超临界二氧化碳制备辐射交联微孔聚丙烯材料的研究进展
|
摘要
利用超临界CO_2发泡技术制备的微孔聚合物材料具有发泡效率高,绿色环保及机械性能好等优点。少量聚合物(例如聚丙烯)由于熔体强度较低,不足以支撑泡孔膨胀,容易造成发泡过程中孔壁破裂和泡孔融合,严重影响发泡材料的力学性能。辐射交联可以使聚合物从二维结构变为三维网状结构,显著提高聚合物熔体强度,明显拓宽聚合物的发泡温度区间。因此,辐射交联技术在超临界CO_2发泡工艺中具有重要的潜在应用。本文主要综述了超临界CO_2发泡改性聚丙烯发泡的研究进展以及辐射交联在超临界CO_2发泡聚丙烯工作中应用的可行性。
Manufacture of microcellular plastic foams using supercritical CO_2 foaming technology has attracted considerable research attention from industries, owing to its numerous excellent advantages like efficient foaming,environmental preservation, good mechanical performance of polymer foam, and good appearance of finished products. Because the melt strength of some types of polymers(e.g. polypropylene(PP)) is very low, i.e. they are easy to rupture and collapse, the mechanical properties of the obtained foams are poor. Radiation cross-linking can change the polymer from a 2-dimensional structure to a 3-dimensional network structure, significantly improving its melt strength, and making it favorable for foaming using supercritical CO_2. Hence, radiation technology has great application potential in supercritical CO_2 foaming of polymers. This paper briefly summarized the characteristics of PP foaming using supercritical CO_2 and the application of radiation cross-linking in the same.
Manufacture of microcellular plastic foams using supercritical CO_2 foaming technology has attracted considerable research attention from industries, owing to its numerous excellent advantages like efficient foaming,environmental preservation, good mechanical performance of polymer foam, and good appearance of finished products. Because the melt strength of some types of polymers(e.g. polypropylene(PP)) is very low, i.e. they are easy to rupture and collapse, the mechanical properties of the obtained foams are poor. Radiation cross-linking can change the polymer from a 2-dimensional structure to a 3-dimensional network structure, significantly improving its melt strength, and making it favorable for foaming using supercritical CO_2. Hence, radiation technology has great application potential in supercritical CO_2 foaming of polymers. This paper briefly summarized the characteristics of PP foaming using supercritical CO_2 and the application of radiation cross-linking in the same.
引文
1 Martini J E.The production and analysis of microcellular foam[D],Boston:Massachusetts Institute of Technology,1981.
2 Kumar V.Microcellular polymers-novel materials for the21st-century[J].Cellular Polymers,1993,12(3):207-223.
3 Collias D I,Baird D G,Borggreve R J M.Impact toughening of polycarbonate by microcellular foaming[J].Polymer,1994,35(18):3978-3983.DOI:10.1016/0032-3861(94)90283-6.
4 Park C B,Cheung L K.A study of cell nucleation in the extrusion of polypropylene foams[J].Polymer Engineering and Science,1997,37(1):1-10.DOI:10.1002/pen.11639.
5 Arora K A,Lesser A J,Mccarthy T J.Preparation and characterization of microcellular polystyrene foams processed in supercritical carbon dioxide[J].Macromolecules,1998,31(14):4614-4620.DOI:10.1021/ma971811z.
6 Arora K A,Lesser A J,Mccarthy T J.Compressive behavior of microcellular polystyrene foams processed in supercritical carbon dioxide[J].Polymer Engineering and Science,1998,38(12):2055-2062.DOI:10.1002pen.10375.
7 Baldwin D F,Park C B,Suh N P.Microcellular shee extrusion system process design models for shaping and cell growth control[J].Polymer Engineering and Science1998,38(4):674-688.DOI:10.1002/pen.10232.
8 Kung E,Lesser A J,Mccarthy T J.Morphology and mechanical performance of polystyrene/polyethylene composites prepared in supercritical carbon dioxide[J]Macromolecules,1998,31(13):4160-4169.DOI10.1021/ma980140h.
9 Matuana L M,Park C B,Balatinecz J J.Structures and mechanical properties of microcellular foamed polyviny chloride[J].Cellular Polymers,1998,17(1):1-16.
10 Park C B,Behravesh A H,Venter R D.Low density microcellular foam processing in extrusion using CO2[J]Polymer Engineering and Science,1998,38(11):1812-1823.DOI:10.1002/pen.10351.
