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Melt Blending (melt + blending)
Selected AbstractsDistributive mixing profiles for co-rotating twin-screw extrudersADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Gifford Shearer Distributive mixing was experimentally measured during polymer melt blending along the length of a co-rotating twin-screw extruder. A mixing limited interfacial reaction between two reactive polymer tracers was employed to gain direct evidence of the generation of interfacial area. Model reactions were performed to validate this novel experimental method. In particular, the conversion was a direct indicator of the interfacial area available for the reaction. Specially designed sampling ports were used to obtain polymer samples along the length of the extruder during its continuous operation. The mixing capabilities of conveying sections and kneading blocks were compared over a wide range of operating conditions. In conveying sections, distributive mixing was controlled by the fully filled fraction. The mixing in kneading blocks depended on the combination of the operating conditions and the stagger angle. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 169,190, 2001 [source] Influence of processing conditions and physicochemical interactions on morphology and fracture behavior of a clay/thermoplastic/thermosetting ternary blendJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010M. Hernandez Abstract This study provides information on the mechanical behavior of epoxy-poly(methyl methacrylate) (PMMA)-clay ternary composites, which have been prepared using the phase separation phenomenon of PMMA and the introduction of organophilic-modified montmorillonites (MMTs), the continuous matrix being the epoxy network. Two dispersion processing methods are used: a melt processing without any solvent and an ultrasonic technique with solvent and a high-speed stirrer. TEM analysis shows that phase separation between PMMA and the epoxy network was obtained in the shape of spherical nodules in the presence of the clay in both process methods used. Nanoclay particles were finely dispersed inside thermosetting matrix predominantly delaminated when ultrasonic blending was used; whereas micrometer-sized aggregates were formed when melt blending was used. The mechanical behavior of the ternary nanocomposites was characterized using three-point bending test, dynamic mechanical analysis (DMA), and linear elastic fracture mechanics. The corresponding fracture surfaces were examined by scanning electron microscopy to identify the relevant fracture mechanisms involved. It was evidenced that the better dispersion does not give the highest toughness because ternary nanocomposites obtained by melt blending present the highest fracture parameters (KIc). Some remaining disordered clay tactoids seem necessary to promote some specific toughening mechanisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effects of addition of acrylic compatibilizer on the morphology and mechanical behavior of amorphous polyamide/SAN blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010D. Becker Abstract Amorphous polyamide (aPA)/acrylonitrile-styrene copolymer (SAN) blends were prepared using methyl methacrylate-maleic anhydride copolymer MMA-MA as compatibilizer. The aPA/SAN blends can be considered as a less complex version of the aPA/ABS (acrylonitrilebutadiene-styrene) blends, due to the absence of the ABS rubber phase in the SAN material. It is known that acrylic copolymer might be miscible with SAN, whereas the maleic anhydride groups from MMA-MA can react in situ with the amine end groups of aPA during melt blending. As a result, it is possible the in situ formation of aPA-g-MMA-MA grafted copolymers at the aPA/SAN interface during the melt processing of the blends. In this study, the MA content in the MMA-MA copolymer and its molecular weight was varied independently and their effects on the blend morphology and stress,strain behavior were evaluated. The morphology of the blends aPA/SAN showed a minimum in the SAN particle size at low amounts of MA in the compatibilizer, however, as the MA content in the MMA-MA copolymer was increased larger SAN particle sizes were observed in the systems. In addition, higher MA content in the compatibilizer lead to less ductile aPA/SAN blends under tensile testing. The results shown the viscosity ratio also plays a very important role in the morphology formation and consequently on the properties of the aPA/SAN blends studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polyamide 6/maleated ethylene,propylene,diene rubber/organoclay composites with or without glycidyl methacrylate as a compatibilizerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Lingyan Zhang Abstract Polyamide 6 (PA6)/maleated ethylene,propylene,diene rubber (EPDM- g -MA)/organoclay (OMMT) composites were melt-compounded through two blending sequences. Glycidyl methacrylate (GMA) was used as a compatibilizer for the ternary composites. The composite prepared through via the premixing of PA6 with OMMT and then further melt blending with EPDM- g -MA exhibited higher impact strength than the composite prepared through the simultaneous blending of all the components. However, satisfactorily balanced mechanical properties could be achieved by the addition of GMA through a one-step blending sequence. The addition of GMA improved the compatibility between PA6 and EPDM- g -MA, and this was due to the reactions between PA6, EPDM- g -MA, and GMA, as proved by Fourier transform infrared analysis and solubility (Molau) testing. In addition, OMMT acted as a compatibilizer for PA6/EPDM- g -MA blends at low contents, but it weakened the interfacial interactions between PA6 and EPDM- g -MA at high contents. Both OMMT and GMA retarded the crystallization of PA6. The complex viscosity, storage modulus, and loss modulus of the composites were obviously affected by the addition of OMMT and GMA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Melt amination of polypropylenesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2005Q.