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1 An acrylic resin was added to an impregnation system using buffered amine oxides and propiconazole, and the coating obtainted was characterized. It was found that the amine oxides reduced the adhesion of the coating and increased its permeability to water + 662 word(s) 662 2020-05-08 12:11:05 |
2 The entry was modified to be a summary of the paper instead of an introduction. Tables, figures and images were added. + 1244 word(s) 1906 2020-08-05 00:21:07 | |
3 format correct -2 word(s) 1904 2020-10-30 07:25:57 |

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Pepin, S.; Blanchet, P.; Landry, V. Acrylic Carrier. Encyclopedia. Available online: https://encyclopedia.pub/entry/809 (accessed on 17 April 2024).
Pepin S, Blanchet P, Landry V. Acrylic Carrier. Encyclopedia. Available at: https://encyclopedia.pub/entry/809. Accessed April 17, 2024.
Pepin, Simon, Pierre Blanchet, Véronic Landry. "Acrylic Carrier" Encyclopedia, https://encyclopedia.pub/entry/809 (accessed April 17, 2024).
Pepin, S., Blanchet, P., & Landry, V. (2020, May 13). Acrylic Carrier. In Encyclopedia. https://encyclopedia.pub/entry/809
Pepin, Simon, et al. "Acrylic Carrier." Encyclopedia. Web. 13 May, 2020.
Acrylic Carrier
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Wood used outdoor is subjected to different sources of degradation and should be protected properly. In this study, acrylic resins were added to a wood impregnation system using amine oxides and propiconazole, an organic fungicide, to create a two-part wood protection preservation treatment. Since amine oxides can diffuse readily into wood, this treatment protected both the surface and inner structure of the treated wood following a simple dipping. Many aspects of the treatment were studied: the adhesion of the acrylic coatings, their permeability to water, and the impregnation depth of the propiconazole. In each case, a particular attention was accorded to the interactions between the resins and the impregnation system. Adhesion and permeability tests were coupled with an artificial aging process simulating severely wet conditions. Amine oxides reduced the adhesion of the coatings, but did not impair their aging properties. Because of their hydrophilic nature, they also increased the permeability to liquid water, although they did not affect the air moisture permeability. The penetration of the propiconazole, estimated with a dye, decreased with the resin. Overall, the two parts of the treatment lightly impaired each other, but the practical aspect of this treatment may overcome these disadvantages.

acrylic coating amine oxides propiconazole wood protection adhesion permeability impregnation artificial aging white pine white spruce

1. Introduction

The use of wood in buildings should be promoted when it is possible, as it is a bio-based material with great properties and aesthetics. Other materials, such as steel and concrete, are sometimes preferred to wood as they are considered more durable. It is however possible to efficiently protect wood from decay and damages with simple treatments.

Wood protection could mainly be separated in two broad and complementary categories: impregnation treatments and coatings. Impregnation treatments are used to penetrate wood cavities with hydrophobic and/or biocidal compounds and improve its durability against insects, decay fungi, molds and dimensional changes [1][2][3][4][5][6]. Some reactive chemicals, like acetic anhydride and formaldehyde, can also be used to modify the chemical nature of the cell walls and improve their properties [7][8]. Wood impregnation usually relies on pressure and vacuum methods to allow for a rapid and deep penetration of the treatments [9][10]. Coatings can be very diverse, from penetrating oils to film-forming alkyds and acrylics [11]. They can prevent the weathering from abiotic elements (wind, sand, rain, etc), decrease the exchanges of moisture, and block the UV rays from the sun with pigments and UV absorbers [12][13][14][15]. The natural look of the wood surface can be preserved with clear coatings, or altered to hidden with increasing amount of pigments.

An aqueous impregnation treatment was recently developed to allow for the impregnation of wood through diffusion after a simple dipping, preventing the need for pressure and vacuum [16]. It uses the abilities of tertiary amine oxides to diffuse into the wood and solubilize organic compounds, like biocides, to protect wood from biodegradation and dimensional changes [17][18]. In a previous paper, we showed that this treatment could nearly inhibit the fungal degradation by Rhodonia placenta and decrease the dimensional changes in eastern white pine (Pinus strobus L) and white spruce (Picea glauca Moench (Voss)) by 29% and 24%, respectively, while barely increasing their density [19]. In another paper, we determined that the treatment did improve the penetration of the fungicides, but only longitudinally. Meanwhile, the antiseptic amine oxides could penetrate perpendicularly to the grain, granting fungal protection below the surface. We also found that the treatment allowed to impregnate enough fungicide to respect the EN standards, even after 2 weeks of leaching by immersion [20].