11陈国华,彭玉成.国外微孔塑料物理发泡研究现状[J]中国塑料,1998(1):15-21.DOI:10.19491/j.issn.1001-9278.1998.01.003.CHEN Guohua,PENG Yucheng.The status of research on physical foaming of microcellular plastics abroad[J]China Plastics,1998(1):15-21.DOI:10.19491/j.issn1001-9278.1998.01.003.
12钟亚林,黄汉雄.基于相形态的微孔发泡PP/POE共混物泡孔结构调控[J].高分子学报,2015,6:720-726DOI:10.11777/j.issn1000-3304.2015.14406.ZHONG Yalin,HUANG Hanxiong.Cellular structure manipulation of microcellular PP/POE blends based on phase morphology[J].Acta Polymerica Sinica,2015,6720-726.DOI:10.11777/j.issn1000-3304.2015.14406.
13 Bao J B,Junior A N,Weng G S,et al.Tensile and impac properties of microcellular isotactic polypropylene(PP)foams obtained by supercritical carbon dioxide[J].The Journal of Supercritical Fluids,2016,111:63-73.DOI10.1016/j.supflu.2016.01.016.
14 Fu D J,Chen F,Kuang T,et al.Supercritical CO2foaming of pressure-induced-flow processed linear polypropylene[J].Materials&Design,2016,93:509-513.DOI:10.1016/j.matdes.2016.01.012.
15 Kong W L,Bao J B,Wang J,et al.Preparation of opencell polymer foams by CO2assisted foaming of polymer blends[J].Polymer,2016,90:331-341.DOI:10.1016/j.polymer.2016.03.035.
16 Yang C G,Wang M H,Zhang M X,et al.Supercritical CO2Foaming of radiation cross-linked isotactic polypropylene in the presence of TAIC[J].Molecules,2016,21(12):1660.DOI:10.3390/molecules21121660.
17 Tawil E A,Monnier A,Nguyen Q T,et al.Microarchitecture of poly(lactic acid)membranes with an interconnected network of macropores and micropores influences cell behavior[J].European Polymer Journal,2018,105:370-388.DOI:10.1016/j.eurpolymj.2018.06.012.
18 Sun J,Xu J,He Z,et al.Role of nano silica in supercritical CO2foaming of thermoplastic poly(vinyl alcohol)and its effect on cell structure and mechanical properties[J].European Polymer Journal,2018,105:491-499.DOI:10.1016/j.eurpolymj.2018.06.009.
19 Zhao J,Zhao Q,Wang L,et al.Development of high thermal insulation and compressive strength BPP foams using mold-opening foam injection molding with in-situ fibrillated PTFE fibers[J].European Polymer Journal,2018,98:1-10.DOI:10.1016/j.eurpolymj.2017.11.001.
20 Suh K W,Park C P,Maurer M,et al.Lightweight cellular plastics[J].Advanced Materials,2000,12(23):1779-1789.DOI:10.1002/1521-4095(200012)12:23<1779::AID-ADMA1779>3.0.Co;2-3
21 Cooper A I.Recent developments in materials synthesis and processing using supercritical CO2[J].Advanced Materials,2001,13(14):1111-1114.DOI:10.1002/1521-4095(200107)13:14.
22邢哲,吴国忠,黄师荣,等.用超临界二氧化碳发泡制备辐射交联聚乙烯微孔材料[J].辐射研究与辐射工艺学报,2008,26(4):193-198.XING Zhe,WU Guozhong,HUANG Shirong,et al.Prep‐aration of microcellular cross-linking polyethylene foams using supercritical CO2[J].Journal of Radiation Research and Radiatiion Processing,2008,26(4):193-198.
23王谋华,邢哲,刘伟华,等.辐射改性聚丙烯的超临界二氧化碳发泡性能研究[J].辐射研究与辐射工艺学报,2014,32(2):40-45.WANG Mouhua,XING Zhe,LIU Weihua,et al.Study on supercritical carbon dioxide foaming properties of radia‐tion modified polypropylene[J].Journal of Radiation Re‐search and Radiation Process,2014,32(2):020303.
24 Damian R M,Tiuc A E,Vermesan H,et al.Improved sound absorption properties of polyurethane foam mixed with textile waste[J].Energy Procedia,2016,85:559-565DOI:10.1016/j.egypro.2015.12.245.