-W. Lu Abstract Amine (primary and secondary) functional polypropylenes were prepared by the melt blending of maleated polypropylenes with small diamines, including hexamethylenediamine (primary,primary diamine), p -xylylenediamine (primary,primary diamine), and N -hexylethylenediamine (primary,secondary diamine), at various diamine/anhydride molar ratios in a batch mixer and a twin-screw extruder. The experimental conversion data by Fourier transform infrared nearly agreed with the assumption of a complete reaction between the primary amine and anhydride. Chain extensions of the maleated polypropylenes by the diamines were monitored by the torques during mixing and further evaluated by rheological (dynamic shear rheometry) and mechanical measurements. We show that these amino polypropylenes are very effective adhesion promoters and compatibilizers of thermoplastic polyurethanes with polypropylene. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4217,4232, 2005 [source] Use of PP Grafted with Itaconic Acid as a New Compatibilizer for PP/Clay NanocompositesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2006Edwin Moncada Abstract Summary: Functionalized PP samples with different percentages of grafted IA, i.e., 0.7, 1 or 1.8 wt.-%, with similar molecular weights were used as compatibilizers in PP/clay nanocomposites. PP nanocomposites containing 1 wt.-% of organically modified clays, i.e., montmorillonite, natural hectorite and synthetic hectorite and 3 wt.-% of grafted PP with three different percentages of grafted IA as compatibilizers and two commercial PP samples of different molecular weights were prepared by melt blending. The nanocomposites were characterized by XRD, TEM and tensile mechanical measurements. It was found that the molecular weight of PP used as matrix as well as the percentage of grafted IA of the compatibilizer affected the degree of intercalation/exfoliation of the clay and consequently the mechanical properties of the nanocomposites. Values of 2,137 MPa for the modulus and 51 MPa for the tensile strength were obtained when natural hectorite was used and 2,117 and 40 MPa were obtained when montmorillonite was used. A comparative study was carried out, where PP grafted with maleic anhydride was used as the compatibilizer. Inferior mechanical properties were obtained for nanocomposites prepared by using this compatibilizer, where values of 1,607 MPa for the tensile modulus and 43 MPa for tensile strength were obtained. This result indicated that IA-grafted PP was far more efficient as compatibilizer for the formation of nanocomposites than commercially available maleic anhydride-grafted PP. Model showing interaction of the organically modified clay with grafted PP used as compatibilizer. [source] Organoclay Nanocomposites from Ethylene,Acrylic Acid CopolymersMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006Sara Filippi Abstract Summary: A study of the structure,property relationships for nanocomposites prepared by melt compounding from ethylene,acrylic acid copolymers of varied composition and molecular architecture, and organoclays modified with different ammonium ions has been made by DSC, POM, SEM, TEM, WAXD, and rheological and mechanical tests. Within the series of clays investigated, the best levels of dispersion were displayed by those organically modified with quaternary ammonium ions containing two long alkyl tails. The relevant nanocomposites were shown to possess mixed exfoliated and intercalated morphology. The spacing of the intercalated clay stacks, most of which comprise few silicate layers, was found to be independent of clay loading, in the range of 2,50 phr, and to change with the molecular architecture of the matrix polymer. An indication that the excess surfactant present in some of the clays, and the organic material added in others to expand the interlayer spacing, were expelled from the clay galleries during melt blending and acted as plasticisers for the matrix polymer, was obtained from WAXD and rheological characterisations. TEM micrograph of the nanocomposite of EAA1 with 11 phr of 15A. [source] Preparation of Clay/PMMA Nanocomposites with Intercalated or Exfoliated Structure for Bone Cement SynthesisMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2006Jyh-Horng Wang Abstract Summary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter-lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (Td) and glass transition temperature (Tg) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35,°C, of the thermal stability (Td) with respect to pure PMMA were achieved for many of the composite samples. The Tg of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery. TEM images of an OA-clay/PMMA composite. [source] Dynamic mechanical study of clay dispersion in maleated polypropylene/organoclay nanocompositesPOLYMER COMPOSITES, Issue 9 2009Yeh Wang Morphological characteristics and the dynamic mechanical properties of maleic anhydride grafted polypropylene (PPgMA) and its clay-filled nanocomposites with different degrees of clay exfoliation have been investigated. Fully and partially exfoliated samples were prepared through powered sonication and melt blending, respectively. Our results indicated that both mechanical , and , relaxations can be identified. The glass (,) transition of the nanocomposites shifted to slightly lower temperatures for nearly all formulations because of reduced chain cooperative motion. However, the broad , transition became more distinct with increasing clay loading for sonicated nanocomposites, and shifted to higher temperatures due to chain confinement of amorphous polymer chains in the crystalline region. The reinforcement in the glassy storage modulus E, of PPgMA was examined by the Halpin,Tsai theory. The high aspect ratio of clay stacks in the fully exfoliated nanocomposites resulted in a significant increase in reinforcing efficiency. