Crosslinking structure and mechanical properties of thermoplastic phenolic resin modified with siloxane prepolymer

doi:10.11949/0438-1157.20220579

Abstract

Abstract:

In this study, the crosslinking networks with different topological structures were constructed by co-curing and curing physical state control of epoxy siloxane (ES) and phenolic resins with different degree of prepolymer. The crosslinking networks with different degree of prepolymer siloxane prepolymer (PES) modified thermoplastic phenolic resins (NR-PES) were investigated and the construction methods for their strengthening and toughening were discussed. On this basis, the regulation to the crosslinking microstrucutre and the strengthening and toughening strategy of NR-PES are systematically discussed. Firstly, based on the analysis of curing reaction and physical state of NR-PES by DSC and rheology, a series of NR-PES with different crosslinking microstructures were obtained. Next, DMA, TGA and mechanical tests were used to study the influence of PES with different prepolymerization degrees on the crosslinking network and properties of NR-PES. As PES polymerization degree is low, the crosslinking density of NR-PES is low, resulting in inferior thermal stability and bending strength. With the increase of PES polymerization degree, the crosslinking density of NR-PES keeps increasing, and the thermal stability and bending strength also increase except that K_IC keeps decreasing. Especially, as the polymerization degree of PES is 30%, 2-NR-PES showed excellent thermal stability, bending strength and fracture toughness with value of 53.43% (C_800℃), 20.51 MPa and 0.389 MPa·m^1/2, respectively. However, when the polymerization of PES is further increase, the thermal stability, bending strength and fracture toughness of NR-PES will be significantly reduced.

Key words: thermoplastic phenolic resin, toughening, network isomers, degree of the performed, mass ratio

摘要：

通过不同预聚程度的环氧化硅氧烷（ES）与酚醛树脂共固化及固化物理状态的调控，构建不同拓扑结构的交联网络，探讨了不同预聚程度的硅氧烷预聚体（PES）改性热塑性酚醛树脂（NR-PES）交联网络的调控及其强韧化的构建方法。首先，合成了一种不同预聚程度的环氧化硅氧烷（PES），通过DSC和流变分析，明确了NR-PES的固化反应和物理状态特征，在此基础上，确定了不同交联结构NR-PES的制备方法。接着，采用DMA、TGA、力学测试研究了PES的预聚程度对NR-PES交联网络和性能的影响规律。结果表明，当PES预聚程度较低时，NR-PES的交联密度较低，导致其热稳定性和弯曲强度较低；随着PES预聚程度的增加，NR-PES的交联密度不断增加，其热稳定性、弯曲强度随之增加，但K_IC不断降低。特别是，PES的预聚程度为30%时，2-NR-PES展现出优异的热稳定性、弯曲强度和断裂韧性，残炭率C_800℃为53.43%，弯曲强度为20.51 MPa，K_IC为0.389 MPa·m^1/2。此外，当PES预聚程度过高时，NR-PES的热稳定性、弯曲强度和断裂韧性显著降低。

关键词: 热塑性酚醛树脂, 增韧, 网络异构体, 预聚程度, 质量比

CLC Number:

TB 324

Li XU, Qianqiu WU, Zixuan LEI, Jiaxuan LI, Yuhong LIU. Crosslinking structure and mechanical properties of thermoplastic phenolic resin modified with siloxane prepolymer[J]. CIESC Journal, 2022, 73(10): 4734-4744.

徐力, 吴谦秋, 雷子萱, 李嘉玄, 刘育红. 硅氧烷预聚体改性热塑性酚醛树脂的交联结构及其力学性能[J]. 化工学报, 2022, 73(10): 4734-4744.

Figures/Tables 13

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氢原子编号	化学位移δ	积分比	结构式
a	2.90~3.03	1.00	4H, —CH—
b	1.80~1.94	0.97	4H, —CH₂—
e	1.51~1.59	0.48	2H, —CH—
f	0.98~1.08	1.02	4H, —CH₂—
g	0.37~0.46	0.95	4H, —CH₂—
h	0~0.05	2.95	12H,—CH₃—

氢原子编号	化学位移δ	积分比	结构式
a	2.90~3.03	1.00	4H, —CH—
b	1.80~1.94	0.97	4H, —CH₂—
e	1.51~1.59	0.48	2H, —CH—
f	0.98~1.08	1.02	4H, —CH₂—
g	0.37~0.46	0.95	4H, —CH₂—
h	0~0.05	2.95	12H,—CH₃—

名称	升温速率/(℃·min^-1)	T_i/℃	T_p/℃	T_f/℃	ΔT/℃	ΔH/(J·g^-1)	ΔH平均值/(J·g^-1)
NH	5	121.0	134.1	150.2	29.2	85.88	84.32
	10	129.8	142.6	158.7	28.9	84.02
	15	137.4	148.7	164.1	26.7	84.92
	20	141.5	152.9	167.5	26.0	82.46
1-NR-PES	5	44.6	122.6	199.6	155.0	245.31	220.33
	10	53.4	129.9	201.0	156.6	240.73
	15	64.2	133.7	213.7	149.5	213.63
	20	80.2	139.7	222.3	142.1	181.64
2-NR-PES	5	63.4	126.9	208.0	144.6	130.22	134.14
	10	66.3	133.7	228.6	162.3	126.65
	15	70.0	140.2	232.2	162.2	127.09
	20	116.0	144.8	243.1	127.1	152.59

名称	升温速率/(℃·min^-1)	T_i/℃	T_p/℃	T_f/℃	ΔT/℃	ΔH/(J·g^-1)	ΔH平均值/(J·g^-1)
NH	5	121.0	134.1	150.2	29.2	85.88	84.32
	10	129.8	142.6	158.7	28.9	84.02
	15	137.4	148.7	164.1	26.7	84.92
	20	141.5	152.9	167.5	26.0	82.46
1-NR-PES	5	44.6	122.6	199.6	155.0	245.31	220.33
	10	53.4	129.9	201.0	156.6	240.73
	15	64.2	133.7	213.7	149.5	213.63
	20	80.2	139.7	222.3	142.1	181.64
2-NR-PES	5	63.4	126.9	208.0	144.6	130.22	134.14
	10	66.3	133.7	228.6	162.3	126.65
	15	70.0	140.2	232.2	162.2	127.09
	20	116.0	144.8	243.1	127.1	152.59

组别	E′ (40℃)/ GPa	T_g1/℃	T_g2/℃	E′ (T_g2 +40℃) /MPa	V_e×10³/(mol·m^-3)	半峰宽
NH	8.52	—	135.4	71.5	7.02	28.95
1-NR-PES-0%	10.08	—	129.16	34.3	3.11	40.15
1-NR-PES-30%	12.92	80.33	126.97	31.2	2.87	39.80
1-NR-PES-60%	15.70	64.88	125.04	32.9	3.01	43.05
1-NR-PES-90%	15.42	60.33	124.23	35.2	3.23	43.18
2-NR-PES-0%	10.93	—	121.13	34.7	3.20	62.84
2-NR-PES-30%	10.89	—	122.02	43.9	4.05	59.89
2-NR-PES-60%	12.66	94.68	130.22	48.4	4.38	52.24
2-NR-PES-90%	12.70	97.16	135.24	46.9	4.18	58.27