Absence Of Compatibilizer Research Articles

Sustainable composites based on polypropylene and clay

The production and consumption of plastic materials have been increasingly studied, since the excessive use of its raw material, oil, and its incorrect final destination can cause serious damage to the environment. For this reason, plastic recycling has been frequently used due to its economic, social and ecological viability. Due to reprocessing, plastics lose properties with each recycling cycle. To optimize the properties of plastics, which are often recycled, natural fibers are mixed with these materials, forming composites. Polymeric composites are increasingly used in a wide range of applications due to their excellent physical-mechanical properties. Recycled HDPE composites were obtained in a twin-screw extruder, with three different fibers in the presence and absence of compatibilizer. Overall, the presence of the fiber promoted a reduction in impact resistance and thermal deflection temperature. On the other hand, it provided an increase in the softening temperature of the composites. Considering the results obtained, the PEZMA composite resulted in a material with greater impact resistance and a higher softening temperature.

Evaluating the mechanical, thermal, and antibacterial properties of poly (lactic acid)/silicone rubber blends reinforced with (3‐aminopropyl) triethoxysilane‐functionalized titanium dioxide nanoparticles

AbstractPoly (lactic acid)/silicone rubber (PLA/SR) blends were reinforced with (3‐aminopropyl) triethoxysilane‐functionalized titanium dioxide nanoparticles, and the effect of the virgin (TDO) and functionalized (FTDO) nanoparticles was investigated in the presence and absence of compatibilizer. The results demonstrated that the functionalization of TDO had no negative effect on the morphology of the blends, and no aggregation was seen in the blends containing TDO and FTDO. Furthermore, nanoparticles were localized at the interface of PLA and SR. Adding TDO in the PLA/SR blends increased the mechanical properties. The same trend was observed after incorporating the compatibilizer and FTDO. Additionally, a good agreement was seen between the theoretical and experimental mechanical properties values. Moreover, introducing SR diminished the crystallinity of PLA, and further reduction was observed by adding TDO, FTDO, and compatibilizer. Also, the modification of TDO did not affect the crystallinity of the blends. Incorporating 1 and 2 phr TDO to the blends increased the thermal stability while diminishing with 3 phr TDO. In addition, FTDO improved thermal stability. The antibacterial test indicated that the higher nanoparticles content, the better the antibacterial properties.

A Theoretical and Experimental Analysis of the Effect of Nanoclay on Gas Perm‐Selectivity of Biodegradable PLA/EVA Blends in the Presence and Absence of Compatibilizer

AbstractPoly (lactic acid) (PLA)‐based compounds are widely used in thin‐film and food packaging industries. Herein, PLA/ethylene vinyl acetate copolymer (EVA)/nanoclay nanocomposites are prepared in various compositions by melt blending. The gas permeability against N2, CO2, and O2 gases is determined as a function of composition and morphology of the nanocomposites. Inclusion of high aspect ratio of platelet‐like nanoclay to the blend reduces the gas diffusion. The best barrier properties against all gases is observed on introducing 5 wt% poly(ethylene/n‐butyl acrylate glycidyl methacrylate) copolymer as compatibilizer to the PLA/EVA/nanoclay (75/25/5) system. The scanning and transmission electron microscopic analyses and wide‐angle X‐ray scattering studies reveal that inclusion of compatibilizer to the filled‐blends improves the blend morphology, dispersion state, and intercalation level of clay platelets which are preferably localized at the interface of the blend. Analysis of selectivity parameter (α) shows the lowest O2 permeability and the highest αCO2/N2 and αO2/N2 values for the compatibilized filled‐blend (75/25/5/5). In situ aspect ratio of clay and the degree of intercalation are theoretically evaluated based on the permeability data using various empirical models. It is found that the compatibilized filled‐blend has the highest aspect ratio and intercalation level that are responsible for the optimum perm‐selectivity performance.

