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Enhancement of thermal properties of bio-based microcapsules intended for textile applications

  • Virginija Skurkytė-Papievienė EMAIL logo , Aušra Abraitienė , Audronė Sankauskaitė , Vitalija Rubežienė and Kristina Dubinskaitė
Published/Copyright: June 23, 2020
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Open Chemistry
From the journal Open Chemistry Volume 18 Issue 1

Abstract

The thermal properties of bio-based phase change material (PCM) microcapsules and their separate components, core and shell, were investigated considering the influence of used thermal enhancer. As a core, bio-based PCM, capric acid (CA), was used. Biodegradable material, such as polylactic acid (PLA), was used as a shell. To improve the thermal conductivity of PLA/CA microcapsules, the multiwall carbon nanotubes (MWCNTs) were used as a thermal enhancer. Composites of PCM with different concentrations of MWCNT as well as composites of PLA with these carbon compounds were prepared and investigated to assess how MWCNT influences the thermal conductivity of the core and the shell. The heat storage and release capacity, as well as the phase change temperatures of CA/MWCNT composites and manufactured PCM microcapsules, were determined using differential scanning calorimetry. To evaluate the thermal conductivity of prepared composites and to compare it with the conductivity of pure materials (without MWCNT), their thermal resistance was measured using the guarded-hotplate test method. To obtain the supplementary information and to assess the dynamic behavior of used PCM during the temperature changes, another technique, such as monitoring of a cold/hot plate with an IR camera, was used. The results of these measurements showed that introduced MWCNT increases the thermal conductivity of PCM used for the core and the conductivity of films prepared from PLA. Consequently, with reference to the results obtained, it could be stated that the introduction of MWCNT into PLA/CA microcapsules improved the thermal properties of these microcapsules. However, it was determined that too large concentration of MWCNT reduces an enthalpy of melting and crystallization of tested PCM and PCM microcapsules. Therefore, during the investigation, an optimal concentration of MWCNT additives has been determined.

Keywords: textiles; bio-based PCM; carbon nanotubes; heat storage; heat release; differential scanning calorimetry

1 Introduction

One of the main purposes of wearing clothes is the comfort of the body. Comfort can be classified into four major classes such as thermal or thermophysiological comfort, sensorial comfort, physiological comfort, and garment fit [1]. The thermal factor is the most decisive one affecting the comfort level [2]. Thermal energy storage is the main concept of making thermoregulated fabrics. Thermal energy can be stored as sensible heat, latent heat, or thermochemical energy. The latent heat storage method is mostly used for thermoregulated fabric as in latent heat storage method high storage density is possible to achieve under nearly isothermal conditions [1,3]. Phase change materials (PCMs) represent an interesting potential energy carrier due to their high latent heat and capacity for energy transfer [4,5,6]. Organic PCMs can be divided into main parts, such as pure alkanes, paraffins, fatty acids and their derivatives, and polyols [7]. Researchers used a broad range of PCM materials such as eicosane [8], n-octadecane [9], fatty acids, such as stearic acid, palmitic acid, myristic acid, and lauric acid, and their blends [10,11], polyethylene glycol (PEG-100) [12], PEG 100 with Na-alginate [13], paraffin and nanomagnetite [14], butyl stearate [15], and others. Organic PCMs are a particularly well-suited candidate for energy storage owing to their especially high latent heat. For textiles application, the paraffinic petroleum-based phase-changing materials are the most commonly used, which are characterized by relatively high latent heat. However, their broad applications are limited due to high flammability and low thermal conductivity [16,17]. Furthermore, fossil fuels are used for the production of paraffin; therefore, it is not considered to be eco-friendly material. Only recently a new alternative of non-paraffinic PCM, the use of fatty acids or their esters was introduced. Despite the suitable origin of these bio-sourced materials, they have a major drawback, low thermal conductivity, which severely reduces the rate of heat storage and extraction during the melting and solidification cycles. The thermal conductivity of most PCMs, including bio-based PCMs, is typically in the range of 0.15–1 W/mK [17], and it means these are too low to provide a required heat exchange rate between the PCM and substrate. Therefore, a thermal conductivity enhancer would be useful to use efficiently the thermal energy stored in the PCM. Using bio-based PCM filled with high thermal conductivity materials could be a good strategy to enhance the thermal properties of the PCM. The thermal conductivity of PCM could be enhanced by using metal fillers, carbon nanofiber fillers, carbon nanotubes, expanded graphite, or exfoliated graphite nanoplatelets [14,18,19,20,21,22]. The thermal conductivity of carbon-based fillers is considerably high and their densities are lower than those of metals. The form of thermal conductivity enhancers also influences their effectiveness.