25 Xu D Y,Chen X,Huang S F.Investigation on fabrication and property of acoustic gradient composites[J]Composites Science and Technology,2016,122:90-96DOI:10.1016/j.compscitech.2015.11.024.
26 Koh D Y,Mccool BA,Deckman H W,et al.Reverse osmosis molecular differentiation of organic liquids using carbon molecular sieve membranes[J].Science,2016,353(6301)804-807.DOI:10.1126/science.aaf1343.
27 Yang C G,Xing Z,Zhang M X,et al.Supercritical CO2foaming of radiation crosslinked polypropylene/highdensity polyethylene blend:cell structure and tensile property[J].Radiation Physics and Chemistry,2017,141276-283.DOI:10.1016/j.radphyschem.2017.07.028.
28 Yang C G,Zhe X,Zhang M X,et al.Radiation effects on the foaming of atactic polypropylene with supercritica carbon dioxide[J].Radiation Physics and Chemistry2017,131:35-40.DOI:10.1016/j.radphyschem.201610.018.
29 Yang C G,Xing Z,Zhao Q,et al.A strategy for the preparation of closed-cell and crosslinked polypropylene foam by supercritical CO2foaming[J].Journal of Applied Polymer Science,2018,135(6):45809.DOI:10.1002APP.45809.
30张国宏,孙奇.高新技术在现代食品工业中的应用--超临界流体萃取技术[J].食品科学,1998,19(12):4-7.ZHANG Guohong,SUN Qi.The application of high-tech‐nology in modern food industry-supercritical fluid extrac‐tion[J].Food Science,1998,19(12):4-7.
31 Kumar V,Suh N P.A process for making microcellular thermoplastic parts[J].Polymer Engineering and Science1990,30(20):1323-1329.DOI:10.1002/pen.760302010.
32 Nalawade S P,Picchioni F,Janssen L P B MSupercritical carbon dioxide as a green solvent for processing polymer melts:Processing aspects and applications[J].Progress in Polymer Science,2006,31(1)19-43.DOI:10.1016/j.progpolymsci.2005.08.002.
33韩布兴.超临界流体科学与技术[M].北京:中国石化出版社,2005.HAN Buxing.Supercritical fluid science and technology[M].Beijing:China Petrochemical Press,2005.
34 Lunabarcenas G,Kanakia S K,Sanchez I C,et al Semicrystalline microfibrils and hollow fibers by precipitation with a compressed fluid antisolvent[J]Polymer,1995,36(16):3173-3182.DOI:10.1016/0032-3861(95)97881-F.
35 Watkins J J,Mccarthy T J.Polymerization in supercritical fluid swollen polymers-a new route to polymer blends[J].Macromolecules,1994,27(17):4845-4847.DOI:10.1021/ma00095a031.
36 Arora K A,Lesser A J,Mccarthy T J.Synthesis,characterization,and expansion of poly(tetrafluoroethylene-co-hexafluoropropylene)/polystyrene blends processed in supercritical carbon dioxide[J].Macromolecules,1999,32(8):2562-2568.DOI:10.1021/ma981794t.
37 Prabhakaran K,Singh P K,Gokhale N M,et al.Processing of sucrose to low density carbon foams[J].Journal of Materials Science,2007,42(11):3894-3900.DOI10.1007/s10853-006-0481-1.
38 Reverchon E,Cardea S.Production of controlled polymeric foams by supercritical CO2[J].Journal of Supercritical Fluids,2007,40(1):144-152.DOI:10.1016/j.supflu.2006.04.013.
39 Xu Z M,Jiang X L,Liu T,et al.Foaming of polypropylene with supercritical carbon dioxide[J].The Journal of supercritical fluids,2007,41(2):299-310.DOI:10.1016/j.supflu.2006.09.007.
40 Jiang X L,Liu T,Xu Z M,et al.Effects of crystal structure on the foaming of isotactic polypropylene using supercritical carbon dioxide as a foaming agent[J].Journal of Supercritical Fluids,2009,48(2):167-175.DOI:10.1016/j.supflu.2008.10.006.
41 Zhai W T,Kuboki T,Wang L,et al.Cell structure evolution and the crystallization behavior of polypropylene/clay nanocomposites foams blown in continuous extrusion[J].Industrial&Engineering Chemistry Research,2010,49(20):9834-9845.DOI:10.1021/ie101225f.
