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Sustainable fragrance release wax oil coating for wood substrate based on peppermint essential oil microcapsules

发布时间：2023-12-23

658546377f13b.png

文章信息

原名：Sustainable fragrance release wax oil coating for wood substrate based on peppermint essential oil microcapsules

译名：基于薄荷精油微胶囊的木质基材可持续脱脂蜡油涂料

期刊：Industrial Crops and Products

5年影响因子：5.9

在线发表时间：2023.11.24

通讯作者： Xiaodong Zhu

第一单位：东北林业大学材料与工程学院

文章亮点

通过将薄荷精油封装到木材中而获得的香味木材。

精油的气味保留在自然暴露中延长了。

含MEOM的蜡油涂层木材具有蜡质、草本和木质的特征。

 

01研究背景

目前，木制品的异味排放是室内环境中感知不适的主要原因。源头控制是减少异味排放的最有效方法。本研究旨在探讨薄荷精油微胶囊对蜡油涂层木制品难闻气味排放的影响。本文在蜡油中加入薄荷精油微胶囊，赋予蜡油涂层木材持续释放香味。结果表明，以明胶和阿拉伯树胶为壁材，薄荷精油为芯材，采用复凝凝聚法制备的微胶囊具有显著的香味缓释能力，热稳定性提高。以10%的质量比在木蜡油中加入微胶囊对漆膜质量没有明显影响，但微胶囊壁材中氨基的存在会导致成品木材发生明显的颜色变化。蜡油涂层木材中芳香气味的释放时间显着延长。早期释放的主要气味物质是具有草本、木本和香脂风味特征的萜烯类。后期释放的气味化合物以烷烃为主，气味表现为蜡状、草本味和木质味。微胶囊在木蜡油中的分散导致木蜡油饰面材料的孔隙结构发生变化，为气味化合物的缓慢释放提供了多种途径。

02研究方案

在这项研究中，薄荷精油被微胶囊化并用于木蜡油整理，以获得可持续的香味释放。为探究释香木制品在气味设计方面的可行性，分析了释香蜡涂油木材的表面涂层质量、颜色稳定性和气味释放特性。开发了一种开发功能性木制品的新方法和方法。

03研究结果

分析了以薄荷精油为芯材，明胶和阿拉伯树胶为壁材制备的MEOM表面微观形貌。微胶囊具有良好的球形度、光滑的表面和良好的分散性。通过扫描电子显微镜（SEM）和透射电子显微镜（TEM）获得的图像显示了具有径向核壳结构和直径为4.0和0.6 mm的高度球形微球。表面的褶皱和凹陷主要是由于微胶囊在干燥过程中的水分流失造成的。薄荷精油的包封率为44.5%。微胶囊粒径集中在2-11 μm范围内，平均粒径为6.6 μm薄荷精油表现出很强的挥发性。薄荷精油暴露48 h和144 h后室温下的保留率分别仅为58.32%和28.7%。MEOM精油的挥发率明显降低。48 h和144 h后精油的保留率分别为94.4%和80.5%。利用Avrami方程分析薄荷精油保留率的结果，确定释放动力学方程。拟合曲线表明，精油的释放机理参数n为0.7527，而微胶囊的释放机理参数为1.2432。据观察，精油在30 °C下的释放过程介于扩散极限动力学和一级反应动力学之间。微胶囊的释放过程与一级反应动力学密切相关。释放速率常数k的计算表明，微胶囊化后薄荷精油的释放速率降低，延缓了异味的释放。

The surface microscopic morphology of MEOM prepared with peppermint essential oil as the core material and gelatin and gum arabic as the wall material was analyzed. Microcapsules present good sphericity, smooth surface and well dispersion. Images obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed highly spherical microspheres with radial core-shell structures and diameters of 4.0 and 0.6 mm (Fig. 2a, b). The folds and depressions on the surface were mainly caused by the water loss of the microcapsules during the drying process. The encapsulation rate of peppermint essential oil was 44.5%. The microcapsule particle size was concentrated in the range of 2–11 µm, with an average particle size of 6.6 µm (Fig. 2c).

