Tomoe Sunada, Mizue Kuriyagawa, T. Kawamura, K. Nitta
The tensile deformation of thermoplastic polyurethanes (TPUs) with varying sizes of hard domain was investigated to produce a new form of constitutive equation. The equation is expressed using the plastic component of the deformation of the hard domains and a network component based on van der Waals' equation. A TPU formulation with a large hard domain shows a higher stress level and higher stress-strain gradient. It was found that the stress level is dominated by the plastic component, resulting from the stiffness of the hard domains and the stress gradient is determined by the network component, resulting from the extension of the soft segment chains between the hard domains.
{"title":"Influence of Domain Structure on The Mechanical Properties of Thermoplastic Polyurethane Materials","authors":"Tomoe Sunada, Mizue Kuriyagawa, T. Kawamura, K. Nitta","doi":"10.2324/EJSM.7.8","DOIUrl":"https://doi.org/10.2324/EJSM.7.8","url":null,"abstract":"The tensile deformation of thermoplastic polyurethanes (TPUs) with varying sizes of hard domain was investigated to produce a new form of constitutive equation. The equation is expressed using the plastic component of the deformation of the hard domains and a network component based on van der Waals' equation. A TPU formulation with a large hard domain shows a higher stress level and higher stress-strain gradient. It was found that the stress level is dominated by the plastic component, resulting from the stiffness of the hard domains and the stress gradient is determined by the network component, resulting from the extension of the soft segment chains between the hard domains.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"25 1","pages":"8-14"},"PeriodicalIF":0.0,"publicationDate":"2011-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76866203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rubber materials are used normally in large deformations, that is, in nonlinear conditions. So, nonlinear viscoelasticity is important for the characterization of rubber materials. So-called Payne effect, strain amplitude dependence of dynamic modulus, is one of the examples for nonlinear behaviors in rubber materials.
{"title":"Nonlinear Viscoelasticity of Rubber Materials: Payne Effect and Differential Dynamic Modulus","authors":"Yoshinobu Isono","doi":"10.2324/EJSM.7.1","DOIUrl":"https://doi.org/10.2324/EJSM.7.1","url":null,"abstract":"Rubber materials are used normally in large deformations, that is, in nonlinear conditions. So, nonlinear viscoelasticity is important for the characterization of rubber materials. So-called Payne effect, strain amplitude dependence of dynamic modulus, is one of the examples for nonlinear behaviors in rubber materials.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"10 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2011-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79345697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Takenaka, Kazuhiko Koyasu, Kohei Yamamoto, M. Miya, Hiroki Takeshita, T. Shiomi
The additive effect of lithium tetrahydrofurfuryloxide (LiTHF) and alkyl lithium on the nucleophilic substitution reaction of anionic living polyisoprene with 4-bromobutoxy-tert-butyldimethylsilane (BBS) in heptane was investigated.When BBS was allowed to react with polyisoprenyllithium in heptane in the absence of any additives, considerable amount of dimeric polymers as well as aimed end-functionalized polymer were formed via lithium-halogen exchange followed by the homo coupling of the polymers. Degree of the dimer formation was dramatically suppressed when the reaction was carried out in the presence of LiTHF. Quantitative introduction of silyl-protected hydroxy group was achieved when the reaction was carried out in heptane at 0°C in the presence of LiTHF (5 eq to active chain end). Similar additive effect was observed for n-butyllithium whereas no such an effect was observed for sec-butyllithium.The cross-association of these lithium compounds with the active chain end of anionic living polyisoprene might have prevented the homo coupling of the polymers.