42 Yang C G,Wang M H,Xing Z,et al.A new promising nucleating agent for polymer foaming:effects of hollow molecular-sieve particles on polypropylene supercritical CO2microcellular foaming[J].RSC Advances,2018,8(36):20061-20067.DOI:10.1039/C8RA03071E.
43 Yang C G,Xing Z,Wang M H,et al.Merits of the addition of PTFE micropowder in supercritical carbon dioxide foaming of polypropylene:ultrahigh cell density,high tensile strength,and good sound insulation[J].Industrial&Engineering Chemistry Research,2018,57(5):1498-1505.DOI:10.1021/acs.iecr.7b04644.
44 Wang G L,Zhao J,Mark L H,et al.Ultra-tough and super thermal-insulation nanocellular PMMA/TPU[J]Chemical Engineering Journal,2017,325:632-646.DOI10.1016/j.cej.2017.05.116.
45 Wang L,Ishihara S,Hikima Y,et al.Unprecedented development of ultrahigh expansion injection-molded polypropylene foams by introducing hydrophobicmodified cellulose nanofibers[J].ACS Applied Materials and Interfaces,2017,9(11):9250-9254.DOI:10.1021acsami.7b01329.
46 Zhao J C,Zhao Q L,Wang C D,et al.High therma insulation and compressive strength polypropylene foams fabricated by high-pressure foam injection molding and mold opening of nano-fibrillar composites[J].Materials and Design,2017,131:1-11.DOI:10.1016/j matdes.2017.05.093.
47 Wang G,Zhao G,Zhang L,et al.Lightweight and tough nanocellular PP/PTFE nanocomposite foams with defectfree surfaces obtained using in situ nanofibrillation and nanocellular injection molding[J].Chemical Engineering Journal,2018,350:1-11.DOI:10.1016/j.cej.2018.05.161.
48 Wang L,Hikima Y,Ohshima M,et al.Unusua fabrication of lightweight injection-molded polypropylene foams by using air as the novel foaming agent[J].Industrial and Engineering Chemistry Research,2018,57(10):3800-3804.DOI:10.1021/acs.iecr.7b05331.
49刘太闯,郑云生,李令尧,等.电子束辐照交联制备聚丙烯发泡片材[J].中国塑料,2006,20(9):49-52.LIU Taichuang,ZHENG Yunsheng,LI Lingyao,et al.Polypropylene foam sheet prepared by electron-beam irra‐diation[J].China Plastics,2006,20(9):49-52.DOI:10.19491/j.issn.1001-9278.2006.09.013.
50钟果平,崔志鹏,张丽叶.辐照交联聚丙烯发泡材料的制备工艺[J].塑料,2010,39(1):12-15.ZHONG Guoping,CUI Zhipeng,ZHANG Liye.Prepara‐tion of polypropylene foaming materials by electronbeam irradiation[J].Plastics,2010,39(1):12-15.
51杨晨光,赵全,王谋华,等.伽马射线辐照对聚丙烯超临界二氧化碳发泡的影响[J].辐射研究与辐射工艺学报,2018,36(1):10301.DOI:10.11889/j.1000-3436.2018.rrj.36.010301.YANG Chenguang,ZHAO Quan,WANG Mouhua,et al.Gamma-ray irradiation effects on scCO2foaming behavior of polypropylene[J].Journal of Radiation Research and Radiation Process,2018,36(1):10301.DOI:10.11889/j.1000-3436.2018.rrj.36.010301.
2 Kumar V.Microcellular polymers-novel materials for the21st-century[J].Cellular Polymers,1993,12(3):207-223.
3 Collias D I,Baird D G,Borggreve R J M.Impact toughening of polycarbonate by microcellular foaming[J].Polymer,1994,35(18):3978-3983.DOI:10.1016/0032-3861(94)90283-6.
4 Park C B,Cheung L K.A study of cell nucleation in the extrusion of polypropylene foams[J].Polymer Engineering and Science,1997,37(1):1-10.DOI:10.1002/pen.11639.
5 Arora K A,Lesser A J,Mccarthy T J.Preparation and characterization of microcellular polystyrene foams processed in supercritical carbon dioxide[J].Macromolecules,1998,31(14):4614-4620.DOI:10.1021/ma971811z.
