Demand for environmentally friendly plastic materials which are obtained from renewable resources such as biomass-based polyesters is of concern. Herein, the enhanced characteristic performances of poly(butylene succinate) (PBS) by employing the fabrication of PBS-based composites with the nanosilver-coated carbon black (AgCB) using an injection-molding method are reported. The preformed AgCB additives are priorly prepared by the benzoxazine oxidation method. Phase characterization of the obtained composite materials examined by X-ray diffraction (XRD) reveals the crystalline PBS matrix and the presence of metallic silver particles, confirming the successful fabrication of the composite materials. Detailed analyses on thermal, mechanical, electrical, and antimicrobial properties of the composite materials are reported. The AgCB-PBS composite materials provide such potential features by an enhancement of electrical conductivity and the antimicrobial activity by an inhibition against
Nowadays, pollution caused by tremendously large amount of usage and disposal of petroleum-based plastic materials is of concern all over the world [
As mentioned that additives could improve the properties of polymers, several organic and inorganic fillers have been used as the additives for the preparation of polymer-based composites. Carbon black (CB) is one of the most popular additives that are known for improving the mechanical properties of polymer matrices, such as tensile strength, tear strength, hardness, and abrasion resistivity. Apart from these properties, its inexpensive cost makes CB suitable for large-scale production. Furthermore, CB has been shown to increase the electrical [
Silver nanoparticles are renowned for their incredible physical, chemical, and biological properties [
In this paper, enhanced PBS characteristics for antimicrobial, conductive, and mechanical properties have been examined by preparing PBS-based composites between PBS as the polymer matrix and carbon black (CB) or nanosilver-coated carbon black (AgCB) as its additive. The AgCB additive was priorly prepared by using a benzoxazine oxidation reaction for using as a filler. Two types of PBS-based composites were fabricated, namely, carbon black blended in PBS (CB-PBS) and nanosilver-coated carbon black blended in PBS (AgCB-PBS), varying the percentage of the additives for 3, 5, 10, and 15%. Note that the notations of
3,4-Dihydro-3,6-dimethyl-1,3,
For the preparation of nanosilver-coated carbon black (AgCB), 10 g of carbon black was weighed and then put in a beaker containing 10 cm3 CH2Cl2. The mixture was then stirred for 3 minutes. After that, the solution of the synthesized reducing agent in CH2Cl2 (1 g/10 cm3) and 1 g of AgNO3 were added to the reaction mixture. Then, the mixture was continuously stirred for a further 8 h to complete the coating of silver onto the carbon black. The obtained AgCB product was filtered out and then washed with CH2Cl2 for 2 times and additionally with acetone for 1 time to remove organic impurities. The product was dried at 75°C for 3 h. After that, the obtained powder was sieved to reduce the particle sizes to be less than 150
Composite materials of PBS and CB, herein called as CB-PBS, were prepared from their compound pellets. Prior to the reaction, PBS (grade 2003D) was dried in an oven at 40°C for 24 h. Next, a small amount of vegetable oil was added so that the additives CB or AgCB can stick in the PBS matrix quickly. The amount of additives (CB or AgCB) was added by varying the percentages of 3, 5, 10, and 15% with respect to the PBS amount.
Melt flow index (MFI) of PBS, CB-PBS, and AgCB-PBS composites was investigated to get the information about processing conditions. The initial temperature for the test was set to be 170°C, and the pressing force was set to be 2.16 kg. Dumbbell-shaped samples of PBS, CB-PBS, and AgCB-PBS composites were fabricated by an injection molding method using a Battenfeld machine (BA 250).