PHYSICAL AND MECHANICAL AND THERMOPHYSICAL PROPERTIES OF POLYMER COMPOSITES BASED ON RECYCLED POLYPROPYLENE FILLED WITH RICE HUSK

The relevance of the study is due to the deterioration of the environmental situation in the world associated with an increase of plastic waste, which determines the feasibility of developing methods for their involvement in recycling for the production of plastic products. Thereby, this article is aimed at studying the patterns of changes in the physical and mechanical and thermophysical properties of polymer composites based on recycled polypropylene filled with rice husk in the absence of compatibilizers. The leading approach to the study of this problem is the determination of the modulus of elasticity in flexure, tensile strength at break, strain-to-failure, and bending strain, bending temperature under load and Vicat softening temperature, Charpy V-notch impact energy and Izod impact strength, as well as the thermophysical parameters of polymer composites. The article shows that with an increase in the content of rice husk in a polymer composite based on recycled polypropylene, an increase in the modulus of elasticity in flexure occurs. Filling polypropylene with rice husk slightly reduces the tensile strength and significantly reduces the elasticity of the polymer. Recycled polypropylene has a higher Charpy V-notch impact energy than Izod impact strength. Filling the polymer with rice husk leads to a decrease in impact strength according to both Charpy and Izod, and with a compound content of more than 5 phr, both of these indicators are almost identical. In this case, there is a slight increase in the onset temperature of the composites, which determines their thermal stability during processing. It was revealed that polymer composites containing 2-10 mass parts of rice husk are characterized by an increased degree of crystallinity of the polymer phase. The materials of the article are of practical value for the processing of recycled thermoplastic polymers, as well as the creation of biodegradable polymer composites.

Thermal evaluation of composites from coffee capsules residue with sugarcane bagasse by TG/DTA and DMA

In this study, new composites were prepared with coffee capsule residue as polymeric matrix reinforced with amounts of 5 or 10% m/m sugarcane bagasse fibers (untreated and treated with 4% NaOH solution). The influence of the bagasse fibers on the thermal properties as well as on the dynamic mechanical behavior of composites was evaluated by Thermogravimetric Analysis (TG), Derivative Thermogravimetry (DTG), Differential Thermal Analysis (DTA) and Dynamic Mechanical Analysis (DMA). TG results of the composites indicated that the thermal stability was influenced by the fiber content. In addition, the alkali fiber treatment decreased the thermal stability of the composites. By the DTA curves, it was possible to assume that polypropylene was the main polymer that constitutes the capsule through the appearance of the melting temperature event. It could be also observed that the samples showed different thermal behavior in the range of 300 and 410 °C due to the fiber content and the use or not of compatibilizer. Based on the results of thermomechanical analysis, it was found that the viscoelastic properties were also influenced by the addition of fiber (untreated or treated) and the presence or absence of compatibilizer. Furthermore, the scanning electron microscopy images of the samples revealed greater adherence between fiber and matrix in the composites that were used compatibilizer.

Microcrystalline cellulose treated by steam explosion and used for thermo-mechanical improvement of polypropylene

The use of cellulose fibers derived from renewable resources as reinforcement in polymeric composites provides positive environmental benefits with respect to disposal and raw material savings. Microcrystalline cellulose is a regenerated cellulose material that is free of lignin and hemicellulose, widely used in various applications. Recently, there has been enormous interest in producing polymer nanocomposites using cellulose nanofibers as reinforcement. Moreover, the steam explosion process is an ecofriendly method to modify cellulose fibers by inducing fibrillation, allowing the production of nanofibers. Fibrillation of microcrystalline cellulose using steam explosion process as the only cellulose treatment process was not yet studied in the literature. In the present work, steam explosion process was applied to commercial microcrystalline cellulose and the obtained fibers were characterized and employed in composites with polypropylene for evaluation of the thermal, mechanical, and morphological properties in relation to the matrix. The results showed that this process promoted partial fibrillation to nanosized diameter, and an increase in crystalline degree and thermal stability of the original fiber. As for the polypropylene/cellulose composites in the absence of compatibilizer, there was an increase of thermal degradation temperature and mechanical properties measured by dynamic-mechanical analysis in comparison with pure polypropylene.

