Mechanical and Morphological Properties of Polypropylene and Regenerated Tire-Rubber Blends

Mechanical properties and morphology of blends prepared from polypropylene (PP) and 5–20 wt% of regenerated tire-rubber (RgR) were studied. The samples were prepared in a twin-screw extruder. The addition of maleic anhydride-functionalized polypropylene (PP-g-MAH) was also investigated. Tensile and flexural moduli, tensile strength at break, elongation at break and Izod impact resistance at 23°C were increased by the addition of 15 wt% of regenerated rubber and 5 wt% of PP-g-MAH. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses showed some interaction between PP and RgR and considerable modification of the compatibilized mixture morphology. The fracture surface of the blend with PP-g-MAH showed a better interaction between the PP matrix and the regenerated rubber domains, for all blends. Well-dispersed particles of the rubber in the polypropylene matrix were observed. DSC showed that PP crystallizes on cooling at lower temperatures as the RgR content increases. The decrease in crystallization temperature is more evident for blends with 5 wt% PP-g-MAH.     

Thermal,Mechanical and Rheological Properties of Polypropylene/Poly(ethylene-co-methyl acrylate) Blends

Isotactic polypropylene (PP) has been blended with poly(ethylene-co-methyl acrylate) (EMA) (75/25 wt/wt%) in a single-screw extruder. The compatibilizing effect of polypropylene grafted with maleic anhydride (PP-g-MAH) has been examined. The nonisothermal crystallization of the developed blends has been investigated using differential scanning calorimetry (DSC) and analyzed using Avrami, Tobin and Liu models. The thermal stability of the blends was assessed through thermogravimetric analysis (TGA). The tensile and impact properties, as well as the melt viscosity, have also been determined. The presence of rubber accelerates the crystallization of PP. The thermal stabilities of the blends are intermediate between those of their constituents. Tensile strength and modulus are reduced upon incorporation of EMA into PP, but ultimate elongation and impact strength are improved. The melt viscosity variation with shear rate for all the systems was typical of shear-thinning behavior. The compatibilizing agent has a pronounced effect on enhancing the thermal and mechanical properties of the blend.     

Morphology,thermal and mechanical behavior of polypropylene nanocomposites toughened with poly(ethylene‐co‐octene)

Rubber‐toughened polypropylene (PP) nanocomposites containing organophilic layered silicates were prepared by means of melt extrusion at 230 °C using a co‐rotating twin‐screw extruder in order to examine the influence of the organoclay and the addition of PP grafted with maleic anhydride (PPgMAH) as a compatibilizer on the morphological, mechanical and thermal properties. The mechanical properties of rubber‐toughened polypropylene nanocomposites (RTPPNCs) were studied through tensile, flexural and impact tests. Scanning electron microscopy (SEM) was used for investigation of the phase morphology and rubber particles size. X‐ray diffraction (XRD) was employed to characterize the formation of nanocomposites. The thermal properties were investigated by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dynamic mechanical properties were examined by using dynamic mechanical analysis (DMA). From the tensile and flexural tests, the optimum loading of organoclay in RTPP was found to be 6 wt%. The optimum loading of PPgMAH, based on the tensile and flexural properties, was also 6 wt%. The increase in the organoclay and PPgMAH content resulted in a severe embrittlement, manifested by a drop in the impact strength and tensile elongation at break. XRD studies revealed that intercalated RTPPNCs had been successfully prepared where the macromolecular PP segments were intercalated into the interlayer space of the organoclay. In addition, the organoclay was dispersed more evenly in the RTPPNC as the PPgMAH content increased. TGA results revealed that the thermal stability of the RTPPNC improved significantly with the addition of a small amount of organoclay. Copyright © 2006 Society of Chemical Industry     

Effect of Organomodified Ni-Al Layered Double Hydroxide (OLDH) on the Properties of Polypropylene (PP)/LDH Nanocomposites