It is common knowledge in heat transfer that when lateral surface area increases, the heat transfer rate also increases [15]. Consequently, rod-type fins, such as carbon nanotubes, could perform better than plate-type ones, for example, expanded graphite or exfoliated graphite nanoplatelets. Therefore, in this study, carbon nanotubes were selected as efficient thermal conductivity enhancers for PCM intended for textile applications.

PCM has been applied to textiles in a variety of processes such as coating, lamination, finishing, melt spinning, bi-component synthetic fiber extrusion, injection molding, and encapsulation [5]. Our goal was to manufacture bio-based PCM microcapsules intended for textile applications and explore their thermal properties. As a core, bio-based PCM, capric acid (CA), was used. Biodegradable material, such as polylactic acid (PLA), was used as the shell.

PLA is a linear aliphatic thermoplastic polyester that can be derived from renewable resources [23,24]. Usually PLAs are used for the pharmaceutical field [25] as contrast agents in ultrasound imaging [26] and others.

Microencapsulated PCMs can be incorporated into textile structures to produce fabrics with thermoregulating properties [27]. The most convenient form of their use in the textile industry is core–shell microcapsules. Many researchers had produced microcapsules [28,29,30,31,32,33,34,35,36].

This study aimed to investigate the possibility to improve the thermal conductivity of produced microcapsules, using multiwall carbon nanotube (MWCNT) as a thermal enhancer. Therefore, the thermal properties of bio-based PCM microcapsules and their separate components, core and shell, were investigated considering the influence of used thermal enhancer.

The analysis of the textile materials with incorporated synthesized PCM microcapsules will complement the research works presented in this paper as a subsequent, separate publication.

2 Methods

2.1 Materials

As the core for the synthesis of microcapsules, bio-based PCM, CA, was used. Biodegradable material, such as PLA, was used as the shell. To improve the thermal conductivity of PLA/CA microcapsules, the MWCNTs were used as a thermal enhancer.

CA (decanoic acid, 99%) of analytical grade was bought from ACROS organics. For the improvement of thermal properties of PCM MWCNT NC7000 aqueous dispersion AQUACYL AQ0302 (producer Nanocyl SA) was used. PLA (Ingeo 6202D Nature works) was used to fabricate the shell of microcapsules.

To analyze the impact of thermal enhancer, MWCNT, on thermal properties of PCM microcapsules, primarily the influence of MWCNT for the thermal conductivity of core and shell was investigated, as it is not possible to control separately the amount of MWCNT in the core and the shell during the encapsulation process. Due to this, separate composites, CA/MWCNT and PLA/MWCNT, were prepared and tested.

2.1.1 Preparation of CA/MWCNT composites

Preparation of composite was carried out by mixing a CA with different contents of MWCNTs (0.5%, 1%, and 3%) using a magnetic stirrer, and after mixing additionally with a mechanical stirrer for 120 min at the rate of 600 rpm/min and a temperature of 60°C (Figure 1 and Table 1). The prepared composites were poured into Petri plates with the same size of 90 mm diameter and 15 mm height, which were intended for further investigation as the core of microcapsules.

Figure 1 Preparation of CA/MWCNT composite.
Figure 1

Preparation of CA/MWCNT composite.

Table 1

Description of samples

CA (only capric acid)
CA-0.5C – capric acid with 0.5% MWCNT
CA-1C – capric acid with 1% MWCNT
CA-3C – capric acid with 3% MWCNT

2.1.2 Preparation of PLA/MWCNT composites

To prepare PLA/MWCNT composites, MWCNT was incorporated into the shell material, PLA. The dependence of PLA thermal conductivity on the quantity of incorporated MWCNT was measured. The films from PLA/MWCNT composites were produced by the following sequence: applying dispersion apparatus T25 digital ULTRA-TURRAX (IKA) 1% and 3% of MWCNTs were incorporated into the solution of the PLA in dichloromethane (DCM), then films of 16 cm × 16 cm size produced were left in the room temperature for the formation. In this way, films from shell material PLA, only PLA (control sample) and PLA with additives 1% and 3% MWCNT, were produced (Table 2).

