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1.
    
The objective of this study is to investigate the effect of low density polyethylene (LDPE) content in linear low density polyethylene (LLDPE) on the crystallinity and strain hardening of LDPE / LLDPE blends. Three different linear low density polyethylenes (LL‐1, LL‐2 and LL‐3) and low density polyethylenes (LD‐1, LD‐2 and LD‐3) were investigated. Eight blends of LL‐1 with 10, 20, 30 and 70 wt % of LD‐1 and LD‐3, respectively, were prepared using a single screw extruder. The elongational behavior of the blends and their constituents were measured at 150°C using an RME rheometer. For the blends of LL‐1 with LD‐1, the low shear rate viscosity indicated a synergistic effect over the whole range of concentrations, whereas for the blends of LL‐1 with LD‐3, a different behavior was observed. For the elongational viscosity behavior, no significant differences were observed for the strain hardening of the 10–30% LDPE blends. Thermal analysis indicated that at concentrations up to 20%, LDPE does not significantly affect the melting and crystallization temperatures of LLDPE blends. In conclusion, the crystallinity and rheological results indicate that 10–20% LDPE is sufficient to provide improved strain hardening in LLDPE. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3070–3077, 2003  相似文献   

2.
    
An experimental study was carried out to investigate the effects of a titanate coupling agent on the mechanical properties, moisture absorption, and thermal conductivity of talc‐filled high‐density polyethylene (HDPE). Talc (0–35 wt %) was used as reinforcement particulate filler in an HDPE matrix and samples were prepared in a micro‐compounder and an injection molding machine. Isopropyl tri(dioctyl)phosphate titanate (0.5 wt %) was used as coupling agent. Composites with and without coupling agent were evaluated for changes in mechanical and thermo‐physical properties, morphology, and void content. Addition of the titanate coupling agent most often resulted in an increase in stiffness and tensile strength. Furthermore, both the void content and the elongation at break of composites were reduced. Results also showed that the coupling agent had no effects on the thermal conductivity, thermal diffusivity, and specific heat capacity of the composites. In addition, it was observed that the coupling agent was more effective at low concentrations of filler. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40449.  相似文献   

3.
    
The influence of octakis(n‐hexadecyldimethylsiloxy)octasilsesquioxane (hdPOSS) on rheological and thermal properties of linear low‐density polyethylene was investigated. Rheological evaluations realized by two different measuring techniques (rotational and extensional rheometry) allowed to obtain a wide range of information concerning an influence of silsesquioxanes on rheological properties of polymeric matrix. The studies were complemented with Differential Scanning Calorimetry measurements. In order to evaluate the miscibility of thermoplastic matrix and hybrid organic‐inorganic nanosized filler, rheological investigations, Dynamic Mechanical Thermal Analysis and Scanning Electron Microscopy were applied. Simultaneously, based on the rheological and thermal investigations, the mechanism of interactions between polymeric matrix and silsesquioxanes was considered. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42825.  相似文献   

4.
    
Three polypropylene‐g‐polystyrene (PP‐g‐PS) graft copolymers with the same branch density but different branch lengths were evaluated as compatibilizing agents for PP/PS blends. The morphological and rheological results revealed that the addition of PP‐g‐PS graft copolymers significantly reduced the PS particle size and enhanced the interfacial adhesion between PP and PS phases. Furthermore, it is verified that the branch length of PP‐g‐PS graft copolymer had opposite effects on its compatibilizing effect: on one hand, increasing the branch length could improve the compatibilizing effect of graft copolymer on PP/PS blends, demonstrated by the reduction of PS particle size and the enhancement of interfacial adhesion; on the other hand, increasing the branch length would increase the melt viscosity of PP‐g‐PS graft copolymer, which prevented it from migrating effectively to the interface of blend components. Additionally, the crystallization and melting behaviors of PP and PP/PS blends were compared. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40126.  相似文献   

5.
    
