The molecular behavior of polyurethane(PU)coating materials during the surface adsorption of poly-α-olefin as a drag reducing polymer was explored by a molecular dynamics simulation.Three different PU capsule wall ma...The molecular behavior of polyurethane(PU)coating materials during the surface adsorption of poly-α-olefin as a drag reducing polymer was explored by a molecular dynamics simulation.Three different PU capsule wall materials were synthesized using two reaction monomers,and a poly-α-olefin/PU drag reducer microcapsule was prepared based on interface polymerization.The structure,morphology,thermal stability,compressive strength,and drag reduction performance of the microcapsules were characterized and compared.The results showed that a non-bonding interaction induced the adsorption of the PU coating material,poly-α-olefin and PU then fused at the interface,and the PU coating material was embedded into the inner grooves of poly-α-olefin in the form of a local mosaic,thereby forming a stable core–shell structure.The morphological characterization indicated that PU and poly-α-olefin could form microcapsule structures.The thermal decomposition temperature of the microcapsule was dependent on the type of capsule wall material.The microcapsule structure had a slight effect on poly-α-olefin drag reduction.The system enabled poly-α-olefin to exist in powdered particles through microcapsulation,and had a good dispersion effect that facilitated storage and transport processes.The method effectively inhibited the accumulation and bonding of poly-α-olefin at room temperature.展开更多
Microcapsules containing oil drag-reducing polymer particles were prepared by melting-scattering and condensing of polyethylene wax,in-situ polymerization of urea and formaldehyde,and interfacial polymerization of sty...Microcapsules containing oil drag-reducing polymer particles were prepared by melting-scattering and condensing of polyethylene wax,in-situ polymerization of urea and formaldehyde,and interfacial polymerization of styrene respectively.The related processes were studied by a molecular dynamics simulation method,and molecular design of microcapsule isolation agent was carried out on the basis of the simulation.The technologies for preparing microencapsulated oil drag-reducing polymer particles were compared and the circulation drag reducing efficiency of the microencapsulated polymer particles was evaluated based on the characterization results and their dissolution properties.Molecular design of a microcapsule isolation agent suggests that a-olefin polymer particles can be stably dispersed in water by using long-chain alkyl sodium salt surfactant which can prevent the agglomeration ofα-olefin polymer particles.The results of simulation of the adsorption process shows that the amount of alkyl sodium salt surfactant can directly affect the stability of microencapsulatedα-olefin polymer particles, and there must be a minimum critical amount of it.After characterization of the morphology by Scanning Electron Microscopy（SEM） and comparison of the static pressure stability,especially the conditions of reaction and technological control of microcapsules with different shell materials,microencapsulation of a-olefin polymer particles with poly-（urea-formaldehyde） as shell material was selected as the optimum scheme,because it can react under mild conditions and its technological process can be controlled in a large range.The relationship of drag reducing rate and dissolving time of microcapsules showed that the formation of microcapsules did not affect the maximum drag reducing rate,and the drag reducing rate of each sample can reach about 35%along with the dissolving time,i.e.microencapsulation did not affect the drag reducing property ofα-olefin polymer.展开更多
The production of poly-α-olefins(PAOs)has attracted attention due to their excellent viscosity-temperature dependence,wear characteristics,oxidative properties,and high thermal stability.In this study,indene extracte...The production of poly-α-olefins(PAOs)has attracted attention due to their excellent viscosity-temperature dependence,wear characteristics,oxidative properties,and high thermal stability.In this study,indene extracted during coal tar refining was used as a raw material to synthesize a bis(indenyl)zirconium dichloride metallocene catalyst.A PAO with low viscosity and a high viscosity index was produced via the oligomerization of 1-decene in the presence of both the prepared metallocene and a methylaluminoxane(MAO)co-catalyst.Notably,the effects of different synthesis reaction parameters,such as Al:Zr ratio,amount of catalyst,and reaction temperature,on the conversion ratio and product selectivity were investigated in detail.The produced PAO was thoroughly characterized using Fourier-transform infrared,^(13)C,and^(1)H nuclear magnetic resonance spectroscopies;gas chromatography;and viscosity measurements.At 70℃,the metallocene catalyst created more stable active sites.In addition,the alkylation effect of MAO was noticeable.Interestingly,the obtained catalysis results demonstrated that a high conversion ratio of~93%was achieved at a low reaction temperature of 70℃,with a catalyst dosage of 0.0848 mmol and Al:Zr ratio of 8.48mmol:0.0848mmol.Moreover,under these optimal conditions,the kinematic viscosity of PAO was 4.25 mm2/s at 100℃,and the viscosity index was 139,indicating good viscosity-temperature properties.展开更多
