超支化聚乙烯亚胺聚磷酸铵对定向刨花板性能的影响

王帅旗; 叶超宇; 段衍筠; 李万兆; 梅长彤; 潘明珠

超支化聚乙烯亚胺聚磷酸铵对定向刨花板性能的影响

1.
南京林业大学材料科学与工程学院, 南京 210037
2.
南京林业大学机电产品包装生物质材料国家地方联合工程研究中心, 南京 210037

基金项目: “十四五”国家重点研发课题(2021YFD2200602-4)

详细信息

通讯作者:
潘明珠，博士，教授，硕士生/博士生导师，研究方向为生物质复合材料　E-mail: mzpan@njfu.edu.cn

中图分类号: TB332; TQ323.3
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- 文章访问数: 42
- HTML全文浏览量: 16
- 被引次数: 0
出版历程
- 收稿日期: 2024-01-18
- 修回日期: 2024-03-13
- 录用日期: 2024-03-14
- 网络出版日期: 2024-04-16

Effect of hyperbranched polyethyleneimine ammonium polyphosphate on the properties of oriented strand boards

1.
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China
2.
National and Local Joint Engineering Research Center of Biomass Materials for Mechatronics Packaging, Nanjing Forestry University, Nanjing 210037, China

Funds: Supported by The National High Technology Research and Development Program of China (2021YFD2200602-4)

摘要

摘要: 本文以超支化聚乙烯亚胺(Polyethyleneimine, PEI)改性的聚磷酸铵(Ammonium polyphosphate, APP)为阻燃剂(PEI/APP)、以酚醛树脂(Phenol formaldehyde resin, PF)为胶黏剂制备定向刨花板(Oriented strand boards, OSB)。采用DSC探讨了PEI/APP对酚醛树脂固化过程的影响，PEI/APP能够与PF形成分子间的氢键和亚胺键(C=N)促进酚醛树脂的固化过程，使其等温固化时的放热峰温度降低至71.6℃，终止固化温度降低至74.1℃。采用力学性能分析仪、数字图像相关(Digital image correlation, DIC)和X射线计算机断层扫描扫描仪(X-ray computed tomography, X-CT)探究OSB的力学性能及其增强机制。相比于APP添加量为9%的定向刨花板，PEI/APP添加量为9%的OSB主向(L)和次向(H)的弹性模量分别提高了21.1%和20.7%；主向和次向的弯曲强度分布提高了10.8%和19.6%，内结合强度提高了6.9%，吸水厚度膨胀率降低了37.9%。DIC显示，OSB在承受弯曲载荷时，应变积累主要发生在顶层和底层，然后沿着或穿过中心层传播。主向的顶层和底层结构变化为股线分层或折断，次向上仅出现折断。X-CT测试结果显示，PEI/APP和PF树脂均匀分散在OSB的表层和芯层。因此，超支化改性提高了APP与大片刨花、PF树脂之间的界面结合，使得应变沿着中心层的传递更明显，中心层吸收载荷能量，从而提高了OSB的弯曲强度。采用LOI和锥形量热仪测试了OSB的阻燃性能，当PEI/APP添加量为9%时，OSB的极限氧指数为46.3%，热释放速率峰值为188.5 kW/m²，相比于APP添加量为9%的OSB，其极限氧指数提高了27.9%，热释放速率峰值降低了14.2%。超支化改性APP能够促使OSB脱水炭化产生连续致密的膨胀炭层，同时产生NH₃，实现气相和凝聚相的协同阻燃。阻燃高强的定向刨花板在绿色建筑、家居、交通应用领域具有十分广阔的应用前景。
- 定向刨花板 /
- 复合聚电解质 /
- 酚醛树脂固化动力学 /
- 动态应变传递 /
- X射线计算机断层扫描
Abstract: In this paper, we are using hyperbranched polyethyleneimine (PEI) modified ammonium polyphosphate (APP) as flame retardant (PEI/APP) and phenol formaldehyde resin (PF) as an adhesive to prepare oriented strand boards. Using DSC to explore the influence of PEI/APP on the curing process of phenol-formaldehyde resin, PEI/APP was able to form intermolecular hydrogen and imine bonds (C=N) with PF to promote the curing process of the phenol-formaldehyde resin, so that the peak temperature of curing was lowered to 71.6℃, and the end of curing temperature was lowered to 74.1℃. Using mechanical property analyzer, digital image correlation and X-ray computed tomography to understand the mechanical properties of oriented strand boards (OSB) and its enhancement mechanism. Compared to the oriented strand board with 9% APP addition, the modulus of elasticity of OSB with 9% PEI/APP addition increased by 21.1% and 20.7% in the major (L) and minor (H) directions, respectively; the major and minor modulus of rupture was increased by 10.8% and 19.6%, the internal bond strength was increased by 6.9%, and the thickness swelling of the absorbed water was reduced by 37.9%. DIC shows that when OSB is loaded in bending, strain accumulation mainly occur in the top and bottom layers and then propagate along or across the central layer. Structural changes in the top and bottom layers of major specimens was either strand delamination or snap off, while only snap off is found in minor specimens. X-CT test results show that PEI/APP and PF resins are widely spread in the surface layer and core layer of OSB. Therefore, the hyperbranching modification improves the interfacial bonding between APP and the large wood shavings and PF resins, which results in making strain transfer along the center layer more pronounced. The center layer absorbs the energy of the load, which im-proves the bending strength of the OSB. The flame retardancy of OSB was tested using LOI and cone calorimetry. Its limiting oxygen index increased by 27.9% and its peak heat release rate decreased by 14.2%. Hyperbranched modified APP could induce OSB dehydration charring to produce a dense and continuous expanded char layer, and at the same time produce NH₃ to realize synergistic flame retardation in both gas and condensed phases. Flame-retardant and high-strength oriented strand board has a very wide application prospect in the field of green building, furniture and transportation applications.
- oriented strand board /
- polyelectrolyte complex /
- curing kinetics of PF /
- dynamic strain transferal /
- X-ray computed tomography