Following many years of studies on polyethylene blends, several indirect classical experimental methods (DSC, XRD, DMA, cryogen fracture surface using SEM, and Rheological Test in Oscillatory Flow) have been used to evaluate the compatibility between polyethylene blends. Here a study of a high-density polyethylene (HDPE)—ultrahigh molecular weight polyethylene (UHMWPE) system, which evidences that the compatibility of mixtures using these experimental methods does not assure good mechanical performance of the blends. In addition, the potential that these blends can perform mechanically may be overestimated. Based on the theory of healing at a polymer-polymer interface, it was shown that the maximum mechanical performance of the HDPE-UHMWPE blend can be obtained for long time molecular diffusion when the mixtures equilibrium (maximum mixing degree) at the HDPE-UHMWPE interphase is achieved. The degree of mixture at the HDPE-UHMWPE interphase was assessed indirectly by the deformation mechanism that each phase and the interphase plays during the tensile test (at solid state). The advances reported in this paper can contribute to understanding the mechanical performance of different systems formed by compatible polyethylene blends.  相似文献   

6.
    
This article reports, for the first time, on how the kinetics and thermodynamics of the melt‐processing control the nano/micro‐structure development and properties of nanoclay‐filled polypropylene (PP)/low‐density polyethylene (LDPE) blend ternary composites. Morphological characterization suggests that the nano/micro‐structure of the PP/LDPE (80/20) blend can be controlled by incorporating nanoclay alone or by adding a mixture of organoclay and maleated compatibilizers. Simultaneous mixing of PP, LDPE, maleated compatibilizers, and organoclay results in homogeneous distribution of intercalated silicate layers in all the phases of the blend, a feature which profoundly affects the thermal stability and tensile and rheological properties of the blend composites. For example, the elongation‐at‐break for PP increases from 28.1 to 155.6% for composite containing both organoclay and maleated compatibilizers, whereas the thermal stability for PP increases from 269.8 to 303.3 °C for the same composite. However, the impact strength of the PP/LDPE blend decreases with incorporation of organoclay, regardless of the phase in which the nanoclay particles are localized. In summary, the obtained results show that regardless of the phase in which the nanoclay is localized, the morphology, and hence the properties, of the ternary composites are superior to those of the neat blend. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46193.  相似文献   

7.
    
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8.
    
The aim of this study was to examine the physical, mechanical, and thermo‐physical properties of high‐density polyethylene (HDPE) modified with talc. Different weight fractions of talc (up to 35 wt %) were compounded with an HDPE matrix containing 2.5 wt % of carbon black (CB) in a twin‐screw compounder. The composites were then processed by injection moulding to obtain specimens for testing. The results indicate that CB causes a significant decrease in the toughness, while talc not only enhances the thermal conductivity and thermo‐physical properties of the composites but can also play a role in compensating for the negative effects of CB on impact resistance. The experimental data show that the presence of CB reduces the impact resistance of HDPE by up to 34%, while addition of up to 8 wt % talc can return this value to close to that of pure HDPE. No significant effect on the composite tensile yield and fracture strength was observed for either component at all concentrations. The thermal conductivity, thermal diffusivity, and specific density values of the composites increased almost linearly, but the increase in moisture absorption in the long term showed nonlinear behavior in the concentration range of the experiment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

9.
    
