• Membrane Journal
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• v.34 no.4
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• pp.216-223
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• 2024

In comparison to commonly employed polypropylene (PP) material, polymethylpentene (PMP) exhibits low surface energy and reduced crystallinity, allowing fabrication of asymmetric membranes with a dense skin layer. However, its higher melting point poses significant challenges with respect to polymer processability. In this work, we utilized the N-TIPS method, which combines the advantages of non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS), to fabricate PMP membranes. Cyclohexane was employed as the solvent for preparing the PMP dope solution, while water, ethanol (EtOH), and isopropanol (IPA) were used as nonsolvents. When cyclohexane-immiscible water was used as the nonsolvent, the resulting membrane exhibited TIPS morphology with unifrom pore structure but lacked suface uniformity. In contrast, when cyclohexane-miscible alcohols (EtOH, IPA) were employed, the membranes displayed NIPS morphology with a dense skin layer with higher mechanical strength. Furthermore, the effect of polyethylene glycol (PEG) as a pore forming agent was investigated to better control the surface pore size.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.687-696
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• 2016

A series of process to design an acoustic lens for underwater imaging is reviewed and the method to evaluate characteristics of the lens is investigated. If the target specification of lens is given, the design process consists of the material selection, evaluation of its properties, lens geometry design, prediction of lens characteristics, manufacturing, and evaluation by measurement. In this study, an actual acoustical lens is made by cutting polymethylpentene block. The characteristics of lens are predicted by the hybrid method, combination of ray tracing and Rayleigh integral. For the direct comparison between the prediction and measurement results, a simulation method based on the equivalent source method is suggested to reflect the actual radiation pattern of transducer used for measurements. Finally, the measurement is conducted in a small water tank to observe the actual characteristics of the manufactured lens.

• Membrane Journal
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• v.13 no.2
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• pp.73-80
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• 2003

Abstract: The surfaces of poly (methylpentene)(PMP) were modified by Af and $NH_3$ plasma treatment, and their effects on permeation characteristics were investigated. The mole ratio of O/C in the surface was increased with Ar plasma treatment and consequently the surface became hydrophilic because of the possible formation of -OH, -COOH and C=O. The surface treated by $NH_3$ plasma also became hydrophilic due to the formation of amine and/or amide groups. The $CO_2$ permeability and its actual selectivity over N_2$ were 182 baller and 6.17 for the optimum condition of Ar-30W-6min, while 144 Baller and 6.13 for that of $NH_3$-30 W-8 min.