PC/HBPS共混物的流变性能

通过熔融共混法制备了PC/HBPS共混物,研究了其流变特性。结果表明,此共混物属于假塑性流体,随着HBPS含量的增加,非牛顿指数增加;随着剪切速率的增加,表观黏度下降,但下降趋势较缓慢;随着温度的增加,表观黏度下降,但下降趋势很快;共混物的粘流活化能都比纯PC的粘流活化能高;随着HBPS含量的增加,表观黏度下降。     

核壳结构改性剂对PBT/PC共混物的增韧作用

采用丙烯腈-丁二烯-苯乙烯（ABS）核壳结构改性剂增韧聚对苯二甲酸丁二醇酯（PBT）/聚碳酸酯（PC）共混物。动态力学测试（DMTA）结果表明,PBT与PC为热力学不相容体系,ABS的引入导致PBT、PC玻璃化转变温度相互靠近,相容性提高;差示扫描量热（DSC）研究结果表明,随着ABS的加入,PBT/PC体系中PBT的...     

PC/ABS共混合金冲击断口形态和强度

研究了不同原料和配比的PC/ABS共混合金冲击破坏断面形态和缺口冲击强度之间的关系。用注射成型方法制备缺口冲击样条,用扫描电镜观察断面形态,用简支梁测定冲击强度,结果表明:冲击强度得到提高的合金断面是PC和ABS部分断面形态的加合和增强。其特征形态是微坑、抛物线和裂纹带分枝。冲击强度较PC和ABS低的合金断面,其形态既不同于PC也不同于ABS。原料和配比对合金断面形态和强度有影响,其中配比的影响最大。     

PA6/ABS共混物的脆-韧转变研究

采用熔融共混方法制备了苯乙烯-马来酸酐共聚物(SMA)增容的PA6/ARS共混物,结合吴守恒的临界基体层厚度(IDc)理论,考察了基体层厚度与界面粘接对PA6/ABS共混物脆一韧转变的影响.结果表明,温度低于8℃,当ID减小时,冲击强度先缓慢增加,当ID＜ID.时,共混物缺口冲击强度急剧增加;测试温度处于13℃～23℃...     

Morphological, rheological and mechanical characterization of polypropylene nanocomposite blends

In the present work, the effectiveness of styrene/ethylene-butylene/styrene rubbers grafted with maleic anhydride (MA) and a metallocene polyethylene (mPE) as toughening materials in binary and ternary blends with polypropylene and its nanocomposite as continuous phases was evaluated in terms of transmission electron microscopy (TEM), scanning electron microscopy (SEM), oscillatory shear flow and dynamic mechanical thermal analysis (DMA). The flexural modulus and heat distortion temperature values were determined as well. A metallocene polyethylene and a polyamide-6 were used as dispersed phases in these binary and ternary blends produced via melt blending in a corotating twin-screw extruder. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in shear viscosity, melt elasticity, flexural or storage moduli and heat distortion temperature values were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene phase exhibited better toughness, lower shear viscosity, flexural modulus, and heat distortion temperature values than that prepared with polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends.     

胺基化反应增容PC/ABS共混物

采用熔融共混方法制备了ABS树脂接枝马来酸酐接枝共聚物(ABS-g-MAH),将接枝共聚物与1-(2氨乙基)哌嗪反应制备了增容剂,通过红外光谱表征确定了预期反应的发生.将增容剂部分替代聚碳酸酯(PC)/ABS共混物中的ABS树脂,考察了增容剂对PC/ABS共混物的力学性能的影响.结果表明,加入增容剂后,PC/ABS共混...     