The effects of compatibilizer on the morphological, thermal, mechanical, and rheological properties of poly(methyl methacrylate) (PMMA)/poly(N‐methyl methacrylimide) (PMMI) (70/30) blends were investigated. The compatibilizer used in this study was styrene–acrylonitrile–glycidyl methacrylate (SAN‐GMA) copolymer. Morphological characterization of the PMMA/PMMI (70/30) blend with SAN‐GMA showed a decrease in PMMI droplet size with an increase in SAN‐GMA. The glass‐transition temperature of the PMMA‐rich phase became higher when SAN‐GMA was added up to 5 parts per hundred resin by weight (phr). The flexural and tensile strengths of the PMMA/PMMI (70/30) blend increased with the addition of SAN‐GMA up to 5 phr. The complex viscosity of the PMMA/PMMI (70/30) blends increased when SAN‐GMA was added up to 5 phr, which implies an increase in compatibility between the PMMA and PMMI components. From the weighted relaxation spectrum, which was obtained from the storage modulus and loss modulus, the interfacial tension of the PMMA/PMMI (70/30) blend was calculated using the Palierne emulsion model and the Choi‐Schowalter model. The results of the morphological, thermal, mechanical, and rheological studies and the values of the interfacial tension of the PMMA/PMMI (70/30) blends suggest that the optimum compatibilizer concentration of SAN‐GMA is 5 phr. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43856.  相似文献   

10.
    
This paper reports an investigation of asynchronous flow marks on the surface of injection molded parts and short shots made from two different blends of polypropylene and ethylene–propylene random copolymer elastomers. Flow marks were observed on the surface with both blends; the spatial frequency of flow marks on the surface was greater in the blend B1, which also exhibited a greater contrast between the surface regions. The same blend was distinctly faster in the linear viscoelastic tests of shear creep recovery and shear viscosity growth. The degree of contrast between the flow‐mark regions and the out‐of‐flow‐mark regions was examined with a detailed analysis of SEM micrographs of the surface regions as well as the near wall regions from short shots. This revealed that the dispersed phase was highly stretched to cylindrical strands in the glossy surface regions of both blends and retracted in the dull regions to different extents in the two cases. A comparison of the particle size distributions and aspect ratio distributions in different regions established that rapid retraction of the suspended elastomer phase was the dominant cause of changes in particle shape between surface regions. Nonlinear shear creep and creep recovery curves of the two elastomer components showed that at a time of 1 s, the fractional strain recovery of the elastomer in B1 was much higher than that of the elastomer in B2. Hence, the nonlinear elastic recovery of the elastomer phase at short times is an important factor in flow mark formation with blends of polypropylene and olefinic elastomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 423–434, 2005  相似文献   

11.
    
We investigated the possibility of using PP as an encapsulant in a photovoltaic module. PP is inexpensive but shows low adhesion strength to glass (and silicon wafer) due to its nonpolar nature as well as opacity due to its crystalline nature. We resolved these problems by employing metallocene catalyzed ethylene‐propylene copolymer (EPR) and a nucleating agent to increase the transparency. Five EPRs having various propylene/ethylene ratios were investigated. EPRs having higher propylene content showed higher adhesion strength to the glass substrate. However, it is not appropriate to use EPRs with higher propylene content because they show low processability in calendaring processing. We therefore used a blend of two EPRs. The blend of the two EPRs showed somewhat low transparency. When the nucleating agent was incorporated in the blend, the transparency was remarkably increased. The adhesion strength to the glass plate was enhanced by a silane coupling agent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43464.  相似文献   

12.
    
Emulsion‐polymerized copolymers of methyl methacrylate and N‐cyclohexylmaleimide were synthesized and used for blending with poly(vinyl chloride) (PVC) to improve the heat resistance of PVC. The thermal stabilities of the blends with different copolymer contents were characterized by thermogravimetric analysis, torsional braid analysis, and the Vicat softening temperature. The mechanical properties and rheological behavior of the blends were also determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 201–205, 2003  相似文献   

13.
    
The solid equal channel angular extrusion (ECAE) process on polypropylene (PP)/high‐density polyethylene (HDPE) blends was carried out. Scanning electron microscopy (SEM) was used to observe the sample structures. Results showed that ECAE process could make PP/HDPE blends to produce orientation structure. Impact performance of ECAE‐PP/HDPE samples after ECAE process improved remarkably, especially for ECAE‐PP/HDPE (90/10)‐O whose impact strength reached 91.91 kJ/m2, 18.1 times higher than that of pure PP and 11.2 times higher than that of PP/HDPE (90/10). The mechanism of enhancing between HDPE and PP was discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39759.  相似文献   

14.
    