This work addresses the effect of organomodified layer double hydroxide (OLDH) on the properties of PP/LDH nanocomposites prepared by melt intercalation method using a single screw extruder with maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer. For this, Ni-Al LDH was first prepared by the co-precipitation method at constant pH using their nitrate salts. The above synthesized pristine LDH was organically modified using sodium dodecyl sulphate (SDS) by the regeneration method. The structural and thermal properties of LDH and PP nanocomposites were performed by X-ray diffraction (XRD), FTIR spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The influence of LDH loading on the mechanical and thermal properties of the nanocomposite was also investigated. The XRD results confirmed the formation of exfoliated PP/LDH nanocomposites. PP/LDH nanocomposites exhibited enhanced thermal stability relative to the pure PP. When 10% weight loss was selected as a point of comparison, the decomposition temperature of PP/LDH (5 wt%) nanocomposite was 15.3°C higher than that of pure PP. The DSC result indicated an increase in crystallization and melting temperature of the PP/LDH nanocomposites compared to pure PP. Overall, the mechanical properties of the PP/LDH nanocomposites increased with an increase in the LDH content. The maximum improvement of tensile strength, Young's modulus, flexural strength, and flexural modulus for the PP/LDH nanocomposite was found to be 11, 22.5, 28, and 22%, respectively, over neat PP. For comparison purposes, a nanocomposite with 5 wt% modified bentonite (PP/B5) was also prepared under the same operating condition and there was no significant improvement in mechanical properties (tensile strength and modulus).     

Preparation and properties of polypropylene‐asphaltene composites

In this study, novel composite materials of polypropylene (PP) with asphaltenes taken from Arab heavy atmospheric residue were prepared and characterized. Composites with various relative amounts of asphaltenes to PP were formed using the melt‐mixing technique. The chemical structure, crystalline form, and morphology of these materials were examined using Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM) measurements. Their thermal properties were measured with differential scanning calorimetry (DSC), their thermal degradation characteristics with thermogravimetric analysis (TGA), and the mechanical properties using an Instron dynamometer. It was found that the crystalline and chemical structure of PP is not affected by the presence of asphaltenes, whereas the thermal stability, crystallinity, and tensile mechanical properties are enhanced with the amount of asphaltenes. Particularly, the addition of 5 wt% asphaltenes could improve tensile strength and the Elastic modulus by almost 10%. Better dispersion is achieved at relative low percentages of asphaltenes. It was found that the optimum amount of asphaltenes to result in composites with good dispersion, enhanced thermal stability, tensile strength, and relative crystallinity was 5 wt%. Most of these properties seem to deteriorate when the amount of asphaltenes added is high (i.e., 10%–15%). Therefore, a new use of a by‐product of the petroleum refinery industry is proposed resulting in improved properties of a commodity polymer. POLYM. COMPOS., 38:1957–1963, 2017. © 2015 Society of Plastics Engineers     

Influence of interfacial adhesion on the structural and mechanical behavior of PP‐banana/glass hybrid composites

Hybrid composites of polypropylene (PP), reinforced with short banana and glass fibers were fabricated using Haake torque rheocord followed by compression molding with and without the presence maleic anhydride grafted polypropylene (MAPP) as a coupling agent. Incorporation of both fibers into PP matrix resulted in increase of tensile strength, flexural strength, and impact strength upto 30 wt% with an optimum strength observed at 2 wt% MAPP treated 15 wt% banana and 15 wt% glass fiber. The rate of water absorption for the hybrid composites was decreased due to the presence of glass fiber and coupling agent. The effect of fiber loading in presence of coupling agent on the dynamic mechanical properties has been analyzed to investigate the interfacial properties. An increase in storage modulus (E′) of the treated‐composite indicates higher stiffness. The loss tangent (tan δ) spectra confirms a strong influence of fiber loading and coupling agent concentration on the α and β relaxation process of PP. The nature of fiber matrix adhesion was examined through scanning electron microscopy (SEM) of the tensile fractured specimen. Thermal measurements were carried out through differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA), indicated an increase in the crystallization temperature and thermal stability of PP with the incorporation of MAPP‐treated banana and glass fiber. POLYM. COMPOS., 31:1247–1257, 2010. © 2009 Society of Plastics Engineers     

Effects of peroxide and gamma radiation on properties of devulcanized rubber/polypropylene/ethylene propylene diene monomer formulation

Mechanical and thermal properties of devulcanized rubber (DR)/polypropylene (PP)/ethylene propylene diene monomer blends (EPDM) were studied at various concentrations of dicumyl peroxide (DCP) and gamma radiation doses. The blends showed improved mechanical properties for vulcanized sample. The coupling of DR/PP/EPDM with different proportions of DCP was investigated by X‐ray diffraction and scanning electron microscopy techniques. Evaluation of the developed blends, unirradiated and gamma irradiated, was carried out using elastic modulus, tensile strength, elongation at break, thermogravimetric analysis, kinetic analysis, and DSC measurements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40611.     