6 Arora K A,Lesser A J,Mccarthy T J.Compressive behavior of microcellular polystyrene foams processed in supercritical carbon dioxide[J].Polymer Engineering and Science,1998,38(12):2055-2062.DOI:10.1002pen.10375.
7 Baldwin D F,Park C B,Suh N P.Microcellular shee extrusion system process design models for shaping and cell growth control[J].Polymer Engineering and Science1998,38(4):674-688.DOI:10.1002/pen.10232.
8 Kung E,Lesser A J,Mccarthy T J.Morphology and mechanical performance of polystyrene/polyethylene composites prepared in supercritical carbon dioxide[J]Macromolecules,1998,31(13):4160-4169.DOI10.1021/ma980140h.
9 Matuana L M,Park C B,Balatinecz J J.Structures and mechanical properties of microcellular foamed polyviny chloride[J].Cellular Polymers,1998,17(1):1-16.
10 Park C B,Behravesh A H,Venter R D.Low density microcellular foam processing in extrusion using CO2[J]Polymer Engineering and Science,1998,38(11):1812-1823.DOI:10.1002/pen.10351.
11陈国华,彭玉成.国外微孔塑料物理发泡研究现状[J]中国塑料,1998(1):15-21.DOI:10.19491/j.issn.1001-9278.1998.01.003.CHEN Guohua,PENG Yucheng.The status of research on physical foaming of microcellular plastics abroad[J]China Plastics,1998(1):15-21.DOI:10.19491/j.issn1001-9278.1998.01.003.
12钟亚林,黄汉雄.基于相形态的微孔发泡PP/POE共混物泡孔结构调控[J].高分子学报,2015,6:720-726DOI:10.11777/j.issn1000-3304.2015.14406.ZHONG Yalin,HUANG Hanxiong.Cellular structure manipulation of microcellular PP/POE blends based on phase morphology[J].Acta Polymerica Sinica,2015,6720-726.DOI:10.11777/j.issn1000-3304.2015.14406.
13 Bao J B,Junior A N,Weng G S,et al.Tensile and impac properties of microcellular isotactic polypropylene(PP)foams obtained by supercritical carbon dioxide[J].The Journal of Supercritical Fluids,2016,111:63-73.DOI10.1016/j.supflu.2016.01.016.
14 Fu D J,Chen F,Kuang T,et al.Supercritical CO2foaming of pressure-induced-flow processed linear polypropylene[J].Materials&Design,2016,93:509-513.DOI:10.1016/j.matdes.2016.01.012.
15 Kong W L,Bao J B,Wang J,et al.Preparation of opencell polymer foams by CO2assisted foaming of polymer blends[J].Polymer,2016,90:331-341.DOI:10.1016/j.polymer.2016.03.035.
16 Yang C G,Wang M H,Zhang M X,et al.Supercritical CO2Foaming of radiation cross-linked isotactic polypropylene in the presence of TAIC[J].Molecules,2016,21(12):1660.DOI:10.3390/molecules21121660.
17 Tawil E A,Monnier A,Nguyen Q T,et al.Microarchitecture of poly(lactic acid)membranes with an interconnected network of macropores and micropores influences cell behavior[J].European Polymer Journal,2018,105:370-388.DOI:10.1016/j.eurpolymj.2018.06.012.
18 Sun J,Xu J,He Z,et al.Role of nano silica in supercritical CO2foaming of thermoplastic poly(vinyl alcohol)and its effect on cell structure and mechanical properties[J].European Polymer Journal,2018,105:491-499.DOI:10.1016/j.eurpolymj.2018.06.009.
19 Zhao J,Zhao Q,Wang L,et al.Development of high thermal insulation and compressive strength BPP foams using mold-opening foam injection molding with in-situ fibrillated PTFE fibers[J].European Polymer Journal,2018,98:1-10.DOI:10.1016/j.eurpolymj.2017.11.001.
20 Suh K W,Park C P,Maurer M,et al.Lightweight cellular plastics[J].Advanced Materials,2000,12(23):1779-1789.DOI:10.1002/1521-4095(200012)12:23<1779::AID-ADMA1779>3.0.Co;2-3
21 Cooper A I.Recent developments in materials synthesis and processing using supercritical CO2[J].Advanced Materials,2001,13(14):1111-1114.DOI:10.1002/1521-4095(200107)13:14.