Lubrication failure accompanying with blackening phenomenon significantly reduces the long-running operational reliability of porous polymide(PPI)lubricated with poly-α-olefin(PAO)oil.Here,the effects of lubrication ...Lubrication failure accompanying with blackening phenomenon significantly reduces the long-running operational reliability of porous polymide(PPI)lubricated with poly-α-olefin(PAO)oil.Here,the effects of lubrication condition and counter-surface chemistry on the blackening failure of PAO impregnated PPI were studied through the comparison of the tribological tests against GCr15 steel ball and Al_(2)O_(3)ceramic ball with and without PAO oil lubrication.Black products were found to be formed on the PAO impregnated PPI surface slid against steel ball or Al_(2)O_(3)ball added with iron nano-particles,but be absent under the conditions without iron or PAO oil.Further analysis indicated that the iron-catalyzed splitting of PAO oil into small molecule alkanes and following the formation of black organic matter should be mainly responsible for the blackening phenomenon.Molecular dynamic(MD)simulations demonstrated that the iron facilitated the separation of hydrogen atom and the following broken of C–C bonds in PAO molecules,final resulting in the splitting of PAO oil.展开更多
Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the chall...Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the challenging separation ofα-olefin/paraffin is achieved through energy-saving ways,for which adsorption separation is an attractive technology.One of the most significant differences between the adsorption separation of long-chain and light hydrocarbons is the steric hindrance of the molecular chain.Herein,we propose a combination of window size,metal node spacing,and bending degree to quantitatively describe the adsorption cavity structure for the separation of long-chainα-olefin/paraffin.The general cavity structural characteristics of microporous materials with good separation performance for long-chainα-olefin/paraffin are revealed.The selective adsorption of liquid C6 and C_(8)α-olefin/paraffin mixtures on CuBTC(BTC=benzene-1,3,5-tricarboxylate)was studied in detail to reveal the influence of the cavity structure on the adsorption and interaction using a combination of batch adsorption experiments and molecular simulation techniques.CuBTC exhibited 360 and 366 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins,respectively.The adsorption energies were−0.540 and−0.338 eV for C8 linearα-olefin and paraffin,respectively.The contributions of different types of interactions to the overall adsorption energy were quantified to illustrate the adsorption energy difference betweenα-olefin/paraffin and CuBTC.This work provides a new understanding of the long-chain hydrocarbon adsorption behavior different from ethylene/ethane and propylene/propane,which guides the design of adsorbents forα-olefin/paraffin separation.展开更多
The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-ch...The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-chainα-olefin/paraffin is achieved.Adsorption separation is an efficient alternative to energy-intensive distillation.Herein,the selective adsorption behavior and interaction mechanism of liquidα-olefin/paraffin on Mg metal–organic framework(MOF)-74 were investigated using a combination of batch adsorption experiments and molecular simulation techniques.Mg-MOF-74 exhibited 301 and 333 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins in binary olefin/paraffin mixtures,respectively,and was still unsaturated at high olefin concentrations.The adsorption isotherms were analyzed and compared with the simulated results by configurational-bias grand canonical Monte Carlo(CB-GCMC)simulation.The visualized adsorption sites by CB-GCMC simulation indicated that all adsorbates were arranged in hexagonal shapes and preferentially adsorbed by the vertex of the hexagon,where the metal node magnesium is located.The adsorption energies were−1.456 and−0.378 eV for C8 linearα-olefin and paraffin,respectively,calculated by density functional theory simulation based on the visualized adsorption sites.The charge transfer was analyzed,and the contributions of different kinds of interactions to the overall adsorption energy were quantified by principle orbital interaction analysis to further reveal the difference in adsorption energy betweenα-olefin/paraffin and Mg-MOF-74.This work also provides a general means to investigate the liquid adsorption performance and host–guest interactions in the adsorption or catalytic processes of nanoporous materials.展开更多
Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefin...Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin.Semicrystalline polyolefins with high melting temperatures(Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.展开更多
Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane（MMAO）, were tested in the polymerization of higher α-olefin（1-hexene, 1-decene and 1-hexadec...Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane（MMAO）, were tested in the polymerization of higher α-olefin（1-hexene, 1-decene and 1-hexadecene） under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers（42-88/1000 C） with high molecular weights（Mn：（4.3-15.2） × 10^4 g·mol^-1） and narrow molecular weight distribution（Mw/Mn = 1.13-1.29, RT）, which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction.展开更多
