聚丙烯酸酯降凝剂对合成蜡油降凝规律的研究

Studies on Pour Point Depression of Synthetic Waxy Oils by Poly(n-Alkyl Acrylates)

以甲苯为溶剂,用自由基溶液聚合方法合成了相对分子质量M不同、烷基链长为14、16、18的3种聚丙烯酸长链烷基酯PA-14、PA-16、PA-18各5个样品。以直馏柴油为溶剂,用DSC方法测定了PA的溶液结晶参数、PA对碳数分布为16-34、19-40的两种生物切片石蜡（A蜡和B蜡）溶液结晶参数及对蜡油（石蜡的油溶液）凝点的影响。PA-14和PA-16对A蜡和B蜡的溶液结晶温度、A蜡油和B蜡油的凝点均无影响。M=5.02×10^4的PA-18溶液结晶热最大,加量100 mg/L时可使A蜡和B蜡的溶液结晶始温、峰温降低,A蜡的最大降幅约为2℃。M在2.7×10^3-1.7×10^5的PA-18可使5%A蜡油和B蜡油的凝点分别下降〉19℃和〉26℃（最低可测凝点为-5℃）;蜡油含蜡量增大时PA-18的降凝效果下降;PA-18降凝剂的最佳M值为2×10^4-5×10^4。利用理想溶液的热力学公式,计算了加剂（PA-18,M=5.02×10^4）和不加剂A蜡和B蜡的溶液结晶热和结晶熵,讨论了PA降凝剂的相关作用。

Poly（n-alkyl acrylates） with alkyl carbon number 14,16 ,and 18 and different molar mass were synthesized and notated as PA-14,PA-16,and PA-18. By using DSC technique and a straight-run diesel as solvent,the solution erystalization characteristics of these polyaerylates ,their effects on the solution erystalization characteristics of mierotome wax A and B with carbon number distributed in range 16--34 and 19---40,respectively, and on the pour point of the 2 synthetic waxy oils（the wax solutions in diesel） were investigated. PA-14 and PA-16 had no effect on the solution crvstalization characteristics of wax A and B and on pour point of waxy oil A and B. PA-18 of molar mass 5.02 × 10^4 gave the largest heat of solution crystalization and, being added at dosage 100 mg/L,caused a decrease in onset and peak temperatures of solution crystalization of wax A and B in diesel,of maximum -2℃ for wax A. PA-18 of molar mass in range 2. 7 × 10^3--1.7 ×10^5 added at dosage 100 mg/L depressed the pour point of 5% waxy oil A and B by 〉 19℃ and 〉26℃ ,respectively（ the lowest detectable pour point was of -5℃）;in waxy oils of higher wax content the pour point depressive ability was lowered;the suitable molar mass of PA-18 as a pour point depressant was in range 2 × 10^4--5 × 10^4. The enthalpy and entropy of crystalization of wax A and B in diesel solution with and without PA-18 （M = 5.02×10^4） added were determined by using the thermodynamic equation of ideal solution;the functions of the polyacrylate pour point depressant were discussed.