The phase formation of the composite materials was investigated by X-ray diffraction (XRD) using an X-PertPRO MPD diffractometer (Cu
Thermal properties of the prepared composite materials were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) using a TGA/DSC 1 METTLER TOLEDO STARe SYSTEM with a heating rate of 10°C/min. Mechanical properties of the prepared composite polymers were further studied according to the standard ASTM D 638-03. Tensile strength was studied by a universal testing machine (UTM). According to the ASTM D 683-03 standard, the tensile force was created from 1000 kg weight with the moving speed of 5 mm/min. The force was continuously applied until the sample was broken so that the tensile strength can be measured in either kg/cm2 or N/mm2. Furthermore, % elongation at break can be calculated using the formula given below:
For the electrical conductivity test, the prepared composite materials were cut into square-shaped samples and then glued using silver paint. The resistance can be measured by applying the voltage of 1000 Volts for 30 mins. The resistivity of the materials can be calculated from the equation:
Antibacterial and antifungal tests of prepared samples were examined using the agar disk diffusion method [
The melt flow study of the pristine PBS, CB-PBS, and AgCB-PBS composite materials was carried out at 170°C using the pressing weight of 2.16 kg, following the ASTM D1238 standard method. The flow rate of pristine PBS was 32.142 g/10 min. When the CB filler was added for 10, 20, 30, and 40 phr (per hundred resin) of CB with respect to the content of PBS matrix, the flow rates were decreased to 19.158, 5.766, 2.412, and 0.768 g/10 min, respectively (Figure
Melting flow rate of pristine PBS and
Photographic images showing physical appearance of (a) pristine PBS, (b) 3CB-PBS, (c) 5CB-PBS, (d) 10CB-PBS, and (e) 15CB-PBS composite materials after proceeded by an injection molding method.
To get insight into the details of phase formation and crystallinity of the as-fabricated products, XRD patterns of the pristine PBS, as well as the
XRD patterns using X-ray of Cu
SEM images of (a) pristine PBS, (b) 3CB-PBS, (c) 5CB-PBS, (d) 10CB-PBS, and (e) 15CB-PBS. Scale bar shown here is equal to 10
To further examine the enhanced characteristic features of the composites by means of the addition of CB filler, thermal properties of the pristine PBS and CB-PBS composites were studied (Figure
(a) DSC and (b) TGA thermograms of the pristine PBS and xCB-PBS composite materials. Note that the labels shown in the plots represent the materials as follows: (A) pristine PBS, (B) 3CB-PBS, (C) 5CB-PBS, (D) 10CB-PBS, and (E) 15CB-PBS.
Mechanical properties of pristine PBS and
(a) Tensile strength, (b) elongation at break, (c) impact strength, and (d) bending strength of the pristine PBS as well as the xCB-PBS composite materials.
For the further step, we additionally integrated the properties of silver nanoparticles into the PBS-based composites in order to enhance their characteristic features. Firstly, the additive so-called nanosilver-coated carbon black (AgCB) was prepared by the benzoxazine oxidation method [
(a) SEM and (b) TEM images of the nanosilver-coated carbon black (AgCB) used as the additive for fabrication of
(a) Calculated XRD peaks of standard silver metal (JCPDS no. 04-0783) and the observed XRD patterns of (b) 3AgCB-PBS, (c) 5AgCB-PBS, (d) 10AgCB-PBS, and (e) 15AgCB-PBS composites.
SEM images of (a) the pristine PBS in comparison with the (b) 3AgCB-PBS, (c) 5AgCB-PBS, (d) 10AgCB-PBS, and (e) 15AgCB-PBS composites. The corresponding EDS elemental mappings of (f) C element, (g) O element, and (h) Ag element of the 15AgCB-PBS composite illustrate the well distribution of the AgCB additive within the PBS matrix. Note that the scale bar depicted in Figures 9(a) to 9(d) is 10
AgCB-PBS composite materials were subjected to studying thermal properties (Figure
(a) DSC and (b) TGA thermograms of the pristine PBS and the AgCB-PBS composite materials. Note that the labels shown in the plots represent the materials as follows: (A) PBS, (B) 3AgCB-PBS, (C) 5AgCB-PBS, (D) 10AgCB-PBS, and (E) 15AgCB-PBS.