{"title":"Effect of Lithium Compounds on the S N 2 Reaction of Anionic Living Polyisoprene with 4-Bromobutoxy-tert-butyldimethylsilane in Heptane","authors":"K. Takenaka, Kazuhiko Koyasu, Kohei Yamamoto, M. Miya, Hiroki Takeshita, T. Shiomi","doi":"10.2324/EJSM.6.1","DOIUrl":"https://doi.org/10.2324/EJSM.6.1","url":null,"abstract":"The additive effect of lithium tetrahydrofurfuryloxide (LiTHF) and alkyl lithium on the nucleophilic substitution reaction of anionic living polyisoprene with 4-bromobutoxy-tert-butyldimethylsilane (BBS) in heptane was investigated.When BBS was allowed to react with polyisoprenyllithium in heptane in the absence of any additives, considerable amount of dimeric polymers as well as aimed end-functionalized polymer were formed via lithium-halogen exchange followed by the homo coupling of the polymers. Degree of the dimer formation was dramatically suppressed when the reaction was carried out in the presence of LiTHF. Quantitative introduction of silyl-protected hydroxy group was achieved when the reaction was carried out in heptane at 0°C in the presence of LiTHF (5 eq to active chain end). Similar additive effect was observed for n-butyllithium whereas no such an effect was observed for sec-butyllithium.The cross-association of these lithium compounds with the active chain end of anionic living polyisoprene might have prevented the homo coupling of the polymers.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"1 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88727481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Distribution of Oil in a PP/EPDM Thermoplastic Elastomer","authors":"Y. Kikuchi, T. Okada, Takashi Inoue","doi":"10.2324/EJSM.5.9","DOIUrl":"https://doi.org/10.2324/EJSM.5.9","url":null,"abstract":"","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"8 1","pages":"9-13"},"PeriodicalIF":0.0,"publicationDate":"2009-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79666733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Takenaka, M. Matsui, Hiroki Takeshita, M. Miya, T. Shiomi
Reversible addition-fragmentation chain transfer (RAFT) polymerization of N,N-diethyl-2-methylene-3-butenamide (DEA), which is a 1,3-butadiene derivative containing a diethylamide function, was carried out in chlorobenzene with using benzyl dithiobenzoate (BDB) as a chain transfer agent. When DEA was polymerized at 70°C using azobisisobutyronitrile (AIBN) as an initiator in the presence of BDB, polymers of narrow molecular weight distribution (Mw/Mn<1.2) were obtained. The molecular weight increased proportionally with conversion, and the observed values were close to the calculated ones based on the molar ratio of monomer to BDB. This indicates that the molecular weight of the polymer can be controlled by the molar ratio of monomer to chain transfer agent. PolyDEA thus obtained contained BDB fragment which was confirmed by MALDI-TOF-MS analysis. Block copolymerization with styrene was carried out using polyDEA having BDB fragment as macro chain transfer agent. Microstructure of polyDEA was predominantly 1,4-sructure. Thus simultaneous control of the molecular weight and microstructure was achieved in the RAFT polymerization of DEA.
{"title":"Polymerization of 1,3-Dienes with Functional Groups. 5. RAFT Polymerization of N,N-diethyl-2-methylene-3-butenamide","authors":"K. Takenaka, M. Matsui, Hiroki Takeshita, M. Miya, T. Shiomi","doi":"10.2324/EJSM.5.1","DOIUrl":"https://doi.org/10.2324/EJSM.5.1","url":null,"abstract":"Reversible addition-fragmentation chain transfer (RAFT) polymerization of N,N-diethyl-2-methylene-3-butenamide (DEA), which is a 1,3-butadiene derivative containing a diethylamide function, was carried out in chlorobenzene with using benzyl dithiobenzoate (BDB) as a chain transfer agent. When DEA was polymerized at 70°C using azobisisobutyronitrile (AIBN) as an initiator in the presence of BDB, polymers of narrow molecular weight distribution (Mw/Mn<1.2) were obtained. The molecular weight increased proportionally with conversion, and the observed values were close to the calculated ones based on the molar ratio of monomer to BDB. This indicates that the molecular weight of the polymer can be controlled by the molar ratio of monomer to chain transfer agent. PolyDEA thus obtained contained BDB fragment which was confirmed by MALDI-TOF-MS analysis. Block copolymerization with styrene was carried out using polyDEA having BDB fragment as macro chain transfer agent. Microstructure of polyDEA was predominantly 1,4-sructure. Thus simultaneous control of the molecular weight and microstructure was achieved in the RAFT polymerization of DEA.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"146 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2009-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77678424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Controlled 1,4-cis specific polymerization of butadiene (Bd) with N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediaminato cobalt (1), in combination with methylaluminoxane (MAO) was investigated. 1/MAO catalyst showed the high activity for the polymerization of Bd. In the polymerization of Bd with 1/MAO catalysts in CH2Cl2 at −30°C, the molecular weight of the polymer increased linearly with an increase of polymer yield, and the line passed through the origin. Moreover, the molecular weight distribution of the polymer was narrow (Mw/Mn=1.29) and microstructure was a high 1,4-cis content (~98%). The results demonstrate that a simultaneous control of 1,4-cis selectivity and the molecular weight of the polymer can be achieved in the polymerization of Bd with the (salen)Co(II) having t-butyl groups at 3,3′,5,5′-positions in the aromatic ring and phenyl groups at N,N′-positions in combination with MAO.