Comparisons of deformation and fracture behaviour of PC/ABS blend and ABS copolymer under dynamic shear loading

Abstract

The dynamic shear deformation and fracture characteristics of PC/ABS blend and ABS copolymer with regard to the relation between mechanical properties and strain rate, are studied experimentally using a torsional split Hopkinson bar at room temperature under strain rates ranging from 8 × 10² s^-1 to 3.4 × 10³ s^-1. Fracture phenomena are analysed by scanning electron microscopy and correlated with macroscopic behaviour. The relative properties and fracture mechanism of both polymers are also compared. Results show that strain rate enhances shear strength of both PC/ABS blend and ABS, but fracture shear strain tends to decrease with increasing strain rate. ABS exhibits better ductility and lower shear strength. For both polymers, strain rate sensitivity increases with increasing range of strain rate, while an inverse tendency occurs for activation volume. Higher strain rate sensitivity and lower activation volume are found in PC/ABS blend. PC/ABS blend fracture is dominated by mixed shearing and tearing, but ABS fracture shows only shearing. Due to the increasing deformation heat, fracture surface viscoplastic flow for both polymers increases with increasing strain rate, inducing lower flow resistance and lower fracture strain at higher stain rates. The viscoplastic flow behaviour in ABS is more active.     

PTFE/PA6和PTFE/PA66共混物的吸水性及流变行为

通过浸水实验、缺口冲击断裂实验和动态流变测试,考察了PTFE含量对PTFE/PA6和PTFE/PA66共混物的吸水率、冲击断裂强度及熔体黏度的影响以及熔体黏度随温度和频率的变化规律。结果表明,PTFE/PA6和PTFE/PA66共混物的吸水率均随着PTFE含量的增加而减小,即PTFE的加入抑制了共混物的吸水性。两种共混物的冲击强度比纯PA明显降低,但是吸收水对两种共混物冲击强度的影响不显著。随着PTFE含量的增加,共混物熔体的黏度先减小后增加,说明适量的PTFE可以改善共混物的成型加工特性。共混物熔体的黏度随加载频率的增大而降低,符合假塑性流体流动规律。有趣的是,对于PTFE/PA6共混物的黏度随着温度的升高而减小,而PTFE/PA66共混物黏度随着温度升高近似成指数规律增大。     

Blends of polycarbonate with unmodified and maleic anhydride grafted ABS: fracture mechanics

Physical blends of polycarbonate (PC) and acrylonitrile-butadiene-styrene terpolymer (ABS) at two different weight fractions were made (PC35/ABS65 and P75/ABS25). Reactive blended similar compositions of PC with maleic anhydride grafted ABS (MABS) were also made at the same compositions. The crack resistance behaviour of these two types of blends and feedstocks (PC and ABS) were studied. The generalized locus method was used to investigate the invariance of crack resistance from any set of characteristic points. PC and PC/ABS blends failed immediately after crack initiation. The modified blends (PC/MABS) exhibited failure through crack propagation after crack initiation started. The resistance to crack initiation is determined in terms of critical J-integral value (J_c). The resistance to crack propagation at maximum load point is also determined from the locus of maximum load point on the load-displacement curves. The resistance to steady state crack growth (R_p) during extensive crack propagation is determined from the total essential energy for a complete fracture. The crack resistance values for modified blends are much high compared to unmodified blends and even feedstocks.     

SMA含量对PA6/ABS共混体系结构和韧-脆转变温度的影响

研究了苯乙烯-马来酸酐共聚物(SMA)含量(0～4.5phr)对PA6/ABS(75/25)共混体系结构和冲击断裂的影响。结果表明,PA6/ABS共混体系的橡胶相粒径和基体层厚度都随着SMA含量的增加而减小。PA6/ABS共混体系冲击断裂存在脆韧转变现象,其脆韧转变温度随SMA含量的增加先减小后增加,并且在对应SMA含量为0.9phr和1.5phr时取得极小值。同时,脆韧转变温度随着基体层厚度的增加而逐渐升高,即升高温度与降低基体层厚度都可以获得脆-韧转变。     

Fracture toughness and fracture mechanisms of polybutylene-terephthalate/polycarbonate/ impact-modifier blends