Mechanochemical Routes to Functionalized Graphene Nanofillers Tuned for Lightweight Carbon/Hydrocarbon Composites

AbstractGraphite exfoliation by shear‐induced dry and wet processes and especially mechanochemistry represent attractive routes to carbon nanofillers. Dry ball‐milling of graphite in a planetary mill under gas pressure is a scalable and environmentally benign one‐step process, which requires neither hazardous solvents nor tedious separate functionalization and purification steps. Gas type, pressure, and milling duration govern average particle size, shape, and functionalization. Ball‐milling under Ar yields hydroxylated spherical carbon particle agglomerates, whereas ball‐milling under CO2 affords functionalized nanoplatelets without encountering agglomeration problems and highly exothermic post‐milling reactions with air. The carboxylation of graphene nanoplatelets enhances their dispersibility in various media including polypropylene (PP) even in the absence of compatibilizers. Large amounts of carboxylated nanoplatelets are dispersed in PP without massive viscosity build‐up. Functionalized carbon nanoplatelet fillers enable tailoring of recyclable lightweight carbon/hydrocarbon composites exhibiting an improved balance of stiffness, strength, toughness, electrical, and thermal conductivity.

Mechanochemically Carboxylated Multilayer Graphene for Carbon/ABS Composites with Improved Thermal Conductivity.

Dry ball milling of graphite under carbon dioxide pressure affords multilayer-functionalized graphene (MFG) with carboxylic groups as nanofiller for composites of carbon and acrylonitrile–butadiene–styrene copolymers (ABSs). Produced in a single-step process without requiring purification, MFG nanoplatelets are uniformly dispersed in ABS even in the absence of compatibilizers. As compared to few-layer graphene oxide, much larger amounts of MFG are tolerated in ABS melt processing. Unparalleled by other carbon nanofillers and non-functionalized micronized graphite, the addition of 15 wt % MFG simultaneously results in a Young’s modulus of 2550 MPa (+68%), a thermal conductivity of 0.321 W∙m−1∙K−1 (+200%), and a heat distortion temperature of 99 °C (+9%) with respect to neat ABS, without encountering massive embrittlement and melt-viscosity build-up typical of few-layer graphene oxide. With carbon filler at 5 wt %, the Young’s modulus increases with increasing aspect ratio of the carbon filler and is superior to spherical hydroxyl-functionalized MFG, which forms large agglomerates. Both MFG and micronized graphite hold promise for designing carbon/ABS compounds with improved thermal management in lightweight engineering applications.

Dynamic mechanical properties of immiscible polymer systems with and without compatibilizer

Blends of polyamide12 (PA12) and isotactic polypropylene (PP) were prepared by melt mixing, in an internal mixer, in the presence and absence of compatibiliser. The compatibiliser used was maleic anhydride grafted PP (PP-g-MA). The dynamic mechanical properties of the blends with and without compatibiliser were studied. Although compatibilization shifted the glass transition temperatures (Tg's) of component polymers only marginally, it significantly enhanced the storage modulus of the blends. The storage moduli of the uncompatibilised blends were compared with those predicted by theoretical models. Correlation between the dynamic mechanical properties of both compatibilised and uncompatibilised blends and their phase morphology was made.

Polypropylene composites reinforced with untreated and chemically treated coir: Effect of the presence of compatibilizer

The effect of coir surface modification on the compatibility of polypropylene (PP)/coir fiber (CF) composites, in the presence and absence of compatibilizer (maleic anhydride grafted polypropylene, PP-g-MA) was assessed. Chemical pulping of the fibers was performed with 2, 4, 8, and 12% NaOH solutions for a period of 2 h at (100 ± 4)°C. Pressed composite samples were subjected to tensile testing, scanning electron (SEM) and atomic force microscopy (AFM). Lignin and holocellulose concentrations of untreated and treated coir were determined. Pulping resulted in increased tensile strength of the composites containing coir treated with up to 2% NaOH, due to increased fiber roughness as evidenced by AFM. This property decreased when higher NaOH concentrations were used, likely due to increased deterioration of coir. The presence of compatibilizer in the PP composites containing treated coir altered adhesion due to chemical changes of the fiber surface. At high NaOH concentrations increased delignification and therefore increased exposure of hydroxyls favors reaction between the fiber hydroxyls and the carboxyl acids of the hydrolyzed maleic anhydride, present in the composites. POLYM. ENG. SCI., 55:2050–2057, 2015. © 2014 Society of Plastics Engineers

