Nd(vers)_(3)/Al(i-Bu)_(2)H/AlEt_(3)/EASC体系催化丁二烯/异戊二烯及丁二烯/异戊二烯/月桂烯共聚合的研究

Copolymerization of Butadiene/Isoprene and Butadiene/Isoprene/Myrcene with Nd(vers)_(3)/Al(i-Bu)_(2)H/AlEt_(3)/EASC Catalyst

采用新癸酸钕(Nd(vers)_(3))/氢化二异丁基铝(Al(i-Bu)2H)/三乙基铝(AlEt3)/乙基倍半氯化铝(EASC)体系催化丁二烯(Bd)/异戊二烯(Ip)及Bd/Ip/月桂烯(My)共聚合.所得丁戊共聚物组成与催化剂用量无关,单体的投料量与共聚物中此单体的含量几乎呈线性关系;用示差扫描量热仪(DSC)测得共聚物只有一个玻璃化转变,共聚物中Ip含量与其玻璃化转变温度(T_(g))呈良好的线性关系.采用Fineman-Ross方法计算竞聚率得到r_(1)=1.04,r_(2)=1.18,Kelen-Tüdos法计算竞聚率得到r_(1)=1.33,r_(2)=1.59;r_(1),r_(2)均接近于1,说明在此催化体系下反应可以得到无规的丁戊共聚物.利用核磁碳谱对共聚物的序列结构进行了分析和归属,采用Bernoulli模型和一级Markov模型验证共聚物的序列结构,通过比较数均序列长度,一级Markov模型计算得到的序列长度与核磁计算的实际值更接近.Bd/Ip/My三元共聚合时,所得共聚物中My单元含量随着投料比的增加而增加,其DSC曲线上只有一个玻璃化转变,Tg值随着My含量的增加而稍增加.

Copolymerization of butadiene(Bd)/isoprene(Ip)and Bd/Ip/myrcene(My)was carried out with Nd(vers)3/Al(i-Bu)2H/AlEt3/EASC catalyst system.For the BD and Ip copolymerization,the catalyst content has rare effect on the copolymer composition and the unit content in copolymer was almost proportional to the monomer feed;only one glass transition temperature(Tg)was detected by DSC and it increased linearly with the increasing Ip unit content in copolymers,which indicated the random structure of copolymers.The reactivity ratios of butadiene(r_(1))to isoprene(r_(2))were calculated with both Fineman-Ross and Kelen-Tüdos method.r_(1) and r_(2) were close to 1,suggesting random copolymerization of Bd and Ip with the present catalyst system.The structure and distribution of copolymer sequences were analyzed and assigned with 13C-NMR.The number average sequence lengths calculated by 13C-NMR and Bernoullian/Markov model,respectively,were compared,and the result showed that Markov model was more suitable for simulating the copolymer sequence distribution.Ternary copolymerization of Bd,Ip and My catalyzed by the catalyst system showed that the My unit content in the copolymer increased with the monomer feed,only one glass transition was detected and the value slowly increased with the increasing My unit content in copolymers.The reactivity ratios calculated by Kelen-Tüdos method were r_(1)2=1.03,r_(2)1=1.69,r_(2)3=1.11,r_(3)2=3.62,r_(1)3=0.80,r_(3)1=4.67.