{"title":"Simultaneous Control of Molecular Weight and 1,4-Cis Selectivity in the Polymerization of 1,3-Butadiene with N,N′-Diphenyl and 3,3′,5,5′-tetra-t-Butyl Substituted (Salen)Co(II) Complex","authors":"K. Nakatani, K. Endo","doi":"10.2324/EJSM.4.7","DOIUrl":"https://doi.org/10.2324/EJSM.4.7","url":null,"abstract":"Controlled 1,4-cis specific polymerization of butadiene (Bd) with N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediaminato cobalt (1), in combination with methylaluminoxane (MAO) was investigated. 1/MAO catalyst showed the high activity for the polymerization of Bd. In the polymerization of Bd with 1/MAO catalysts in CH2Cl2 at −30°C, the molecular weight of the polymer increased linearly with an increase of polymer yield, and the line passed through the origin. Moreover, the molecular weight distribution of the polymer was narrow (Mw/Mn=1.29) and microstructure was a high 1,4-cis content (~98%). The results demonstrate that a simultaneous control of 1,4-cis selectivity and the molecular weight of the polymer can be achieved in the polymerization of Bd with the (salen)Co(II) having t-butyl groups at 3,3′,5,5′-positions in the aromatic ring and phenyl groups at N,N′-positions in combination with MAO.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"3 1","pages":"7-11"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81518959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Takenaka, N. Shibata, Shinsuke Tsuchida, Hiroki Takeshita, M. Miya, T. Shiomi
Anionic polymerization of N,N-diethyl-2-methylene-3-butenamide (DEA), which is a 1,3-butadiene derivative containing a diethylamide function, was carried out in tetrahydrofurane (THF) under various conditions. When DEA was polymerized in THF at −78°C using potassium naphthalenide (K-Naph) or diphenylmethylpotassium (DPMK) as an initiator, a polymer of predictable molecular weight with a narrow molecular weight distribution was obtained. However, the rate of polymerization was extremely slow to reach 80% conversion after 720 h. When the polymerization temperature was raised to 20°C, a low molecular weight oligomer with a broad molecular weight distribution was obtained because of a chain transfer reaction. On the other hand, no such side reaction occurred even at 20°C, when polymerization was carried out in the presence of LiCl. Also, the chain transfer reaction did not occur in lithium naphthalenide (Li-Naph) initiated polymerization. The microstructure of the polymer prepared using a potassium counter cation was a 1 : 1 mixture of 1,4-E and 1,2- structures. In the case of Li-Naph or DPMK/LiCl systems, the microstructure was a complicated mixture of 1,4-E, 1,4-Z, and 1,2-structures.
{"title":"Polymerization of 1,3-Dienes with Functional Groups. 4.","authors":"K. Takenaka, N. Shibata, Shinsuke Tsuchida, Hiroki Takeshita, M. Miya, T. Shiomi","doi":"10.2324/EJSM.4.23","DOIUrl":"https://doi.org/10.2324/EJSM.4.23","url":null,"abstract":"Anionic polymerization of N,N-diethyl-2-methylene-3-butenamide (DEA), which is a 1,3-butadiene derivative containing a diethylamide function, was carried out in tetrahydrofurane (THF) under various conditions. When DEA was polymerized in THF at −78°C using potassium naphthalenide (K-Naph) or diphenylmethylpotassium (DPMK) as an initiator, a polymer of predictable molecular weight with a narrow molecular weight distribution was obtained. However, the rate of polymerization was extremely slow to reach 80% conversion after 720 h. When the polymerization temperature was raised to 20°C, a low molecular weight oligomer with a broad molecular weight distribution was obtained because of a chain transfer reaction. On the other hand, no such side reaction occurred even at 20°C, when polymerization was carried out in the presence of LiCl. Also, the chain transfer reaction did not occur in lithium naphthalenide (Li-Naph) initiated polymerization. The microstructure of the polymer prepared using a potassium counter cation was a 1 : 1 mixture of 1,4-E and 1,2- structures. In the case of Li-Naph or DPMK/LiCl systems, the microstructure was a complicated mixture of 1,4-E, 1,4-Z, and 1,2-structures.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"1 1","pages":"23-29"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82986863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuan Gao, Hiroki Takeshita, Y. Takata, K. Takenaka, T. Shiomi
Time-resolved simultaneous synchrotron small-angle X-ray scattering and differential scanning calorimetry experiments have been performed on crystallization of polyethylene-polyisoprene diblock copolymers (HEI or LEI) and their blends with corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp). For the neat block copolymer having a 50 wt% of the crystalline component, preexisting microphase separation structure in the melt was kept at high and low crystallization temperatures Tc (Tc≥94°C and Tc<60°C), while disrupted at intermediate Tc (60°C≤Tc<94°C). This complex behavior was interpreted by combination of two mechanisms. The behavior in the crystallization below 94°C was attributed to the competition between the crystallization and chain diffusion rates, that is, the fast crystallization rate at lower Tc makes it difficult to rearrange the phase structure in the melt. On the other hand, at a higher Tc (≥94°C), the preservation of the microphase separation structure was explained by a small degree of crystallinity due to the ethyl branch of polyethylene (hydrogenated poly(butadiene)). For HEI/PE blends, crystallization behavior was the simple superposition of those for HEI and PE, while, for HEI/PIp with a small composition of PE, suppression of crystallinity was observed. Crystallization kinetics in the neat block copolymer and all the blends was not so different from that in the PE homopolymer.
