杜仲胶/天然胶/低密度聚乙烯共混相容性的MD模拟

为预测杜仲胶/天然胶/低密度聚乙烯共混的相容性,采用MD模拟方法在COMPASS力场下,对杜仲胶/天然胶/低密度聚乙烯共混物的溶度参数等进行模拟计算.通过比较溶度参数差值(△δ)的大小及分子间径向分布函数,可以预测杜仲胶/天然胶/低密度聚乙烯共混物属于相容体系,与TEM实验结果一致.径向分布函数分析同时揭示了杜仲胶/天然胶/低密度聚乙烯共混物组分之间的相互作用本质.此模拟方法可以作为预测杜仲胶/天然胶/低密度聚乙烯共混物相容性的有利工具     

PE/PE-g-MAH/PA6共混物的制备及性能研究

采用熔融接枝的方法制备聚乙烯接枝马来酸酐(PE-g-MAH),将其作为PE/PA6共混物体系的相容剂,研究PE-g-MAH对PE/PA6共混物性能的影响,并探讨增容机理。结果表明,在PE/PA6共混物中加入PE-g-MAH后,共混物的力学性能得到明显的提高,当加入量在15wt%左右时,PE/PE-g-MAH/PA6共混物的拉伸强度和冲击强度达到最大值。     

相容剂改性PE/PP共混物在滴灌带中的应用

介绍了相容剂改性聚乙烯/聚丙(烯PE/PP)共混物在生产滴灌带中的应用,探讨了相容剂改性PE/PP共混体系的相容机理,通过大量的实验找到了最佳配比方案。结果表明:以相容剂改性PE/PP共混物生产的滴灌带与普通滴灌带对比界面黏结性强;改善和提高了PE/PP共混物的相容性和力学性能。     

PE-g-PEO/PEO共混体系的相容性及结晶行为研究

利用傅里叶红外光谱(FTIR)对聚乙烯(PE)接枝聚氧化乙烯(PEO)共聚物(PE-g-PEO)进行结构表征。采用溶液共混方法制备了PE-g-PEO/PEO共混物,采用偏光显微镜、差动热分析仪(DSC)等对比分析了PE-gPEO/PEO和PE/PEO共混物的相容及结晶性。结果表明,共混物的相容性与其组成有关,在PE-g-PEO与PEO共混质量比为9∶1时相容性最好。PEO质量分数超过70%时室温下能观察到球晶的生长过程。PE-g-PEO/PEO共混体系的相容性比PE/PEO好,PE-g-PEO在共混过程中起到了增容剂的作用。     

增加聚烯烃共混物界面粘结力的研究

在加工设备中制备聚乙烯、聚丙烯树脂的马来酸酐(MAH)接枝共聚物(PE-g-MAH,PP-g-MAH)。用偏光显微镜、相差显微镜及扫描电镜研究了PP-g-MAH及PP共混物的形态、分散状态与相界面。考察了PE-g-MAH/PET,PE/PET复合薄膜的剥离强度及PE-g-MAH/CaCO_3,PE/CaCO_3共混物的力学性能。所有结果均表明聚烯烃马来酸酐接枝物可显著增加聚烯烃共混物中组分间的相容性和界面粘结力,并讨论了其机理。     

TPI/NR力学性能的分子动力学模拟

为研究杜仲胶(TPI)和天然橡胶(NR)之间的相容性、TPI/NR共混物的力学性能,采用分子动力学(MD)法在Compass力场条件下对其进行了模拟。研究结果表明:通过比较溶度参数差值(Δδ)的大小可预测TPI与NR之间的相容性,TPI/NR属于相容体系;与纯TPI相比,TPI/NR共混物的静态力学性能及动态拉伸抗疲劳性能更加优越。     

SEBS弹性体增韧改性PE-HD/PS共混物及其相容性研究

采用聚苯乙烯嵌段聚（乙烯亚丁基）嵌段聚苯乙烯（SEBS）弹性体增韧改性高密度聚乙烯（PE-HD）/聚苯乙烯（PS）共混物,通过哈克转矩流变仪制备了PE-HD/PS/SEBS三元共混物,采用扫描电子显微镜（SEM）、旋转流变仪、冲击试验机、热重分析仪（TG）和差式扫描量热仪（DSC）等手段研究了PE-HD/PS/SEBS共混体系的相容性。结果表明,SEBS对共混体系具有良好的增容作用,但当SEBS添加量大于8 %(质量分数,下同)后,部分SEBS出现团聚现象,导致共混体系相容性降低;SEBS的引入对共混物的耐热性影响不大,共混物中连续相PE-HD的熔点稍有降低;随着SEBS添加量的增加,共混物的悬臂梁缺口冲击强度大幅提高。     