Exfoliation of organic montmorillonite in iPP free of compatibilizer through the multistage stretching extrusion

Polypropylene (PP)/organic montmorillonite (OMMT) nanocomposites were first prepared through twin-screw extruder and then subjected to multistage stretching extrusion with an assembly of laminating-multiplying elements (LMEs, which divide and recombine polymer melts). The exfoliated efficiency of LMEs on OMMT dispersed in PP matrix was investigated by optical microscopy, scanning electron microscope, transmission electron microscopy and X-ray diffraction. Because of the absence of compatibilizer, molecular chains of PP were not intercalated into the galleries of OMMT during the multistage stretching extrusion. The exfoliation of OMMT was induced by the strong force occurred in LMEs, which can destruct van der Waal’s interaction between the laminate OMMT platelets. The exfoliation degree of OMMT has been improved with the increase of number of LMEs used. The dispersion morphology of OMMT was thermodynamically stable after secondary melt processing. As a result, the mechanical properties of composites have been enhanced with increasing LME number. We realized the exfoliation of OMMT by the function of strong shear field without the incorporation of compatibilizer.

Characterization of polyethylene-based multiphase systems containing zero- and two-dimensional nanoparticulate reinforcement materials by analytical electron and atomic force microscopy

Multiphase polymer nanomaterials with reinforcements of different structural features have immense commercial applications. Characterization of the morphological features in these nanocomposites like filler dispersion, effect of filler and compatibilizer on polymer phase morphology, interaction of filler and compatibilizer, and so on is of significant importance as these shape the composite behavior and properties. To study these aspects, polyethylene (PE) nanocomposites generated with and without compatibilizer using two different types of fillers were comprehensively characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM) including analytical TEM (e.g. energy-dispersive x-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS)). Differential scanning calorimetric analysis was performed in order to quantify thermotropical properties of the nanocomposites. The filler dispersion was poor in the absence of compatibilizer, whereas its addition enhanced the filler delamination owing to the positive interactions between the polar filler surface and polar component of the compatibilizer. The compatibilizer addition also decreased the melt enthalpy due to reduced crystallinity along with change in polymer phase morphology. The filler pullout was also observed even in the compatibilized samples leading to higher AFM height variation in these composites. The EELS and EDXS analysis was further useful in analyzing the type of filler phase as well as interactions between the filler and compatibilizer phases. The compatibilizer was also observed to concentrate near the interface with the filler as signal of oxygen atoms associated with compatibilizer chains did not enhance in matrix, but increased at organic–inorganic interface.

Liquid-State and Solid-State Properties of Nanotube/Polypropylene Nanocomposites Elaborated via a Simple Procedure.

Non-modified Multiwalled Carbon Nanotubes (MWCNT) and polypropylene (PP) in absence of compatibilizer have been chosen to elaborate MWCNT/PP nanocomposites using a simple melt-mixing dispersing method. Calorimetry results indicate little effect of MWCNTs on crystallinity of PP, revealing not much interaction between nanotubes and PP chains, which is compatible with the employed manufacturing procedure. In any case, a hindering of polymer chains motion by MWCNTs is observed in the molten state, using oscillatory flow experiments, and a rheological percolation threshold is determined. The percolation limit is not noticed by Pressure-Volume-Temperature (PVT) measurements in the melt, because this technique rather detects local motions. Keeping the nanocomposites in the molten state provokes an electrical conductivity increase of several orders of magnitude, but on ulterior crystallization, the conductivity decreases, probably due to a reduction of the ionic conductivity. For a concentration of 2% MWCNTs, in the limit of percolation, the conductivity decreases considerably more, because percolation network constituted in the molten state is unstable and is destroyed during crystallization.