The macromolecular architecture is the crucial factor in determining the arrangement of the ordering structures,which,because of the multiscale feature,may exhibit distinct melting behaviors and induce the so-called m...The macromolecular architecture is the crucial factor in determining the arrangement of the ordering structures,which,because of the multiscale feature,may exhibit distinct melting behaviors and induce the so-called memory effect to affect the following recrystallization.Until present,the correlation between the occurrence of memory effect and the intrinsic molecular structure is still far from the comprehensive understanding.In this work,four kinds of 1-butene/α-olefin random copolymers were designed and synthesized using the(pyridyl-amino)hafnium catalyst to introduce the different branches.The branch length was precisely controlled by the specific α-olefin comonomers,which include 1-hexene,1-decene,1-tetradecene,and 1-octadecene,while the branch density was tuned by the incorporation.As expected,the incorporation of α-olefin co-units to poly(1-butene)backbone decreases the non-isothermal crystallization kinetics and the degree of crystallinity.More interestingly,the resulting linear branch can induce the occurrence of memory effect and the threshold concentration of co-units(i.e.,branch density)decreases with increasing the branch length.Based on the results of these 1-butene/α-olefin copolymers with designable branches,a direct correlation with the occurrence of memory effect and the fraction of amorphous region was established,which quantitatively indicates the degree of local segregation of the crystallized poly(1-butene)sequences by theα-olefin co-units.展开更多
基金This paper is supported by the Shandong Provincial Key Research and Development Program(Project No.2020CXGC010403)the Key Projects of New and Old Kinetic Energy Conversion(No.[2020]1220)the scientific research project of SINOPEC Corporation(CLY19005).
文摘The molecular behavior of polyurethane(PU)coating materials during the surface adsorption of poly-α-olefin as a drag reducing polymer was explored by a molecular dynamics simulation.Three different PU capsule wall materials were synthesized using two reaction monomers,and a poly-α-olefin/PU drag reducer microcapsule was prepared based on interface polymerization.The structure,morphology,thermal stability,compressive strength,and drag reduction performance of the microcapsules were characterized and compared.The results showed that a non-bonding interaction induced the adsorption of the PU coating material,poly-α-olefin and PU then fused at the interface,and the PU coating material was embedded into the inner grooves of poly-α-olefin in the form of a local mosaic,thereby forming a stable core–shell structure.The morphological characterization indicated that PU and poly-α-olefin could form microcapsule structures.The thermal decomposition temperature of the microcapsule was dependent on the type of capsule wall material.The microcapsule structure had a slight effect on poly-α-olefin drag reduction.The system enabled poly-α-olefin to exist in powdered particles through microcapsulation,and had a good dispersion effect that facilitated storage and transport processes.The method effectively inhibited the accumulation and bonding of poly-α-olefin at room temperature.
文摘Microcapsules containing oil drag-reducing polymer particles were prepared by melting-scattering and condensing of polyethylene wax,in-situ polymerization of urea and formaldehyde,and interfacial polymerization of styrene respectively.The related processes were studied by a molecular dynamics simulation method,and molecular design of microcapsule isolation agent was carried out on the basis of the simulation.The technologies for preparing microencapsulated oil drag-reducing polymer particles were compared and the circulation drag reducing efficiency of the microencapsulated polymer particles was evaluated based on the characterization results and their dissolution properties.Molecular design of a microcapsule isolation agent suggests that a-olefin polymer particles can be stably dispersed in water by using long-chain alkyl sodium salt surfactant which can prevent the agglomeration ofα-olefin polymer particles.The results of simulation of the adsorption process shows that the amount of alkyl sodium salt surfactant can directly affect the stability of microencapsulatedα-olefin polymer particles, and there must be a minimum critical amount of it.After characterization of the morphology by Scanning Electron Microscopy（SEM） and comparison of the static pressure stability,especially the conditions of reaction and technological control of microcapsules with different shell materials,microencapsulation of a-olefin polymer particles with poly-（urea-formaldehyde） as shell material was selected as the optimum scheme,because it can react under mild conditions and its technological process can be controlled in a large range.The relationship of drag reducing rate and dissolving time of microcapsules showed that the formation of microcapsules did not affect the maximum drag reducing rate,and the drag reducing rate of each sample can reach about 35%along with the dissolving time,i.e.microencapsulation did not affect the drag reducing property ofα-olefin polymer.
