Effects of the compatibilizer PP-g-GMA on morphology and mechanical properties of PP/PC blends

Effects of the compatibilizer polypropylene grafted with glycidyl methacrylate(PP-g-GMA) on the morphology, thermal, rheological and mechanical properties of polypropylene and polycarbonate blends (PP/PC) were studied. It was found that the addition of PP-g-GMA significantly changed their morphology. The mean size of domains reduced from 20 μm to less than 5 μm. The dispersed domain size is also strongly dependent upon the content of PP-g-GMA. The interfacial tension of PP/PC/PP-g-GMA (50/30/20) is only about one-tenth of PP/PC (70/30). The crystallization temperature of PP in PP/PC/PP-g-GMA is 5–8°C higher than that of PP in PP/PC blends. Characterization studies based on mechanical properties, differential scanning calorimetry, rheology and morphological evidence obtained by using scanning electron microscopy support the hypothesis that an in-situ copolymer PP-g-PC was formed during the blending process.     

Effects of processing conditions on the mechanical performance of maleic anhydride compatibilized in-situ composites of polypropylene with liquid crystalline polymer

Maleic anhydride compatibilized blends of isotactic polypropylene (PP) and thermotropic liquid crystaline polymer (LCP) were prepared either by the direct injection molding (one-step process), or by twin-screw extrusion blending, after which specimens were injection molded (two-step process). The morphology and mechanical properties of these injection molded in situ LCP composites were studied by means of scanning electron microscopy (SEM), Izod impact testing, static tensile, and dynamic mechanical measurements. SEM observations showed that fine and elongated LCP fibrils are formed in the maleic anhydride compatibilized in situ composites fabricated by means of the one-step process. The tensile strength and modulus of these composites were considerably close to those predicted from the rule of mixtures. Furthermore, the impact behavior of LCP fibril reinforced composites was similar to that of the glass fiber reinforced polymer composites. On the other hand, the maleic anhydride compatibilized blends prepared from the two-step process showed lower mechanical performance, which was attributed to the poorer processing behavior leading to the degradation of PP. The effects of the processing steps, temperatures, and compatibilizer addition on the mechanical properties of the PP/LCP blends are discussed.     

绢英粉填充改性聚丙烯的研究

制备绢英粉填充聚丙烯共混材料 ,研究了绢英粉的粒度和处理方法对共混物力学性能的影响。通过 SEM、DSC、GPC、TMA和 MI的测定研究了绢英粉填充聚丙烯共混材料的组分变化和形态结构对其力学性能的影响。初步探讨了聚丙烯 /绢英粉共混材料的耐紫外老化性能。利用微波辐照处理聚丙烯 /绢英粉共混物改善了界面粘合性 ,提高了材料的抗冲击强度     

材料组分对PP/PE-LD水发泡注塑件延展性能的影响

以水为发泡剂在常规注塑机中制得具有不同材料组分的聚丙烯（PP）/低密度聚乙烯（PE-LD）共混物微孔制件,并对该制件进行力学性能测试及微观结构表征。结果表明,微孔的存在能够提高PP/PE-LD材料的延展性能,而不同的PP/PE-LD组分对制件的微孔结构及力学性能均有较大影响;当PP含量为90 %~50 %（质量分数,下同）时,PP与PE LD两相的相容性较差,导致PP/PE-LD共混物形成泡孔更加容易,微孔的分布更加均匀,从而其延展性更易提高。     

聚烯烃改性PET的研究

通过PET与PP、HDPE、EPDM挤出共混，注射模塑制得试样。经DTA、SEM和力学性能测试，表征了共混体系的热行为、结构形态和力学性能。结果表明，在PET/PP(EPDM、HDPE)共混体系中，加入少量的PP-g-MI(EPDM-g-MAH、PE-g-MI)，可较好地改善PEt与PP(EPDM、HDPE)之间的相容性，使分散相在PET基体连续相中分散均匀，分散相尺寸减小，增加了两相间界面的粘结力；同时对PET的结晶有较强的促进作用，使其冷结晶温度降低，改善了PET的加工性能；并且能大幅度提高共混物的冲击强度。     

Injection molding of polypropylene/polycarbonate blends

This work deals with the effects of material and processing parameters on the mechanical behavior and morphology of noncompatlbilized polypropylene-polycarbonate (PP-PC) blends. The blends containing between 0 and 40 vol. percent of polycarbonate were compounded using a twin screw extruder and converted by injection molding using molds with rectangular as well as dogbone shaped cavities. The blends exhibit a complex skin-core morphology which evolves with the composition. Despite the absence of interfacial adhesion, the low strain modulus increases with PC concentration and follows approximately the Takayanagi model for systems with perfect adhesion. A slight increase of stiffness and strength with increasing PP/PC viscosity ratio is also observed. Weldline strength of these blends is generally poor and decreases with the increasing PC concentration.     