Table 2

Description of samples

PLA – 0 (only PLA [control sample])
PLA-C1 – PLA with 1% MWCNT
PLA-C1 – PLA with 3% MWCNT

2.1.3 Preparation of coated samples

To assess the dynamic thermal behavior of used PCM (see Section 2.2.3), the prepared CA/MWCNT composites were coated manually on the 3D PES knitted fabric by the screen printing method. In this study were investigated – 3D PES knitted fabric without coating, coated with pure CA and CA/MWCNT (0,5%, 1% and 3%) composites (Table 3).

Table 3

Description of samples

F-K – control specimen (3D PES knitted fabric, further – fabric)
F-CA – fabric coated with CA
F-CA 0.5C – fabric coated with CA + 0.5% MWCNT
F-CA 1C – fabric coated with CA + 1% MWCNT
F-CA 3C – fabric coated with CA + 3% MWCNT

2.1.4 Encapsulation

PLA was used to fabricate the shell of the microcapsules. CA (decanoic acid) (Acros Organics BVBA) was used as the core of the microcapsules. Polyvinyl alcohol (PVA; Acros Organics BVBA), with an average molecular weight of 1,46,000–1,86,000 g mol−1 and 87%–89% hydrolyzed, was used as the emulsifier. DCM (Chempur), with a density of 1,320 kg−m−3, was used as the solvent for the oil medium. Deionized water was used as an aqueous medium. All materials and chemicals were used as received. The physical properties of PLA and CA (decanoic acid) are summarized in Table 4.

Table 4

Physical properties of PLA and of CA (decanoic acid)

MaterialsDensity (kg m−3)Crystalline melting temperature (°C)Glass transition temperature (°C)Boiling temperature (°C)
PLA1,24017058–61—
CA (decanoic acid)89030–32—268–270

Microencapsulation of the capric core in the PLA shell was conducted by the solvent evaporation method accompanied by oil in water emulsification [23]. In general, the fabrication process involves four main steps: (1) dissolution of CA and PLA in DCM; (2) emulsification of this organic phase (i.e., dispersed phase) in a continuous aqueous phase of deionized water containing PVA; (3) extraction and evaporation of solvent from the dispersed phase, which transforms the dispersed phase into solid microspheres (i.e., microcapsules); and (4) recovery and drying of microcapsules to eliminate residual solvent and emulsifier. For the aqueous phase, a 5% PVA solution was prepared by dissolving 5 g of PVA in 95 mL of deionized water. The solution was cured for 30 min at room temperature. After it swelled, it was heated up to 80°C for 2 h to completely dissolve PVA. The oil phase, 1.2 g of PLA, and 1 g of CA were added to 29 mL of DCM. The oil phase was cured for 2 h to obtain a PLA–CA solution. When the preparation of both phases was conducted, 10 g of PLA–CA solution was added to 80 g of PVA solution. The oil–water system was first stirred by a magnetic stirrer at 300 rpm for 3 h at room temperature. Then, emulsion was stirred at 1,000 rpm for 10 min using a mechanical stirrer. In the next steps, DCM was evaporated by elevating the emulsion temperature to 45°C while the emulsion was continuously stirred at 200 rpm for 1 h. The solution was kept at room temperature for 24 h to precipitate the fabricated microcapsules. Then, microcapsules were repeatedly washed with deionized water at 60°C and were filtrated to remove the PVA residues. The filtrated microcapsules are first dried in an oven and then in a desiccator (Figure 2). Similarly, the microcapsules were prepared with the CA and 1% MWCNT. The composite CA 1C, whose preparation is described in Section 2.1.1, was used.

Figure 2 (a) Preparation of microcapsules and (b) image of the prepared microcapsules.
Figure 2

(a) Preparation of microcapsules and (b) image of the prepared microcapsules.

