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 共查询到19条相似文献,搜索用时 93 毫秒
1.
PS/LDPE共混体系形变机理的TEM研究徐世爱,江明(复旦大学高分子科学系、聚合物分子工程实验室,上海,200433)沈静姝(中国科学院北京化学所高分子物理开放实验室)关键词形变机理,银纹,透射电镜,共混物在PS/LDPE共混体系中加入接枝或嵌段共...  相似文献   

2.
LLDPE/LDPE共混体系的相容性与性能   总被引:3,自引:0,他引:3  
杨毓华  李喜 《应用化学》1996,13(5):88-90
LLDPE/LDPE共混体系的相容性与性能杨毓华,花荣,白春霞,于旻李三喜,葛铁军(中国科学院长春应用化学研究所长春130022)(沈阳化工学院高分子系沈阳)关键词DSC,WAXD,力学性能,LLDPE,LDPE,共混,相容性非晶-非晶-结晶共混体系...  相似文献   

3.
DSC和SEM研究结果表明聚苯乙烯(PS)与一种热致液晶聚合物(LCP)(PHB/PET(60/40)共聚酯)完全不相容.共混体系具有与组分无关的Tg,并且表现出明显的两相结构.将PS进行化学改性(引入磺酸基团)制备成磺化聚苯乙烯(SPS),随中和盐离子的变化有:酸式、Li、Na、Zn和Mn盐五种形式.用DSC和SEM对LCP与SPS共混物的热性能和形态进行了分析和表征.共混体系有一个与组成相关,且明显低于纯SPS的Tg.这表明了PS与LCP的相容性因为磺酸基团的引入而得到了改善.同时用Fox方程计算了LCP的Tg.当SPS含量较低时(不大于50%)在各个共混体系中,所估算的LCP的Tg相互吻合.表明共混体系满足Fox方程的前提条件,即LCP与SPS形成相容体系.当SPS含量较低时(25%),LCP/SPS的共混物为较均一体系,断面光滑;而SPS含量较高时,在脆断面可以观察到纳米级的颗粒.电子能谱分析证明了这些颗粒是SPS负离子的聚集体.  相似文献   

4.
李三喜 《应用化学》1995,12(2):88-91
通过DSC和WAXD研究了高密度聚乙烯/低密度聚乙烯/乙烯-醋酸乙烯共聚物(HDPE/LDPE/EVA)三元共混体系的热行为和结晶性能,发现当HDPE含量小于40%时,EVA对LDPE起稀释剂作用,促进HDPE、LDPE的晶相分离,使HDPE、LDPE单独结晶,当HDPE含量高于40%时,LDPE片晶入进HDPE晶相,形成与LDPE在片晶水平上的共晶。  相似文献   

5.
通过DSC和WAXD研究了高密度聚乙烯/低密度聚乙烯/乙烯-醋酸乙烯共聚物(HDPE/LDPE/EVA)三元共混体系的热行为和结晶性能。发现当HDPE含量小于40%时,EVA对LDPE起稀释剂作用,促进HDPE、LDPE的晶相分离,使HDPE、LDPE单独结晶.当HDPE含量高于40%时,LDPE片晶进入HDPE晶相。形成与LDPE在片晶水平上的共晶。  相似文献   

6.
EVA增容PP/HDPE共混体系的形态结构与性能   总被引:4,自引:0,他引:4  
采用乙烯-醋酸乙烯酯共聚物(EVA)作为聚丙烯(PP)/高密度聚乙烯(HDPE)共混体系的增容剂,通过冲击实验、拉伸实验、示差量热扫描仪(DSC)和扫描电镜(SEM),系统地研究了共混体系的性能与其形态结构之间的。结果表明,EVA是PP/HDPE共混物较好物增容剂,EVA可以使PP、HDPE的晶相结构受到一定程度的破坏,增加PP和HDPE的相容性,同时共混物的冲击韧性明显提高。  相似文献   

7.
极低密度聚乙烯与其它聚乙烯的共混   总被引:3,自引:0,他引:3  
从结构角度,用DSC,WAXD,SAXS研究了聚乙烯(PE)家族中极低密度聚乙烯(VLDPE)与其它PE的互容性.HDPE/VLDPE是共晶互容的,以其大量无规部分“溶解”了HDPE的结晶缺陷部分,提高了HDPE的Tc,Tm,Xc,结晶峰半高宽变窄,晶胞参数随组成而有最低值.VLDPE与LLDPE结构极为相似,DSC及WAXD证明其共混物是共晶相容体系.LDPE/VLDPE的结晶度符合按组成的计算值,但晶胞参数a,b以及晶粒尺寸增大,DSC上有分别相应于两组份的两个Tm;VLDPE的Tc,Tm峰高之和高于按组份的计算值,LDPE的Tm,Tc则低于计算值.认为是正如LLDPE/LDPE,LDPE向充满整个体积的VLDPE中不断填入,以VLDPE为晶核而结晶,形成相分离的不相容体系.  相似文献   