22邢哲,吴国忠,黄师荣,等.用超临界二氧化碳发泡制备辐射交联聚乙烯微孔材料[J].辐射研究与辐射工艺学报,2008,26(4):193-198.XING Zhe,WU Guozhong,HUANG Shirong,et al.Prep‐aration of microcellular cross-linking polyethylene foams using supercritical CO2[J].Journal of Radiation Research and Radiatiion Processing,2008,26(4):193-198.
23王谋华,邢哲,刘伟华,等.辐射改性聚丙烯的超临界二氧化碳发泡性能研究[J].辐射研究与辐射工艺学报,2014,32(2):40-45.WANG Mouhua,XING Zhe,LIU Weihua,et al.Study on supercritical carbon dioxide foaming properties of radia‐tion modified polypropylene[J].Journal of Radiation Re‐search and Radiation Process,2014,32(2):020303.
24 Damian R M,Tiuc A E,Vermesan H,et al.Improved sound absorption properties of polyurethane foam mixed with textile waste[J].Energy Procedia,2016,85:559-565DOI:10.1016/j.egypro.2015.12.245.
25 Xu D Y,Chen X,Huang S F.Investigation on fabrication and property of acoustic gradient composites[J]Composites Science and Technology,2016,122:90-96DOI:10.1016/j.compscitech.2015.11.024.
26 Koh D Y,Mccool BA,Deckman H W,et al.Reverse osmosis molecular differentiation of organic liquids using carbon molecular sieve membranes[J].Science,2016,353(6301)804-807.DOI:10.1126/science.aaf1343.
27 Yang C G,Xing Z,Zhang M X,et al.Supercritical CO2foaming of radiation crosslinked polypropylene/highdensity polyethylene blend:cell structure and tensile property[J].Radiation Physics and Chemistry,2017,141276-283.DOI:10.1016/j.radphyschem.2017.07.028.
28 Yang C G,Zhe X,Zhang M X,et al.Radiation effects on the foaming of atactic polypropylene with supercritica carbon dioxide[J].Radiation Physics and Chemistry2017,131:35-40.DOI:10.1016/j.radphyschem.201610.018.
29 Yang C G,Xing Z,Zhao Q,et al.A strategy for the preparation of closed-cell and crosslinked polypropylene foam by supercritical CO2foaming[J].Journal of Applied Polymer Science,2018,135(6):45809.DOI:10.1002APP.45809.
30张国宏,孙奇.高新技术在现代食品工业中的应用--超临界流体萃取技术[J].食品科学,1998,19(12):4-7.ZHANG Guohong,SUN Qi.The application of high-tech‐nology in modern food industry-supercritical fluid extrac‐tion[J].Food Science,1998,19(12):4-7.
31 Kumar V,Suh N P.A process for making microcellular thermoplastic parts[J].Polymer Engineering and Science1990,30(20):1323-1329.DOI:10.1002/pen.760302010.
32 Nalawade S P,Picchioni F,Janssen L P B MSupercritical carbon dioxide as a green solvent for processing polymer melts:Processing aspects and applications[J].Progress in Polymer Science,2006,31(1)19-43.DOI:10.1016/j.progpolymsci.2005.08.002.
33韩布兴.超临界流体科学与技术[M].北京:中国石化出版社,2005.HAN Buxing.Supercritical fluid science and technology[M].Beijing:China Petrochemical Press,2005.
34 Lunabarcenas G,Kanakia S K,Sanchez I C,et al Semicrystalline microfibrils and hollow fibers by precipitation with a compressed fluid antisolvent[J]Polymer,1995,36(16):3173-3182.DOI:10.1016/0032-3861(95)97881-F.
35 Watkins J J,Mccarthy T J.Polymerization in supercritical fluid swollen polymers-a new route to polymer blends[J].Macromolecules,1994,27(17):4845-4847.DOI:10.1021/ma00095a031.
36 Arora K A,Lesser A J,Mccarthy T J.Synthesis,characterization,and expansion of poly(tetrafluoroethylene-co-hexafluoropropylene)/polystyrene blends processed in supercritical carbon dioxide[J].Macromolecules,1999,32(8):2562-2568.DOI:10.1021/ma981794t.
37 Prabhakaran K,Singh P K,Gokhale N M,et al.Processing of sucrose to low density carbon foams[J].Journal of Materials Science,2007,42(11):3894-3900.DOI10.1007/s10853-006-0481-1.
38 Reverchon E,Cardea S.Production of controlled polymeric foams by supercritical CO2[J].Journal of Supercritical Fluids,2007,40(1):144-152.DOI:10.1016/j.supflu.2006.04.013.