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图 1 阻燃定向刨花板的制备流程示意图

Figure 1. Preparation flow chart of flame retardant oriented strand board.

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图 2 PEI/APP与酚醛树脂(PF)交联体系的表征结果: (a) PEI/APP交联PF的固化前的FTIR；(b)固化后的FTIR; PF和PF-PEI/APP 9%的XPS图谱:(c) C1s; (d) N1s; (e)不同APP添加量下交联体系的DSC曲线; (f) 不同PEI/APP添加量下交联体系的DSC曲线

Figure 2. Characterization results of PEI/APP and phenol formaldehyde resin (PF) cross-linking system: (a) FTIR of PEI/APP cross-linked PF before curing; (b) FTIR after curing; XPS spectra of PF and PF-PEI/APP 9%resin: (c) C1s; (d) N1s; (e) DSC curves of cross-linked systems under different APP dosage;(f) DSC curves of cross-linked systems with different PEI/APP additions.

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图 3 不同升温速率下PEI、APP、PEI/APP对PF固化过程的影响: (a) 5℃/min; (b) 10℃/min; (c) 15℃/min

Figure 3. Effects of PEI, APP, and PEI/APP on PF curing process at different heating rates: (a) 5℃/min; (b) 10℃/min; (c) 15℃/min.

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图 4 (a) Kissinger方程线性拟合图；(b) Ozawa方程线性拟合图；(c)两组方程得到的活化能; (d) PEI、APP以及PEI/APP交联PF后的T_onset、T_peak和T_end的线性拟合

Figure 4. (a) Kissinger equation linear fitting diagram; (b) Ozawa equation linear fitting diagram; (c) Activation energy obtained from two sets of equations; (d) Linear fitting of T_onset, T_peak, and T_end after PEI, APP, and PEI/APP crosslinked PF.

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图 5 (a)OSB实物图和CT扫描图; (b)空白组、(c)APP-9%以及(d)PEI/APP-9%分布的可视化效果图;

Figure 5. (a) Physical drawing and CT scan of OSB; Visualization of (b) control, (c) APP-9%, and (d)PEI/APP-9% distribution.

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图 6 定向刨花板的物理力学性能: (a) TS; (b) MOE-L; (c) MOR-L; (d) IB; (e) MOE-H; (f) MOR-H

Figure 6. Physical and mechanical properties of oriented particle board: (a) TS; (b) MOE-L; (c) MOR-L; (d) IB; (e) MOE-H; (f) MOR-H

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图 7 PB-1、PB-2、PB-4和PB-7在加载过程中的主向上的弯曲和剪切应变分布图

Figure 7. Distribution of bending and shear strains in the main upward direction during the loading process for PB-1, PB-2, PB-4, and PB-7.

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图 8 PB-1、PB-2、PB-4和PB-7在加载过程中的次向上的弯曲和剪切应变分布图

Figure 8. Distribution of bending and shear strains in the secondary direction during the loading process for PB-1, PB-2, PB-4, and PB-7.

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图 9 PEI/APP交联PF树脂制备OSB的力学性能的可能增强机制

Figure 9. Possible enhancement mechanism of mechanical properties of OSB prepared by PEI/APP cross-linked PF resins.

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图 10 定向刨花板的LOI和锥形量热测试：(a) LOI; (b) HRR; (c) THR; (d) SPR

Figure 10. LOI and cone calorimetry testing of oriented particle board: (a) LOI; (b) HRR; (c) THR; (d) SPR.

