**1. Introduction**

Nowadays, nanoscience and nanotechnology have increased the scope of polymeric materials application, with the ultimate goal of dramatically enhanced performance [1, 2]. The most popular performance is to introduce nanoparticles into the polymer matrix to treat the polymer/nano-sized particles composites. The second is the fabrication of polymeric nanoscale materials [3, 4]. Both the mentioned approaches have been applied for various polymeric systems [5]. Based on the revolutionary researches, nanotechnology has been successfully applied to produce different kinds of biopolymer materials with valuable quality and high performance in various fields [6].

The tissue engineering, which is considered as a multidisciplinary field in medicine and industry, is emerging as the promising new approach in the reconstruction of imperfect or damaged body tissues [7, 8]. Also, tissue engineering is multidisciplinary field of integrating materials science, biotechnology, industrial engineering, and medical engineering [9]. This chapter focuses on the development of biotechnical substitutes for restoration, replacement, maintaining, or enhancing tissue and organ functionalities. The artificial scaffolds like framework play a basic role in supporting the structural cells to settle and guide their growth to find the

specific tissue with acceptable structure [10]. Therefore, designation of artificial scaffolds has a great importance in tissue engineering. An artificial scaffold that covers the preferred characteristics such as biocompatibility, biodegradability, and high porosity structure could provide as template for bone growth [11]. In the same case, fibrous artificial scaffolds, biodegradable and biocompatible polymers, which are frequently used as artificial scaffold materials, are naturally soft in order to mimic the rigidity of natural tissues [12, 13].

Using fillers as a reinforcing agent is not a new idea in the world. Straws were used to reinforce mud bricks since 4000 BC [14]. Now, fibers made from so many kinds of materials in mesoscale such as glass, boron, silicon carbide, alumina, and especially carbon has been used as fillers in composites. Polymer nanocomposites are combination of a polymer matrix and inclusions that have at least one dimension (i.e., length, width, or thickness) in the nanometer size range (**Figure 1**).

In order to achieve ultimate effective properties, the fabrication of nanoparticle reinforced polymers must be optimized [15, 16]. Nowadays, there are several issues that are not well understood in this area and need more theoretical and experimental researches. However, individual research groups have made significant processing advances for particular nanoparticle-polymer systems, universal guidelines regarding the fabrication of nanocomposites do not exist [17]. This is in part due to the complexity of the polymer chemistry, the lack of detailed models describing the processing conditions, and the large list of parameters (specific to the types of polymer and nanotube under consideration) that can influence the polymer/ nanoparticle interaction and impact the effective reinforcement properties.

There are four main system requirements for effective reinforcement. These are a large aspect ratio (1), good dispersion (2), alignment (3), and interfacial stress transfer (4).

Reinforcement of biodegradable and biocompatible polymers is a possible approach to overcome some natural limitations of mentioned polymers such as in adequate mechanical properties, insufficient stiffness, high brittleness, and low toughness [18–22]. Also, some researches were focused on evaluation of the properties of biopolymer blends and copolymers [23–27]. Some kinds of polyesters are widely studied as matrix polymer in biocomposites that reinforced with many kinds of reinforcing fillers for improving their applications. Biopolymers are used to produce harmless fluorescent microparticles for in-vivo material penetration researches.

Biodegradable and biocompatible nanomaterials, because of their properties such as controlled release, low toxicity, and enhanced encapsulation effect, are used frequently as drug delivery systems. Nanotechnology highlighted the impact of nanoencapsulation of various disease-related drugs on biodegradable nanoparticles such as poly(L-lactide-*co*-glycolide) (PLGA), poly lactic acid (PLA), chitosan, gelatin, poly caprolactone, and poly-alkyl-cyanoacrylates [3].

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*Poly(L-Lactide) Bionanocomposites*

*DOI: http://dx.doi.org/10.5772/intechopen.85035*

**2. Polymer nanocomposites fabrication**

**2.1 Solution blending of nanocomposites**

and thermoplastic polymers.

the polymer matrix.

**2.2 Melt blending**

loadings.

applied to produce nanomaterial/polymer nanocomposites.