马来酸酐接枝PP／POE共混物对PC的改性研究

使用本实验室自制的(PP／POE)-g-MAH共混物作为聚碳酸酯(PC)的改性剂。研究了不同改性剂用量对PC共混物的力学、热学、加工及耐沸水性能的影响。结果表明，加入5％的(PP／POE)-g-MAH可明显提高PC的缺口冲击强度，改善PC的加工性能和耐沸水性能，从而得到一种综合性能较好的材料。同时使用扫描电镜对改性共混物的液氮脆断断面进行了观察。     

The morphology and mechanical properties of dynamic packing injection molded PP/PS blends

As a part of long-term project aimed at super polyolefin blends, in this work, we report the mechanical reinforcement and phase morphology of the immiscible blends of polypropylene (PP) and polystyrene (PS) achieved by dynamic packing injection molding (DPIM). The shear stress (achieved by DPIM) and interfacial interaction (obtained by using styrene-butadiene-styrene (SBS) as a compatibilizer) have a great effect on phase morphology thus mechanical properties. The shear-induced morphology with core in the center and oriented zone surrounding the core was observed in the cross-section areas of the samples. The phase inversion was also found to shift towards lower PS content under shear stress, at 70 wt% in the core and 30 wt% in the oriented zone, compared with 80 wt% for static samples (without shear). The tensile strength, tensile modules and impact strength were found largely increase by means of either shear stress or compatibilizer. The PS particle size is greatly reduced with adding of SBS, and the reduced particle size results in greater resistance to deformation, which causes the co-continuous structure at oriented zone change into droplet morphology. The morphology resulting from blending and processing was discussed based on effect of interfacial tension, shear rate, phase viscosity ratio and composition. The observed change of mechanical properties was explained based on the combined effect of phase morphology (droplet-matrix or co-continuous phase) and molecular orientation under shear stress.     

Influence of Matrix Polymer on Deformation and Morphology of Injection Molded Immiscible Blends with High Interfacial Contact

Abstract:

Immiscible blends of poly(ethylene terephthalate) (PET)/polypropylene (PP), polycarbonate (PC)/PP and PC/linear low-density polyethylene (LLDPE) were examined to study the influence of the high interfacial contact (pseudo-adhesion) on the mechanical properties and the morphology developed during elongation. The high interfacial contact resulted from the contraction difference of the two polymers during cooling from processing temperature to room temperature. It was confirmed that high interfacial contact could improve the mechanical properties of the blends. By calculation, the compressive force in the PET particles for PET/PP blends exceeded the yield stress of PET, satisfying the conditions for solid in-situ fibrillation. But scanning electronic microscopy (SEM) micrographs showed that PET particles were only slightly deformed into ellipsoids. The morphological evolution of PC/PP and PC/LLDPE blends were in line with the prediction for solid in-situ fibrillation. In addition, the factors determining the solid in-situ fibrillation of the immiscible blends were summarized: (a) the specimen has sufficient large deformation, (b) the matrix has sufficient high modulus, and (c) interfacial interactions are strong enough.     

Processing‐improved properties and morphology of PP/COC blends

The aim of this study was to improve mechanical properties of polypropylene/cycloolefin copolymer (PP/COC) blends by processing‐induced formation of long COC fibers. According to the available literature, the fibrous morphology in PP/COC blends was observed just once by coincidence. For this reason, we focused our attention on finding processing conditions yielding PP/COC fibrous morphology in a well‐defined, reproducible way. A number of PP/COC blends were prepared by both compression molding and injection molding (IM). Neat polymers were characterized by rheological measurements, whereas phase morphology of the resulting PP/COC blends was characterized by means of scanning electron microscopy (SEM). The longest COC fibers were achieved in the injection molded PP/COC blends with compositions 75/25 and 70/30 wt %. Elastic modulus and yield strength of all blends were measured as functions of the blend composition using an Instron tensile tester; statistically significant improvement of the yield strength due to fibrous morphology was proved. Moreover, two different models were applied in the analysis of mechanical properties: (i) the equivalent box model for isotropic blends and (ii) the Halpin‐Tsai model for long fiber composites. In all PP/COC blends prepared by IM, the COC fibers were oriented in the processing direction, as documented by SEM micrographs, and acted as a reinforcing component, as evidenced by stress–strain measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Irradiation processing of immiscible PP/EOC blend: Morphology control and processability modification

