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聚甲基乙撑碳酸酯的交联

2023-12-06 来源:好走旅游网
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第46卷增刊 中山大学学报(自然科学版) Vo1.46 Sup. 2007年6月 ACTA SCIENTIARUM NATURALIUM UNIVERSITATIS SUNYATSENI Jun. 2007 Crosslinking of Poly(propylene carbonate)by Peroxide Crosslinking Agent Dicumyl Peroxide(DCP) WANG X L ,MENG Y Z ,L/R K,,3 (1.Key hb of Rubber-plastics(QUST),Ministry of Education,Qingdao University of Science and Technology,Qingdao 266042,China; 2.School of Physics and Engineering,Sun Yat—sen University,Guangzhou 5 1 0275,China; 3.Department of Physics and Materials Science,City University of Hong Kong,83 Tat Chee Avenue, Kowloon,Hong Kong) Abstract:The gel content,glass transition temperature(Tg),tensile strength,and elastic modulus of crossliked Poly(propylene carbonate)(PPC)were investigated using modulated differential scanning calorimetry(MDSC)and tensile tester respectively.PPC call be crosslinked by peroxide crosslinking agent Dicumyl peroxide(DCP)and in a solution casting and heating process.The concen tration of DCP showed a great influence on the crosslinking of PPC.The crosslinking of PPC resuhed in the increase in gel content、 mechanical strength、elastic modulus and Tg.The optimum of mechanical properties may be attained at 1%DCP Key words:Polycarbonate;Crosslink;Dicumyl peroxide;Triallyl isocyanurate CLC number:063 Document code:A Article ID:0529-6579(2007)S1 4)004-03 2 Experimental 1 Introduction 2.1 Materials Poly(propylene carbonate)(PPC)synthesized The PPC used in this work was prepared in our pi— from carb0n dioxide and propylene oxide has been lot—scale experimental apparatus.The polymerization proved to be biodegradable polymer owing to the ester product was dried directly without further treatment. bonds on its backbone.In this regard,it has attracted Trichloromethane,AR.was obtained rfom Tianjin Fuyu considerable attention recentlyl卜 .The PPC exhibited Chemical Inc.of China.Dicumyl peroxide f DCP)was good biodegradability in both soil——burial and buffer supplied by Shanghai Gaoqiao Chemical Co.Ltd.6f solution.Moreover,the PPC exhibited superior thermal China. and mechanical properties.However,the alternating 2.2 Preparation of Crosslinked PPC PPC also showed poor mechanical properties and rela. PPC and the crosslink agent were dissolved in tri. tively lower glass transition temperature(Tg). chloromethane at 60c(=for more than 3h.Most solvent Crosslinking is an important method.for improving poly- was allowed to evaporate at 80c(=.To further remove re. mer properties,in particular,high—temperature prop- sidual solvent,all the blends were dried under vacuum erties. at 60c(=for more than 48h until constant weight.The In the present study.the crosslinking of PPC is in. resulting blends were compression molded into plates. vestigated.The crosslinked PPC was prepared using hTe mold was heated to 160c(=and kept for 5 minutes peroxide crosslinking technique by solution casting. prior to the introduction of blend.The molding temper- The aim of this paper is to show some effects of ature is 1 60℃. n1e crosslinking time is 30 minutes. crosslinking agent content on properties of crosslinked The samples for analysis and mechanical testing were P cut out from the compression molded plates. 2.3 Molecular Weight Determination The number average molecular wei ght(M )value 0f the PPC was determined with a gel permeation chro一 收稿日期:2007-01—10 作者简介:王勋林(1963年生),男,副教授;E-mail:wang xl@qust.edu.cn 维普资讯 http://www.cqvip.com 增刊 王勋林等:聚甲基乙撑碳酸酯的交联 3.2 Glass transition temperature 5 matography(GPC)system 2.4 Thermal Analysis DSC trace of the crosslinked PPC was determined The viscoelastic properties of polymers are markedly dependent on the type of crosslink and on the degree of crosslinking.Crosslinking raises the glass transition temperature,Tg,of a polymer by introducing restictions on the molecular motions of the chairn.Low in a modulated thermal analysis DSC instrument f mod. el 200PC)under a nitrogen flow of 20 mL/min. 2.5 Mechanical Prope ̄y The static tensile properties were measured at degrees of crosslinking such as those found in normal vulcanized rubbers act in a similar way to entangle— ments and raise Tg only slightly above that of the un— 23℃using a SANS CMT tensile tester.The crosshead speed was set at 50 mm/min.The samples were stand. ard dogbone tensile bars(ASTM D638)with dimen. crosslinked polymer[5J.However,in thermosets such sions of 25 mm x4 mm x 1 mm.cut from the compres. as epoxy resins,Tg is markedly increased by crosslink・ sion molded plates. ing【 .Fig.2 shows the variations of Tg for crosslinked 2.6 Determination of GeI Content PPC with various DCP contents when the TAIC content The gel content was determined according to was constant(4%).The Tg increased slightly with in— ASTM 2765.Weighed samples in small pieces and in a creasing peroxide concentration.However,the Tg did copper net were put into boiling dimethyl sulfoxide f0r not change when DCP content was higher than 1%. 24 h.The extracted samples were dried to a constant weight in a vacuum oven.The gel content is expressed in terms of the percentage of the weight remaining.The values of gel fraction deviated from the average by less 兰 than 2%.The gel content was calculated using the fol— 三 皂 lowing equation: 巨 gel’  content =____ ——t上 ——_= initial welght墼  oI= sampl———上。 一 e x UU100%【1)(1) 3 Results and discussion DCP(_onenff% 3.1 Gel content 、 Fig.2 Variations of Tg for crosslinked PPC Fig.1 shows the evolution of gel for PPC with various DCP contents crosslinked with different amounts of DCP when the TAIC content was constant(4%).Gel was formed at 3.3 Tensile properties low levels of peroxide.The gel content increased with Fig.3 shows the variations of mechanical proper- increasing peroxide concentration.This is as expected ties for crosslinked PPC with variOUS DCP contents since the higher the level of peroxide used,the higher when the TAIC content was constant(4%).In the the concentration of polymer radicals generated.The presence of peroxide,crosslinking occurred,leading to gel content did not change when DCP content was high— signiifcant changes in the mechanical properties.A er than 1%.The maximum gel content obtained from transition point of mechanical properties is clearly seen this technique is about 60%. at 1%DCP.Before this point.the mechanical proper— ties increased rapidly with increasing peroxide concen— tration.Beyond this point,the mechanical properties did not increase almost with increasing peroxide con— centration.hTe tensile strength increased from 13.5MPa(0%DCP)to 26.4MPa(1%DCP).The elastic modulus changed from 320MPa(0%DCP)to 670MPa f 1%DCP).This demonstrated that the effect of the crosslink network on the mechanical properties is DCP content/% significant.This can be explained by the restriction of Fig.1 Variations of gel for crosslinked PPC chain movement brought about by the crosslink net— with various DCP contents work. 维普资讯 http://www.cqvip.com