聚丙烯/聚烯烃弹性体共混物的制备与性能研究

通过熔融共混法制备了一系列聚丙烯(PP)/聚烯烃弹性体(POE)共混物,采用热重分析、示差扫描量热分析和拉伸测试对所得样品进行了热性能及力学性能的表征。结果表明,随着POE含量的增加,PP的抗拉强度和断裂伸长率均呈现先增加后减小的趋势。而当POE的含量低于5%时,样品的熔融温度明显低于纯PP的熔融温度;而当其含量超过5%时,样品的熔融温度与纯样基本一致。另外,POE的引入导致PP的热降解温度降低。     

Influence of miscibility on the morphology and properties of polycarbonate/(maleic anhydride)-grafted-polypropylene blend

Maleic-anhydride-grafted polypropylene (MAH-g-PP) was added to polycarbonate (PC) as a processing agent. Its influence on the morphological, thermal, rheological, and mechanical properties of PC/MAH-g-PP blends was investigated by differential scanning calorimetry (DSC), dynamic mechanical spectroscopy (DMS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic contact angle goniometry, and tensile and impact strength experiments. The results indicated that the processability and miscibility of the blends were improved significantly by addition of 5–20 wt% MAH-g-PP to PC. The melting temperature of MAH-g-PP increased as the relative composition of MAH-g-PP in the blends increased mainly because of enlargement of the crystallite size. The DSC, FTIR as well as SEM results strongly suggested that a chemical reaction might have taken place between the PC and MAH-g-PP. This chemical reaction could have contributed to the improvement of the mechanical properties of the blends and the miscibility between the PC and MAH-g-PP components.     

Compatibilizing effect of maleated polypropylene on the mechanical properties and morphology of injection molded polyamide 6/polypropylene/organoclay nanocomposites

Polyamide 6/polypropylene (PA6/PP=70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic modified montmorillonite (organoclay) were prepared using twin screw extruder followed by injection molding. Maleated polypropylene (MAH-g-PP) was used to compatibilize the blend system. The mechanical properties of PA6/PP nanocomposites were studied through tensile and flexural tests. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to assess the fracture surface morphology and the dispersion of the organoclay, respectively. X-ray diffraction (XRD) was used to characterize the formation of nanocomposites. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The dynamic mechanical properties of PA6/PP nanocomposites were analyzed by using dynamic mechanical thermal analyzer (DMTA). The strength and stiffness of PA6/PP nanocomposites were improved significantly in the presence of MAH-g-PP. This has been attributed to the synergistic effect of organoclay and MAH-g-PP. The MAH-g-PP compatibilized PA6/PP nanocomposites showed a homogeneous morphology supporting the compatibility improvement between PA6, PP and organoclay. TEM and XRD results revealed the formation of nanocomposites as the organoclay was intercalated and exfoliated. A possible chemical interaction between PA6, PP, organophilic modified montmorillonite and MAH-g-PP was proposed based on the experimental work.     

Melt blending of poly(ethylene terephthalate) with polypropylene in the presence of silane coupling agent

A silane coupling agent (SCA) was used as a compatibilizer for polypropylene–poly(ethylene teraphthalate) (PP–PET) blends with 20, 40, 50, and 60% PET compositions by weight. PP–PET mixtures were blended with and without an SCA by a single‐screw extruder. The effect of silane modification on the tensile and impact properties of the blends was investigated. The morphology and thermal behavior of the blends were examined with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The presence of the SCA used in this work extensively improved the mechanical properties of the blends. Mechanical properties were found to be highly dependent on the numbers of extrusions. SEM studies showed that substantially different morphology with better adhesion existed when SCA‐treated blends were compared to nontreated PP–PET blends. The presence of individual melting temperatures of the polymers in all compositions with no significant T_m depression indicated that PET and PP were crystallized separately. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1039–1048, 2003     

