogravimetric analyses provide complimentary and supplementary characterization information to DSC, by measuring the amount and rate (velocity) of change in the mass of a sample as a function of temperature or time in a controlled atmosphere. Measurements are used primarily to determine the thermal and/ or oxidative stabilities of materials as well as their compositional properties. The technique can analyze materials that exhibit either mass loss or gain due to decomposition, oxidation, or loss of volatiles (such as moisture). TGA were performed using a DSC Mettler Toledo apparatus, according to ASTM E1641-07, by using

X-ray diffraction is a technique used for determining anatomic structure: it consists in a constructive interference of a wave from X-ray incident beam in relation to

In this technique Bragg's law is applied, defined by *n* = 2*dsen*, where *n* is an entire value for wavelength generated by a specific target according to a given electronic transition and *sen* is the angle where the constructive interference occurs; therefore, it is possible to determine interplanar distances (*d*) for each crystalline plane. The identification of crystalline phase of a material is given from a database defined by the Joint Committee on Powder Diffraction Standards (JCPDS) that

It was employed herein a X-Ray diffractometer, RigakuMultiflex, graphite monochromator, 40 kV, 20 mA, X-rays tube, copper anode λ*Cuk* <sup>=</sup> 1, <sup>5418</sup>*A*̊

scanning 2θ within 3°–60°, speed 0.06°/4 s, fixed time. It provides, among others, information on sample crystallinity, via diffractograms, distinguishing between

Electronic microscopy technique is a major tool for the study of material structure and morphology; it allows the visualization of details in a micrometric scale of

Morphology investigations were accomplished in a FEG-SEM equipment, model F-50, capable to read up to 20 nanometers, in various magnification micrographs. Samples were freeze-fractured in liquid nitrogen and gold coated in a Balzers SCD

one was calculated separately, upon the second heating by using Eq. 1 [43]:

for PLA and 114 J g<sup>−</sup><sup>1</sup>

5–9 mg of foam sample, within a 25–600°C program, at 10°C min<sup>−</sup><sup>1</sup>

compares position of obtained peaks with intensity relationship.

to evaluate the ability of PLA, PBAT, and their com-

*<sup>o</sup>* × \_\_\_ <sup>100</sup>

m is the enthalpy of fusion for a crystal having infinite

for PBAT).

*Hm Hm*

. The percent crystallinity of each

*<sup>w</sup>* . (1)

, in a nitrogen

,

*DOI: http://dx.doi.org/10.5772/intechopen.85462*

samples were heated back to 200°C at 10°C min<sup>−</sup><sup>1</sup>

*xc* (%Crystallinity) = \_\_\_\_

down to 30°C at 10°C min<sup>−</sup><sup>1</sup>

PBAT in the blend, and ΔH*<sup>o</sup>*

**3.2 Thermogravimetric analyses (TG)**

.

**3.3 X-ray diffraction analysis (XRD)**

crystal thickness (93 J g<sup>−</sup><sup>1</sup>

flow of 50 ml min<sup>−</sup><sup>1</sup>

a uniform atomic spacing.

amorphous and crystalline states.

changes in the material.

**3.4 Scanning electron microscopy (SEM)**

050 sputtering before accomplishment of analyses.

*Study of Bio-Based Foams Prepared from PBAT/PLA Reinforced with Bio-Calcium Carbonate… DOI: http://dx.doi.org/10.5772/intechopen.85462*

down to 30°C at 10°C min<sup>−</sup><sup>1</sup> to evaluate the ability of PLA, PBAT, and their compositions listed in **Table 2** to crystallize upon cooling. After cooling treatment, the samples were heated back to 200°C at 10°C min<sup>−</sup><sup>1</sup> . The percent crystallinity of each one was calculated separately, upon the second heating by using Eq. 1 [43]:

$$\propto\_{c} \{ \text{\textquotedblleft(\text{\textquotedblright}Cystallality\textquotedblright)} \} \quad = \, \frac{\Delta H\_{m}}{\Delta H\_{m}^{\text{v}}} \times \frac{100}{w} . \tag{1}$$

where ΔHm is the measured heat of fusion, w is the weight fraction of PLA or PBAT in the blend, and ΔH*<sup>o</sup>* m is the enthalpy of fusion for a crystal having infinite crystal thickness (93 J g<sup>−</sup><sup>1</sup> for PLA and 114 J g<sup>−</sup><sup>1</sup> for PBAT).

