Presence Of Inorganic Fillers Research Articles

Effects of Surface Modification with Stearic Acid on the Dispersion of Some Inorganic Fillers in PE Matrix

To evaluate the effects of surface modification with stearic acid on the dispersion of some inorganic fillers in polyethylene (PE) matrix, masterbatches containing 20–40 wt% of stearic acid uncoated and coated inorganic fillers and the linear low-density polyethylene (LLDPE) films containing 3–7% stearic acid uncoated and coated inorganic fillers were prepared. Two types of inorganic fillers used in the masterbatch included bentonite and silica. The structural change of inorganic fillers, whose surface was modified with stearic acid, was studied using IR spectroscopy. The dispersion of inorganic fillers in LLDPE matrix was evaluated using scanning electron microscope (masterbatch samples) and optical microscope (film samples). Changes in the melting temperature of LLDPE in the presence of inorganic fillers were evaluated by using differential scanning calorimeter (DSC). The mechanical properties of the films were evaluated according to ASTM D882. Surface-treated fillers with stearic acid dispersed in the masterbatches and films better than untreated fillers did. Stearic acid did not change the melting temperature of the filler/PE masterbatches. The mechanical properties of the films containing stearic acid coated fillers were higher than those containing unmodified fillers.

An Effective Package of Antioxidants for Avoiding Premature Failure in Polypropylene Random Copolymer Plastic Pipes under Hydrostatic Pressure and High Temperature.

Pipes of polypropylene random (PP-R) copolymers are the best choice for hot- and cold-water networks. Validation of a severe test, accomplishing the ISO 1167 standard, is mandatory to assess their service lifetime expectancy. This work evaluates the behavior shown by three commercial pipes, either the original ones (new pipes) or after being subjected to a hydrostatic pressure test at elevated temperature (aged pipes). Several features with relevance for the final performance have been examined: crystalline characteristics, phase transitions in crystalline regions, effect of high temperature and pressure on these transitions, and oxidation induction time. Moreover, the presence of inorganic fillers, and the content of different antioxidants together with their depletion, have also been analyzed. Films from the new pipes were also prepared for replication of the different environments in order to achieve a better and complete understanding of the phase transitions in the crystalline regions and of the consumption of antioxidants. Distinct environments surrounded the inner and outer parts of the pipes exposed to the failure aging test at 110 °C: hot water and warm dry air, respectively. These features play a key role in the loss of additives and in the subsequent initiation of degradation. Even if the crystalline characteristics are appropriate in the polymeric matrix, the success of a pipe lies in the homogeneous dispersion of components for avoiding damage at interfacial properties, and in a correct package of antioxidants used in its formulation.

The Effect of Inorganic Fillers on the Polyaniline Synthesis

The kinetics of the synthesis of polyaniline in the presence of inorganic fillers was studied. It is shown that the acid-base surface properties of the inorganic filler affect the polymerization time. The introduction of a filler in the reaction mass containing aniline leads to a decrease in the induction period of oxidative polymerization. The decrease in the induction period is due to the fact that aniline is adsorbed on the surface of the filler. This leads to the fact that polyaniline is formed as a thin layer on the surface of the carrier. With a further increase in the content of inorganic filler, the time of the induction period increases. This is due to the fact that the surface of talc has a basic character. The use of mica as an inorganic filler leads to a decrease in the induction period of polymerization in the entire range of the carrier content studied.

Alkaline hydrolysis of radio-oxidized aliphatic polymers

Organic molecules are part of the Long-Lived Intermediate-Level Waste (LL-ILW) packages. These packages are planned to be delivered at the French deep geological repository, consequently their degradation has to be thoroughly understood in order to support the safety studies. In a first period, these organic molecules, which include polymers, are radio-oxidized because of their close proximity with radionuclides. In a second period, water will diffuse inside the site up to the packages, leading to the alkaline hydrolysis of the radio-oxidized polymers. The objective of this study is to evaluate the parameters having a major influence on these radio-oxidized polyolefins hydrolysis at high pH. Aliphatic polymers are chosen because of their relative importance, in quantity, in the French LL-ILW packages.In this work, we have first radio-oxidized aliphatic polymers in conditions that are representative of their ageing in the first period of the LL-ILW packages: we have employed different doses up to 10 MGy, different emitters - or their equivalent -, i.e. γ-rays and swift heavy ions (SHI) irradiation to model α-rays. To model the second period of ageing of these LL-ILW packages, we have hydrolyzed under alkaline conditions and under inert atmosphere these radio-oxidized polymers.We have evaluated the influence of the materials’ composition (the resin chemical structure, presence of charges and fillers) and of the irradiation conditions (irradiation type, linear energy transfer (LET) and dose). We observed that hydrolysis is influenced not only by the molecular structure of the polymer, but also by the presence of inorganic fillers and organic additives. The hydrolysis increases with increasing dose and increasing LET for SHI. The most penalizing conditions were encountered under low LET ionizing rays. This is related to the higher oxidation level induced under γ-rays: the higher the oxidation rate, the higher the polyolefins sensitivity to alkaline hydrolysis.