Studies on the curing behavior,thermal, and mechanical properties of epoxy resin-co-amine-functionalized lead phthalocyanine

A high performance copolymer was prepared by using epoxy (EP) resin as matrix and 3,10,17,24-tetra-aminoethoxy lead phthalocyanine (APbPc) as additive with dicyandiamide as curing agent. Fourier-transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetric analysis (DSC), and thermogravimetric analysis (TGA) were used to study the curing behavior, curing kinetics, dynamic mechanical properties, impact and tensile strength, and thermal stability of EP/APbPc blends. The experimental results show that APbPc, as a synergistic curing agent, can effectively reduce the curing temperature of epoxy resin. The curing kinetics of the copolymer was investigated by non-isothermal DSC to determine kinetic data and measurement of the activation energy. DMA, impact, and tensile strength tests proved that phthalocyanine can significantly improve the toughness and stiffness of epoxy resin. Highest values were seen on the 20 wt% loading of APbPc in the copolymers, energy storage modulus, and impact strength increased respectively 388.46 MPa and 3.6 kJ/m², T_g decreased 19.46°C. TGA curves indicated that the cured copolymers also exhibit excellent thermal properties.     

Mechanical and thermal properties of poly(butylene succinate)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) biodegradable blends

Biodegradable polymer blends of poly(butylene succinate) (PBS) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) were prepared with different compositions. The mechanical properties of the blends were studied through tensile testing and dynamic mechanical thermal analysis. The dependence of the elastic modulus and strength data on the blend composition was modeled on the basis of the equivalent box model. The fitting parameters indicated complete immiscibility between PBS and PHBV and a moderate adhesion level between them. The immiscibility of the parent phases was also evidenced by scanning electron observation of the prepared blends. The thermal properties of the blends were studied through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC results showed an enhancement of the crystallization behavior of PBS after it was blended with PHBV, whereas the thermal stability of PBS was reduced in the blends, as shown by the TGA thermograms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42815.     

Thermo-mechanical properties of devulcanized rubber/high crystalline polypropylene blends modified by ionizing radiation

Ground tire rubber (GRT) poses a challenging environmental, economical, and disposal problem in the world because of their crosslinked three-dimensional network structure. Waste rubber from end-of-life passenger car tires was successfully devulcanized by using mechanical–chemical process. The coupling of DR with PP in different proportion was investigated by FTIR, X-ray diffraction and SEM techniques. The mechanical and thermal behaviors of the blends composed of devulcanized rubber (DR) and high crystalline polypropylene (PP) in different proportions were studied. Evaluation of the mechanical and thermal properties of the developed blends, unirradiated and gamma irradiated, was carried out using tensile strength (Ts), elongation at break (E_b), hardness, TGA and DSC measurements.     

Experimental investigation of the effects of a compatibilizing agent on the properties of a recycled poly(ethylene terephthalate)/polypropylene blend

This study deals with the behavior of a recycled polyethylene terephthalate (PET)/polypropylene (PP) blends. The compatibilizing effect has been investigated to examine the recycling feasibility in industrial production. The compatibilizing efficiency of olefinic copolymers containing epoxy groups for a/polypropylene (PET/PP) blends was examined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), mechanical testing and rheological one. The effect of ethylene-glycidyl methacrylate (E-GMA, 92/8 wt%, Lotader AX8840) and ethylene–methyl acrylate-glycidyl methacrylate (E-MA-GMA, 68/24/8 wt%, Lotader AX8900) copolymers was investigated. The blends of PET/PP/compatibilizer at compositions 80/15/5, 85/11.25/3.75, 90/7.5/2.5 and 95/3.75/1.25 (wt%) were prepared by melt mixing in a single-screw extruder. Test specimens were prepared by compression moulding at processing temperatures of 250 °C. The incorporation of the compatibilizers has a large effect on the dispersion of the PP phase. Moreover, the copolymer was more efficient than the terpolymer. Especially, E-GMA was found to improve the elongation at break of the blends containing 80 % PET.     