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图 11 不添加、添加PEI以及添加APP、PEI/APP的定向刨花板燃烧后的残炭照片(a₁，b₁，c₁，d₁，a₂，b₂，c₂，d₂)及其残炭的表层和内层的SEM图像(a₃，b₃，c₃、d₃、a₄、b₄、c₄、d₄)；锥形量热测试后残炭的拉曼光谱(e); 阻燃机制示意图(f)

Figure 11. Digital photos of the residual carbon of the oriented particle without or with the addition of PEI, APP, and PEI/APP after combustion (a₁, b₁, c₁, d₁, a₂, b₂, c₂, d₂) and their exterior and interior layers of the residual carbon SEM images (a3, b3, c3, d3, a4, b4, c4, d4) after cone calorimetry testing; Raman spectra of carbon residue from cone calorimeter test (e), and the flame-retardant mechanism diagram (f).

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表 1 定向刨花板(OSB)中阻燃剂的类型和添加量

Table 1. Types and addition of flame retardants in oriented strand boards (OSB)

Sample	Type of flame retardant	Additive amount/wt%	Density/ (g·cm⁻³)
PB-1	\	\	0.72±0.05
PB-2	Polyethyleneimine (PEI)	0.82	0.73±0.04
PB-3	Ammonium polyphosphate (APP)	6	0.75±0.04
PB-4	APP	9	0.73±0.05
PB-5	APP	12	0.72±0.03
PB-6	PEI/APP	6	0.70±0.06
PB-7	PEI/APP	9	0.73±0.05
PB-8	PEI/APP	12	0.74±0.04
Notes: the addition amount of flame retardant is the ratio of the mass of flame retardant to the mass of absolute dry wood shavings. Repeat once for each condition.

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表 2 各组分在不同升温速率下的DSC参数

Table 2. DSC parameters of each component at different heating rates

Sample	β/(℃·min⁻¹)	T_onset /℃	T_peak /℃	T_end /℃	ΔH/(J·g⁻¹)
PF	5	68	117.6	135.4	232.3
	10	72.8	127.8	149.1	238.4
	15	80.1	139.8	159.5	120.5
PF-PEI0.82%	5	67.6	119.4	134.1	204.9
	10	63.2	131.8	154.9	156.3
	15	56.2	144.4	164.4	84.7
PF-APP9%	5	59.5	82.5	145.8	55.7
	10	56.1	99.9	156.2	87.9
	15	54.2	103.8	159.8	34.2
PF-PEI/APP9%	5	51.7	80.7	101.7	35.3
	10	62.8	100.7	138.6	90.4
	15	69.1	103.8	161.5	43.5
Notes: β is the heating rate; T_onset is the initial curing temperature; T_peak (T_p) is the peak curing temperature; T_end is the curing termination temperature; ΔH is the enthalpy change during the curing process.

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表 3 各组分在升温速率为0℃/min时的固化工艺参数

Table 3. Curing process parameters of each component at a heating rate of 0℃/min

Sample	T_onset /℃	T_peak /℃	T_end /℃
PF	61.5	106.2	123.9
PF-PEI0.82%	73.7	106.9	120.8
PF-APP9%	61.9	73.8	139.9
PF-PEI/APP9%	43.8	71.6	74.1

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表 4 定向刨花板的锥形量热仪的测试结果

Table 4. Test results of cone calorimeter of oriented particle board

Sample	TTI/s	Average HRR (60 s)/(kW·m⁻²)	Average HRR (120 s) /(kW·m⁻²)	Peak HRR/ (kW·m⁻²)	THR/ (MJ·m⁻²)	Average EHC (120 s)/(MJ·kg⁻¹)	TSP/m²
PB-1	18.5(2.5)	176.7(0.8)	159.0(2.4)	252.2(17.5)	102.7(0.8)	11.5(0.2)	5.6(0.2)
PB-2	16.0(2.0)	180.8(3.1)	163.7(1.8)	261.9(21.3)	106.6(0.3)	11.3(0.1)	7.8(0.1)
PB-4	18.5(0.5)	149.5(1.6)	122.4(4.6)	180.0(7.6)	70.5(1.6)	10.8(0.5)	2.4(0.1)
PB-7	22(0)	127.1(1.2)	107.3(1.6)	131.2(3.9)	67.3(1.4)	9.9(0.1)	3.1(0.3)
Notes: TTI is the ignition time; Average HRR in 60 s is the average heat release rate in 60 seconds; Average HRR in 120 s is the average heat release rate in 120 seconds; Average EHC in 120 s is the average heat of combustion in 120 seconds; TSP is the smoke production of the whole combustion process.

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