Vibration Welding of Amorphous Thermoplastic Nanocomposites

Polycarbonate (PC) nanoclay composites and noryl nanoclay composites were prepared by melt blending technique both in presence and absence of compatibilizer. The compatibilizer used for dispersing nanoclay in PC was poly (caprolactone) (PCL). In case of noryl, polystyrene (PS) was used as a compatibilizer. The nanoclay used in this study is Cloisite 20 A. The main aim in utilizing the nanoclay was to improve the mechanical properties and reduce the viscosity of the amorphous thermoplastic nanocomposites. Vibration welding has been done on pure and nanoclay-filled PC and noryl polymer matrices. The dispersion of nanoclay in the polymer matrices was observed through high resolution transmission electron microscopy (HR-TEM). Both PC and noryl nanocomposites prepared in presence of compatibilizers showed better dispersion of nanoclay platelets in the polymer matrices compared to the nanocomposites system prepared in absence of compatibilizer. The nanoclay filled polymer systems show increase in percentage crystalinity compared to the pure ones, which may be due to the nucleating effect of nanoclay. The mechanical properties were tested for the pure and nanoclay-filled PC and noryl welded joints. The mechanical properties showed a drop for the polymer nanocomposites, which contains nanoclay dispersed directly in the polymer matrices. On the other hand, PC and noryl nanocomposites prepared in the presence of compatibilizer showed improved mechanical properties compared to pure one. The compatibilizer helps to improve the dispersion of nanoclay platelets in the base polymer matrix. This indeed improves the weld strength of the thermoplastic nanocomposites.

Lignin as additive in polypropylene/coir composites: Thermal, mechanical and morphological properties

Abstract PP/CF composites were prepared and the effect of lignin incorporation in the presence and absence of compatibilizer (maleic anhydride grafted polypropylene, PP-g-MA) was investigated by means of mechanical, thermal and morphological properties. Lignin added to the composite was obtained by the Acetosolv process. The composites were prepared in a Haake torque rheometer and assessed by means of tensile testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that in the absence of PP-g-MA, incorporation of lignin did not affect tensile strength and in its presence this property was reduced. Thermal analysis revealed that incorporation of lignin in the composites resulted in increase in both the initial thermal decomposition temperatures and oxidation induction times.

Development of butyl rubber nanocomposites in presence and absence of compatibiliser

Chlorobutyl rubber nanocomposites containing organically modified nanoclay (CI-C) were prepared by solution mixing. The nanoclay used in this study was Cloisite 20A. The obtained nanocomposites were incorporated in butyl rubber (IIR) with sulphur as a curing agent. Morphology, curing characteristics, mechanical and gas barrier properties of the nanocomposites were analysed. The morphological studies proved the partial exfoliation along with agglomeration of nanoclay platelets in chlorobutyl rubber, and further incorporation of CI-C in IIR matrix enhance the exfoliation of the nanoclay platelets. Curing study demonstrated shorter scorch time, cure time and increase in maximum torque for the nanoclay loaded IIR compound in the presence of chlorobutyl rubber as a compatibiliser compared to pure and IIR-nanoclay compound without compatibilisers. Dynamic mechanical thermal analysis results showed tremendous improvement in storage modulus and decrease in tan δ value for the one containing a compatibiliser. This particular compound exhibited substantial improvement in mechanical and gas barrier properties.

Effect of nanoclay on vibration welding of LLDPE nanocomposites in presence and absence of compatibiliser

Welding is employed to develop bonded joints with mechanical properties that draw near the parent material. Vibration welding has been applied to join pure and nanoclay filled linear low density polyethylene (LLDPE). Ethylene maleic anhydride copolymer (PE‐g‐MA) is used as a compatibiliser in this study. High resolution transmission electron microscopic images showed the combination of exfoliation and intercalation of nanoclay platelets in LLDPE in the presence of a compatibiliser. The mechanical properties were studied for both the body part and the welded joints. The tensile strength and modulus of the body part for the nanoclay filled LLDPE in the presence of a compatibiliser were substantially improved. The welded joints of the same system showed better enhancement in the modulus. X‐ray diffraction analysis observed from the welded joints showed that the crystallite size of the nanoclay filled LLDPE composites in the presence of a compatibiliser was lower than that of nanocomposites in the absence of a compatibiliser.