6 中山大学学报(自然科学版) 第46卷 日 蓦 q1 ∞一一su Refefences: WANG S J,TJONG S C,DU L C,et a1.Synthesis and properties of alternating copolymer of carbon dioxide and propylene oxide[J].App1.Polym.Sci.,2002,85 (11):2327. [2] ZHU Q,MENG Y Z,TJONG S C,et a1.Thermally stable and high mol ̄ulr weiaght poly(propylene car— Fig.3 Variations of mechanical properties for crosslinked PPC with variOUS DCP contents bonate)S from carbon dioxide and propylene oxide [J].Polym.Int.,2002,51(10):1079. [3] MENG Y Z,DU L C,ZHU Q,et 1.Efafects f ocatlayst morphologies and structure of zinc glutarate Oil the fixa— 4 Conclusions PPC can be crosslinked by peroxide crosslinking agent DCP in a solution casting and heating process. The concentration of DCP and TAIC showed a great in. luence on the crfosslinking of PPC. I'lle crosslinking of PPC resulted in the increase in gel content、mechani. cal strength、elastic modulus and Tg.The optimum of mechanical properties may be attained at 1%DCP. tion of carbon dioxide into polymer[J].Polym.Sci. Part A,Polym.Chem.,2002,40(21):3579. [4] LI X H,MENG Y Z,ZHU Q,et a1.Melt processible and biodegradable aliphatic polycaronatbes from carbon dioxide and propylene oxide[J].App1.Polym.Sci., 2003,89(12):3301. [5] NIELEN L E,LANDEL R F.Mechanical properties of polymem and composites[M].2nd ed.New York: Marcell Dekker,1994. 聚甲基乙撑碳酸酯的交联 。 王勋林 ,孟跃中 ,R.K.Y.LI (1.青岛科技大学橡塑材料与工程教育部重点实验室,山东青岛266042; 2.中山大学理工学院,广东广州510275; 3.香港城市大学物理与材料科学系,香港) 摘 要:利用过氧化物过氧化二异丙苯(DCP)和多官能团化合物三烯丙基异氰尿酸酯(TAIC),对聚甲基乙撑碳酸酯 (PPC)进行了交联研究。研究发现,DCP和TAIC的用量对PPC的交联均有较大影响,PPC交联后,其凝胶含量、机械性 能、弹性模量、玻璃化转变温度均有所增加,1%的DCP和4%的TAIC用量可得到较理想的交联PPC材料。 关键词:聚碳酸酯;交联;过氧化二异丙苯;三烯丙基异氰尿酸酯 中图分类号:063 

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