The methods for fabrication of nanocomposite have considered on improvement of nanomaterials dispersion because significantly higher distribution in the biopolymer matrices to improve the properties of polymeric nanocomposite. Like nanoparticle suspensions in solvents, pristine nanoparticles have not valuable dispersion in polymers illustrating the extreme difficulty to overcome the inherent thermodynamic driving of nanoparticles to agglomerate. The dispersion of nanoparticles in polymer should be evaluated over a various size scales of nanoparticles. The solution blending, melt blending, and in situ polymerization are widely

Solution blending is a common technique for fabrication of polymeric nanocomposites because it is both amenable for various sizes and effectiveness. The solution blending includes three steps: dispersion of nanoparticles in a solvent, mixing with the polymer solution at effective temperature, and finally recover the composite after precipitation or casting the film. Solution-based casting methods provide an advantage through low viscosities, which facilitate mixing and dispersion of the nanoparticles. Many studies have used these methods for processing both thermoset

As mentioned earlier, it is difficult to disperse nanoparticles in solvents by simple stirring. The instruments such as ultrasonicator are suitable for making metastable suspensions of reinforcing filler/polymer mixtures in solvents. It is necessary to consider that ultrasonication for a long time affects the nanoparticles. When using solution blending, nanoparticles tend to agglomerate during slow solvent evaporation, leading to inhomogeneous distribution of the nanoparticles in

The melt blending need heat and high shear pressure to disperse the nanoparticles in polymer matrix and it is well-matched with present industries. In comparison with solution blending, the melt mixing has less effective at dispersion of nanoparticles in polymer matrix and has limitation for low concentration of nanoparticle because of high viscosities of the composites at higher nanoparticles

Melt mixing of nanoparticles into thermoplastic polymer matrix using conventional processing techniques, such as extrusion, injection molding, and blow molding are particularly desirable, due to the speed, simplicity, and availability of the process in plastic industries. These methods are also benefit due to free of solvent and related contaminant. The nanoparticles has a unique advantage in thermoplastic polymer compounding and molding, because less fiber cutting or breaking occurs, and a high aspect ratio is maintained for one dimensional fillers in contrast to larger, microscale fillers. Application of shear mixing with long processing time may improve the dispersion of fillers, and when coupled with elongating extrusion, should yield adequate aligned nanofillers. Increasing in viscosity is higher for nanofibers than that of large diameter fibers such as carbon black, so shear mixing is necessary to overcome the high viscose polymer/nanofibers composites. Additionally, another advantage is the vision of recycling thermoplastic nanocomposites to decrease the financial expenses and to become safe for environment. Nevertheless, much needs to be learned about the ability of nanofibers to withstand

**Figure 1.** *The scheme of nanofillers for polymer nanocomposites.*

*Peptide Synthesis*

transfer (4).

researches.

mimic the rigidity of natural tissues [12, 13].

specific tissue with acceptable structure [10]. Therefore, designation of artificial scaffolds has a great importance in tissue engineering. An artificial scaffold that covers the preferred characteristics such as biocompatibility, biodegradability, and high porosity structure could provide as template for bone growth [11]. In the same case, fibrous artificial scaffolds, biodegradable and biocompatible polymers, which are frequently used as artificial scaffold materials, are naturally soft in order to

Using fillers as a reinforcing agent is not a new idea in the world. Straws were used to reinforce mud bricks since 4000 BC [14]. Now, fibers made from so many kinds of materials in mesoscale such as glass, boron, silicon carbide, alumina, and especially carbon has been used as fillers in composites. Polymer nanocomposites are combination of a polymer matrix and inclusions that have at least one dimension (i.e., length, width, or thickness) in the nanometer size range (**Figure 1**).

In order to achieve ultimate effective properties, the fabrication of nanoparticle reinforced polymers must be optimized [15, 16]. Nowadays, there are several issues that are not well understood in this area and need more theoretical and experimental researches. However, individual research groups have made significant processing advances for particular nanoparticle-polymer systems, universal guidelines regarding the fabrication of nanocomposites do not exist [17]. This is in part due to the complexity of the polymer chemistry, the lack of detailed models describing the processing conditions, and the large list of parameters (specific to the types of polymer and nanotube under consideration) that can influence the polymer/ nanoparticle interaction and impact the effective reinforcement properties.

There are four main system requirements for effective reinforcement. These are a large aspect ratio (1), good dispersion (2), alignment (3), and interfacial stress

Reinforcement of biodegradable and biocompatible polymers is a possible approach to overcome some natural limitations of mentioned polymers such as in adequate mechanical properties, insufficient stiffness, high brittleness, and low toughness [18–22]. Also, some researches were focused on evaluation of the properties of biopolymer blends and copolymers [23–27]. Some kinds of polyesters are widely studied as matrix polymer in biocomposites that reinforced with many kinds of reinforcing fillers for improving their applications. Biopolymers are used to produce harmless fluorescent microparticles for in-vivo material penetration

Biodegradable and biocompatible nanomaterials, because of their properties such as controlled release, low toxicity, and enhanced encapsulation effect, are used frequently as drug delivery systems. Nanotechnology highlighted the impact of nanoencapsulation of various disease-related drugs on biodegradable nanoparticles such as poly(L-lactide-*co*-glycolide) (PLGA), poly lactic acid (PLA), chitosan,

gelatin, poly caprolactone, and poly-alkyl-cyanoacrylates [3].

*The scheme of nanofillers for polymer nanocomposites.*

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**Figure 1.**
