SEP对PP/PS共混物的增容作用

研究了苯乙烯 -乙烯 /丙烯二嵌段共聚物 (SEP)对聚丙烯 /聚苯乙烯 (PP/PS)共混物的形态和力学性能的影响。结果表明 ,SEP在PP/PS共混物中作为增容剂 ,降低了分散相的聚结 ,减小了分散相的平均粒子尺寸 ,大大改变了共混物的形态 ,提高了共混物的力学性能 ,对PP/PS( 2 0 /80 )共混物的增容作用较为显著     

共聚物在聚合物共混体系中的增容作用I.嵌段共聚物

随着高分子合金领域的研究发展，以共聚物作为增容剂对不相容的聚合物共混体系进行改性已得到了广泛的研究和应用。本文分为两篇，分别介绍利用嵌段共聚物、接枝共聚物和无规共聚物所做的增容改性研究。本篇着重讨论嵌段共聚物(包括两嵌段和三嵌段以及多嵌段共聚物)在聚合物共混体系中的增容作用和增容机理。     

共聚物在聚合物共混体系中的增容作用Ⅱ.接枝共聚物和无规共聚物

在不相容的聚合物共混体系中加入共聚物作为增容剂可以有效地改善两相间的界面状况，得到力学性能优良的合金材料。本文主要讨论接枝共聚物和无规共聚物在聚合物共混体系中的增容作用和增容机理。     

EPR-g-PS热塑弹性体的形态结构

电子显微镜观察表明,以乙丙橡胶(EPR)为主干,聚苯乙烯(PS)为支链的接枝共聚物EPR-g-PS的基本形态是高度分散的聚苯乙烯微区(约几百?)存在于乙丙橡胶连续相中的两相体系,随接枝共聚物中聚苯乙烯含量增加,微区形态发生变化,少量的接枝共聚物在PS与EPR共混物中起“增容剂”作用,使分散相微区变得小而均匀,多重玻璃化转变的存在进一步证实了接枝共聚物相分离的形态结构。     

聚乳酸/聚己内酯/聚(ε-己内酯-L-丙交酯)共聚物三元共混体系的结构与性能

通过开环共聚合,合成了3种不同单元比例的ε-己内酯(ε-CL)与L-丙交酯(L-LA)的共聚物P(CLco-LA)。通过熔融共混制备了聚乳酸(PLA)/聚己内酯(PCL)/P(CL-co-LA)三元共混材料,研究了P(CL-coLA)对共混材料微观形貌、热性能以及力学性能的影响。结果表明,共聚物P(CL-co-LA)作为PLA/PCL不相容体系的界面增容剂,减小了PCL分散相的尺寸,改善了PLA/PCL共混体系的相容性,提高了共混材料的韧性。固定m(PLA)∶m(PCL)∶m(P(CL-co-LA))=80∶20∶10时,以P(CL49/LA51)(其中数字代表摩尔分数(%))作为界面增容剂效果最佳,共混材料的断裂伸长率可达到(210±30)%。     

聚乙烯-g-聚苯乙烯对线性低密度聚乙烯/聚苯乙烯共混物机械性能和发泡行为的影响

以通过开环易位聚合、加氢反应和原子转移自由基聚合技术结合制备的聚乙烯-g-聚苯乙烯(PE-g-PS)作为增容剂,研究了加入不同PS支链长度的PE-g-PS对于线性低密度聚乙烯/聚苯乙烯(LLDPE/PS)共混物的机械性能和发泡行为的影响。 以典型组成m(LLDPE):m(PS)=70:30共混物为例,考察了PE-g-PS对共混物拉伸性能的影响。 相对于二元共混物,增容剂的加入使得断裂伸长率、拉伸强度和屈服强度皆提高,且含长PS支链的增容体系提高更明显。 采用超临界CO₂釜式发泡工艺,考察了PE-g-PS中PS支链长度对共混物发泡行为的影响。 结果表明,相对于短PS支链体系,加入PE-g-PS_1.59k(PS相对分子质量为1590)后的泡孔结构更加均一,完全没有“缝隙”形貌的出现。 当发泡温度降至80 ℃时,即使存在LLDPE发泡空间限制作用(LLDPE无法发泡),加入支链长度更长的PE-g-PS_1.59k后泡孔分布也更加均一。     