2.2 Methods of investigation

2.2.1 Heat storage and release capacity determination (of CA, CA/MWCNT composites, and microcapsules)

The heat storage and release capacity, as well as the phase change temperatures of PCM – pure CA and CA/MWCNT composites and microcapsules as well, were determined by the standard method EN 16806-1, using differential scanning calorimetry (DSC; Instrument, DSC Q10). The samples underwent a heating–cooling–heating cycle from −20°C to 60°C at a heating and cooling rate of 5°C/min.

2.2.2 Thermal conductivity (of CA, CA/MWCNT composites and PLA, PLA/MWCNT composites)

The thermal conductivity of the shell (PLA) and core materials (CA), used for the manufacturing of bio-based PCM microcapsules, was evaluated based on the measurements of reciprocal parameter – thermal resistance (Rct).

To this purpose, the films made from the shell material, PLA and PLA composites with different loadings of carbon nanotubes (MWCNT), were prepared and measured. The thermal resistance values of the core, pure CA, and the composites of CA with MWCNT were also measured.

Rct under steady-state conditions was measured using sweating guarded-hotplate (apparatus-M259B Sweating guarded hotplate) according to the modified standard method ISO 11092:2014. The principle of this method is that the specimen to be tested is placed on an electrically heated plate with conditioned airflow across and parallel to its upper surface. For the determination of thermal resistance, the heat flux through the test specimen is measured after the steady-state conditions have been reached.

The thermal resistance Rct (m2 K/W) was measured in the following way: the difference of the temperature between the two faces of the material was divided by the resultant heat flux per unit area in the direction of a steadily applied temperature gradient.

During the test, an area of measurement unit of 0.04 m2 was diminished till 0.004 m2 by covering it with the thermal insulating material. The samples of films prepared from the shell material were placed directly on the measuring unit, an electrically heated plate, and the samples of core material were placed into the tubes with a bottom of liquid–water impermeable cellophane membrane (to prevent PCM leakage during its melting).

Thermal resistance was calculated using the following formula:

Rct=(Tm−Ta)AH−ΔHc−Rct0[m2K/W]

where Tm = 35°C (temperature of the measuring unit), Ta = 20°C (air temperature in the test enclosure), H is the heating power supplied to the measuring unit, in watts, A is the area of measuring unit in square meters, Rct0 is the apparatus constant, in square meters kelvin per watt, ΔHc = 0 (correction term for heating power), coefficient of the thermal conductivity λ, W/(m K), was calculated using the formula:

λ=D/Rct[W/(mK)]

where D is the thickness of the sample (m) and Rct is the thermal resistance (m2 K/W).

2.2.3 Evaluation of dynamic thermal behavior (of coated fabrics)

To obtain the supplementary information and to assess the dynamic thermal behavior of used PCM when the temperature changes, another technique, such as monitoring of a cold/hot plate with an IR camera, was used. For this purpose, textile samples coated with PCM, pure CA and of CA/MWCNT composites, were prepared and tested.

The electrically heated measuring unit of apparatus, M259B Sweating guarded hotplate, was used as a plate. Test samples were placed across the measuring unit, with the backside (not coated with PCM) toward the measuring unit (face side on the top). The samples were heated approximately till the melting temperature of the used PCM. The outer surface temperature of the samples was periodically recorded with a calibrated thermal imaging camera, InfraCam (FLIR SYSTEMS AB, Sweden), operating in the mid-infrared wavelength range (7.5–13 µm) and providing detailed thermographic images. For the analysis of images, FLIR tools+ software was used.

2.2.4 SEM (of microcapsules)

PLA/CA synthesized microcapsules morphology was investigated by scanning electron microscopy (SEM) using Quanta 200 FEG device (FEI Netherlands) at 20 keV (low vacuum). All microscopic images were taken in the same technical and technological conditions: electron beam heating voltage −20.00 kV, beam spot −5.0, magnification −500×, 5,000×, working distance −6.0 mm, low vacuum – 80 Pa, and detector – LFD.