The rheological properties of blends consisting of a long chain branched low‐density polyethylene (LDPE) and two linear low‐density polyethylenes (LLDPE) are studied in detail. The weight fractions of the LDPE used in the blends are 5 and 15%. The linear viscoelastic characterization is performed at different temperatures for all the blends to check thermorheological behavior and miscibility in the melt state. Blends containing metallocene LLDPE as the matrix display thermorheologically complex behavior and show evidences of immiscibility in the melt state. The linear viscoelastic response exhibits the typical additional relaxation ascribed to the form deformation mechanism of dispersed phase droplets (LDPE). The Palierne model satisfactorily describes the behavior of these blends in the whole frequency range explored. However, those blends with Ziegler‐Natta LLDPE as the matrix fulfill the time‐temperature superposition, but exhibit a broad linear viscoelastic response, further than the expected for an immiscible system with a sharp interface. The rheological analysis reveals that, in addition to the droplets form relaxation, another mechanism at lower frequencies exists. The broad linear response of the blends with the Ziegler‐Natta LLDPE can be explained by hypothesizing a strong interaction between the high molecular weight linear fraction of the LLDPE and the low molecular weight (almost linear) chains of the LDPE phase, forming a thick interface with its own viscoelastic properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

15.
    
Polylactide (PLA)/linear low‐density polyethylene (LLDPE), (PLA/LLDPE), blends and nanocomposites were prepared by melt mixing process with a view to fine tune the properties. Two different commercial‐grade nanoclays, Cloisite® 30B (30B) and Cloisite® 15A (15A) were used. A terpolymer of ethylene, butylacrylate (BA) and glycidylmethacrylate (GMA) was used as a reactive compatibilizer. The influence of type of clay on the morphology and mechanical properties of two PLA‐rich and LLDPE‐rich blend systems was studied. Morphological analysis using X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy revealed that the organoclay layers were dispersed largely at the interface of PLA/LLDPE. Decreasing the PLA content changed the morphology from droplet‐in matrix to coarse co‐continuous. In comparison with 30B, due to less affinity of 15A towards compatibilizer and PLA phase, the reduction of the size of dispersed phase was less than that of the equivalent 30B composites. The mechanical results demonstrated that the composites containing both types of organoclay exhibited higher modulus but lower elongation and tensile strength as compared to the neat blends. The injection molded nanocomposites were shown to have the sequential fracture behavior during tensile test. The tensile testing results on the neat blends and nanocomposites showed significant increase in elongation at break and decrease in the modulus as compared with the neat PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 749‐758, 2013  相似文献   

16.
    
The relation between composition and mechanical performance of a series of binary polyolefin blends was studied in this article. A fractionation of these model compounds with temperature rising elution fractionation (TREF) was applied to study the possibility to fractionate industrially relevant heterophasic polyolefin systems. The separation quality according to molecular structures or chemical composition was found to be good for most of the systems, but especially the separation of ethylene‐propylene random copolymer and high density polyethylene by TREF turned out to be difficult if not impossible. An extensive mechanical characterisation including the determination of brittle‐to‐ductile transition curves showed significant effects of modifier type and amount. Toughness effects can be related primarily to the modulus differences between modifier and matrix. Compatibility and particle size only have a secondary influence, but must be considered for a detailed interpretation of the mechanics of the investigated systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

17.
    