聚苯醚羧酸酯对C-PPO/PS共混体系的增容作用

前曾报道羧化度为8～lOmol%的羧化聚苯醚(C-PPO)与PS共混体系具有UCST和LCST共存的特殊相行为^[1],而羧化度大于11.6mol%时,C-PPO/PS共混体系表现出不相容性^[2,3]。化学改性PPO可作为PPO与其他聚合物共混的增容剂。本文讨论C-PPO的正十二酯(Lau-CPPO)对C-PPO/PO共混体系混溶性的影响。     

剪切作用下马来酸酐接枝乙烯-辛烯共聚物和乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯共聚物对PA1010/PP共混物的增容作用比较

采用熔体共混的方法制备了两种增容剂增容的聚酰胺1010/聚丙烯(PA1010/PP)共混物,通过扫描电镜(SEM)、力学性能和差示扫描量热(DSC)测试,对动态保压注射成型(动态)和普通注射成型(静态)中增容剂POE-g-MAH(马来酸酐接枝乙烯-辛烯共聚物)和PTW(乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯共聚物)对PA1010/PP共混物的增容作用进行了比较研究.研究结果表明,普通注射成型中,PTW增容体系具有更小的分散相粒子,在DSC测试中出现两个结晶峰,即出现异相成核结晶和均相成核结晶,具有更好的拉伸和冲击性能,增容作用更佳.动态保压注射成型中施加剪切可以提高所有共混物的拉伸强度、拉伸模量和缺口冲击强度,PTW和POE-g-MAH两种增容剂增容体系冲击性能相近,但POE-g-MAH增容体系的分散相相区尺寸减小明显、分布均匀性显著增加,材料冲击强度增加幅度更大,表明剪切更有利于POE-g-MAH增容作用的进行.两种增容剂增容作用的不同源于它们化学组成的不同引起的材料形态差别.     

聚乳酸/聚己内酯/聚(ε-己内酯-L-丙交酯)共聚物三元共混体系的结构与性能

通过开环共聚合,合成了3种不同单元比例的ε-己内酯(ε-CL)与L-丙交酯(L-LA)的共聚物P(CL-co-LA)。通过熔融共混制备了聚乳酸(PLA)/聚己内酯(PCL)/P(CL-co-LA)三元共混材料,研究了P(CL-co-LA)对共混材料微观形貌、热性能以及力学性能的影响。 结果表明,共聚物P(CL-co-LA)作为PLA/PCL不相容体系的界面增容剂,减小了PCL分散相的尺寸,改善了PLA/PCL共混体系的相容性,提高了共混材料的韧性。 固定m(PLA):m(PCL):m(P(CL-co-LA))=80:20:10时,以P(CL49/LA51)(其中数字代表摩尔分数(%))作为界面增容剂效果最佳,共混材料的断裂伸长率可达到(210±30)%。     

用于聚合物共混体系的共聚物增容剂

在不相容多相聚合物体系中，共聚物增容剂的存在将对共混物的形态结构及力学性能产生极大的影响，它们的作用是增强相间粘合力，减小相表面张力。本文系统论述了共聚物增容剂的分子设计及其分子特性对增容效果的影响，并分别讨论了反应型及非反应型共聚物增容剂的近期发展。     

Reactive compatibilization of nylon copolymer/EPDM blends: experimental aspects and their comparison with theory

In situ reactive compatibilization was first time applied to a low melting nylon (nylon 6 and 66 copolymer) and EPDM blend system. The effects of in situ compatibilization and concentration of compatibilizer on the morphology and mechanical properties of nylon/EPDM blends have been investigated. The influence of EPM‐g‐MA on the phase morphology was examined by the scanning electron microscopy (SEM) after preferential extraction of the minor phase. The SEM micrographs were quantitatively analyzed for domain size measurements. The compatibilizer concentrations used were 0, 1, 2.5, 5, and 10 wt%. The graft copolymer (nylon‐g‐EPM) formed at the interface showed relatively high emulsifying activity. A maximum phase size reduction was observed when 2.5 wt% of compatibilizer was added to the blend system. This was followed by a leveling‐off at higher loadings indicating interfacial saturation. The conformation of the compatibilizer at the interface was deduced based on the area occupied by the compatibilizer at the blend interface. The experimental compatibilization results were compared with theoretical predictions of Noolandi and Hong. It was concluded that the molecular state of compatibilizer at interface changes with concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties. Measurement of tensile properties shows increased elongation as well as enhanced modulus and strength up on compatibilization. At higher concentrations of compatibilizer, a leveling‐off of the tensile properties was observed. A good correlation has been observed between the mechanical properties and morphological parameters. Copyright © 2007 John Wiley & Sons, Ltd.     