Study of changes in the physico-mechanical properties of composites based on secondary polymeric raw materials in the presence of inorganic fillers under the influence of environmental factors

Study of changes in the physico-mechanical properties of composites based on secondary polymeric raw materials in the presence of inorganic fillers under the influence of environmental factors

Simulation of Rheological Behavior of Secondary Polymer Feedstock in the Presence of Inorganic Fillers under Conditions Corresponding to Processing of Polymers by Extrusion and Die Casting

Simulation of Rheological Behavior of Secondary Polymer Feedstock in the Presence of Inorganic Fillers under Conditions Corresponding to Processing of Polymers by Extrusion and Die Casting

Surface modification and improved adhesion of wood-plastic composites (WPCs) made with different polymers by treatment with atmospheric pressure rotating plasma jet

Because of the low polarity of the polymers used for manufacturing wood plastic composites (WPCs), they have low surface energy and their adhesion properties are limited. In this study, the surface modification with atmospheric pressure rotating plasma jet (APPT) of several WPCs made with different polymers is proposed as an environmentally friendly alternative for increasing their hydrophilicity and adhesion. Both the nozzle-WPC surface distance and the platform speed were varied during APPT treatment and only one pass was carried out. APPT treatment of the WPCs made with polyethylene and polypropylene removed most of the wood component and exposed the polymer to the surface, changing their chemistry, surface energy and topography. An improvement in adhesion of the WPCs to different coatings was obtained which was ascribed to the creation of new polar carbon-oxygen moieties, and the removal of wood component on the WPC surfaces. The less surface modification caused by APPT treatment of the WPC made with poly (vinyl chloride) was ascribed to its low wood content and the presence of inorganic fillers.

Effects of silica on the morphology, structure, and properties of thermoplastic cassava starch/poly(vinyl alcohol) blends

ABSTRACTThermoplastic cassava starch (TPS)/poly(vinyl alcohol) (PVA)/silica (SiO2) composites were prepared by a melt‐mixing method. The effects of the content and surface properties of SiO2 on the processing, mechanical properties, thermal stability, morphology, and structure of the TPS/PVA/SiO2 composites were investigated. With increasing SiO2 content, the plasticizing times of the TPS/PVA/SiO2 composites were shortened. After the SiO2 surface was treated with a silane coupling agent (KH550), the plasticizing times of the TPS/PVA/SiO2 composites decreased significantly. The tensile strength, elongation at break, and Young's modulus of the TPS/PVA/SiO2 composites increased. The mechanical properties of the TPS/PVA/SiO2 composites containing treated SiO2 were higher than those with untreated SiO2. The thermal decomposition temperatures of the TPS/PVA/SiO2 composites were improved with the addition of SiO2. The presence of inorganic fillers was beneficial to the improvement of the thermal stability of the polymers. The reaction between the treated SiO2 and the starch molecules was beneficial to the formation of more stable structures. The treated SiO2 indicated good interfacial adhesion and uniform dispersion in the matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44020.

