**1. Introduction**

Polymeric materials are widely used in greenhouses and in food packaging. Typical examples of such materials are polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) [1, 2].

In recent years, many studies have been done, and much effort has been devoted to polymer nanocomposites which have attracted a great attention from scientists [3]. The literature contains a plethora of experiments illustrating the thus involved parameters. At turns and among others, fabrication technique, matrix nature, nanofiller shape factor, and complex nature of the additives may be the determinants on the end-result properties of the polymer nanocomposites [4]. The dispersion of nanoparticles in the polymer matrix [5, 6] and the property of the interface between nanoparticle and polymer are regarded as key factors

affecting the insulating properties of nanocomposites [7, 8]. Polymer nanocomposites often show superior mechanical properties compared to the conventional composites at a lower loading of the nanoparticles [9]. So far, a few researches have systematically studied the effects of different nanoparticles on the performances of composite materials [3].

The excellent properties of silicon dioxide film have attracted attention in industry and academia, due to its hardness, corrosion resistance, anti-resistance [10], dielectric properties [11], optical transparency, etc. [12]. Silicon dioxide as a thin film is widely used to improve the surface properties of materials. This is why silicon dioxide films are used in many fields as in antireflection coating field [13]. Silicon dioxide films are used as barrier layers in polymer packaging materials in the packaging industry. Most of the modern packaging materials do not provide an efficient barrier against the permeation of gases. This leads to drink and food not getting rotten quickly. Because of this, a silicon dioxide film deposited on the surface of polymer packaging becomes indispensable and popular. In addition, silicon dioxide films can be also used as corrosion protective layers of metals. Besides, the preparation of silica with high quality is always an important aim of scientific research because of the universal application of silicon dioxide films in various fields [14].

Currently, a number of different barrier coating technologies are being developed. Theoretically, a barrier function can be incorporated into a plastic-based packaging material via two different means, either by mixing a barrier material with the base polymer or by coating a layer of the barrier material [15, 16].

Presently, the traditional and simplest method of preparing polymer/silica composites is direct mixing of the silica into the polymer. The mixing can generally be done by melt blending and solution blending. This mixing process always results in the effective dispersion of the silica nanoparticles in the polymer matrix. The basic difficulty is when they usually tend to agglomerate [17].

This work represents the results of experiments on silicon dioxide insulation materials mixed with LDPE at a different proportion to prevent the transmittance of IR domain and to allow the transmittance of UV–Vis domains, so we can keep the thermal radiation of the ground in the greenhouse. The mechanical properties of nanocomposites such as tensile were evaluated and discussed.

Samples of neat LDPE and nanocomposites in different ratios (0.5, 1, 2.5, 5, 7.5, and 10 wt% SiO2) were produced. Many material properties were investigated and will be discussed.

By studying blackbody thermal radiation, all objects with a temperature above absolute zero emit energy in the form of electromagnetic radiation. A blackbody is a model or theoretical body which absorbs all radiation falling

**137**

**Table 1.**

*Nanosilica Composite for Greenhouse Application DOI: http://dx.doi.org/10.5772/intechopen.92181*

at 9.5 μm [14].

**2.1 Materials**

**2. Material and methods**

**2.2 Sample preparation**

and the pressure of 50 bars.

monomer ethylene with a density of 0.922 g/cm3

and chemical properties for fumed nanosilica.

on it. It is a hypothetical object which is a "perfect" absorber and a "perfect" emitter of radiation. The electromagnetic radiation emitted by a blackbody has a specific intensity and spectrum that depend only on the body's temperature; the thermal radiation spontaneously emitted by ordinary objects, for example, plants and land, can be approximated as blackbody radiation. **Figure 1** shows the blackbody radiation spectrum at different several temperatures. We are interested in the vicinity of 10 μm (9–11 μm), because at the temperatures near 0°C (273 K), the thermal radiation from the ground is maximum at 10 μm while at the temperature 30°C (303 K), thermal radiation from the ground is maximum

Low-density polyethylene (LDPE) which is a thermoplastic made from the

Samples were prepared by blending LDPE in different ratios (0.5, 1, 2.5, 5, 7.5, and 10 wt% SiO2) and making plates from composite material. In different nanosilica ratios, nanosilica composites were mechanically mixed with LDPE granules at the processing temperature of 130°C and speed at 50 rpm min<sup>−</sup><sup>1</sup> for 10 min using the internal mixer (Brabender Plasti-Corder PL-2200, W50, Germany). Films of the neat LDPE with dimension of 10 cm × 10 cm × 120 μm and nanocomposites were prepared by a hot press method at the temperature of 140°C

**Properties Value** Physical state Solid Color White Form Powder pH 3.7–4.5 Melting point/range Approx. 1700°C Surface area 200 ± 25 m2

Density Approx. 2.2 g/cm3 Thermal decomposition >2000°C Water solubility >1 mg/l Loss on drying ≤1.5% (2 h at 105°C) Silica content based on ignited material >99.8%

*Information on basic chemical and physical properties for nanosilica.*

Industries Corporation (SABIC). High-purity fumed nanosilica (purity >99%) with the trademarks of A200 with an average particle size of ~12 nm was obtained from Evonik Degussa AG (Germany). **Table 1** shows the information on basic physical

was purchased from Saudi Basic

/g

**Figure 1.** *Blackbody radiation spectra at 273, 293, 313, 333, 373, 393, 413, 433, and 453 K [14].* *Nanosilica Composite for Greenhouse Application DOI: http://dx.doi.org/10.5772/intechopen.92181*

on it. It is a hypothetical object which is a "perfect" absorber and a "perfect" emitter of radiation. The electromagnetic radiation emitted by a blackbody has a specific intensity and spectrum that depend only on the body's temperature; the thermal radiation spontaneously emitted by ordinary objects, for example, plants and land, can be approximated as blackbody radiation. **Figure 1** shows the blackbody radiation spectrum at different several temperatures. We are interested in the vicinity of 10 μm (9–11 μm), because at the temperatures near 0°C (273 K), the thermal radiation from the ground is maximum at 10 μm while at the temperature 30°C (303 K), thermal radiation from the ground is maximum at 9.5 μm [14].