6585464d4ec20.png

Fig. 2. Characterization of MEOM. (a) Surface morphology of microcapsules, (b) TEM image, (c) particle size distribution, (d) sustained release curve, (e) FTIR and (f) TG/DTG curves.

Peppermint essential oil showed a strong volatile nature. The retention rates of peppermint essential oil at room temperature after 48 h and 144 h of exposure were only 58.32% and 28.7%, respectively. There was a significant reduction in the volatilization rate of MEOM essential oil. The retention rates of essential oil after 48 h and 144 h were 94.4% and 80.5%, respectively. The results of the retention rates of peppermint essential oil were analyzed using the Avrami's equation to determine the release kinetic equation. The fitted curves showed that the release mechanism parameter n for the essential oil was 0.7527, while for the microcapsules it was 1.2432. It was observed that the release process of the essential oil at 30 °C was between diffusion-limited kinetics and first-order reaction kinetics. The release process of the microcapsules closely followed first-order reaction kinetics. Calculation of the release rate constant k showed that the release rate of the peppermint essential oil decreased after microencapsulation, which delayed the odorous emissions.

The results of IR spectroscopy analysis revealed (Fig. 2e) that in peppermint essential oil, the characteristic absorption peak at 1710 cm−1 was due to carbonyl (CO) stretching vibrations, corresponding to the ester component of the essential oil. The CC stretching vibration peak at 1457 cm−1 is the characteristic peak of olefins (limonene, lauricene, etc.) in peppermint essential oil (Kasiri and Fathi, 2017). The characteristic peak at 3290 cm−1 of the microcapsule wall material is attributed to the overlap of the -OH of carboxylic acid in gum Arabic and the N-H stretching vibration peak of amino acid in gelatin. 2920 cm−1 is the stretching vibration peak of C-H in -CH2 (Rousi et al., 2019). The peak observed in gelatin spectrum at Amide Ⅰregion shifted to 1640 cm−1, peaks at 1606 and 1417 cm−1 which give the information of carboxylic acids adsorption in gum arabic disappeared and shifted to a lower wavelength. This is an indication of electrostatic interaction between amino groups of gelatin and carboxylic groups of gum arabic. In comparison with the infrared spectra of gum Arabic and gelatin, the microcapsule wall material was at 1545 cm−1 mainly due to the electrostatic attraction binding between gum Arabic and gelatin by analysis. The intensities of the characteristic absorption peaks of -CH2, CO, and CC at 2920 cm−1, 1710 cm−1 and 1457 cm−1 of MEOM were significantly enhanced, indicating that peppermint essential oil was successfully encapsulated in the microencapsulated wall material.

Encapsulation significantly improved the thermal stability of the essential oil (Fig. 2f). High temperature accelerates the essential oil mass loss. Peppermint essential oil suffered a large loss of mass during the heating process from 40 °C to 130 °C. The temperature of 5% mass loss were 52.8 °C and 163 °C for peppermint essential oil and MEOM. The mass residue of peppermint essential oil was only 5.4% after being warmed to 130 °C. No significant mass loss occurred during the heating process from 40 °C to 190 °C for the microencapsulated essential oil. Temperature increases from 190 °C to 400 °C led to the mass residue decreasing from 90.3% to 8.5%, primarily due to ruptures of microcapsule walls.