In this study, applying electron beam irradiation method at a relatively low-irradiation dose (20 kGy) under the air atmosphere to prepare injectable polypropylene (PP)/ethylene-octene copolymer (EOC) blends with fine morphology and appropriate performance was investigated. For this purpose, an extrusion PP grade with an EOC grade suitable to improve its impact resistance was melting blended. Gel content and rheological measurements revealed long-chain branching is predominant phenomenon occurring during the irradiation process of EOC. Blend irradiation resulted in changing its melt flow index proper for injection molding. A fine morphology obtained for the unirradiated blend was preserved for the irradiated blend. Moreover, irradiation thermally stabilized the blend morphology. Blends linear viscoelastic behavior discussed by proper rheological models revealed the existence of interfacial interactions and a reduction of the interfacial tension between irradiated blend phases. No significant effect of irradiation on the crystallization characteristics of EOC and the blend was observed. The satisfying impact resistance of the irradiated blend was near to that of the unirradiated blend, although its tensile mechanical properties were less.     

Studies on blends of polyethylene terephthalate with bisphenol-a-polycarbonate and polypropylene

Moldability and mechanical properties of polyethylene terephthalate (PET) under normal molding conditions were found to improve significantly when it was blended with bisphenol-A-polycarbonate (PC) and polypropylene (PP) to form ternary polymer blend systems. DSC results of these blends revealed that the PET and PC components formed a miscible blend while PP being incompatible with them, formed a separate phase. PP was also found to form a sleeve around the PET-PC miscible phase and, thereby, showed a skin-core type of morphology. Variations of mechanical properties with varying amounts of PP was measured keeping the ratio of PET and PC constant. Tensile and flexural properties of the blends decrease with the amount of PP. Notched impact strength increases up to a certain level of PP and then decreases, while the unnotched values decrease gradually. The effect of annealing on the mechanical properties of these blends have been discussed on the basis of the increased crystallinity of some of the components.     

剪切作用下POE-g-MAH和PP-g-MAH对PA1010/PP共混物的增容作用

采用熔融共混的方法制备了聚酰胺1010/聚丙烯（PA1010/PP）共混物,通过扫描电镜、力学性能和差示扫描量热等方法研究了剪切作用下马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH）和马来酸酐接枝聚丙烯（PP-g-MAH）对PA1010/PP共混物的增容作用。结果表明,同样条件下,PP-g-MAH增容体系的相区尺寸较小,相界面更模糊,PP相的结晶温度和结晶度明显提高,共混物的拉伸强度和冲击强度均高于非增容体系。而POE-g-MAH增容体系的相区尺寸相对较大,PP相的结晶温度和结晶度明显降低,共混物只有冲击强度明显高于非增容体系,拉伸强度略低于非增容体系。     

Effects of waste ground rubber tire powder (WGRT) and chemical blowing agent content on the cell morphology and physicomechanical properties of injection‐molded polypropylene/WGRT foams

Microcellular polypropylene (PP)/WGRT blends, a new outlet for the recycling of waste tire rubber, were prepared in an injection‐molding process by using a chemical blowing agent. The effects of WGRT content and chemical blowing agent content on the density, cell morphology, and physicomechanical properties of the foamed PP/WGRT blends were investigated. The foam morphologies were characterized in terms of void fraction, average cell size, and cell density. The results indicated that both the WGRT and the blowing agent content had huge effects on the cell morphology and tensile properties of the PP/WGRT foams. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

硅灰石填充改性聚丙烯体系结构与性能的研究

采用机械共混的方法制备了聚丙烯(PP)/硅灰石共混体系,并对共混体系的拉伸强度、冲击强度、断口形貌进行了测试与分析。在共混体系中加入弹性体乙烯-醋酸乙烯共聚物(EVA)和苯乙烯-丁二烯-苯乙烯(SBS),以增加体系的韧性;添加马来酸酐(MAH),以提高组分间的界面结合力。结果表明:EVA对共混体系增韧效果不明显,SBS能够增加体系韧性,MAH能够提高体系强度;当硅灰石质量分数为30%,SBS和PP-g-MAH的质量分数均为15%时,体系的力学性能最佳。     

Structure and properties of injection moldings of polypropylene/polystyrene blends

A homoisotactic polypropylene (PP) was melt blended with 0–30 wt % of three kinds of polystyrene (PS) with melt flow indexes lower than, similar to, and higher than that of PP. The blends were injection molded at cylinder temperatures of 200–280°C, and the structure and properties of the injection moldings were studied. With PS blending, although the PP molding whitened, no surface defect such as layer peeling and pearl-like appearance occurred. The rigidity and dimensional accuracy of the molding improved without much deterioration in impact strength and heat resistance. At the same time the fluidity also improved. The injection moldings of PP/PS blends did not show clear skin/core structure under a polarizing microscope. The degrees of crystallinity and crystalline c-axis orientation decreased with PS blending. PS particles were the smallest when the ratio of the viscosity of the PS to that of PP at molding shear rate was slightly lower than unity. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1015–1027, 1997     