Thermal degradation and crystallisation studies of reactively compatibilised polymer blends

The thermal degradation and crystallisation behaviours of polyamide12/isotactic polypropylene (PA12/PP) blends were studied. Effects of blend ratio and compatibiliser concentration on the thermal degradation properties of the blends were analysed. The activation energy for degradation in compatibilised and uncompatibilised blends computed using Horowitz–Metzger equation was reported. The blend ratio as well as the presence of compatibiliser has significant effect on the thermal stability of the blends. Phase morphology was found to be one of the decisive factors that affected the thermal stability of both uncompatibilised and compatibilised blends. Melting and crystallisation behaviours of the blends in the presence and absence of compatibiliser were evaluated. It was observed that blending has no significant effect on the melting and crystallisation properties of PA12 and PP. Compatibilisation of 70/30 and 50/50 PA12/PP blends didn't affect the crystallisation and melting behaviours of PA12 and PP even though some discrepancies were observed.

Properties of polypropylene/layered-silicate nanocomposites and melt-spun fibers

Polypropylene (PP)/layered-silicate organoclay nanocomposites and their fibers were prepared by melt compounding and melt spinning, respectively, in the presence or absence of compatibilizer (PP-based maleic anhydride compatibilizer) to examine the effects of the organoclay dispersion and rheological behavior on the internal structure and tensile properties of the nanocomposite fibers. The compatibilized nanocomposites showed solidlike plateau behavior and strain hardening due to a three-dimensional network structure in the shear and uniaxial elongational flows. The tensile properties of the nanocomposite fibers were reduced compared with those of the pure PP fibers because some of the layered silicates were present as partially aggregated forms and the molecular weight of the compatibilizer was lower than that of the pure PP matrix. It was also found that the tenacity of the nanocomposite fiber increased and then decreased as the compatibilizer content increased because the compatibilizer affected the internal structure of the nanocomposite fibers. The positive effect of the compatibilizer was to generate a more effective exfoliated structure of organoclay in the polymer matrix. The negative effect was that the melt-spun nanocomposite fiber had a lower molecular weight than the pure PP fiber because the compatibilizer had a lower molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of reactive compatibilization on droplet coalescence in shear flow

The evolution of the morphology of blends of polyethylene and polyamide with a droplet–matrix morphology, generated by transient shear flows, has been determined using a method based on quenching following deformation of the samples kept between the parallel plates of a rheometer. Droplet size evolution and transient viscosity of blends compatibilized with different amounts of polyethylene-graft-maleic anhydride were measured as a function of the total strain. The effects of applied shear rates and concentration of the reactive compatibilizer were investigated. The results indicate that initially the droplet size was governed by coalescence, whereas, when the droplet size became comparable to the break-up limit, no further significant increase was observed at large strain values. A significant coalescence inhibition was only observed when a relatively high amount of compatibilizer was used. This corresponded to an important interfacial coverage of the interface by the grafted copolymer chains. In that situation, the intensity of the coalescence became independent of the applied shear rate. On the contrary, the coalescence was favoured by the absence of compatibilizer or the use of a low compatibilizer concentration and increased with increasing shear rate. The rather “complex” effect of the compatibilizer addition on coalescence phenomena has been analyzed in terms of blend microstructure changes induced by the compatibilizer addition in relation to droplet collision frequency. Predictions of the droplet size evolution and viscosity under transient shear flows using a modified version of Lee and Park model is shown to describe the coalescence and break-up phenomena under large deformation shear flow. The predictions of the droplet size evolution are greatly improved when an additional parameter for non-affine deformation (slip parameter), is introduced in the model. On the other hand, the predictions are much less satisfactory for the transient viscosity data.