A series of polybutylene-terephthalate/polycarbonate (PBT/PC) blends with different compositions were prepared using a twin-screw extruder. The morphologies of the blends were revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that a 50/50 PBT/PC blend possessed a bicontinuous structure and the other blends had a dispersed phase of either PBT or PC depending on which was the minor component. A relatively strong interface was observed in the blends with 20%, 40% and 50% PBT; but poor interfacial adhesion was found in the blends with 60% and 80% PBT. The strength of the interfacial boundary was believed to depend on the composition and blending conditions of the individual blend. Fracture experiments showed that the sharp-notch fracture toughness of PC could be significantly increased by mixing with up to 50% PBT without losing its modulus and yield stress. The toughening mechanisms involved in the fracture processes of the blends were studied using both SEM and TEM together with single-edge-double-notched-bend (SEDNB) specimens. It was found that in the toughened blends the growing crazes initiated by the triaxial stress in front of the crack tip were stabilized by the PC domains. The debonding-cavitation mechanism occurred at the PBT/PC interface, which relieved the plane-strain constraint and promoted shear deformation in both PBT and PC. This plastic deformation absorbed a tremendous amount of energy. Crack-interface bridging by the PC domains was clearly verified by the TEM study. Thus, the PC domains not only stabilized the growing crazes they also bridged crack surfaces after the crack has passed by. This effect definitely caused a large plastic-damage zone and hence a high crack resistance. Poor crack resistances of the blends rich in PBT was caused by the poor interfacial adhesion between PBT and PC. In these polymer blends, the growing crazes easily developed into cracks, which subsequently passed through the weak interface of PBT/PC and finally produced fast unstable fracture.     

PBT树脂对核壳粒子增韧聚碳酸酯结构与性能的影响

合成了甲基丙烯酸甲酯-丁二烯-苯乙烯-甲基丙烯酸环氧丙酯(MBS-g-GMA)核壳粒子用于聚碳酸酯(PC)的增韧,并在PC/MBS-g-GMA共混物中引入聚对苯二甲酸丁二醇酯(PBT)以提高性能。PBT的加入使MBS-g-GMA在PC中分散更均匀;共混物缺口冲击强度进一步提高,PBT质量分数为20%时,冲击强度接近700J/m;PBT提高了PC/MBS-g-GMA共混物的熔体流动速率,使加工性能得到改善。断裂形态表明,PBT加入后共混物应力发白区尺寸增加,剪切屈服更明显,共混物韧性提高。     

Structural-mechanical relationship of epoxy compatibilized polyamide 6/polycarbonate blends

Polyamide 6 (PA6)/polycarbonate (PC) blends compatibilized with solid epoxy resin (bisphenol type-A) were prepared by extrusion followed by injection molding. The effects of epoxy resin on the microstructure, tensile, impact and compatibility of the PA6/PC blends were investigated. The results showed that both the tensile modulus and elongation at break of PA6/PC blends were inferior as compared to their parent polymers. This resulted from incompatibility between the PA6 and PC phases. SEM observation revealed that the introduction of 0.5 part per hundred (phr) epoxy resin into the PA6/PC75/25 blend yields a finer dispersion of PC phase in PA6 matrix. The boundaries between the PC domains and PA6 matrix became obscure with the incorporation of 1 phr epoxy resin. Such an improvement in compatibility was suggested to be resulted from the formation of in situ epoxy bridged PA6-PC block copolymer in the blend during compounding. Consequently, the tensile modulus, yield strength and impact strength of the PA6/PC 75/25 blend improved considerably with increasing epoxy content.     

PTT/ABS-g-MAH/SCF复合材料的制备与性能

研究了聚对苯二甲酸丙二酯(PTT)/马来酸酐接枝丙烯腈-丁二烯-苯乙烯共聚物(ABS-g-MAH)/短炭纤维(SCF)复合材料的力学性能、流变和结晶熔融行为.结果表明,ω(SCF)=10%时,复合材料的拉伸强度和弯曲强度达到板值,冲击强度略有升高,SCF对PTT起到了较好的增强效果且不影响韧性;ω(SCF)>10%时,...     