Crystallization behavior and mechanical properties of polypropylene random copolymer/poly(ethylene‐octene) blends

New polymer blends of polypropylene random copolymer (PP‐R) and poly(ethylene‐octene) (POE) were prepared by melt‐blending process using a corotating twin‐screw extruder. The POE content was varied up to 35%. The toughening efficiency of POE for PP‐R was evaluated by the mechanical properties of the resulted PP‐R/POE blends. The crystallization behavior and morphology of the blends were also studied. Results show that POE acts as nucleation agent to induce the crystallization of PP‐R matrix at higher crystallization temperature. Super‐toughened PP‐R/POE blends (Izod impact strength more than 500 J/m) can be readily achieved with only 10 wt % of POE. The high toughness of PP‐R/POE is attributed to cavitation and shear yielding of matrix PP‐R, as revealed by the morphology studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of poly(lactic acid)/recycled polypropylene blends with and without the coupling agent,n-(6-aminohexyl)aminomethyltriethoxysilane

Blends of polylactide (PLA) and recycled polypropylene (rPP) were prepared by melt-processing using a corotating twin-screw extruder and subsequent pelletizing of the extrudates for injection molding. The PLA/rPP blends were characterized by Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), rheometer (MCR-102), scanning electron microscopy(SEM), tensile tests, and impact measurements. The results indicate that the PLA/rPP blend is immiscible and has a two-phase structure. TGA revealed enhancement of the thermal stability of the blends upon addition of rPP. The storage modulus, loss modulus, and complex viscosity of the blends increased with rPP concentration. Mechanical studies showed that introduction of rPP results in a decrease in tensile strength and modulus and enhancement of the impact strength of PLA in the blends. The effects of a silane coupling agent on the morphology and on the tensile and impact properties of the rPP blends of silane-modified PLA were also examined. SEM studies suggest that silane is an effective interfacial modifier. Thus, better interfacial adhesion was observed with silane-modified blends as compared with unmodified blends. Silane also improved the mechanical properties of the modified blends. The blends reached maximum tensile strength at 1.5 wt.% silane (relative to modified PLA content), and impact strength increased with increasing silane concentration. These results confirm the enhancing effect of silane on modified PLA/rPP blends.     

Mechanical Properties and Morphology of Ternary PP/EPDM/PE Blends

The ternary blends of high‐density polyethylene (PE), EPDM terpolymer and polypropylene (PP) have been used as a model low interfacial tension system to study encapsulation dynamics in ternary blends and their relation to the blends' mechanical properties. It was found that the modulus, tensile strength and impact resistance can be improved by PE addition if the PE is localized within the EPDM phase. A range of blend morphology was found depending on the PE viscosity and polymer incorporation sequence in the twin‐screw extruder. In the most favorable sequence, PE and EPDM were mixed together prior to their dispersion in the PP matrix. This practice resulted in a 50% increase in impact resistance when compared to mixing the three components in a single‐step.     

Mechanical and thermal behavior of poly(acrylonitrile-butadiene-styrene)/polycarbonate blends reinforced with potassium titanate whiskers

Poly(acrylonitrile-butadiene-styrene) (ABS)/polycarbonate (PC) blends reinforced with potassium titanate (K₂Ti₆O₁₃) whiskers were prepared in a twin screw extruder followed by injection molding. The whiskers were pretreated with tetrabutyl orthotitanate prior to compounding. The tensile, dynamic mechanical, impact, morphology and thermal properties of the blends were studied. Tensile tests showed that the modulus of ABS/PC/K₂Ti₆O₁₃ blend increased markedly with increasing whisker content. However, the variation of the modulus of ABS/PC/K₂Ti₆O₁₃ blend with PC content followed a sigmoidal relation. In addition, the tensile strength of the blends containing 20 wt% PC tended to increase markedly with increasing whisker content. But the impact strength of the blends containing 20 wt% PC decreased rapidly with increasing whisker content. Dynamic mechanical analyses (DMA) results indicated that the storage modulus of the blends increased markedly with increasing K₂Ti₆O₁₃ whisker content. Differential thermal analysis and thermogravimetric measurements showed that potassium titanate whiskers tend to induce chemical decomposition of PC during blending of the PC/whisker blends. However, the incorporation of ABS into PC was beneficial to reduce the PC decomposition during compounding with the whiskers.