  1. Ethical approval: The conducted research is not related to human or animal use.

3 Results and discussion

As it can be seen from the results presented in Table 5 and Figure 3, the incorporation of MWCNT into CA (MWCNT NC7000 aqueous dispersion AQUACYL AQ0302 (producer Nanocyl SA)) has a certain influence on the enthalpy and phase change temperatures of investigated PCM. In all cases, the presence of MWCNT reduces the peak of melting temperature by about 1°C and the peak of crystallization temperature is even less. However, the onset of melting temperature of the composites differs relatively significantly from CA melting start temperature, that is, to say, the additives of MWCNT accelerate the melting process of CA. The influence of used carbon compounds on the reduction of CA onset melting temperature depends on its concentration in composite – the higher the MWCNT concentration, the lower the melting start temperature (Table 5). Although the addition of MWCNT has a negligible effect on the peak of melting and crystallization temperatures of CA, it reduces the enthalpy of fusion and crystallization as the concentration increases. Only samples of composites with 0.5% of MWCNT have similar heat storage and release capacity as pure CA. The increase in MWCNT concentration up to 1% or 3% reduces the enthalpy of fusion by about 5% and the enthalpy of crystallization by about 10% and thereby turns down the heat storage and release capacity of used PCM.

Table 5

Thermal properties of investigated PCM and its composites with carbon nanotubes determined using the DSC method

Sample codeMeltingCrystallization
Peak melting temperature, Tp,m , °CExtrapolated onset melting temperature, Tei,m, °CExtrapolated end melting temperature, Tef,m, °CEnthalpy of fusion, ΔH, J/gPeak crystallization temperature, Tp,c, °CExtrapolated onset crystallization temperature, Tei,c, °CExtrapolated end crystallization temperature, Tef,c, °CEnthalpy of crystallization, ΔH, J/g
CA33.7326.2343.10144.926.3027.0014.73151.7
CA-0.5C32.5724.0040.83148.026.5527.6716.13153.4
CA-1C32.6521.8541.91138.026.0927.4515.95139.5
CA-3C32.3519.5541.35138.325.2527.7014.05132.2
Figure 3 DSC thermal curves of tested PCM and prepared composites: CA (a), CA/0.5% MWCNT (b), CA/1% MWCNT (c), and CA/3% MWCNT (d).
Figure 3

DSC thermal curves of tested PCM and prepared composites: CA (a), CA/0.5% MWCNT (b), CA/1% MWCNT (c), and CA/3% MWCNT (d).

From the results of DSC analysis, it can be concluded that the optimal amount of MWCNT in composites with CA could be in the interval from 0.5% to 1%, as the higher amount of additive reduces positive properties of heat storage and release capacity of CA.

The DSC test was performed with microcapsules as well. There were two kinds of microcapsules used with PLA/CA and with PLA/CA and with 1% of MWCNT (PLA/CA + C).

The morphology of PLA/CA synthesized microcapsules was investigated using SEM (Figures 4 and 5). These figures illustrate the microscopic morphology of microcapsules fabricated by different recipes with and without WMCNT. The micrographs reveal that all microcapsules were spherical and had a considerably smooth surface. Some pores were observed to be on their surface and were believed to be caused by the evaporation of DCM from the inner region of the emulsion. Figure 5b is a microscopic picture of microcapsule darkening possibly due to the introduction of WMCNT into the composition of the microcapsules. Both types of microcapsules have morphologically similar images. Differences are only observed from the result obtained in the size distribution of microcapsule (Figures 6 and 7). A larger distribution of particle size is observed, within microcapsules containing WMCNT. Although the manufacturing conditions of both types of microcapsules were the same, only the composition differed, the use of WMCNTs is likely to have influenced the size of the microcapsules and the diameter of distribution results.

Figure 4 SEM micrograph of microcapsules (PLA/CA (a) and PLA/CA + C (b)).
Figure 4

SEM micrograph of microcapsules (PLA/CA (a) and PLA/CA + C (b)).

Figure 5 SEM micrograph of microcapsules (PLA-/CA (a) and PLA/CA + C (b)) (bigger increase).
Figure 5

SEM micrograph of microcapsules (PLA-/CA (a) and PLA/CA + C (b)) (bigger increase).

Figure 6 Distribution of particle size in the microcapsules PLA/CA.
Figure 6

Distribution of particle size in the microcapsules PLA/CA.

