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    基于线形聚丙烯酰胺聚合物溶液流变学行为的影响因素

    Influencing Factors of Rheological Behavior Based on Linear Polyacrylamide Polymer Solution

    • 摘要: 通过溶液聚合合成了线形聚丙烯酰胺(LPA),分别在 LPA 水溶液中聚合NN-二甲基丙烯酰胺(DMA)和 N-羟乙基丙烯酰胺(HEA),合成了 LPA/PDMA 和 LPA/PHEA 准互穿聚合物网络。研究了 LPA 黏均分子量、剪切速率、温度等因素对上述准互穿聚合物网络流变学的影响。结果表明,LPA 溶液的临界缠结浓度随着黏均分子量的增加而下降; LPA、LPA/PHEA 和 LPA/PDMA 溶液均表现出明显的剪切变稀行为,LPA/PHEA 和 LPA/PDMA 溶液黏度要显著小于对应黏均分子量的 LPA 溶液的黏度;聚合物溶液黏度均随温度的升高而下降,并且 LPA/PHEA、LPA/PDMA 溶液对温度更加敏感。黏弹性结果显示:当聚合物的质量浓度为0.025 g/mL时,基于中、高黏均分子量 LPA 的聚合物溶液以弹性为主,聚合物网络结构较稳定;基于低黏均分子量 LPA 的聚合物溶液则以黏性为主,聚合物网络结构不稳定,易被外力破坏。

       

      Abstract: Linear polyacrylamide (LPA) was synthesized through an oxidation-reduction initiator system in aqueous solution. Linear polyacrylamide/poly(N, N-dimethylacrylamide) (LPA/PDMA) and linear polyacrylamide/poly(N-hydroxyethyl acrylamide) (LPA/PHEA) quasi-interpenetrating polymer networks were synthesized by polymerizing N, N-dimethylacrylamide (DMA) and N-hydroxyethyl acrylamide (HEA) in LPA aqueous solution, respectively. Characterization techniques, including 1H-Nuclear Magnetic Resonance Spectra(1H-NMR), Fourier Transform Infrared Spectrometer(FT-IR), and Differential Scanning Calorimetry(DSC), were employed to analyze the structures. The intrinsic viscosity of LPA, LPA/PDMA and LPA/PHEA were determined using a Ubbelohde viscometer, and the viscosity average molecular weight (Mη) was calculated based on the intrinsic viscosity. The rheological properties of the above quasi-interpenetrating polymer networks were systematically investigated, focusing on the effects of LPA intrinsic viscosity molecular weight, shear rate, temperature, and other factors. When the mass concentration of polymer(ρ) is less than the critical entanglement concentration(ρ*), the specific viscosity(ηsp) of LPA solution increases slowly with ρ. When ρ is more than ρ*, ηsp increases rapidly with ρ. And ρ* of LPA solution decreases as molecular weight increases. LPA, LPA/PHEA, and LPA/PDMA solutions exhibit significant shear-thinning behavior, and the apparent viscosity(η) of LPA/PHEA and LPA/PDMA solutions is significantly lower than that of the corresponding LPA solution. The η of polymer solutions decreases with increasing temperature, and LPA/PHEA and LPA/PDMA are more temperature-sensitive. The viscoelastic results show that in the linear viscoelastic region, at a mass concentration of 0.025 g/mL, polymer solutions based on medium and high molecular weight LPA are predominantly elastic, indicating a relatively stable polymer network structure, while those based on low molecular weight LPA are predominantly viscous, indicating that the polymer network structure is unstable and easily disrupted by external forces.

       

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