Paint film hardness is an important property of coating mechanical strength. Paint films without and with microcapsules can both achieve 3 H classification, and the hardness of the film is not affected by microcapsule addition (Table 1). The paint film was worn out and represented white in several places, and the paint film's abrasion resistance was graded as grade 2. During the process of finishing wood with wood wax oil, a cross structure is formed by the wax entering the surface and combining with the fibrous tissue. This cross structure is responsible for adhesion. Table 1 shows that the microcapsules did not affect the bonding of wax components to wood substrates, and the adhesion grading was rated as 0. The cut edges of the surface of the paint film were complete and smooth without peeling, and the addition of microcapsules did not reduce the adhesion of the paint film. Cold liquid resistance tests were conducted on wood surfaces coated with fragrance-releasing wood wax oil, and the results showed that peppermint essential oil microcapsules had no effect. The results of cold liquid resistance tests on wood surfaces coated with fragrance-releasing wood wax oil showed that the addition of MEOM had no effect on the water, acid and alkali resistance of the paint film.

Samples

Pencil hardness

Adhesion grade

Cold liquids resistance

Wear resistance

10% Sodium carbonate solution

10% acetic acid solution

water

Wax oil-coated wood

3 H

0

unchanged

unchanged

unchanged

2

Fragrance wax oil-coated wood

3 H

0

unchanged

unchanged

unchanged

2

According to Fig. 3a, the surface morphology of the oak wood after surface sanding shows the structural unevenness caused by mechanical cutting. Oak wood had a porosity of 53.36%, a pore volume of 0.85 mL/g, a total pore area of 43.84 m2/g, and an average diameter of 77.40 nm according to mercury pressure tests. In the range of 100–1000 nm, the pore size that transports mercury increases the fastest. The maximum volume of intrusion mercury was observed at pore sizes of 21 nm, 348 nm and 180 nm (Fig. 4). By coating the wood substrate with wood wax oil, the uneven surface structure of the wood could be masked, and the cured paint film had a smooth surface. The distribution of MEOM in the coating can be observed on the surface of the wood wax oil film. Compared to oak wood and wax oil-coated wood, wax oil-coated wood with fragrance released increased significantly in mercury intrusion, with the greatest increase in mercury intrusion occurring within pore sizes of 5–200 nm. MEOM increased the porosity of wax oil-coated wood by 61.42%, the pore volume was 0.95 mL/g, the pore area was 38.25 m2/g, and the average pore diameter was 99.00 nm. The maximum intrusion mercury volume was observed at pore diameters of 21 nm and 482 nm. Microcapsules accumulated as the wood wax oil coating penetrated into the macroporous pores of the wood, causing an increase in pore size within 100–1000 nm.

6585467906cba.png

Fig. 3. Surface morphology of wood (a), wax-coated wood (c), fragrance wax-coated wood (d) and FTIR analysis (b).

65854689b6728.png


04研究结论

本研究的重点是利用创新的聚结方法开发可持续的香味释放微胶囊。微胶囊由明胶阿拉伯胶作为壁材，薄荷精油作为核心成分。封装过程涉及通过阿拉伯树胶和明胶之间的静电吸引形成规则的球形核壳结构。薄荷精油在核壁比为2：1（w/w）和pH值为3.7时，包封率为44.5%，平均粒径为6.6 μm。将薄荷精油封装在明胶/阿拉伯树胶微胶囊中表明，精油的释放可以显着延长。自然暴露48 h后，精油的截留率提高到94.4%。有效提高了薄荷精油的热稳定性。MEOM的5%质量损失温度达到163 °C。 研究了MEOM涂蜡木材的物理性质、颜色稳定性和气味特征。当木材涂上薄荷精油微胶囊时，漆膜的表面物理和机械性能没有改变。用MEOM涂蜡油的木材漆膜性能达到3H硬度，2级耐磨性。然而，微胶囊中的氨基增加了成品的表面色差。香薰蜡油涂布木材在暴露180天后达到18的∆E*值。导致标本表面色差增加。精油释放期延长，蜡油涂层木材样品的气味特征从最初的萜烯优势变为烷烃优势。气味的特征是蜡质、草药和木质。微胶囊和薄膜的表面孔结构。为薄荷精油中气味化合物成分的迁移释放提供多种途径，从而实现芳香气味的可持续释放。