基金supported by the Chinese Academy of Sciences Strategic Pilot Science and Technology Special (Class A)(XDA21020000)the National Natural Science Foundation of China (22072175,21673272)support from the Ulam program,awarded by the Polish National Agency for Academic Exchange (NAWA),Poland,under project No.PPN/ULM/2020/1/00006/DEC/1
文摘The production of poly-α-olefins(PAOs)has attracted attention due to their excellent viscosity-temperature dependence,wear characteristics,oxidative properties,and high thermal stability.In this study,indene extracted during coal tar refining was used as a raw material to synthesize a bis(indenyl)zirconium dichloride metallocene catalyst.A PAO with low viscosity and a high viscosity index was produced via the oligomerization of 1-decene in the presence of both the prepared metallocene and a methylaluminoxane(MAO)co-catalyst.Notably,the effects of different synthesis reaction parameters,such as Al:Zr ratio,amount of catalyst,and reaction temperature,on the conversion ratio and product selectivity were investigated in detail.The produced PAO was thoroughly characterized using Fourier-transform infrared,^(13)C,and^(1)H nuclear magnetic resonance spectroscopies;gas chromatography;and viscosity measurements.At 70℃,the metallocene catalyst created more stable active sites.In addition,the alkylation effect of MAO was noticeable.Interestingly,the obtained catalysis results demonstrated that a high conversion ratio of~93%was achieved at a low reaction temperature of 70℃,with a catalyst dosage of 0.0848 mmol and Al:Zr ratio of 8.48mmol:0.0848mmol.Moreover,under these optimal conditions,the kinematic viscosity of PAO was 4.25 mm2/s at 100℃,and the viscosity index was 139,indicating good viscosity-temperature properties.
基金supported by the National Natural Science Foundation of China(Nos.52350411 and 52122507)the National Key R&D Program of China(No.2023YFB3405500)+1 种基金Sichuan Science and Technology Program(Nos.2023NSFSC1988 and 23NSFTD0030)the Independent Project of State Key Laboratory of Traction Power(No.2023TPL-T04).
文摘Lubrication failure accompanying with blackening phenomenon significantly reduces the long-running operational reliability of porous polymide(PPI)lubricated with poly-α-olefin(PAO)oil.Here,the effects of lubrication condition and counter-surface chemistry on the blackening failure of PAO impregnated PPI were studied through the comparison of the tribological tests against GCr15 steel ball and Al_(2)O_(3)ceramic ball with and without PAO oil lubrication.Black products were found to be formed on the PAO impregnated PPI surface slid against steel ball or Al_(2)O_(3)ball added with iron nano-particles,but be absent under the conditions without iron or PAO oil.Further analysis indicated that the iron-catalyzed splitting of PAO oil into small molecule alkanes and following the formation of black organic matter should be mainly responsible for the blackening phenomenon.Molecular dynamic(MD)simulations demonstrated that the iron facilitated the separation of hydrogen atom and the following broken of C–C bonds in PAO molecules,final resulting in the splitting of PAO oil.
基金supported by the National Natural Science Foundation of China(Nos.21878169 and 21991102)the National Key Research and Development Program of China(No.2019YFA0905100)the Tsinghua University Initiative Scientific Research Program(No.2018Z05JZY010).
文摘Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the challenging separation ofα-olefin/paraffin is achieved through energy-saving ways,for which adsorption separation is an attractive technology.One of the most significant differences between the adsorption separation of long-chain and light hydrocarbons is the steric hindrance of the molecular chain.Herein,we propose a combination of window size,metal node spacing,and bending degree to quantitatively describe the adsorption cavity structure for the separation of long-chainα-olefin/paraffin.The general cavity structural characteristics of microporous materials with good separation performance for long-chainα-olefin/paraffin are revealed.The selective adsorption of liquid C6 and C_(8)α-olefin/paraffin mixtures on CuBTC(BTC=benzene-1,3,5-tricarboxylate)was studied in detail to reveal the influence of the cavity structure on the adsorption and interaction using a combination of batch adsorption experiments and molecular simulation techniques.CuBTC exhibited 360 and 366 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins,respectively.The adsorption energies were−0.540 and−0.338 eV for C8 linearα-olefin and paraffin,respectively.The contributions of different types of interactions to the overall adsorption energy were quantified to illustrate the adsorption energy difference betweenα-olefin/paraffin and CuBTC.This work provides a new understanding of the long-chain hydrocarbon adsorption behavior different from ethylene/ethane and propylene/propane,which guides the design of adsorbents forα-olefin/paraffin separation.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21878169 and 21991102)Key Technologies Research and Development Program of China(No.2019YFA0905100)Tsinghua University Initiative Scientific Research Program(No.2018Z05JZY010).