Structure and properties of injection molded blends of poly(ether imide) and a thermotropic copolyester

The phase structure and mechanical properties of blends composed of poly(ether imide) and a thermotropic liquid-crystalline copolyester, Rodrun LC-5000, processed by injection molding were studied in the PEI-rich region. The addition of Rodrun to PEI produces fully immiscible blends and strongly improves the processability of PEI. Injection molding gave rise in very poor LCP blends to fine dispersed phases; in the rest of compositions it gave rise to coarse structures. This was probably due to the very large viscosity difference between the components of the blends. An increase in the melt temperature led to a smaller viscosity difference and as a consequence dispersed phase dispersion improved. The Young's modulus clearly increased with the Rodrun content. The tensile strength was maintained up to a LCP content of 5% but decreased at higher contents because of the coarse morphologies obtained. The overall mechanical behavior was a main consequence of the lack of fibrillation and of the LCP dispersion level in the matrix.     

铋粉对PP熔融流变性能及成纤性能的影响

采用熔融共混法制备铋/聚丙烯共混材料(Bi/PP),利用旋转流变仪对其熔融流变特性进行测试分析。再通过熔融纺丝法制备初生纤维,采用扫描电镜、单纤维强力仪等对初生纤维的结构及性能进行表征。研究表明:共混材料表现非牛顿流体特性;共混材料的表观黏度与温度及剪切速率呈负相关;相同温度下,随铋粉含量增加,共混物的表观黏度也相应上升,铋粉在PP基体中的分散性较好但团聚增多,初生纤维内部孔隙结构增多,力学性能有所降低。     

挤出次数及相容剂对ABS/PMMA合金性能的影响

用熔融共混的方法制备了丙烯腈-苯乙烯-丁二烯共聚物(ABS)/聚甲基丙烯酸甲酯(PMMA)合金,研究了挤出次数和相容剂对合金性能的影响,采用差示扫描量热法(DSC)测定了ABS/PMMA合金的玻璃化转变温度,用场发射扫描电镜(SEM)观察了材料冲击断口的表面形貌。结果表明,挤出次数对拉伸强度没有明显影响,对冲击强度有小幅度影响;苯乙烯-马来酸酐共聚物(SMA)作为相容剂增加了合金的拉伸强度,降低了合金的韧性。SEM观察表明,PMMA使材料由韧性断裂向脆性断裂转变,SMA对于ABS/PMMA合金的相容性没有明显的改善作用。     

Structure and mechanical properties of the extruded blends of a liquid crystalline polymer with polypropylene

Blends of a thermoplastic, isotatic polypropylene (PP) and a liquid-crystalline polymer (LCP) based on a copolyester of hydroxynapthoic acid and hydroxybenzoic acid, were extruded. The LCP exhibited a higher viscosity than that of the PP under the extrusion conditions. Calorimetric, microscopic, static and dynamic mechanical tests were performed on these blends. Differential scanning calorimetry thermograms indicated that the crystallization temperature of PP increases slightly with increasing LCP content. Scanning electron microscopy examinations revealed that the LCP phase was elongated into microfibrils in the blends investigated. However, some undeformed spherical droplets were dispersed in the PP matrix in addition to microfibrils for the blends containing high LCP concentrations. Static tensile tests showed that the addition of LCP to PP results in an increase of the modulus of elasticity but a decrease in tensile strength. The storage modulus of the extruded blends was found to increase with the addition of LCP.     

热致液晶高分子及其共混物的流变性能

在 Instron 毛细管流变仪上测定了热致液晶高分子 KU 9221/聚碳酸酯(PC)共混物和热致液晶高分子 KU 9231/聚醚砜(PES)共混物的流变性能。低切变速率下,液晶高分子的粘度大于 PC 和 PES 的粘度,液晶的加入未能使 PC 和 PES 的粘度下降。高切变速率(通常注塑成型的注塑速率)下,液晶的加入能显著降低体系的粘度。低切变速率下液晶相尺寸大,长径比小。高切变速率下液晶相尺寸小,长径比大。     

PC/SAN相容性研究进展

从分子量、共聚物中不同单体含量、剪切作用等方面概速了PC／SAN体系相容性的影响因素及其研究进展，讨论了改善该体系相容性的方法，并展望了聚合物共混物体系相容性研究的发展前景。