By introducing dynamic acetal bonds into phenolic resin and combining it with hexamethylenetetramine (HMTA) as a curing agent,a thermosetting phenolic resin (PRB) with both degradable and reprocessable properties,as well as its basalt fiber composite,was prepared.The thermal properties,mechanical properties,degradation rates,and recyclability of the material were systematically investigated.The results showed that PRB-1.0 exhibited a glass transition temperature of 66.38℃,a tensile strength of 33.45 MPa,and an elongation at break of 3.92%.After the addition of HMTA,the glass transition temperature of PRB-1.0-5% increased to 86.82℃,the tensile strength improved to 48.99 MPa,and the elongation at break was 3.65%.In a 0.1 M hydrochloric acid/acetone solution at 50℃,the degradation rate of PRB-1.0-5% reached 16.67 mg·mL-1·h-1.The degradation products can react with 1,4-butanediol divinyl ether to undergo re-curing,enabling closed-loop recycling of the resin.Furthermore,basalt fiber composites prepared using PRB-1.0-5% were also found to be completely degradable under weakly acidic conditions.Composites remanufactured from the recovered basalt fibers exhibited a tensile strength of 394.11 MPa,retaining over 97% of the performance of the original composite (405.28 MPa).
固定PR用量为6.8 g,改变1,4-丁二醇二乙烯基醚与HMTA的用量,制备了7个样品:PRB-0.25(2.4 mL 1,4-丁二醇二乙烯基醚)、PRB-0.5(4.8 mL)、PRB-0.75(7.2 mL)、PRB-1.0(9.4 mL)、PRB-1.0-1%(9.4 mL 1,4-丁二醇二乙烯基醚,0.068 g HMTA)、PRB-1.0-3%(9.4 mL,0.204 g)和PRB-1.0-5%(9.4 mL,0.34 g)。将各样品混合均匀后倒入模具,先在90℃真空烘箱中加热12 h进行预固化,随后在120℃下用平板硫化机压制 30 min,再依次在140℃固化2 h和160℃固化4 h。
1.3 玄武岩纤维复合材料的制备
将13.6 g PR与18.8 mL 1,4-丁二醇二乙烯基醚和0.68 g HMTA充分混合后涂覆于3层平纹玄武岩纤维布(10 cm×10 cm)上,置于90℃真空烘箱中脱气30 min以去除挥发物及夹杂气泡。随后将材料转移至平板硫化机,在120℃、10 MPa压力下压制30 min,最后于160℃真空烘箱中进行4 h后固化处理。
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