{"title":"Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers","authors":"Yuan Gao, Hiroki Takeshita, Y. Takata, K. Takenaka, T. Shiomi","doi":"10.2324/EJSM.4.12","DOIUrl":"https://doi.org/10.2324/EJSM.4.12","url":null,"abstract":"Time-resolved simultaneous synchrotron small-angle X-ray scattering and differential scanning calorimetry experiments have been performed on crystallization of polyethylene-polyisoprene diblock copolymers (HEI or LEI) and their blends with corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp). For the neat block copolymer having a 50 wt% of the crystalline component, preexisting microphase separation structure in the melt was kept at high and low crystallization temperatures Tc (Tc≥94°C and Tc<60°C), while disrupted at intermediate Tc (60°C≤Tc<94°C). This complex behavior was interpreted by combination of two mechanisms. The behavior in the crystallization below 94°C was attributed to the competition between the crystallization and chain diffusion rates, that is, the fast crystallization rate at lower Tc makes it difficult to rearrange the phase structure in the melt. On the other hand, at a higher Tc (≥94°C), the preservation of the microphase separation structure was explained by a small degree of crystallinity due to the ethyl branch of polyethylene (hydrogenated poly(butadiene)). For HEI/PE blends, crystallization behavior was the simple superposition of those for HEI and PE, while, for HEI/PIp with a small composition of PE, suppression of crystallinity was observed. Crystallization kinetics in the neat block copolymer and all the blends was not so different from that in the PE homopolymer.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"36 1","pages":"12-22"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73320208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junhao Wu, Suguru Saitoh, S. Fujii, S. Kawahara, Yoshinobu Isono
Measurements of shear dynamic modulus have been made on the polybutadiene samples firstly cross-linked partly followed by the second cross-linking in large extension. The polymers prepared in this manner were expected to keep anisotropic chain configuration. The polymers showed different behaviors in G′ and tanδ from those cross-linked at no deformation. The former polymers showed lower values of G′ and higher values of tanδ than the latter polymers. The deviations became large with increase in degree of extension. It may be concluded that chain anisotropy is really one of the origins for nonlinear viscoelasticity of polymers. It lowers the energy storage term and raises the energy loss term.
{"title":"Chain Anisotropy Effect on Polymer Nonlinear Viscoelasticity","authors":"Junhao Wu, Suguru Saitoh, S. Fujii, S. Kawahara, Yoshinobu Isono","doi":"10.2324/EJSM.4.1","DOIUrl":"https://doi.org/10.2324/EJSM.4.1","url":null,"abstract":"Measurements of shear dynamic modulus have been made on the polybutadiene samples firstly cross-linked partly followed by the second cross-linking in large extension. The polymers prepared in this manner were expected to keep anisotropic chain configuration. The polymers showed different behaviors in G′ and tanδ from those cross-linked at no deformation. The former polymers showed lower values of G′ and higher values of tanδ than the latter polymers. The deviations became large with increase in degree of extension. It may be concluded that chain anisotropy is really one of the origins for nonlinear viscoelasticity of polymers. It lowers the energy storage term and raises the energy loss term.","PeriodicalId":11628,"journal":{"name":"E-journal of Soft Materials","volume":"62 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81056920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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