Figure 7 Distribution of particle size in the microcapsules PLA/CA + C.
Figure 7

Distribution of particle size in the microcapsules PLA/CA + C.

For the DSC test, four specimens of each kind of microcapsules were used. Results are presented in Table 6.

Table 6

Thermal properties of investigated microcapsules with PCM and with PCM with carbon nanotubes determined using the DSC method

Sample codeMeltingEncapsulation efficiency, % (by latent heat of melting)Crystallization
Peak melting temperature, Tp,m ,°CExtrapolated onset melting temperature, Tei,m, °CExtrapolated end melting temperature, Tef,m, °CEnthalpy of fusion, ΔH, J/gPeak crystallization temperature, Tp,c, °CExtrapolated onset crystallization temperature, Tei,c, °CExtrapolated end crystallization temperature, Tef,c, °CEnthalpy of crystallization, ΔH, J/g
PLA/CA33.8226.2842.0235.9924.824.2926.2715.9221.70
Standard deviation0.630.221.012.30—0.120.431.132.49
PLA/CA + C33.8326.6242.0430.8621.324.3126.4416.2818.31
Standard deviation0.340.500.132.32—0.210.301.060.71

The phase change latent heat of microcapsules can be determined by calculating the area under the endothermic peak. The encapsulation efficiency of PLA/CA microcapsules can be calculated using the following equation:

(1)Encapsulationefficiency=(ΔH/ΔHPCM)×100%

where ΔH and ΔHPCM are the latent heat of fusion of microcapsules and CA, respectively.

The peak of melting temperature, enthalpy of fusion, and enthalpy of crystallization were determined. The results revealed that melting and crystallization temperatures of PCM in the microcapsules are equal. The results show that the beginning and the end of the glass transition remain unchanged. Also, the enthalpy of fusion of PLA/CA + C is lower than PLA/CA only in 4%, for example, MWCNT reduces the enthalpy of fusion only in 4%. Also, the content of MWCNT 1% slightly reduces enthalpy of crystallization, but further results of thermal behavior of PCM and PCM + MWCNT on fabric showed that the MWCNT content increases the rate of glass transition.

To evaluate the thermal comfort and to assess the thermal behavior of PCM and its composites (core of microcapsules) and PLA, and also its composites (shell of microcapsules), the thermal resistance test was performed. According to the obtained results of thermal resistance, the coefficients of thermal conductivity and surface resistivity were calculated. For this purpose, CA and CA composites with MWCNT and the PLA and PLA composites with MWCNT were tested. As shown in Tables 7 and 8, although the thickness of PCM layers D is not precisely the same, but the same rank, MWCNT influences the coefficient of thermal conductivity of PCM, coefficient of thermal conductivity is increasing according to the increase in MWCNT in PCM. The same process can be noticed in PLA and PLA composites with different loadings of MWCNT. The coefficient of thermal conductivity is rising according to the increase in MWCNT amount in PLA. Moreover, the surface resistivity of PLA composites is decreasing when the quantity of MWCNT increases.

Table 7

Thermal conductivity of core material (pure CA and composites of CA with MWCNT)

Code of sampleThickness of PCM layer D, mmCoefficient of thermal conductivity λ, W/(m K)
CA90.214
CA-0.5C90.225
CA-1C80.242
CA-3C100.272
Table 8

Thermal conductivity and electrostatic properties of films from shell material (PLA and PLA composites with different amounts of MWCNT)

Code of sampleThickness of film D, mmCoefficient of thermal conductivity λ, W/(m K)Electrostatic properties*
Surface resistivity ρ, ΩElectrical resistance through the material (vertical resistance) Ry, Ω
PLA-01.240.17.92 × 10135.2 × 1012
PLA-C11.040.25.86 × 105<2 × 103
PLA-C31.280.253.58 × 104<2 × 103

*Electrostatic properties were determined according to the standard methods – EN 1149-1 and EN 1149-2.

To obtain supplementary information and to assess the dynamic thermal behavior of used PCM when the temperature changes, another technique, monitoring of a cold/hot plate with an IR camera, was applied. For this purpose, textile samples, control sample, and samples coated with pure CA and with CA/MWCNT composites were prepared and tested. Textile material was used just as the basis for coating since the main aim of this test was to evaluate the thermal behavior of CA and CA/MWCNT composites.