8.
PP/LDPE共混体系的辐射效应   总被引:1,自引:0,他引:1  
研究了在多官能团单体—三烯丙基异氰脲酸酯存在下PP/LDPE共混体系接受γ-辐射的效果。用溶解度参数和TEM技术评估了共混体系的相容性与多官能团单体在共混体系中的分布,并用SEM、DSC、动态力学等方法对共混体系相容性进行了表征。结果表明,PP/LDPE是不相容的共混体系,三烯丙基异氰脲酸酯主要分布在共混体系的相界面区域,辐照强化了共混体系的相间结合,增加了界面厚度,改善了共混体系的相容性。  相似文献   

9.
PSt-b-PEO增容PA6/PS共混体系的研究   总被引:1,自引:0,他引:1  
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.  相似文献   

10.
用DSC和WAXD方法研究了高密度聚乙烯/聚(乙烯丙烯辛烯-1)(HDPE/EPO)共混体系的结晶性能。共混物的DSC曲线皆呈单峰,表明共混体系形成了共晶。晶胞参数a及结晶度随共混物组成而变,进一步证明HDPE/EPO共混体系的相容性.  相似文献   

11.
In this study, ethylene/styrene interpolymer (ESI) was used as compatibilizer for the blends of polystyrene (PS) and low‐density polyethylene (LDPE). The mechanical properties including impact, tensile properties, and morphology of the blends were investigated by means of uniaxial tension, instrumented falling‐weight impact measurements, and scanning electron microscopy. Impact measurements indicated that the impact strength of the blends increases slowly with LDPE content up to 40 wt %; thereafter, it increases sharply with increasing LDPE content. The impact energy of the LDPE‐rich blends exceeded that of pure LDPE, implying that the LDPE polymer can be further toughened by the incorporation of brittle PS minor phase in the presence of ESI. Tensile tests showed that the yield strength of the PS/LDPE/ESI blends decreases considerably with increasing LDPE content. However, the elongation at break of the blends tended to increase significantly with increasing LDPE content. The compatibilization efficiency of ESI and polystyrene‐hydrogenated butadiene‐polystyrene triblock copolymers (SEBS) for PS/LDPE 50/50 was further compared. Mechanical properties show that ESI is more effective to achieve a combination of LDPE toughness and PS rigidity than SEBS. The correlation between the impact property and morphology of the ESI‐compatibilized PS/LDPE blends is discussed. The excellent tensile ductility of the LDPE‐rich blends resulted from shield yielding of the matrix. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2136–2146, 2007  相似文献   

12.
Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the 75/25 and 25/75 wt/wt ratios and shaped into ribbons with a Brabender single screw extruder. An ethylene-acrylic acid copolymer (EAA) was used in the 2 phr concentration as a compatibilizer precursor (CP). The morphology of the ribbons and its evolution during high temperature annealing were investigated by scanning electron microscopy (SEM). The results confirmed that EAA does actually behave as a reactive compatibilizer for the LDPE/PA blends. In fact, in the presence of EAA, the interfacial adhesion is improved, the dispersion of the minor phase particles is enhanced and their tendency toward fibrillation is increased, especially for the blends with the higher molar mass LDPE grade. The mechanical properties of the latter blends were found to be considerably enhanced by the addition of EAA, whereas the improvement was relatively modest for the blends with the lower molar mass LDPE. The fracture properties of double end notched samples of the ribbons prepared with the blends containing the lower molar mass LDPE grade were also studied. It was shown that, despite of the increased interfacial adhesion caused by the presence of EAA, the latter plays a measurable positive effect on the fracture properties only for the blends with LDPE as the matrix.  相似文献   

13.
Evidence is presented which suggests that during high temperature processing of LDPE/PVC blends with limited air access, cross-phase chemical interaction occurs to give LDPE/PVC graft copolymers. A similar process also appears to occur during photo-oxidation of LDPE/PVC blends, leading to improvement in blend properties (tensile strength).During thermal oxidation, stabilised PVC acts as a heat stabiliser for LDPE/PVC blends, whereas unstabilised PVC acts as a thermal sensitiser. The latter process is believed to be due to the formation of HCl which catalyses the decomposition of LDPE macroperoxides to free radicals.  相似文献   

14.
The effects of ultrasonic oscillations on linear viscoelastic behaviors of metallocene‐catalyzed linear low density polyethylene (mLLDPE) and its blends with low density polyethylene (LDPE) were investigated in this article. The experimental results showed that ultrasonic oscillations can increase the cross modulus, characteristic time, plateau modulus, complex viscosity, zero shear viscosity, and flow activation energy of mLLDPE. Molecular weight of mLLDPE increases but molecular polydispersity index decreases in the presence of ultrasonic oscillations. It has been found for mLLDPE/LDPE blends that the addition of LDPE as well as ultrasonic oscillations can decrease the cross modulus but increase the characteristic time of the blends. The complex viscosity, zero shear viscosity, and flow activation energy of the blends increase by the addition of LDPE, but decrease in the presence of ultrasonic oscillations. Shear thinning effect of the blends is improved because of the addition of LDPE. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3030–3043, 2005  相似文献   