马来酸酐接枝PS对PS/PLA共混体系发泡行为的影响

通过熔融共混法制备PS/PLA共混物,研究了PLA和马来酸酐接枝PS（PS-g-MAH）含量对PS/PLA共混体系的CO2溶解度、流变行为、相态结构以及发泡行为的影响。结果表明,PLA可以有效提高PS/PLA共混体系的CO2溶解度,当PLA含量为25份(质量份,下同)时,CO2溶解度比PS提高了22 %;PS-g-MAH的加入,显著改善PS/PLA共混体系的相容性,减小分散相的粒径,以及降低PS/PLA共混体系的泡沫密度。     

导热绝缘PE-LD/PE-g-MAH/h-BN泡沫塑料的制备及性能研究

采用熔融共混法制备了一系列导热绝缘的低密度聚乙烯/马来酸酐接枝聚乙烯/六方氮化硼(PE-LD/PE-g-MAH/h-BN新型泡沫塑料,研究了相容剂PE-g-MAH的加入、h-BN含量对PE-LD/PE-g-MAH/h-BN泡沫体系导热性能、绝缘性能、力学性能及热稳定性的影响。结果表明,PE-g-MAH有利于增加PE?LD与h?BN的界面黏结,增强泡沫体系拉伸强度和断裂伸长率,显著提高其热导性能;当h-BN含量为30 %时, PE-LD/PE-g-MAH/h-BN泡沫体系的导热率为0.256 W/(m·K),相对于PE-LD/h-BN泡沫体系的0.217 W/(m·K) 和纯PE-LD泡沫体系的0.039 W/(m·K),热导率分别提高1.18和6.57倍,同时保持较好的绝缘性和热稳性。     

PS及其共混、复合体系超临界CO_2发泡行为研究

以聚苯乙烯(PS),PS/聚乙烯(PS/PE)共混体系和PS/纳米CaCO3(PS/nano-CaCO3)复合体系为研究对象,以超临界CO2为发泡剂,选择典型工艺条件开展了发泡实验,采用扫描电子显微镜(SEM)观察泡孔结构,比较分析了不同工艺条件下的发泡行为,为利用PS,PS/PE共混体系和PS/nano-CaCO3复合体系提供研究基础。研究结果表明,PS具有较好的成孔性能,在发泡压力为22 MPa、发泡温度为80℃和饱和时间为2 h时,可制得泡孔孔径为(11.19±2.12)μm、泡孔密度为5.31×107个/cm3、发泡倍率2.64的微孔发泡材料。与PS相比,在相同工艺条件下,当添加PE的质量分数为10%时,PS/PE共混体系的泡孔孔径显著减小,泡孔密度有所提高,可通过调节工艺条件调整泡孔形貌;添加质量分数为5%经硅烷偶联剂表面改性的nano-CaCO3,可促进PS/nano-CaCO3复合体系的泡孔成核,改善其泡孔形态,增加泡孔密度,减小泡孔孔径。     

原位增容PS/LLDPE共混物的结构与性能

在熔融状态下,利用大分子之间的Friedel-Crafts烷基化反应就地增容聚苯乙烯(PS)/线型低密度聚乙烯(LL-DPE)共混物。考察了AlCl3用量对高PS含量PS/LLDPE(80/20,质量比,下同)共混物的PS接枝百分比和力学性能的影响,同时研究了增容前后共混物的热性能与微观结构。结果表明,在PS/LLDPE共混物中加入0.4份的AlCl3,PS的接枝百分比较高;与简单共混体系相比,共混物力学性能与热稳定性都有所提高,同时PS也有一定程度的降解。     

Effects of the Competition between Grafting Reaction and Decomposition on the Miscibility and Rheological Behaviors of PS/POE Blends in the Presence of AlCl3

For increasing the compatibility of polystyrene (PS) and polyolefin elastomer (POE) blends, a Lewis acid catalyst, aluminium chloride (AlCl₃), was adopted to initiate the Friedel-Crafts alkylation reaction and induce the formation of PS-graft-POE copolymer. The dynamic mechanical and rheological tests were used to study the effects of catalyst content on the miscibility and rheological behaviors. The results showed that the viscosity increased and the MFI decreased with the increase of the catalyst content. However, when the catalyst content was overmuch, the viscosity decreased and the MFI increased. The variety of miscibility and rheological behaviors of PS/POE blends was the results of the competition between in situ graft reaction and decomposition of blending compounds.     