Reactively and physically compatibilized immiscible polymer blends: stability of the copolymer at the interface

This paper reports on the interfacial behaviour of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/PA6 and polymethylmethacrylate (PMMA)/PA6 blends have been reactively compatibilized by a styrene-maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence. In PS/LDPE blends compatibilized by preformed PS/hydrogenated polybutadiene (hPB) block copolymers, a tapered diblock stabilizes efficiently a co-continuous two-phase morphology, in contrast to a triblock copolymer that was unable to prevent phase coarsening during annealing at 180°C for 150 minutes.     

Thermogravimetric and wide angle X-ray diffraction analysis of thermoplastic elastomers from nylon copolymer and EPDM rubber

Nylon copolymer (PA6, 66) and ethylene propylene diene (EPDM) blends with and without compatibilizer were prepared by melt mixing using Brabender Plasticorder. The thermal stability of nylon copolymer (PA6, 66)/ethylene propylene diene rubber (EPDM) blends was studied using thermogravimetric analysis (TGA). The morphology of the blends was investigated using scanning electron microscopy (SEM). In this work, the effects of blend ratio and compatibilisation on thermal stability and crystallinity were investigated. The incorporation of EPDM rubber was found to improve the thermal stability of nylon copolymer. The kinetic parameters of the degradation process were also studied. A good correlation was observed between the thermal properties and phase morphology of the blends. By applying Coats and Redfern method, the activation energies of various blends were derived from the Thermogravimetric curves. The compatibilization of the blends using EPM-g-MA has increased the degradation temperature and decreased the weight loss. EPM-g-MA is an effective compatibilizer as it increases the decomposition temperature and thermal stability of the blends. Crystallinity of various systems has been studied using wide angle X-ray scattering (WAXS). The addition of EPDM decreases the crystallinity of the blend systems.     

Morphologies, crystallinity and dynamic mechanical characterizations of polypropylene/polystyrene blends compatibilized with PP-g-PS copolymer: Effect of the side chain length

PP-g-PS copolymers were synthesized with the same polypropylene (PP) backbones and various side chain lengths of PS sequences via reactive comonomer p-allyltoluene (p-AT) by Ziegler–Natta copolymerization and the subsequent living anionic graft-polymerization. ¹H NMR characterized that the PP-g-PS copolymer had grafted 3.15 side chains per 1000 carbons in the PP backbones and the length of PS sequences varied in the range of 25.8–309.9 units. PP/PS blends with the PP-g-PS copolymer as compatibilizer (wt. 75/25/5) were prepared and characterized by SEM, WAXD and DMA to investigate the morphologies, crystallinity and glass transition temperatures of the PP/PS blends. All the results pointed out that the average side chain length (GL) of the graft copolymer (GL is from 25.8 to 309.9) made great effects of the PP/PS blends, such as the PS dispersed phase, the crystallinity of the PP component and the two glass transition temperatures of the blends, which showed the same trend with the increase of the GL. Overall, only with a suitable average side chain length, the PP-g-PS copolymer could achieve optimal compatibilizing efficiency of the PP/PS blends.     

PSt-b-PEO增容PA6/PS共混体系的研究

采用动态力学方法（ＤＭＡ），形态学方法（ＳＥＭ），研究了ＰＳｔ ｂ ＰＥＯ存在下尼龙６（ＰＡ６）／聚苯乙烯（ＰＳ）共混体系的相容性．研究表明，ＰＡ６和ＰＳ的简单共混体系，分散相相畴尺寸大，相界面清晰，断裂面光滑，呈脆性断裂，相容性极差，属不相容体系．而加入少量ＰＳｔ ｂ ＰＥＯ后分散相尺寸变小，界面层变厚，界面粘结力增强，表现出韧性特征．     

Ring-opening copolymerization of epoxy-terminated polystyrene macromer with epichlorohydrin and study on properties of the copolymers