39 Xu Z M,Jiang X L,Liu T,et al.Foaming of polypropylene with supercritical carbon dioxide[J].The Journal of supercritical fluids,2007,41(2):299-310.DOI:10.1016/j.supflu.2006.09.007.
40 Jiang X L,Liu T,Xu Z M,et al.Effects of crystal structure on the foaming of isotactic polypropylene using supercritical carbon dioxide as a foaming agent[J].Journal of Supercritical Fluids,2009,48(2):167-175.DOI:10.1016/j.supflu.2008.10.006.
41 Zhai W T,Kuboki T,Wang L,et al.Cell structure evolution and the crystallization behavior of polypropylene/clay nanocomposites foams blown in continuous extrusion[J].Industrial&Engineering Chemistry Research,2010,49(20):9834-9845.DOI:10.1021/ie101225f.
42 Yang C G,Wang M H,Xing Z,et al.A new promising nucleating agent for polymer foaming:effects of hollow molecular-sieve particles on polypropylene supercritical CO2microcellular foaming[J].RSC Advances,2018,8(36):20061-20067.DOI:10.1039/C8RA03071E.
43 Yang C G,Xing Z,Wang M H,et al.Merits of the addition of PTFE micropowder in supercritical carbon dioxide foaming of polypropylene:ultrahigh cell density,high tensile strength,and good sound insulation[J].Industrial&Engineering Chemistry Research,2018,57(5):1498-1505.DOI:10.1021/acs.iecr.7b04644.
44 Wang G L,Zhao J,Mark L H,et al.Ultra-tough and super thermal-insulation nanocellular PMMA/TPU[J]Chemical Engineering Journal,2017,325:632-646.DOI10.1016/j.cej.2017.05.116.
45 Wang L,Ishihara S,Hikima Y,et al.Unprecedented development of ultrahigh expansion injection-molded polypropylene foams by introducing hydrophobicmodified cellulose nanofibers[J].ACS Applied Materials and Interfaces,2017,9(11):9250-9254.DOI:10.1021acsami.7b01329.
46 Zhao J C,Zhao Q L,Wang C D,et al.High therma insulation and compressive strength polypropylene foams fabricated by high-pressure foam injection molding and mold opening of nano-fibrillar composites[J].Materials and Design,2017,131:1-11.DOI:10.1016/j matdes.2017.05.093.
47 Wang G,Zhao G,Zhang L,et al.Lightweight and tough nanocellular PP/PTFE nanocomposite foams with defectfree surfaces obtained using in situ nanofibrillation and nanocellular injection molding[J].Chemical Engineering Journal,2018,350:1-11.DOI:10.1016/j.cej.2018.05.161.
48 Wang L,Hikima Y,Ohshima M,et al.Unusua fabrication of lightweight injection-molded polypropylene foams by using air as the novel foaming agent[J].Industrial and Engineering Chemistry Research,2018,57(10):3800-3804.DOI:10.1021/acs.iecr.7b05331.
49刘太闯,郑云生,李令尧,等.电子束辐照交联制备聚丙烯发泡片材[J].中国塑料,2006,20(9):49-52.LIU Taichuang,ZHENG Yunsheng,LI Lingyao,et al.Polypropylene foam sheet prepared by electron-beam irra‐diation[J].China Plastics,2006,20(9):49-52.DOI:10.19491/j.issn.1001-9278.2006.09.013.
50钟果平,崔志鹏,张丽叶.辐照交联聚丙烯发泡材料的制备工艺[J].塑料,2010,39(1):12-15.ZHONG Guoping,CUI Zhipeng,ZHANG Liye.Prepara‐tion of polypropylene foaming materials by electronbeam irradiation[J].Plastics,2010,39(1):12-15.
51杨晨光,赵全,王谋华,等.伽马射线辐照对聚丙烯超临界二氧化碳发泡的影响[J].辐射研究与辐射工艺学报,2018,36(1):10301.DOI:10.11889/j.1000-3436.2018.rrj.36.010301.YANG Chenguang,ZHAO Quan,WANG Mouhua,et al.Gamma-ray irradiation effects on scCO2foaming behavior of polypropylene[J].Journal of Radiation Research and Radiation Process,2018,36(1):10301.DOI:10.11889/j.1000-3436.2018.rrj.36.010301.