A new copolymer has been synthesized by the copolymerization of acrylic acid with crotonaldehyde in water using K 2S 2O 8 as initiator.The copolymer was characterized by DSC,IR and 13C-NMR.The effects of pH on the rat...A new copolymer has been synthesized by the copolymerization of acrylic acid with crotonaldehyde in water using K 2S 2O 8 as initiator.The copolymer was characterized by DSC,IR and 13C-NMR.The effects of pH on the rate and conversion of copolymerization and copolymer’s composition have been investigated.The results show that,as pH increases,the rate and conversion decrease,especially at pH 5～7,while the content of crotonaldehyde in copolymer increases.It has been proved by IR that there is hydrogen bond between acrylic acid and crotonaldehyde at low pH.The study indicates that hydrogen bond improves the ability of polymerization.However,at high pH,acrylic acid was found as electron acceptor; crotonaldehyde as electron donor.A model of “charge transfer polymerization” was employed to illustrate the copolymerization at high pH.展开更多
以聚乙烯醇(PVA)和丁烯醛为主要原料,合成了聚乙烯醇缩丁烯醛(PVBE)。讨论了反应时间、丁烯醛用量、HCl含量和PVA浓度等因素对PVBE黏度的影响。结果表明:200 mL PVA(质量浓度大于5%)溶液中加入0.75～1.5 mL的HCl,当丁烯醛用量(ρ)在0.15...以聚乙烯醇(PVA)和丁烯醛为主要原料,合成了聚乙烯醇缩丁烯醛(PVBE)。讨论了反应时间、丁烯醛用量、HCl含量和PVA浓度等因素对PVBE黏度的影响。结果表明:200 mL PVA(质量浓度大于5%)溶液中加入0.75～1.5 mL的HCl,当丁烯醛用量(ρ)在0.15～0.25之间,通过调节以上因素,室温反应120～216 h可制得适宜黏度的PVBE水溶液;同时介绍了PVBE中去除残余醛的两种方法;最后研究了低残余醛PVBE作为增稠剂、保护胶体在聚醋酸乙烯(PVAc)乳液中的应用。展开更多
文摘A new copolymer has been synthesized by the copolymerization of acrylic acid with crotonaldehyde in water using K 2S 2O 8 as initiator.The copolymer was characterized by DSC,IR and 13C-NMR.The effects of pH on the rate and conversion of copolymerization and copolymer’s composition have been investigated.The results show that,as pH increases,the rate and conversion decrease,especially at pH 5～7,while the content of crotonaldehyde in copolymer increases.It has been proved by IR that there is hydrogen bond between acrylic acid and crotonaldehyde at low pH.The study indicates that hydrogen bond improves the ability of polymerization.However,at high pH,acrylic acid was found as electron acceptor; crotonaldehyde as electron donor.A model of “charge transfer polymerization” was employed to illustrate the copolymerization at high pH.
文摘以聚乙烯醇(PVA)和丁烯醛为主要原料,合成了聚乙烯醇缩丁烯醛(PVBE)。讨论了反应时间、丁烯醛用量、HCl含量和PVA浓度等因素对PVBE黏度的影响。结果表明:200 mL PVA(质量浓度大于5%)溶液中加入0.75～1.5 mL的HCl,当丁烯醛用量(ρ)在0.15～0.25之间,通过调节以上因素,室温反应120～216 h可制得适宜黏度的PVBE水溶液;同时介绍了PVBE中去除残余醛的两种方法;最后研究了低残余醛PVBE作为增稠剂、保护胶体在聚醋酸乙烯(PVAc)乳液中的应用。
