摘要
CO2基塑料(PPC)是通过CO2与环氧丙烷共聚所得的生物降解高分子,由于PPC的耐紫外老化性能较差,随紫外线的照射不仅PPC的相对分子质量快速下降,且其拉伸强度和断裂伸长率等力学性能也迅速降低,而农用地膜长期处于紫外线照射的环境中,因此亟待改善PPC的耐紫外老化性能。本文设计合成了含紫外吸收基团的单体2-羟基-4(2,3-环氧丙氧基)二苯甲酮(HEB),与CO 2和环氧丙烷进行三元共聚制备了耐紫外光老化的CO2共聚物(PPCH)。在保证PPCH相对分子质量不低于5.0×10^4的前提下,PPCH中HEB单元的摩尔分数最高可达0.32%,相应地其玻璃化转变温度(Tg)和起始热分解温度(Td-5%)分别为26.7和216.9℃,拉伸强度达到30.97MPa。普通PPC经过240h的紫外辐照后,其数均相对分子质量下降了67.8%,相应地其拉伸强度和断裂伸长率分别下降了10.1%和40.1%。即使PPCH中的HEB摩尔分数仅为0.06%,经过240 h辐照后其数均相对分子质量仅下降了6.2%,相应地其拉伸强度和断裂伸长率也仅分别下降了1.7%和13.3%,证明PPCH具有较强的耐紫外老化性能,原因在于其主链含有HEB单元,对紫外光具有较好的吸收性能。PPCH的紫外吸收性能随HEB单元在聚合物中含量的增加而增强,因此随着共聚物中引入的HEB单元含量增加,PPCH的相对分子质量和力学性能的保持率均得到了大幅度提高。另一方面,对PPCH共聚物与相同二羟基二苯甲酮(BP)含量的PPC/BP共混物进行120h的50℃热水萃取实验,PPCH显示出稳定的紫外光吸收性能,而PPC/BP共混物的紫外吸收性能随热水萃取时间的增长而快速下降,表明三元共聚反应能够有效解决普通共混物面临的小分子紫外吸收剂的外迁移问题。
CO2 based plastics(PPC)is a high molecular mass copolymer of carbon dioxide and propylene oxide.PPC is quite sensitive to ultraviolet(UV)irradiation and its molecular mass decreases quickly with UV-irradiation accompanied by significant loss of mechanical strength.To improve the UV irradiation resistance of PPC is of key importance for its application as agricultural mulching film,which is always under UV irradiation during the whole coverage.In this work,an epoxide with UV absorber function,i.e.,2-hydroxy-4(2,3-epoxypropoxy)benzophenone(HEB),was designed and prepared.By means of terpolymerization of CO2,propylene oxide and HEB,terpolymer PPCH with UV absorber side chain was successfully synthesized,where the chemical structure as well as the HEB content was determined by 1 H NMR spectroscopy.Under the premise of ensuring PPCH molecular mass not less than 5.0×10^4,the maximum molar fraction of HEB incorporated into the PPCH terpolymer was 0.32%,and such PPCH showed a tensile strength of 30.97 MPa,a glass transition temperature(Tg)of 26.7℃,and the temperature at 5%mass loss of thermal decomposition(Td-5%)of 216.9℃.When PPC was exposed under UV irradiation for 240 h,its number-average molecular mass decreased by 67.8%,accompanied by 10.1%loss of tensile strength and 40.1% loss of elongation at break.As a comparison,the number-average molecular mass of PPCH with 0.06% molar fraction HEB showed only 6.2% decrease correspondingly.It showed 1.7% loss of tensile strength and 13.3% decrease of elongation at break,indicating that PPCH had improved UV-irradiation resistance performance due to the existence of UV absorbable functional group like HEB.PPCH and PPC blended with similar 2,4-dihydroxyl benzophenone(BP)content were compared for hot water(50℃)extraction test.No BP was extracted in PPCH providing stable UV absorption performance,while the PPC/BP blend showed sharp drop in UV absorption upon hot water extraction.Therefore,terpolymerization of CO2,propylene oxide with UV absorbable monomer is an effective way to improve the UV irradiation resistance performance of CO2 copolymer.
作者
蔡毅
郭洪辰
曹瀚
高凤翔
周庆海
王献红
CAI Yi;GUO Hongchen;CAO Han;GAO Fengxiang;ZHOU Qinghai;WANG Xianhong(Key Laboratory of Polymer Ecomaterials,Changchun Institute of Applied Chemistry,Chinese Acdemy of Sciences,Changchun 130022,China;University of Chinese Academy of Sciences,Beijing 100049,China;University of Science and Technology of China,Hefei 230026,China)
出处
《应用化学》
CAS
CSCD
北大核心
2019年第11期1248-1256,共9页
Chinese Journal of Applied Chemistry
基金
中国科学院科技服务网络计划(STS计划)(KFJ-STS-QYZD-047)支持~~
关键词
CO2
CO2共聚物
三元共聚反应
耐紫外光老化性能
力学性能
carbon dioxide
carbon dioxide copolymer
terpolymerization
ultraviolet irradiation resistance
mechanical performance