#### **3.2 Thermogravimetric analyses (TG)**

*Use of Gamma Radiation Techniques in Peaceful Applications*

**Characteristics of PLA Characteristics of PBAT** Grade: ingeo biopolymer 3251 D Commercial name: Ecoflex FS

Melting point: 168°C Melting point: 110–120°C

Glass transition temperature: 62°C Glass transition temperature: −30°C Average molecular weight: 100,000 g mol<sup>−</sup><sup>1</sup> Average molecular weight: 40,000 g mol<sup>−</sup><sup>1</sup>

Supplier: nature works Supplier: BASF

and finally dried at 100 ± 2°C for 2 h in an air-circulating oven. Eggshells were size reduced to fine powder, particle size equal or lower than 125 μm, by using ball mills and granulometric sieve, respectively. Then they were dried again at 100 ± 2°C, for

*Material designation and composition for PBAT/PLA/CaCO3/PLA 150 kGy gamma-irradiated.*

**Designation PBAT (wt%) PLA (wt%) CaCO3 (phr) PLA 150 kGy (phr)**

PBAT 100 — — — PBAT50 50 50 — — PBAT65 65 35 — — PBAT82 82 18 — — PBAT50CI 50 50 10 5 PBAT65CI 65 35 10 5 PBAT82CI 82 18 10 5 PLA — 100 — —

Composite materials were prepared according to **Table 2**; they were first homogenized by melting extrusion process, using a corotating twin-screw extruder (HAAKE Rheomex 332p, 3.1 L/D, 19/33 compression ratio), by using a 120–145°C

Homogenized samples (pellets) were further subjected to extrusion under pressure, by expansion physical method using carbon dioxide (CO2) as blowing agent,

Thermal behavior was examined in a DSC Mettler Toledo apparatus, according to ASTM D3418-08. A set of heating/cooling ramps was carried out following a three-step process; the samples were firstly heated to 200°C and kept in the molten state for 10 min to erase the thermal history of the material. They were then cooled

). A mono-screw specific for foaming was

24 h, in order to reduce its moisture content to less than 2%.

used, maintaining the same temperature profile: 130–145°C.

**3.1 Differential scanning calorimetric analyses (DSC)**

**2.2 Preparation and processing**

**Table 2.**

**Table 1.**

*Main characteristics of used polymers.*

temperature profile and 50 rpm.

**3. Characterization**

at 10 bar (approximately 10 kgf cm<sup>−</sup><sup>2</sup>

**142**

Thermogravimetric analyses provide complimentary and supplementary characterization information to DSC, by measuring the amount and rate (velocity) of change in the mass of a sample as a function of temperature or time in a controlled atmosphere. Measurements are used primarily to determine the thermal and/ or oxidative stabilities of materials as well as their compositional properties. The technique can analyze materials that exhibit either mass loss or gain due to decomposition, oxidation, or loss of volatiles (such as moisture). TGA were performed using a DSC Mettler Toledo apparatus, according to ASTM E1641-07, by using 5–9 mg of foam sample, within a 25–600°C program, at 10°C min<sup>−</sup><sup>1</sup> , in a nitrogen flow of 50 ml min<sup>−</sup><sup>1</sup> .

#### **3.3 X-ray diffraction analysis (XRD)**

X-ray diffraction is a technique used for determining anatomic structure: it consists in a constructive interference of a wave from X-ray incident beam in relation to a uniform atomic spacing.

In this technique Bragg's law is applied, defined by *n* = 2*dsen*, where *n* is an entire value for wavelength generated by a specific target according to a given electronic transition and *sen* is the angle where the constructive interference occurs; therefore, it is possible to determine interplanar distances (*d*) for each crystalline plane. The identification of crystalline phase of a material is given from a database defined by the Joint Committee on Powder Diffraction Standards (JCPDS) that compares position of obtained peaks with intensity relationship.

It was employed herein a X-Ray diffractometer, RigakuMultiflex, graphite monochromator, 40 kV, 20 mA, X-rays tube, copper anode λ*Cuk* <sup>=</sup> 1, <sup>5418</sup>*A*̊ , scanning 2θ within 3°–60°, speed 0.06°/4 s, fixed time. It provides, among others, information on sample crystallinity, via diffractograms, distinguishing between amorphous and crystalline states.

#### **3.4 Scanning electron microscopy (SEM)**

Electronic microscopy technique is a major tool for the study of material structure and morphology; it allows the visualization of details in a micrometric scale of changes in the material.

Morphology investigations were accomplished in a FEG-SEM equipment, model F-50, capable to read up to 20 nanometers, in various magnification micrographs. Samples were freeze-fractured in liquid nitrogen and gold coated in a Balzers SCD 050 sputtering before accomplishment of analyses.