原文链接：https://www.sciencedirect.com/science/article/pii/S0926669023016138#sec0045


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Sustainable fragrance release wax oil coating for wood substrate based on peppermint essential oil microcapsules

发布时间：2023-12-23

658546377f13b.png

文章信息

原名：Sustainable fragrance release wax oil coating for wood substrate based on peppermint essential oil microcapsules

译名：基于薄荷精油微胶囊的木质基材可持续脱脂蜡油涂料

期刊：Industrial Crops and Products

5年影响因子：5.9

在线发表时间：2023.11.24

通讯作者： Xiaodong Zhu

第一单位：东北林业大学材料与工程学院

文章亮点

通过将薄荷精油封装到木材中而获得的香味木材。

精油的气味保留在自然暴露中延长了。

含MEOM的蜡油涂层木材具有蜡质、草本和木质的特征。

 

01研究背景

目前，木制品的异味排放是室内环境中感知不适的主要原因。源头控制是减少异味排放的最有效方法。本研究旨在探讨薄荷精油微胶囊对蜡油涂层木制品难闻气味排放的影响。本文在蜡油中加入薄荷精油微胶囊，赋予蜡油涂层木材持续释放香味。结果表明，以明胶和阿拉伯树胶为壁材，薄荷精油为芯材，采用复凝凝聚法制备的微胶囊具有显著的香味缓释能力，热稳定性提高。以10%的质量比在木蜡油中加入微胶囊对漆膜质量没有明显影响，但微胶囊壁材中氨基的存在会导致成品木材发生明显的颜色变化。蜡油涂层木材中芳香气味的释放时间显着延长。早期释放的主要气味物质是具有草本、木本和香脂风味特征的萜烯类。后期释放的气味化合物以烷烃为主，气味表现为蜡状、草本味和木质味。微胶囊在木蜡油中的分散导致木蜡油饰面材料的孔隙结构发生变化，为气味化合物的缓慢释放提供了多种途径。

02研究方案

在这项研究中，薄荷精油被微胶囊化并用于木蜡油整理，以获得可持续的香味释放。为探究释香木制品在气味设计方面的可行性，分析了释香蜡涂油木材的表面涂层质量、颜色稳定性和气味释放特性。开发了一种开发功能性木制品的新方法和方法。

03研究结果

分析了以薄荷精油为芯材，明胶和阿拉伯树胶为壁材制备的MEOM表面微观形貌。微胶囊具有良好的球形度、光滑的表面和良好的分散性。通过扫描电子显微镜（SEM）和透射电子显微镜（TEM）获得的图像显示了具有径向核壳结构和直径为4.0和0.6 mm的高度球形微球。表面的褶皱和凹陷主要是由于微胶囊在干燥过程中的水分流失造成的。薄荷精油的包封率为44.5%。微胶囊粒径集中在2-11 μm范围内，平均粒径为6.6 μm薄荷精油表现出很强的挥发性。薄荷精油暴露48 h和144 h后室温下的保留率分别仅为58.32%和28.7%。MEOM精油的挥发率明显降低。48 h和144 h后精油的保留率分别为94.4%和80.5%。利用Avrami方程分析薄荷精油保留率的结果，确定释放动力学方程。拟合曲线表明，精油的释放机理参数n为0.7527，而微胶囊的释放机理参数为1.2432。据观察，精油在30 °C下的释放过程介于扩散极限动力学和一级反应动力学之间。微胶囊的释放过程与一级反应动力学密切相关。释放速率常数k的计算表明，微胶囊化后薄荷精油的释放速率降低，延缓了异味的释放。

The surface microscopic morphology of MEOM prepared with peppermint essential oil as the core material and gelatin and gum arabic as the wall material was analyzed. Microcapsules present good sphericity, smooth surface and well dispersion. Images obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed highly spherical microspheres with radial core-shell structures and diameters of 4.0 and 0.6 mm (Fig. 2a, b). The folds and depressions on the surface were mainly caused by the water loss of the microcapsules during the drying process. The encapsulation rate of peppermint essential oil was 44.5%. The microcapsule particle size was concentrated in the range of 2–11 µm, with an average particle size of 6.6 µm (Fig. 2c).