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] PANI,LDPE composites: Effect of blending conditionsPOLYMER COMPOSITES, Issue 1 2009M. Cote A composite based on polyaniline (PANI) and low density polyethylene (LDPE) with electrical conductivity was developed. Polyaniline was polymerized by chemical oxidation and doped with dodecyl-benzene-sulfonic acid (DBSA). PANI,LDPE composites were prepared via melt blending and the films were obtained by compression molding. The influence of three variables of the blending (temperature, [PANI], rotor speed) on conductivity, microstructure and mechanical properties of the composites was studied by means of statistical tools and a 23 experimental design. The results show that the PANI concentration is the most influential variable, which mainly affects the conductivity and the elongation at break of the composites. These changes are related to the microstructure of the composites. Statistically, the other variables don't show significant influence on conductivity and mechanical properties in the studied range. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers. [source] Thermal and dielectric properties of fiber reinforced polystyrene compositesPOLYMER COMPOSITES, Issue 11 2008Suzhu Yu Thermal and dielectric properties of polymer composites are important for many applications such as microelectronic packaging. In this work, glass fiber, alumina fiber, and carbon fiber reinforced polystyrene composites have been prepared with melt blending. The thermal conductivity, thermal expansion, and dielectric properties of the composites have been systematically studied as a function of fiber fraction. It is found that all the three types of the fibers, particularly the carbon fiber, can significantly increase the thermal conductivity and decrease the thermal expansion of the polymer. Moreover, the incorporation of the glass or alumina fibers does not have obviously adverse effect on the dielectric constant of the polymer. The thermal conductivities of the fibers reinforced composites have also been analyzed with Agari's model to reveal the conductive enhancement nature of the fibers to the polymer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Polymerization compounding composites of nylon-6,6/short glass fiberPOLYMER COMPOSITES, Issue 4 2003Wei Feng Nylon-6,6 was grafted onto the surface of short glass fibers through the sequential reaction of adipoyl chloride and hexamethylenediamine onto the fiber surface. Grafted and unsized short glass fibers (USGF) were used to prepare composites with nylon-6,6 via melt blending. The glass fibers were found to act as nucleating agents for the nylon-6,6 matrix. Grafted glass fiber composites have higher crystallization temperatures than USGF composites, indicating that grafted nylon-6,6 molecules further increase crystallization rate of composites. Grafted glass fiber composites were also found to have higher tensile strength, tensile modulus, dynamic storage modulus, and melt viscosity than USGF composites. Property enhancement is attributed to improved wetting and interactions between the nylon-6,6 matrix and the modified surface of glass fibers, which is supported by scanning electron microscopy (SEM) analysis. The glass transition (tan ,) temperatures extracted from dynamic mechanical analysis (DMA) are found to be unchanged for USGF, while in the case of grafted glass fiber, tan , increases with increasing glass fiber contents. Moreover, the peak values (i.e., intensity) of tan , are slightly lower for grafted glass fiber composites than for USGF composites, further indicating improved interactions between the grafted glass fibers and nylon-6,6 matrix. The Halpin-Tsai and modified Kelly-Tyson models were used to predict the tensile modulus and tensile strength, respectively. [source] Polyethylene-Palygorskite nanocomposite prepared via in situ coordinated polymerizationPOLYMER COMPOSITES, Issue 4 2002Junfeng Rong A polyethylene/palygorskite nano-composite (IPC composite) was prepared via an in-situ coordinated polymerization method, using TiCl4 supported on palygorskite fibers as catalyst and alkyl aluminum as co-catalyst. These composites were compared with those prepared by melt blending (MBC composites). It was found that in the IPC composites, nano-size fibers of palygorskite were uniformly dispersed in the polyethylene matrix. In contrast, in the MBC composites, the palygorskite was dispersed as large clusters of fibers. Regarding the mechanical properties of the IPCs, the tensile modulus increased and the elongation at break decreased with increasing fiber content, while the tensile strength passed through a maximum. The tensile strength and elongation at break were much smaller for the MBC composites. The final degree of crystallinity of the IPC composites decreased with increasing palygorskite content. Regarding the kinetics of crystallization, the ratio between the degree of crystallinity at a given time and the final one was a universal function of time. It was found that large amouns of gel were present in the IPC composites and much smaller amountes in the MBC composites. [source] From carbon nanotube coatings to high-performance polymer nanocompositesPOLYMER INTERNATIONAL, Issue 4 2008Stéphane Bredeau Abstract Since their discovery at the beginning of the 1990s, carbon nanotubes (CNTs) have been the focus of considerable research by both academia and industry due to their remarkable and unique electronic and mechanical properties. Among numerous potential applications of CNTs, their use as reinforcing materials for polymers has recently received considerable attention since their exceptional mechanical properties, combined with their low density, offer tremendous opportunities for the development of fundamentally new material systems. However, the key challenge remains to reach a high level of nanoparticle dissociation (i.e. to break down the cohesion of aggregated CNTs) as well as a fine dispersion upon melt blending within the selected matrices. Therefore, this contribution aims at reviewing the exceptional efficiency of CNT coating by a thin layer of polymer as obtained by an in situ polymerization process catalysed directly from the nanofiller surface, known as the ,polymerization-filling technique'. This process allows for complete destructuring of the native filler aggregates. Interestingly enough, such surface-coated carbon nanotubes can be added as ,masterbatch' in commercial polymeric matrices leading to the production of polymer nanocomposites displaying much better thermomechanical, flame retardant and electrical conductive properties even at very low filler loading. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||