Studies on morphology,mechanical, thermal,and rheological behavior of extrusion‐blended polypropylene and thermotropic liquid crystalline polymer

Polypropylene (PP) was melt‐blended in a single‐screw extruder with a thermotropic Vectra B‐950 liquid crystalline polymer (LCP) in different proportions. The mechanical properties of such blends were compared in respect of their Young's moduli, ultimate tensile strength (UTS), percent elongation at break, and toughness to those of pure PP. The thermal properties of these blends were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The morphology was studied by using a polarizing light microscope (PLM) and a scanning electron microscope (SEM) while the rheological aspects of the blends and the pure PP were studied by a Haake Rheowin equipment. Mechanical analysis (tensile properties) of the blends showed pronounced improvement in the moduli and the UTS of the PP matrix in the presence of 2–10% of LCP incorporation. TGA of all the blends showed an increase in the thermal stability for all the blends with respect to the matrix polymer PP, even at a temperature of 410°C, while PP itself undergoes drastic degradation at this temperature. DSC studies indicated an increase in the softening range of the blends over that of PP. Morphological studies showed limited mixing and elongated fibril formation by the dispersed LCP phase within the base matrix (PP) at the lower ranges of LCP incorporation while exhibiting a tendency to undergo gross phase separation at higher concentrations of LCP, which forms mostly agglomerated fibrils and large droplets. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 767–774, 2003     

Compatibilization by main‐chain thermotropic liquid crystalline ionomer of blends of PBT/PP

The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEM and optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends. The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1% LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1110–1117, 2002     

Mechanical,Thermal and Morphological Characterization of High-Density Polyethylene and Vermiculate Composites

High-density polyethylene composites containing 7, 10, 15 and 20% w/w vermiculite (VMT) were prepared by extrusion in a twin-screw extruder at various shear rates. The thermal and mechanical properties and morphological characteristics of the composites were evaluated and compared with pure high-density polyethylene. The blend morphologies were determined by scanning electron microscopy (SEM). The thermal properties of the composites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The TGA results reveal that the use of VMT particles to fill polyethylene increased the thermal stability of the composite. The results obtained indicate that a shear speed of 400 rpm and vermiculite content of 7% showed the best properties of impact resistance. These observations were confirmed by morphology analysis.     

Studies on the engineering properties of LCP‐Vectra B 950/PP blends with the variations of EAA content

Polypropylene (PP) was melt blended with Vectra B‐950 [a thermotropic liquid crystalline polymer (LCP)], in a single screw extruder in presence of different doses of ethylene acrylic acid (EAA) copolymer, as modifier. The effect of incorporation in different proportions of EAA at a fixed dose of 5% LCP, on mechanical, thermal, morphological, and rheological properties of such blends was studied and the same were compared with that of pure PP and amongst themselves. Mechanical analysis (tensile properties) of the prepared blends exhibited improvements in ultimate tensile strength (UTS), modulus, toughness, hardness, and impact strength of PP matrix with the incorporation of EAA. The improvement in mechanical properties is associated with the formation of LCP fibrils as evidenced by scanning electron microscopy (SEM). A strong interaction through H‐bonding between the segments of Vectra B‐950 and EAA was established by FTIR study. Differential scanning calorimetry (DSC) studies indicated substantial increase in melting point of the blends, and thermogravimetric analysis (TGA) showed that the thermal stability of PP was improved with the addition of LCP and EAA. Rheological properties showed that LCP and EAA drop down the melt viscosity of PP and thus facilitate processibility of blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of zinc borate and microcapsulated red phosphorus on mechanical properties and flame retardancy of polypropylene/magnesium hydroxide composites

In this paper, the mechanical properties and flame retardancy of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) in flame-retardant polypropylene (PP) were studied by mechanical properties test, UL-94 test, and thermogravimetric analysis (TGA). The crystallization behaviors of the composites were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The addition of ZB could improve tensile strength and elongation at break of PP/MH composite. The MRP powders had a little effect on the mechanical properties of the PP composites. DSC results showed the addition of ZB and MRP weakened the heterogeneous nucleation effect of MH on PP. The addition of ZB and MRP had a great effect on the flammability of the PP/MH/EG composites. The thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites was better than that of PP/MH composite.