An approach for fabrication of microfiltration membranes by solvent extraction of one of the immiscible components from a polymer blend was developed. Poly(4‐methyl‐1‐pentene) (PMP) was the membrane material, and poly(isobutylene) (PIB) was the extractable component. The PIB content varied in the wide range 0–45 wt%, and all blends could be melted and processed at a temperature of 240 °C. A rheological study demonstrated a pronounced non‐Newtonian behavior of PMP/PIB blends and their very low viscosity due to interlayer slip. With a PMP content of 55 and 60 wt%, it was possible to fabricate microfiltration membranes with a water permeability of 31 and 3.7 m3 m?2 h–1 bar–1, respectively. The microfiltration membranes based on both compositions demonstrated good rejection performance at the level of 93%–98% for submicron particles of phthalocyanine dye with a size of 240 nm. These results indicate that the PMP/PIB system can be utilized for fabrication of filtration membranes by means of 3D printing followed by solvent extraction. © 2019 Society of Chemical Industry  相似文献   

18.
    
Linear-viscoelastic characteristics and performance are evaluated throughout the blending process of polyethylene and polypropylene with bitumen. Results indicate that type, form and percentage of polyolefin play a significant role in the time evolution of the composite's mechanical response. Toluene extraction of modified bitumen revealed, for the first time, the formation of a sponge-like polymer network. Visual inspection and Fourier transform infrared analysis of the polyolefins recovered after extraction indicates higher affinity of the polyethylene with bitumen in agreement with the rheological test results. The use of polypropylene is discouraged if rutting performance is a concern, and polyethylene in both pellets and powder form at 4%, and after 210 min of blending produces a modified bitumen with acceptable performance.  相似文献   

19.
    
Summary: Blends of single‐site catalysed ethylene‐α‐butene (C4VLDPE) and ethylene‐α‐octene (C8VLDPE) copolymers were prepared by melt extrusion. The phase morphology, thermal and mechanical properties of the blends have been investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile test and dynamic mechanical analysis (DMA). Depending on the composition and thermal history, significant differences in structure and behaviour were found. It was also found that some degree of co‐crystallization occurred for quenched blends; whereas most of the oven slowly cooled blends showed two well‐defined melting peaks, indicating that the slow cooling favoured partial segregation of the fractions with different degrees of branching to form two morphologies. Moreover, SEM revealed morphology of the thinner crystals distributed in‐between the thicker sheaf‐like crystals for the slowly cooled blends with 20–50% C8VLDPE. Therefore, the synergism in mechanical properties for the blends with 20–50% C8VLDPE is due to a combination of larger crystal size, more complete phase separation and interfacial interaction produced by the segregation effect of the slow cooling treatment. DMA studies showed that the storage modulus increased as the addition of C8VLDPE and modulus for the slowly cooled blends are about twice those measured for the quenched ones, indicating higher stiffness of the blends. The smooth shift of β relaxation temperature with addition of C8VLDPE for both sets of blends confirmed the miscibility in the amorphous phase.

SEM image of the C4VLDPE‐C8VLDPE (50/50) blend after oven slow cooling treatment.  相似文献   


20.
    
In this study, the crystallization behavior of the β‐isotactic polypropylene (β‐iPP) samples nucleated by a rare earth based β‐nucleating agent (β‐NA) WBG‐II and a metal salts compound β‐NA NAB83 (denoted as WPP and NPP, respectively) under different cooling conditions were comparatively investigated. The thermal conditions such as the cooling rate, isothermal crystallization temperature, isothermal crystallization time, and the subsequent cooling to room temperature. The results of WAXD, SEM, and nonisothermal crystallization reveal that under the same processing conditions, the crystallite size of NPP is smaller, which arrange more compactly as compared with WPP. Meanwhile, NPP has shorter crystallization rate and higher β‐nucleation selectivity, but WPP can crystallization at wider temperature range. The results of isothermal crystallization showed that NPP has higher selectivity and higher β‐nucleation efficiency, which favors the formation of high proportion of β‐phase at the isothermal crystallization temperature of 110–130°C with and without subsequent cooling; WPP has lower selectivity, which can only induce high content of β‐phase under isothermal crystallization without subsequent cooling to 25°C. In tuning the crystallization behavior and the properties of β‐PP, the joint influence of the efficiency and selectivity of the β‐NA, and the thermal conditions should be taken into consideration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40115.  相似文献   

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