消防服应用的磺化PBI纤维热解特性及其动力学研究

doi:10.11949/0438-1157.20251132

摘要/Abstract

摘要：

本研究采用热重（TG）、差示扫描量热（DSC）与TG-IR联用技术，系统分析了磺化聚苯并咪唑（PBI）纤维在氮气下的热解行为与动力学。结果表明，其热失重过程分为水分脱除、磺酸基分解及主链裂解三个阶段。DSC曲线显示与失重阶段对应的两个显著吸热峰，其中磺酸基分解的强吸热行为表明材料具备优异的热防护潜力。热解释放出SO₂、NH₃和HCN等气体，1000℃时残炭率达67%（表观值为58.5%），显示出良好热稳定性与成炭能力。采用FWO、KAS、Friedman和Starink四种无模型法进行动力学分析，发现第一阶段活化能随转化率升高，机制由化学控制转向扩散控制；第二阶段活化能呈“先降后升”，存在竞争反应路径。Malek分析进一步揭示两阶段在反应后期均发生机理转变，无法由单一模型描述。本研究阐明了sPBI纤维热解的复杂多步反应特征，为其在高温防护领域的应用与热防护性能模拟提供了理论支撑。

关键词: 磺化PBI纤维, 热解, 动力学模型

Abstract:

This work systematically investigated the pyrolysis behavior and kinetics of sulfonated PBI (sPBI) fiber under nitrogen atmosphere using thermogravimetry (TG), differential scanning calorimetry (DSC), and TG-IR coupled techniques. The results indicate that the mass loss process consists of three distinct stages: moisture removal, decomposition of sulfonic acid groups, and main chain cleavage. The DSC curve reveals two prominent endothermic peaks corresponding to these mass loss stages, with the strong endothermic behavior during sulfonic group decomposition suggesting excellent thermal protection potential. The pyrolysis process releases gases such as SO₂, NH₃, and HCN, and a high char residue of 67% is achieved at 1000°C(with an apparent value of 58.5%). This demonstrates superior thermal stability and char-forming ability. Kinetics analysis using four model-free methods (FWO, KAS, Friedman, and Starink) reveals that in the first decomposed stage, the activation energy increases with conversion, indicating a transition from chemical reaction control to diffusion control. In the second decomposed stage, the activation energy initially decreases and then increases, suggesting competing reaction pathways. Malek analysis further indicates a mechanism shift in the later phase of both stages, which cannot be described by a single reaction model. This work elucidates the complex multi-step nature of sPBI fiber pyrolysis, providing a theoretical foundation for its application in high-temperature protection and the simulation of its thermal protective performance.

Key words: sPBI fiber, pyrolysis, kinetic modeling

中图分类号:

TS 104.76

朱方龙, 冯倩倩. 消防服应用的磺化PBI纤维热解特性及其动力学研究[J]. 化工学报, DOI: 10.11949/0438-1157.20251132.

Fanglong ZHU, Qianqian FENG. Pyrolysis characteristics and kinetics of sulfonated PBI fibers used for firefighting clothing[J]. CIESC Journal, DOI: 10.11949/0438-1157.20251132.

图/表 12

图1 PBI纤维的磺化机制[8]

Fig.1 Sulfation mechanism of PBI fibers[8]

表1 常见的固体动力学机理函数［11］

Table 1 Common solid kinetics mechanism functions

数学模型		微分形式f(α)	积分形式g(α)
扩散模型	一维扩散(D1)	0.5α	α²
	二维扩散 (D2) (Valensi model)	[-ln(1-α)]^-1	α+(1-α)ln(1-α)
	三维扩散 (D3) (Jander model)	3/2(1-α)^2/3[1-(1-α)^1/3]^-1	[1-(1-α)^1/3]²
	三维扩散 (D4) (Ginstling model)	3/2[(1-α)^1/3-1]^-1	1-2/3α-(1-α)^2/3
实验成核模型	幂定律 (P_2/3)	2/3α^-1/2	α^3/2
	幂定律 (P2)	2α^1/2	α^1/2
	幂定律 (P3)	3α^2/3	α^1/3
	幂定律 (P4)	4α^3/4	α^1/4
随机成核生长模型	随机成核(A1)	3/2(1-α)[-ln(1-α)]^1/3	[-ln(1-α)]^2/3
	随机成核(A2)	2(1-α)[-ln(1-α)]^1/2	[-ln(1-α)]^1/2
	随机成核(A3)	3(1-α)[-ln(1-α)]^2/3	[-ln(1-α)]^1/3
	随机成核(A4)	4(1-α)[-ln(1-α)]^3/4	[-ln(1-α)]^1/4
反应级数	一级反应 (F1)	1-α	-ln(1-α)
	二级反应 (F2)	(1-α)²	(1-α)^-1-1
	三级反应 (F3)	(1-α)³	[(1-α)^-2-1]/2
几何收缩模型	收缩圆柱模型(R2)	2(1-α)^1/2	1-(1-α)^1/2
几何收缩模型	收缩圆球模型(R3)	2(1-α)^2/3	1-(1-α)^1/3