6585464d4ec20.png

Fig. 2. Characterization of MEOM. (a) Surface morphology of microcapsules, (b) TEM image, (c) particle size distribution, (d) sustained release curve, (e) FTIR and (f) TG/DTG curves.

Peppermint essential oil showed a strong volatile nature. The retention rates of peppermint essential oil at room temperature after 48 h and 144 h of exposure were only 58.32% and 28.7%, respectively. There was a significant reduction in the volatilization rate of MEOM essential oil. The retention rates of essential oil after 48 h and 144 h were 94.4% and 80.5%, respectively. The results of the retention rates of peppermint essential oil were analyzed using the Avrami's equation to determine the release kinetic equation. The fitted curves showed that the release mechanism parameter n for the essential oil was 0.7527, while for the microcapsules it was 1.2432. It was observed that the release process of the essential oil at 30 °C was between diffusion-limited kinetics and first-order reaction kinetics. The release process of the microcapsules closely followed first-order reaction kinetics. Calculation of the release rate constant k showed that the release rate of the peppermint essential oil decreased after microencapsulation, which delayed the odorous emissions.

The results of IR spectroscopy analysis revealed (Fig. 2e) that in peppermint essential oil, the characteristic absorption peak at 1710 cm−1 was due to carbonyl (CO) stretching vibrations, corresponding to the ester component of the essential oil. The CC stretching vibration peak at 1457 cm−1 is the characteristic peak of olefins (limonene, lauricene, etc.) in peppermint essential oil (Kasiri and Fathi, 2017). The characteristic peak at 3290 cm−1 of the microcapsule wall material is attributed to the overlap of the -OH of carboxylic acid in gum Arabic and the N-H stretching vibration peak of amino acid in gelatin. 2920 cm−1 is the stretching vibration peak of C-H in -CH2 (Rousi et al., 2019). The peak observed in gelatin spectrum at Amide Ⅰregion shifted to 1640 cm−1, peaks at 1606 and 1417 cm−1 which give the information of carboxylic acids adsorption in gum arabic disappeared and shifted to a lower wavelength. This is an indication of electrostatic interaction between amino groups of gelatin and carboxylic groups of gum arabic. In comparison with the infrared spectra of gum Arabic and gelatin, the microcapsule wall material was at 1545 cm−1 mainly due to the electrostatic attraction binding between gum Arabic and gelatin by analysis. The intensities of the characteristic absorption peaks of -CH2, CO, and CC at 2920 cm−1, 1710 cm−1 and 1457 cm−1 of MEOM were significantly enhanced, indicating that peppermint essential oil was successfully encapsulated in the microencapsulated wall material.

Encapsulation significantly improved the thermal stability of the essential oil (Fig. 2f). High temperature accelerates the essential oil mass loss. Peppermint essential oil suffered a large loss of mass during the heating process from 40 °C to 130 °C. The temperature of 5% mass loss were 52.8 °C and 163 °C for peppermint essential oil and MEOM. The mass residue of peppermint essential oil was only 5.4% after being warmed to 130 °C. No significant mass loss occurred during the heating process from 40 °C to 190 °C for the microencapsulated essential oil. Temperature increases from 190 °C to 400 °C led to the mass residue decreasing from 90.3% to 8.5%, primarily due to ruptures of microcapsule walls.