文摘The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-chainα-olefin/paraffin is achieved.Adsorption separation is an efficient alternative to energy-intensive distillation.Herein,the selective adsorption behavior and interaction mechanism of liquidα-olefin/paraffin on Mg metal–organic framework(MOF)-74 were investigated using a combination of batch adsorption experiments and molecular simulation techniques.Mg-MOF-74 exhibited 301 and 333 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins in binary olefin/paraffin mixtures,respectively,and was still unsaturated at high olefin concentrations.The adsorption isotherms were analyzed and compared with the simulated results by configurational-bias grand canonical Monte Carlo(CB-GCMC)simulation.The visualized adsorption sites by CB-GCMC simulation indicated that all adsorbates were arranged in hexagonal shapes and preferentially adsorbed by the vertex of the hexagon,where the metal node magnesium is located.The adsorption energies were−1.456 and−0.378 eV for C8 linearα-olefin and paraffin,respectively,calculated by density functional theory simulation based on the visualized adsorption sites.The charge transfer was analyzed,and the contributions of different kinds of interactions to the overall adsorption energy were quantified by principle orbital interaction analysis to further reveal the difference in adsorption energy betweenα-olefin/paraffin and Mg-MOF-74.This work also provides a general means to investigate the liquid adsorption performance and host–guest interactions in the adsorption or catalytic processes of nanoporous materials.
基金financially supported by the National Natural Science Foundation of China (Nos. 21674130, 51873234)Natural Science Foundation of Guangdong Province (No. 2017A030310 349)+1 种基金Fundamental Research Funds for the Central Universities (No. 17lgjc02)PetroChina Innovation Foundation (No. 2017D-5007-0505)
文摘Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin.Semicrystalline polyolefins with high melting temperatures(Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.
基金financially supported by the Fundamental Research Funds for the Central Universities (WK2060200025)Advanced Catalysis and Green Manufacturing Collaborative Innovation Center (ACGM2016-06-01)Yixing Taodu Ying Cai Program
文摘Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane（MMAO）, were tested in the polymerization of higher α-olefin（1-hexene, 1-decene and 1-hexadecene） under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers（42-88/1000 C） with high molecular weights（Mn：（4.3-15.2） × 10^4 g·mol^-1） and narrow molecular weight distribution（Mw/Mn = 1.13-1.29, RT）, which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction.
基金financially supported by the National Natural Science Foundation of China(No.52022065)the National Key Research and Development Program of China(No.2018YFB0704200).
文摘The macromolecular architecture is the crucial factor in determining the arrangement of the ordering structures,which,because of the multiscale feature,may exhibit distinct melting behaviors and induce the so-called memory effect to affect the following recrystallization.Until present,the correlation between the occurrence of memory effect and the intrinsic molecular structure is still far from the comprehensive understanding.In this work,four kinds of 1-butene/α-olefin random copolymers were designed and synthesized using the(pyridyl-amino)hafnium catalyst to introduce the different branches.The branch length was precisely controlled by the specific α-olefin comonomers,which include 1-hexene,1-decene,1-tetradecene,and 1-octadecene,while the branch density was tuned by the incorporation.As expected,the incorporation of α-olefin co-units to poly(1-butene)backbone decreases the non-isothermal crystallization kinetics and the degree of crystallinity.More interestingly,the resulting linear branch can induce the occurrence of memory effect and the threshold concentration of co-units(i.e.,branch density)decreases with increasing the branch length.Based on the results of these 1-butene/α-olefin copolymers with designable branches,a direct correlation with the occurrence of memory effect and the fraction of amorphous region was established,which quantitatively indicates the degree of local segregation of the crystallized poly(1-butene)sequences by theα-olefin co-units.
