공단량체의 종류 및 조성이 지글러-나타 중합된 이중 분자량 분포 고밀도 폴리에틸렌의 물성에 미치는 영향 The Effect of Comonomer Type and Content on the Properties of Ziegler-Natta Bimodal High-Density Polyethylene원문보기
Meng, Weijuan
(State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology)
,
Li, Hongbo
(Yanshan Branch, Beijing Research Institute of Chemical Industry, SINOPEC)
,
Li, Jianwei
(State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology)
,
Chen, Biaohua
(State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology)
지글러-나타 촉매를 사용하여 에틸렌을 중합함으로써 다양한 공단량체의 종류와 조성을 갖는 이중 분자량 분포의 고밀도 폴리에틸렌이 합성되었다. 이들의 구조와 물성을 GPC, NMR, DSC, 인장 측정기를 이용하여 연구하였다. 에틸렌/1-헥센 공중합체가 에틸렌/1-부텐 공중합체보다 비슷한 조성을 가질 경우 높은 인장강도와 파단연신율을 가짐을 확인 하였다. 분자량은 고분자의 공단량체 비율이 증가할수록 감소하였다. 짧은 곁사슬은 결정화도에 영향을 주어 결과적으로 이중 분자량 분포를 갖는 고밀도 폴리에틸렌의 모폴로지와 기계적 물성에 영향을 미쳤다. SSA로 처리 후 다수의 발열 곡선이 관찰되었으며 이는 주로 에틸렌 배열길이와 라멜라 두께의 불균일성에 기인한다. 분포지수의 차이로부터 공단량체의 조성이 높은 폴리에틸렌의 SCB 분포가 균일도를 향상시킴을 알 수 있었다.
지글러-나타 촉매를 사용하여 에틸렌을 중합함으로써 다양한 공단량체의 종류와 조성을 갖는 이중 분자량 분포의 고밀도 폴리에틸렌이 합성되었다. 이들의 구조와 물성을 GPC, NMR, DSC, 인장 측정기를 이용하여 연구하였다. 에틸렌/1-헥센 공중합체가 에틸렌/1-부텐 공중합체보다 비슷한 조성을 가질 경우 높은 인장강도와 파단연신율을 가짐을 확인 하였다. 분자량은 고분자의 공단량체 비율이 증가할수록 감소하였다. 짧은 곁사슬은 결정화도에 영향을 주어 결과적으로 이중 분자량 분포를 갖는 고밀도 폴리에틸렌의 모폴로지와 기계적 물성에 영향을 미쳤다. SSA로 처리 후 다수의 발열 곡선이 관찰되었으며 이는 주로 에틸렌 배열길이와 라멜라 두께의 불균일성에 기인한다. 분포지수의 차이로부터 공단량체의 조성이 높은 폴리에틸렌의 SCB 분포가 균일도를 향상시킴을 알 수 있었다.
Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher te...
Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher tensile strength and elongation at break than that of ethylene/1-butylene copolymer with similar comonomer content. The molecular weight decreases as the comonomer content of the polymer increases. Short chain branching affects the crystallinity and thus the morphology and consequently the mechanical properties of the corresponding bimodal high-density polyethylenes. After SSA treated, the multiple endothermic peaks were observed. Multiple endothermic peaks are mainly attributed to the heterogeneity of ethylene sequence length and lamellar thickness. The difference of broadness index indicates that SCB distribution of polyethylene containing higher comonomer content has improved uniformity.
Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher tensile strength and elongation at break than that of ethylene/1-butylene copolymer with similar comonomer content. The molecular weight decreases as the comonomer content of the polymer increases. Short chain branching affects the crystallinity and thus the morphology and consequently the mechanical properties of the corresponding bimodal high-density polyethylenes. After SSA treated, the multiple endothermic peaks were observed. Multiple endothermic peaks are mainly attributed to the heterogeneity of ethylene sequence length and lamellar thickness. The difference of broadness index indicates that SCB distribution of polyethylene containing higher comonomer content has improved uniformity.
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가설 설정
1. The sample was heated to 170 ℃ and maintained at that temperature for 5 min to eliminate the thermal history.
2. The sample was cooled to 30 ℃ to create the socalled initial “standard” state.
3. The sample was heated to a selected thermal treatment temperature (Ts) located in the final melting temperature range of initial “standard” state and held at that temperature for 5 min.
4. The sample was cooled to 30 ℃ again, during this cooling the initially molten fraction of the polymer at Ts will crystallize during cooling using the unmelted crystal fragments produced in step 3 as self-nuclei.
6. Steps 4 and 5 are repeated at increasingly lower Ts: The differences in Ts were always kept constant at 5 ℃. The number of repetitions can be chosen to cover the entire melting range of the sample with a ‘standard’ thermal history or a shorter range.
제안 방법
For the purpose of studying the effect of comonomer content on crystallization behavior of ethylene copolymer, three polyethylene samples with different content of 1-hexene were synthesized. The analyzed results of DSC were summarized in Table 2.
In order to investigate the effect of comonomer type on the mechanical properties of ethylene copolymer, two bimodal HDPE samples that had similar comonomer content but different comonomer type were synthesized. The comonomer content and tensile properties of the obtained samples were listed in Table 1.
In this study, two bimodal HDPE resins based on 1-butene, 1-hexene that have been synthesized in a multistep cascaded process using supported Z-N catalyst, were examined to specifically investigate the effect of the comonomer type on mechanical properties. We also have produced three bimodal HDPE with different 1-hexene content to investigate the effect of the comonomer content on crystallization behavior, mechanical and microstructural properties of polymer, two of which was used to study the distribution of short chain branching and lamellar thickness by successive self-nucleation/annealing (SSA) thermal fractionation technique.
이론/모형
Tensile properties were measured at room temperature with an Instrom universal tensile tester (Model 1175) in accordance with the GB/T 1040 II test. The average molecular weights and molecular weight distributions were determined in a high temperature Waters 220 gel permeation chromatograph (GPC).
참고문헌 (19)
Marzena, B.; Krystyna, C.; Beata, S. M. Thermochim. Acta. 2005, 429, 149.
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