In this paper, we brought the treatment one step further by adding acrylic resins to its composition. It allowed for both the impregnation and the coating of wood in a single step. After characterizing the treatment solutions and the dry films, we tested the adhesion of the films, their permeability to water and air moisture, and the impregnation depth of an indigo blue dye (Fig. 1). The adhesion and water permeability tests were combined with artificial aging. The main results are summarized in the next section and discussed in further details in the paper.

Figure 1. Experimental procedure of the study

2. Main results

2.1. Properties of the treatments

The treatment solutions were prepared using a factorial design with acrylic resins and amine oxides (AO)  conditions as the factors. They would contain no resin (R0) or one of three commercial resins (R1, R2, R3), and either no amine (AO0), only dimethyldodecylamine oxide (DDAO)(AO1), or a mix of DDAO and dimethylhexadecalmine oxide (DHAO)(AO2).

We found that both the amine oxides and the acrylic resins increased the viscosity of the treatment solutions. Consequently, the dry films of the treatments containing amine oxides were also thicker. The amine oxides usually led to a faster drying time and a lower Tg, particularly for AO2.

Table 1. Properties of the treatment solutions (at 65 oC) and of the dry coatings.

Treatment

Viscosity

(cP)

Film thickness

m)

Drying time

(s)

Theorical Tg* (oC)

Experimental Tg (oC)

Particle size*

m)

Pine

Spruce

R0-AO0

0.63

N/A

N/A

N/A

N/A

N/A

N/A

R0-AO1

0.77

N/A

N/A

N/A

N/A

N/A

N/A

R0-AO2

6.47

N/A

N/A

N/A

N/A

N/A

N/A

R1-AO0

56

65.5

60

461

15

11.01

0.10

R1-AO1

66

62.5

68.5

431

15

6.90

0.10

R1-AO2

91

88.5

62.5

375

15

5.06

0.10

R2-AO0

32

40.5

49.5

165

20

14.69

0.23

R2-AO1

66

53.5

47.5

114

20

11.34

0.23

R2-AO2

164

62.0

83.5

2344

20

8.96

0.23

R3-AO0

27

55.5

55.3

130

14

11.55

0.30

R3-AO1

46

62.0

63.5

144

14

15.18

0.30

R3-AO2

66

62.5

69

161

14

11.07

0.30

*These properties are provided by the supplier of the acrylic resins

2.2. Permeability to water

The permeability to water of the treatments was studied by comparing the mass of water absorbed by treated and untreated samples after 30 minutes of soaking [21]. The water repellent efficiency (WRE) was calculated with eq. 1:

WRE (%) = 100 x ((Mua - Mub) - (Mta - Mtb))/(Mua - Mub)

where Mua and Mub represent the mass (in grams) of untreated samples after and before soaking, and Mta and Mtb the mass (in grams) of treated samples after and before soaking, respectively. The samples for this test were either unaged or aged for 14 cycles (Table 2).

Table 2. Conditions of one cycle of artificial aging.

Conditions

Temperature (oC)

Relative humidity

Duration

Rainy night

5 oC

98% + rain

10 h

Cold night

5 oC

98%

22 h

Winter

-15 oC

N/A

8 h

Dry day

50 oC

20%

8 h

The results showed that the amine oxides reduced the permeability to water of uncoated samples (R0-AO1 and R0-AO2), but increased the permeability of the coated ones. It was attributed to the amine oxides being less hydrophilic than the wood cells, but more than the acrylic resins. In both scenarios, the treatments with DHAO (AO2) were less hydrophilic. All three resins reduced significantly the permeability to water of white spruce before aging. They however did not perform well after aging as the samples were cracked, which greatly increased the absorption of water. This cracking was attributed to the freezing of trapped water into the wood during the aging cycles.

Figure 2. Water repellent efficiency (WRE) of the white spruce before and after artificial aging.

Figure 3. Water repellent efficiency (WRE) of the white pine before and after artificial aging.

In the case of white pine, R2 and R3 did not perform well before aging, which would be caused by an insufficient protection of the latewood (Fig. 4). The WRE of these samples however increased by a large margin after artificial aging, as the resins still managed to prevent these samples from cracking during the aging process.