增容剂流动性对PE-LLD/PS/PET三元共混物性能的影响

通过Friedel-Crafts烷基化反应,制备了线型低密度聚乙烯(PE-LLD)/聚苯乙烯(PS)(质量比50/50)增容母料,并将其与甲基丙烯酸缩水甘油酯(GMA)熔融接枝,制成接枝改性母料。在等质量的接枝改性母料中,添加不同用量的高熔体流动速率(MFR)的PE-LLD(HFPE-LLD),同时添加PS,使HFPE-LLD与PS的质量比始终保持在50/50,制成流动性不同的三元增容母料。将有效组分含量相同的上述三元增容母料,添加到PE-LLD/PS/聚对苯二甲酸乙二酯(PET)三元共混物中,考察了三元增容母料的流动性对共混物力学性能、动态流变性能及微观结构的影响。结果表明,随着三元增容母料流动性的增大,共混物的力学性能逐渐上升。相比未增容的共混物,添加了MFR为10.1 g/10 min的三元增容母料的共混物,力学性能达到最佳,其拉伸强度由8.2 MPa增至17.5 MPa,增幅为113.4%,断裂伸长率由2.3%增至23.5%,增幅为921.7%;在高频区,随着三元增容母料流动性的增大,共混物的储能模量、损耗模量、复数黏度逐渐上升,损耗因子逐渐下降。扫描电子显微镜照片显示,三元增容母料的流动性增大后,分散相粒径明显减小,相界面逐渐模糊。     

Deformation behavior of HDPE/(PEC/PS)/SEBS blends

Immiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC) were compatibilized with various amounts of a styrene-hydrogenated butadiene block copolymer (SEBS). PEC is structurally similar to poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). Using a liquid displacement stress dilatometer, the volume change of samples during uniaxial mechanical straining was determined and related to the various modes of deformation. Blends were fabricated by both injection and compression molding. Miscible PEC and PS blends were found to undergo a craze to shear yielding transition between 40 and 60% PS, which occurred at higher PS concentrations as SEBS was added. Blends with a HDPE matrix and a dispersed glassy phase showed reduced volume dilatation on adding SEBS, indicating better interfacial adhesion between the incompatible blend components. Increases in the sample volume were substantially less in blends with a PEC/PS glassy phase instead of pure PS, suggesting more effective compatibilization by the SEBS copolymer in blends with PEC. This trend is presumed to stem from an exothermic heat of mixing between the PS endblocks of SEBS and the PEC-rich phases in the blend. Microscopic evidence of the improved adhesion and modes of deformation agrees with the results obtained by dilatometry. The volume dilatation of compression-molded materials do not seem to be similarly affected by the composition of the glassy phase which may reflect morphological differences between injection-and compression-molded blends.     

Mechanical properties of HDPE/(PEC/PS)/SEBS blends

Various amounts of a styrene-butadiene-based triblock copolymer (SEBS) was used to compatibilize immiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC). PEC is structurally similar to poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). Mechanical properties were determined for blends fabricated by injection and compression molding. The inherently brittle two-phase HDPE/(PEC/PS) blends show significant increases in ductility and impact strength resulting from addition of SEBS. These improvements coincide with a slight loss in modulus and yield strength. If the amount of HDPE and SEBS is held constant, impact strength and ductility increase with the amount of PEC in the glassy phase. These trends evidently result from the added ductility of glassy phases containing PEC and perhaps from better interfacial adhesion in blends after adding SEBS. The latter stems from the thermodynamic miscibility between PEC and PS endblocks of SEBS which provide an enthalpic driving force for compatibilization. Differences between the properties of compression and injection-molded blends can be attributed to the degree of crystallinity and orientation induced during molding.     

Impact and tensile properties of SEBS copolymer compatibilized PS/HDPE blends

In this study, polystyrene–hydrogenated polybutadiene–polystyrene (SEBS) triblock copolymer was used as a compatibilizer for the blends of polystyrene (PS) and high-density polyethylene (HDPE). The morphology and static mechanical and impact properties of the blends were investigated by means of scanning electron microscopy, uniaxial tension, and instrumented falling-weight impact measurements. Tensile tests showed that the yield strength of the PS/HDPE/SEBS blends decreases considerably with increasing HDPE content. However, the elongation at break of the blends tended to increase significantly with increasing HDPE content. The excellent tensile ductility of the HDPE-rich blends resulted from shield yielding of the matrix. Charpy impact measurements indicated that the impact strength of the blends increases slowly with HDPE content up to 50 wt %; thereafter, it increases sharply with increasing HDPE content. The impact energy of the HDPE-rich blends exceeded that of pure HDPE, implying that the HDPE polymer can be further toughened by the incorporation of brittle PS minor phase in the presence of SEBS compatibilizer. The correlation between the impact property and morphology of the blends is discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1099–1108, 1998     