The synthesis and ring-opening copolymerization of epoxy-terminated polystyrene (PS-ep) macromer with epichlorohydrin (ECH) as well as some properties of the graft copolymers, were studied. The results showed that content of the epoxy-terminated macromer in the crude macromer can be increased by anionic polymerization of styrene in cyclohexane, and capping with propylene sulfide, followed by termination with ECH at 0 °C. The ring-opening copolymerization of ECH with the macromer can be performed by using a quaternary catalyst system which was composed of triisobutyl aluminium-phosphoric acid-water-amine in the molar ratio of 1:0.25:0.25:0.1-0.15. When the charging weight percentage of PS-ep/ECH=25-65% and M_n of PS-ep was 2.6-10×10³, the conversion of ECH was greater than 95% and the conversion of the macromer or grafting efficiency was 35-65%. The purified copolymer was characterized by IR, ¹H NMR and dynamic viscoelastometer to be a copolymer of ECH with polystyrene (PS) grafts. Transmission electron microscope showed the existence of PS domains in the continuous phase of polyepichlorohydrin (PECH). In a certain range of compositions the graft copolymer behaves like a thermoplastic elastomer. The graft copolymer can be melted and processed repeatedly. Its oil and solvent resistance were better than PS and similar to PECH rubber. The graft copolymer can be used as a compatibilizer for blending PECH with PS to form thermoplastic elastomer blends. Only 2% of it based on the blend is needed to raise the tensile strength of the blends obviously.     

Block copolymers as compatibilizers for blends of linear low density polyethylene and polystyrene

Compatibilization of blends of linear low-density polyethylene (LLDPE) and polystyrene (PS) with block copolymers of styrene (S) and butadiene (B) or hydrogenated butadiene (EB) has been studied. The morphology of the LLDPE/PS (50/50) composition typically with 5% copolymer was characterized primarily by scanning electron microscopy (SEM). The SEB and SEBS copolymers were effective in reducing the PS domain size, while the SB and SBS copolymers were less effective. The noncrystalline copolymers lowered the tensile modulus of the blend by as much as 50%. Modulus calculations based on a coreshell model, with the rubbery copolymer coating the PS particle, predicted that 50% of the rubbery SEBS copolymer was located at the interface compared to only 5–15% of the SB and SBS copolymers. The modulus of blends compatibilized with crystalline, nonrubbery SEB and SEBS copolymers approached Hashin's upper modulus bound. An interconnected interface model was proposed in which the blocks selectively penetrated the LLDPE and PS phases to provide good adhesion and improved stress and strain transfer between the phases. © 1995 John Wiley & Sons, Inc.     

Investigation of phase morphology of incompatible polyethylene/nylon 6 blends containing EPDM-based functionalized compatibilizers

Graft copolymer and graft terpolymer were prepared by solution grafting of maleic anhydride (MAH) or acrylonitrile (AN) alone and mixture of MAH and AN on to ethylene–propylene–diene terpolymer (EPDM) using benzoyl peroxide (BPO) as an initiator. The resulting EPDM-g-MAH, EPDM-g-AN and EPDM-g-(MAH-co-AN) have been used to obtain a binary blend of Nylon 6/functionalized EPDM and a ternary blend of polyethylene/Nylon 6/functionalized EPDM by melt blending. The effects of the nature and the amount of the grafted species on the phase morphology, crystallization behavior and mechanical properties of the blends were characterized through scanning electron microscopy, optical microscopy, infrared spectroscopy and using a dynamic mechanical analyzer. From the morphological study, it can clearly be seen that the presence of the functionalized EPDMs in these blends resulted in an improvement of the dispersion degree in incompatible polyethylene/Nylon 6 blends.     

Can random copolymers serve as effective polymeric compatibilizers?

We investigate the compatibilizing performance of a random copolymer in the melt state, using transmission electron microscopy. Blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) are chosen as a model system, and a random copolymer of styrene and methyl methacrylate (SMMA) with 70 wt % styrene is used as a compatibilizer. From TEM photographs it is clear that SMMA moves to the interface between PS and PMMA domains during melt mixing, and forms encapsulating layers. However, the characteristic size of the dispersed phase increases gradually with annealing time for all blend systems studied. This demonstrates that the encapsulating layer of SMMA does not provide stability against static coalescence, which calls into question the effectiveness of random copolymers as practical compatibilizers. We interpret the encapsulation by random copolymers in terms of a simple model for ternary polymer blends. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2835–2842, 1997