Moreover, the study on mechanical properties of AgCB-PBS was also performed in a similar way as the CB-PBS materials (Figure
(a) Tensile strength, (b) elongation at break, (c) impact strength, and (d) bending strength of the pristine PBS as well as the
To prove the enhanced characteristic features of the composites by means of the presence of Ag particles within the composites, the electrical conductivity of the AgCB-PBS composite materials was measured in comparison with the pristine PBS. The results clearly show an improvement of the electrical conductivity of the AgCB-PBS composites for approximately an order of magnitude. Specifically, the pristine PBS has a conductivity of 1.73 × 10−7 (Ωm)−1, whereas the 3AgCB-PBS, 5AgCB-PBS, 10AgCB-PBS, and 15AgCB-PBS reveals the electrical conductivity of 2.28 × 10−6, 3.62 × 10−7, 9.40 × 10−7, and 3.01 × 10−6 (Ωm)−1, respectively. Note that, the electrical conductivities of AgCB-PBS composite materials observed herein are even higher for about an order of magnitude than those of AgCB-PLA composite materials prepared by using a similar procedure reported by our group previously [
Not only an enhancement of electrical conductivity, the antimicrobial activities of the AgCB-PBS composites were also studied by the agar disk diffusion method using different microorganisms, namely,
Positive tests for antimicrobial properties on
Antimicrobial properties of AgCB-PBS composite materials.
Nanosilver-coated material | Microbial strains (clear zone) | |||||
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|
|
|
|
|
| |
3AgCB-PBS | − | − | − | − | − | − |
5AgCB-PBS | − | − | − | − | − | − |
10AgCB-PBS | − | − | − | − | − | + |
15AgCB-PBS | + | − | − | − | − | + |
An additional phase analysis of the 1-year-aged CB-PBS and AgCB-PBS composite materials was performed using the synchrotron-based grazing incidence XRD (GIXRD). The GIXRD patterns (Figure
One-dimensional integration XRD patterns of the 1-year-aged (a) xCB-PBS composites and (b) xAgCB-PBS composites in comparison with the pristine PBS material obtained from the two-dimensional grazing incidence X-ray diffraction (2d-GIXRD) patterns using synchrotron monochromatic X-ray of energy 12 keV (wavelength of 1.0332 Å) and grazing incidence angle of 0.5°.
In this work, the pre-formed additive so-called nanosilver-coated carbon black (AgCB), which was prepared by the benzoxazine oxidation method to distribute silver nanoparticles onto the surface of carbon black, is used to blend with the PBS polymer matrix in order to enhance its characteristic features. Phase identification using XRD of the as-fabricated CB-PBS and AgCB-PBS composites fabricated by the injection molding mainly shows the XRD peaks according to the crystalline phase of the PBS matrix. The XRD peaks of metallic silver particles are additionally observed in the as-fabricated materials, indicating the successful preparation of the AgCB-PBS composite materials. Addition of the CB and AgCB fillers affects the glass transition temperature, the endothermic melting peak, and the thermal decomposition temperature of the PBS matrix. Mechanical properties in terms of tensile strength, elongation at break, impact strength, and bending strength are slightly decreased in the composites in comparison with the pristine PBS materials. However, they are still within the acceptable regions. As a highlight of this work, AgCB-PBS composite materials, especially the 15AgCB-PBS, reveal an enhancement of the electrical conductivity for approximately an order of magnitude as well as exhibit the antimicrobial activities for inhibition against
The data used to support the findings of this study are available upon request through Dr. Worawat Wattanathana via e-mail (
The authors declare there are no conflicts of interest regarding the publication of this paper.
The authors would like to acknowledge the financial support from the National Research Council of Thailand (NRCT) and Kasetsart University Research and Development Institute (KURDI). Appreciation is also expressed to the Department of Materials Engineering, Faculty of Engineering, Kasetsart University, and Department of Chemistry, Faculty of Science, Kasetsart University, for the support of research facilities. Beamline 1.1W (Multiple X-ray Techniques, MXT) of the Synchrotron Light Research Institute, Thailand, is acknowledged for the GIXRD beamtime and the facilities during GIXRD measurements.