Extrusion of PE/PS blends with supercritical carbon dioxide

The effects of dissolved supercritical carbon dioxide on the viscosity and morphological properties were investigated for polyethylene/polystyrene blends in a twin-screw extruder. The viscosities of the blend/CO₂ solutions were measured using a wedge die mounted on the extruder. A considerable reduction of viscosity was found when CO₂ was dissolved in the blend. It was observed that the dissolution of CO₂ into PE/PS blends, regardless of the CO₂ content used, led to decreased shear thinning behavior resulting in an increase of the power law index from 0.29 to 0.34. The cell structures of foamed PE/PS blends showed a typical dependence of pressure and CO₂ concentration, with higher operating pressures and CO₂ content leading to a smaller cell size. Also, it was noted that the size of the dispersed PS phase in the PE/PS phase blends decreased by increasing the CO₂ concentration, and that the dispersed PS phase domains were highly elongated in the direction normal to the cell radius.     

Study of PS/SBS/nano-CaCO3 blends

Abstract

The effect of SBS and nano-CaCO₃ on the mechanical properties of PS blends was studied, and their morphologies were characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Izod impact strengths of notched samples of PS/SBS/CaCO₃ blends with nanometre particles of nano-CaCO₃ and SBS are higher than those of PS and PS/SBS blends with the same content of SBS, and the tensile strengths are higher than those of PS/SBS blends. The inclusion of nano-CaCO₃ within the dispersed phase of SBS enlarges the volume of the domains of SBS, which increases the toughness of the ternary blends (PS/SBS/CaCO₃). The mass ratio of SBS/CaCO ₃ plays an important role in the properties of the ternary blends because it affects the concentration of SBS in these blends, the dispersion of nano-CaCO₃ and the morphology of the ternary blends.     

Compatibilizing Effect of SEBS for Electrical Properties of LDPE/PS Blends

Summary: In the previous study, we observed compatibilizing effects of low density polyethylene (LDPE)/polystyrene (PS) with polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene (SEBS), a triblock copolymer. Blends consisting of 70 wt.‐% LDPE and 30 wt.‐% PS were prepared with a SEBS concentration of up to 10 wt.‐%. This study examined the electrical properties such as the electrical breakdown, water tree length, permittivity and tan δ in the blends. The possibility of using these blends as insulating material substitutes for LDPE was investigated. The electrical breakdown strength reached a maximum of 66.67 kV/mm, which is superior to 50.27 kV/mm of the LDPE used as electrical insulators for cables. In addition, the water tree length decreased with increasing SEBS concentration. The water tree lengths of the blends containing SEBS were shorter than that of the LDPE. The permittivity of the blends was 2.28–2.48 F/m, and decreased with increasing SEBS concentration with the exception of S‐0. Tan δ of the blends increased smoothly with increasing SEBS content.

Breakdown strength , water tree length, permittivity and tan δ of the LDPE/PS/SEBS blends and raw materials.     

Phase separation and segregation morphology of PCL/PS blends: Quantitative effect of the crystallization temperature,composition, and molecular weight of PS

The phase diagrams for blends of semicrystalline poly(ε‐caprolactone) (PCL) with amorphous polystyrene (PS) were determined and it was noticed that when molecular weight increases, the critical composition diminishes while its temperature increases. That is the same effect that produces the increase in the polydispersity of PS. From the fitting of phase diagrams of blends of PCL with oligomers and homopolymers of PS, taking into account the polydispersity, it was possible to conclude that the miscibility in these systems is due only by entropic effects. The crystalline fraction as well as the interlamellar spacing increased with crystallization temperature while the volume fraction of the amorphous PCL in the interfibrillar regions increases for the pure PCL and in its blends with low concentration of PS. Increasing the mass fraction of PS increases the average long spacing (L) till a weight fraction of 60%, for higher mass fractions L is almost constant indicating the interfibrillar segregation of PS. The PCL lamellar morphology is not affected when the molecular weight of PS employed is similar or higher than the molecular weight of PCL. If the PS has a higher molecular weight its penetration into the structure is inhibited. POLYM. ENG. SCI., 57:1062–1072, 2017. © 2016 Society of Plastics Engineers