Paint film hardness is an important property of coating mechanical strength. Paint films without and with microcapsules can both achieve 3 H classification, and the hardness of the film is not affected by microcapsule addition (Table 1). The paint film was worn out and represented white in several places, and the paint film's abrasion resistance was graded as grade 2. During the process of finishing wood with wood wax oil, a cross structure is formed by the wax entering the surface and combining with the fibrous tissue. This cross structure is responsible for adhesion. Table 1 shows that the microcapsules did not affect the bonding of wax components to wood substrates, and the adhesion grading was rated as 0. The cut edges of the surface of the paint film were complete and smooth without peeling, and the addition of microcapsules did not reduce the adhesion of the paint film. Cold liquid resistance tests were conducted on wood surfaces coated with fragrance-releasing wood wax oil, and the results showed that peppermint essential oil microcapsules had no effect. The results of cold liquid resistance tests on wood surfaces coated with fragrance-releasing wood wax oil showed that the addition of MEOM had no effect on the water, acid and alkali resistance of the paint film.

Samples

Pencil hardness

Adhesion grade

Cold liquids resistance

Wear resistance

10% Sodium carbonate solution

10% acetic acid solution

water

Wax oil-coated wood

3 H

0

unchanged

unchanged

unchanged

2

Fragrance wax oil-coated wood

3 H

0

unchanged

unchanged

unchanged

2

According to Fig. 3a, the surface morphology of the oak wood after surface sanding shows the structural unevenness caused by mechanical cutting. Oak wood had a porosity of 53.36%, a pore volume of 0.85 mL/g, a total pore area of 43.84 m2/g, and an average diameter of 77.40 nm according to mercury pressure tests. In the range of 100–1000 nm, the pore size that transports mercury increases the fastest. The maximum volume of intrusion mercury was observed at pore sizes of 21 nm, 348 nm and 180 nm (Fig. 4). By coating the wood substrate with wood wax oil, the uneven surface structure of the wood could be masked, and the cured paint film had a smooth surface. The distribution of MEOM in the coating can be observed on the surface of the wood wax oil film. Compared to oak wood and wax oil-coated wood, wax oil-coated wood with fragrance released increased significantly in mercury intrusion, with the greatest increase in mercury intrusion occurring within pore sizes of 5–200 nm. MEOM increased the porosity of wax oil-coated wood by 61.42%, the pore volume was 0.95 mL/g, the pore area was 38.25 m2/g, and the average pore diameter was 99.00 nm. The maximum intrusion mercury volume was observed at pore diameters of 21 nm and 482 nm. Microcapsules accumulated as the wood wax oil coating penetrated into the macroporous pores of the wood, causing an increase in pore size within 100–1000 nm.

6585467906cba.png

Fig. 3. Surface morphology of wood (a), wax-coated wood (c), fragrance wax-coated wood (d) and FTIR analysis (b).

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04研究结论

本研究的重点是利用创新的聚结方法开发可持续的香味释放微胶囊。微胶囊由明胶阿拉伯胶作为壁材，薄荷精油作为核心成分。封装过程涉及通过阿拉伯树胶和明胶之间的静电吸引形成规则的球形核壳结构。薄荷精油在核壁比为2：1（w/w）和pH值为3.7时，包封率为44.5%，平均粒径为6.6 μm。将薄荷精油封装在明胶/阿拉伯树胶微胶囊中表明，精油的释放可以显着延长。自然暴露48 h后，精油的截留率提高到94.4%。有效提高了薄荷精油的热稳定性。MEOM的5%质量损失温度达到163 °C。 研究了MEOM涂蜡木材的物理性质、颜色稳定性和气味特征。当木材涂上薄荷精油微胶囊时，漆膜的表面物理和机械性能没有改变。用MEOM涂蜡油的木材漆膜性能达到3H硬度，2级耐磨性。然而，微胶囊中的氨基增加了成品的表面色差。香薰蜡油涂布木材在暴露180天后达到18的∆E*值。导致标本表面色差增加。精油释放期延长，蜡油涂层木材样品的气味特征从最初的萜烯优势变为烷烃优势。气味的特征是蜡质、草药和木质。微胶囊和薄膜的表面孔结构。为薄荷精油中气味化合物成分的迁移释放提供多种途径，从而实现芳香气味的可持续释放。

原文链接：https://www.sciencedirect.com/science/article/pii/S0926669023016138#sec0045


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