15.
The synergism of ethylene-propylene-diene monomer copolymer (EPDM) and dicumyl peroxide (DCP, a crosslinking agent) in low density polyethylene (LDPE)/poly(vinyl chloride) (PVC) blends was investigated. When EDPM and DCP are added to the blends simultaneously, the tensile properties could be improved significantly, especially for the blends with LDPE matrix. For example, incorporation of 10/1 (mass ratio) EPDM/DCP improves the tensile strength of the LDPE/PVC (mass ratio 80/20) blend from 7.9 MPa to 8.5 MPa and the elongation at break from 25% to 503%. Results from selective extraction, phase-contrast microscopy and thermal analysis reveal that the improvement in the tensile properties of the blends with LDPE matrix is principally due to the formation of a fine crosslinking network of the LDPE and EPDM phase. The outstanding modification effect of EPDM is explained by its dual functions: molecular entanglement with LDPE and the enhanced efficiency of DCP in the blends.  相似文献   

16.
Commercial copolymers of 1‐octene and ethylene: metallocene catalyzed (mLLDPE) and Ziegler‐Natta catalyzed (znLLDPE), a low density polyethylene (LDPE), and high density polyethylene (HDPE), were characterized with respect to branching, crystallization behaviour and dynamic‐mechanical properties. It was found that the crystallinity of the polymers is more influenced by the homogeneity of the short‐chain branching than by its content. The study of blends of mLLDPE and znLLDPE with LDPE and HDPE showed that the interaction between mLLDPE and LDPE is stronger than between znLLDPE and LDPE. Blends containing mLLDPE showed a composition depending improvement of the storage modulus G' which was not observed in znLLDPE/LDPE blends. The HPDE blends followed a linear mixing rule. Co‐crystallization was found mLLDPE/LDPE and partially in znLLDPE/LDPE and znLLDPE/HDPE blends, respectively.  相似文献   

17.
To evaluate the compatibilizing effects of isocyanate (NCO) functional group on the polyethylene terephthalate/low density polyethylene (PET/LDPE) blends, LDPE grafted with 2-hydroxyethyl methacrylate-isophorone diisocyanate (LDPE-g-HI) was prepared and blended with PET. The chemical reaction occurred during the melt blending in the PET/LDPE-g-HI blends was confirmed by the result of IR spectra. In the light of the blend morphology, the dispersions of the PET/LDPE-g-HI blends were very fine over the PET/LDPE blends. DSC thermograms indicated that PET microdispersions produced by the slow cooling of the PET/LDPE-g-HI blends were largely amorphous, with low crystallinity, due to the chemical bonding. The tensile strengths of the PET/LDPE-g-HI blends were higher than those of the PET/LDPE blends having a poor adhesion. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 447–453, 1998  相似文献   

18.
Although polyaniline (PANI) has high conductivity and relatively good environmental and thermal stability and is easily synthesized, the intractability of this intrinsically conducting polymer with a melting procedure prevents extensive applications. This work was designed to process PANI with a melting blend method with current thermoplastic polymers. PANI in an emeraldine base form was plasticized and doped with dodecylbenzene sulfonic acid (DBSA) to prepare a conductive complex (PANI–DBSA). PANI–DBSA, low‐density polyethylene (LDPE), and an ethylene/vinyl acetate copolymer (EVA) were blended in a twin‐rotor mixer. The blending procedure was monitored, including the changes in the temperature, torque moment, and work. As expected, the conductivity of ternary PANI–DBSA/LDPE/EVA was higher by one order of magnitude than that of binary PANI–DBSA/LDPE, and this was attributed to the PANI–DBSA phase being preferentially located in the EVA phase. An investigation of the morphology of the polymer blends with high‐resolution optical microscopy indicated that PANI–DBSA formed a conducting network at a high concentration of PANI–DBSA. The thermal and crystalline properties of the polymer blends were measured with differential scanning calorimetry. The mechanical properties were also measured. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3750–3758, 2004  相似文献   

19.
Extensive thermal and relaxational behavior in the blends of linear low-density polyethylene (LLDPE) (1-octene comonomer) with low-density polyethylene (LDPE) and high-density polyethylene (HDPE) have been investigated to elucidate miscibility and molecular relaxations in the crystalline and amorphous phases by using a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). In the LLDPE/LDPE blends, two distinct endotherms during melting and crystallization by DSC were observed supporting the belief that LLDPE and LDPE exclude one another during crystallization. However, the dynamic mechanical β and γ relaxations of the blends indicate that the two constituents are miscible in the amorphous phase, while LLDPE dominates α relaxation. In the LLDPE/HDPE system, there was a single composition-dependent peak during melting and crystallization, and the heat of fusion varied linearly with composition supporting the incorporation of HDPE into the LLDPE crystals. The dynamic mechanical α, β, and γ relaxations of the blends display an intermediate behavior that indicates miscibility in both the crystalline and amorphous phases. In the LDPE/HDPE blend, the melting or crystallization peaks of LDPE were strongly influenced by HDPE. The behavior of the α relaxation was dominated by HDPE, while those of β and γ relaxations were intermediate of the constituents, which were similar to those of the LLDPE/HDPE blends. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1633–1642, 1997  相似文献   

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