表2 四种等转化率方法

Table 2 Four iso-conversion rate methods

方法类别	方法原理	等转化率计算公式
Friedman法	微分法	$l n β d α d T = - E a R T + l n A f α$
FWO法	积分法	$l n β = l n A E a R g α - 5.331 + 1.052 E a R T$
KAS法		$l n β T 2 = l n A R E a g α - E a R T$
Starink法		$l n β T 1.92 = C o n s t a n t - 1.0008 E a R T$

表2 四种等转化率方法

Table 2 Four iso-conversion rate methods

方法类别	方法原理	等转化率计算公式
Friedman法	微分法	$l n β d α d T = - E a R T + l n A f α$
FWO法	积分法	$l n β = l n A E a R g α - 5.331 + 1.052 E a R T$
KAS法		$l n β T 2 = l n A R E a g α - E a R T$
Starink法		$l n β T 1.92 = C o n s t a n t - 1.0008 E a R T$

图2 sPBI纤维的TG-DTG曲线

Fig.2 TG-DTG curves of sPBI fibers

图3 sPBI纤维的DSC曲线

Fig.3 DSC curve of sPBI fibers

图4 不同升温速率下的sPBI纤维TG-DTG曲线

Fig.4 TG-DTG curves of sPBI fibers at different heating rates

图5 sPBI纤维的TG-IR三维图谱

Fig.5 TG-IR three-dimensional spectrum of sPBI fibers

表3 sPBI纤维热解过程中主要气体产物的红外特征吸收峰

气体产物	特征波数范围(cm^-1)	振动模式归属	主要释放阶段(对应温度区间)
H₂O	3650-3700(宽峰)	O-H伸缩振动	第一阶段（< 200 ℃）物理吸附水脱附
SO₂	1300–1400	不对称伸缩振动 (ν₃)	第二阶段（400–550 ℃）磺酸基分解
NH₃	950–1000	面内弯曲振动 (ν₂)	第三阶段（> 600 ℃）主链含氮结构断裂
HCN	710–730	C–H 弯曲振动 (ν₂)	第三阶段（> 600 ℃）主链断裂
HCN	3260–3360	C≡N 伸缩振动 (ν₁)	第三阶段（高温后期）主导产物
CH₄	1305	C–H 弯曲振动 (ν₄)	第三阶段（> 600 ℃）脂肪链或碎片重组
CH₄	3015	C–H 伸缩振动 (ν₃)	第三阶段（> 600 ℃）脂肪链或碎片重组
CO₂	670, 2350	弯曲振动 (ν₂)、不对称伸缩振动 (ν₃)	第三阶段（高温后期）含氧杂质反应
CO	2000–2250	C≡O 伸缩振动	第三阶段（高温后期）炭碎片氧化

图6 等转化率方法拟合

Fig.6 Iso-conversion rate method fitting

表4 不同模型方法计算得到的动力学参数

Table 3 Kinetics parameters calculated using different modeling methods

转化率(α)	FWO模型				KAS模型				Friedman模型				Starink 模型
	分解阶段一		分解阶段二		分解阶段一		分解阶段二		分解阶段一		分解阶段二		分解阶段一		分解阶段二
	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²	E_a (kJ/mol)	R²
0.2	238.89	0.9291	742.21	0.9858	240.54	0.9230	765.20	0.9852	242.94	0.9533	744.59	0.9866	240.72	0.9237	763.93	0.9853
0.3	249.99	0.9675	732.02	0.9902	251.69	0.9647	753.98	0.9898	266.79	0.9682	747.79	0.98846	251.89	0.9650	752.80	0.9899
0.4	264.53	0.9812	673.52	0.9828	266.60	0.9797	692.02	0.9819	267.66	0.9908	665.09	0.96804	266.77	0.9798	691.12	0.9820
0.5	268.95	0.9907	593.73	0.9794	268.95	0.9898	607.73	0.9782	298.87	0.9965	582.47	0.96496	271.12	0.9899	607.17	0.9784
0.6	268.96	0.9954	562.39	0.9738	270.94	0.9950	574.44	0.9723	273.92	0.9969	564.24	0.96442	270.91	0.9951	574.04	0.9724
0.7	273.53	0.9979	572.90	0.9645	275.24	0.9977	585.15	0.9624	290.58	0.9994	619.80	0.95242	275.50	0.9977	584.74	0.9627
0.8	283.24	0.9988	660.25	0.9250	285.29	0.9988	672.63	0.9212	300.47	0.9976	800.21	0.90134	285.49	0.9988	675.92	0.9216
平均值	264.01	-	648.45	-	265.61	-	664.45	-	277.32	-	674.88	-	266.06	-	664.25	-

图7 热解反应活化能值随转化率的变化关系

Fig.7 Variation relationship between activation energy and conversion rate

图8 10 ℃/min升温速率下实验曲线与机理函数曲线的比较

Fig.8 Comparisons of experimental curves with mechanism function curves at the heating rate of 10 ℃/min

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