As shown in Figure 8 and Table 9, MWCNT influences the thermal behavior of used PCM, the surface temperature of fabrics coated with composites increases more rather than in samples with pure CA. The concentration of MWCNT has no considerable impact on the rate of surface heating. The results of these measurements prove the influence of MWCNT on the acceleration of the CA melting process and positive effect on the thermal properties of used bio-PCM.

Figure 8 Dynamic thermal behavior of textile samples coated with pure CA and composites of CA with MWCNT, during heating.
Figure 8

Dynamic thermal behavior of textile samples coated with pure CA and composites of CA with MWCNT, during heating.

Table 9

Temperatures of textile samples coated with pure CA and composites of CA with MWCNT during heating

Code of sampleTime of retention on the heating plate, min
Temperatures of sample, °C
12357101112 1722
F-K (control sample)28.629.13131.931.83232.132.132.132.3
F-CA27.927.929.129.530.130.630.831.130.930.8
F-CA 0.5C27.828.830.330.330.430.53130.930.931
F-CA 1C27.62929.9303030.5313130.430.4
F-CA 3C27.62929.930.530.8313131.131.231.3

Figure 9 presents an example of how the surface of fabric samples heats. Figure 9 shows the surface of tested samples heated for 5 min. There are only instant images of samples. For the analysis of images FLIR tools + software was used, and the mean temperature was calculated (Table 9).

Figure 9 Thermographs of samples after 5 min of heating.
Figure 9

Thermographs of samples after 5 min of heating.

4 Conclusion

The thermal properties of bio-based PCM microcapsules and their separate components, core and shell, were investigated considering the influence of used thermal enhancer. Composites of PCM with different concentrations of MWCNT as well as composites of PLA with these carbon compounds were prepared and investigated to assess how MWCNT influences the thermal conductivity of the core and the shell. The heat storage and release capacity, as well as the phase change temperatures of CA/MWCNT composites and manufactured PCM microcapsules, were determined using DSC. To analyze the thermal behavior of core and shell of microcapsules, the thermal resistance test was conducted. To obtain supplementary information and to assess the dynamic behavior of used PCM and its composites with MWCNT, when the temperature changes, monitoring of a cold/hot plate with an IR camera was carried out.

It was determined that the presence of MWCNT reduces the peak of the melting temperature of CA about 1°C and even less peak crystallization temperature. Although the addition of MWCNT has a negligible effect on the peak melting and crystallization temperatures of CA, it reduces the enthalpy of fusion and crystallization as the concentration increases. Compared with studies of other authors, the obtained results are compatible enough [20,35]. According to the gained results, it could be stated that the optimal amount of MWCNT in composites with CA could be in the interval from 0.5% to 1%, as the higher amount of additive reduces positive properties of heat storage and release capacity of CA. The same process is noticed in the results of the microcapsule investigation, and the reduction of the melting and crystallization enthalpy in microcapsules, which was produced with MWCNT, can be observed. The same process is noticed in works of other authors, who investigated different carbon additives [37]. The coefficient of thermal conductivity and the thermal resistivity showed that MWCNT improved the thermal behavior of core and shell materials of microcapsules. Analysis of thermal behavior of the prepared composites also has proven the influence of MWCNT on the acceleration of CA melting process and positive effect on thermal properties of used bio-based PCM.

  1. Conflict of interest: The authors declare no conflict of interest.

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Received: 2019-06-18
Revised: 2020-02-28
Accepted: 2020-04-02
Published Online: 2020-06-23

© 2020 Virginija Skurkytė-Papievienė et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

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  6. Molecular dynamics simulation of sI methane hydrate under compression and tension
  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
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https://doi.org/10.1515/chem-2020-0064
Keywords for this article
textiles; bio-based PCM; carbon nanotubes; heat storage; heat release; differential scanning calorimetry
Creative Commons
BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)
  3. Kinetic models of the extraction of vanillic acid from pumpkin seeds
  4. On the maximum ABC index of bipartite graphs without pendent vertices
  5. Estimation of the total antioxidant potential in the meat samples using thin-layer chromatography
  6. Molecular dynamics simulation of sI methane hydrate under compression and tension
  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
  15. DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones
  16. Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils
  17. A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts
  18. Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark
  19. Rapid identification of direct-acting pancreatic protectants from Cyclocarya paliurus leaves tea by the method of serum pharmacochemistry combined with target cell extraction
  20. Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)
  21. Assessment of methyl 2-({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl] sulfamoyl}methyl)benzoate through biotic and abiotic degradation modes
  22. Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops
  23. Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
  24. Molecular Properties of Carbon Crystal Cubic Structures
  25. Synthesis and characterization of calcium carbonate whisker from yellow phosphorus slag
  26. Study on the interaction between catechin and cholesterol by the density functional theory
  27. Analysis of some pharmaceuticals in the presence of their synthetic impurities by applying hybrid micelle liquid chromatography
  28. Two mixed-ligand coordination polymers based on 2,5-thiophenedicarboxylic acid and flexible N-donor ligands: the protective effect on periodontitis via reducing the release of IL-1β and TNF-α
  29. Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation
  30. Development of ultrasound-assisted dispersive solid-phase microextraction based on mesoporous carbon coated with silica@iron oxide nanocomposite for preconcentration of Te and Tl in natural water systems
  31. N,N′-Bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells
  32. Determination of the content of selected trace elements in Polish commercial fruit juices and health risk assessment
  33. Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study
  34. Keratin 17 is induced in prurigo nodularis lesions
  35. Anticancer, antioxidant, and acute toxicity studies of a Saudi polyherbal formulation, PHF5
  36. LaCoO3 perovskite-type catalysts in syngas conversion
  37. Comparative studies of two vegetal extracts from Stokesia laevis and Geranium pratense: polyphenol profile, cytotoxic effect and antiproliferative activity
  38. Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry
  39. Investigation of polyphenol profile, antioxidant activity and hepatoprotective potential of Aconogonon alpinum (All.) Schur roots
  40. Lead discovery of a guanidinyl tryptophan derivative on amyloid cascade inhibition
  41. Physicochemical evaluation of the fruit pulp of Opuntia spp growing in the Mediterranean area under hard climate conditions
  42. Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
  43. New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties
  44. Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles
  45. Synthesis of orotic acid derivatives and their effects on stem cell proliferation
  46. Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis
  47. Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives
  48. Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate
  49. Enhancement of thermal properties of bio-based microcapsules intended for textile applications
  50. Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique
  51. A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water
  52. Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants
  53. Removal of H2S by vermicompost biofilter and analysis on bacterial community
  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
  55. A self-breaking supramolecular plugging system as lost circulation material in oilfield
  56. Synthesis, characterization, and pharmacological evaluation of thiourea derivatives
  57. Application of drug–metal ion interaction principle in conductometric determination of imatinib, sorafenib, gefitinib and bosutinib
  58. Synthesis and characterization of a novel chitosan-grafted-polyorthoethylaniline biocomposite and utilization for dye removal from water
  59. Optimisation of urine sample preparation for shotgun proteomics
  60. DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases
  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
  62. New derivatives of a natural nordentatin
  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
  71. Citrullus colocynthis (L.) Schrad: Chemical characterization, scavenging and cytotoxic activities
  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
  74. Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid
  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
  76. A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells
  77. A Zn(ii)–organic cage with semirigid ligand for solvent-free cyanosilylation and inhibitory effect on ovarian cancer cell migration and invasion ability via regulating mi-RNA16 expression
  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
  81. Concentrations of dioxins, furans and dioxin-like PCBs in natural animal feed additives
  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
  83. Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models
  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
  95. Investigations of metallic elements and phenolics in Chinese medicinal plants
  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
  98. Adsorption and sugarcane-bagasse-derived activated carbon-based mitigation of 1-[2-(2-chloroethoxy)phenyl]sulfonyl-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea-contaminated soils
  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
  113. An overview of Monascus fermentation processes for monacolin K production
  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
  126. The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide
  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
  138. Special Issue on the International conference CosCI 2018
  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
  144. Biocompatibility and osteoconductivity of scaffold porous composite collagen–hydroxyapatite based coral for bone regeneration
  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
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