New N-(2-carboxybenzyl)chitosan composite scaffolds containing nanoTiO2 or bioactive glass with enhanced cell proliferation for bone-tissue engineering applications

ABSTRACTIn the present study N-(2-carboxbenzyl)chitosan (CBCS) 3D macroporous hybrid scaffolds with interconnected pore system, containing 0.5, 2.5, and 5 wt% TiO2 nanoparticles (nTiO2) and 2.5 wt% Bioglass 45S5 (BG) have been synthesized using freeze-drying technique. Compressive strength values verified that the modification of chitosan combined with the presence of inorganic fillers can attribute significant mechanical stiffness to the scaffold. The in vitro biomineralization test confirmed that all samples were bioinert as mineral deposits were detected with X-ray diffractometry after incubation in SBF. Cytotoxicity and biocompatibility of all scaffolds were tested by using and Wharton’s jelly–derived mesenchymal stem cells (WJ-MSCs) and human embryonic kidney 293 (HEK 293) cell line. Metabolic activity, proliferation, migration, and attachment to the scaffolds were examined. Cells appeared to attach around the superficial pores and migrate in them. Cells also maintained their morphology, proliferated, and migrated across the scaffolds and showed consistent and proved compatibility.

Alkylammonium AlPO-kanemite as support for tuning catalytic activity of metallocene: In situ preparation of polyethylene nanocomposites

Several alkylammonium-AlPO-kanemites were prepared to display a range of interlayer distances due to the presence of variable n-butyl/n-dodecylammonium concentrations. Zirconocene and titanocene dichlorides reacted with these layered materials to produce new supported metallocene catalysts. The characterization of these materials confirmed their formation and the presence of the anchored metallocene on the solid support. This study aimed to test these samples for the first time as catalysts for ethylene polymerization for verification of the influence of the metallocene supports with tunable interlayer distances on the catalytic behavior and for in situ production of nanocomposites. The data showed that the highly active new supported systems reaches values of activity comparable to that obtained by analogous homogeneous system. The increase in the interlayer space acted to increase the activity, showing that the possibility of change the interlayer space is a tool to control the activity. Polymers obtained by the supported catalysts presented higher molecular weight and lower polydispersities index than that synthetized with homogeneous catalyst. The ethylene polymerization promoted the exfoliation of the alkylammonium-AlPO-kanemite layers in the polymer matrix, characterizing the formation of a nanocomposite. Compared to the pristine polymer, the presence of inorganic fillers in the polymer matrix increased the melting temperature of the nanocomposite.

Study of the Photo-oxidation and Photolysis of Unsaturated and Cross-linked Polyesters (UP) in the Presence of Photoactive or not Inorganic Fillers

Abstract Disturbances of the photochemical evolution involved in the photolysis and in the photo-oxidation at long wavelengths (e?300 nm) of poly(propylene glycol-maleatophtalate cross-linked by the styrene (UP),caused by the addition of photo-active pigment such as zinc sulphide or black iron oxides,and no photoactive inorganic fillers such as calcium carbonate have been analysed by means of FTIR and U.V. spectrophotometry. The photo-oxidation observed by FTIR of the polymer UP in the presence of inorganic fillers leads to the same photoproducts such as ones of the photo-oxidation of the virgin polymer, but the oxidation rate is greatly affected by the nature and the percentage of the inorganic filler. Zinc sulfide and black iron are incorporated in the film of polymers, the absorption spectra of ZnS reveals that this pigment is not as absorbent as titanium oxide in a more limited field. On the other hand, with a very low inner filter effect, black iron oxides promote the formation of absorbing photoproducts. The addition of Calcium carbonate non- absorbing filler to the UP, causes a slight decrease in the evolution of the I.R

Modified PVA moiety with PbO as humidity sensor

Polyvinyl alcohol (PVA)-composed lead oxide (PbO) films were prepared by solution casting method. Proposed composite moiety reveals the presence of orthorhombic and monoclinic multiphase structural modification due to loading of PbO which was demonstrated by X-ray diffraction. The electronic transition due to oxide impurity decreases the transmission intensity and shift of wavelength confirmed by ultraviolet tool. The magnitude of dielectric polarization is directly proportional to the loaded PbO% and is based on the Debye model. The composite morphology demonstrates the presence of inorganic filler with a cross linked network of polymer PVA confirmed by AFM. The synthetic film loaded with PbO sensing for varying RH% with linearity (decreasing) in resistance may apply as humidity sensor.

Simulation of conversion profiles inside a thick dental material photopolymerized in the presence of nanofillers

In dental composites, the presence of inorganic fillers in the organic matrix leads to a light-scattering phenomenon that modifies the light intensity and, consequently, the ultimate polymerization yield. In this study, we aimed to characterize the impact of light scattering on the photopolymerization profiles inside thick materials. First, the photopolymerization kinetics of dental composites containing alumina or zirconia nanofillers were studied. An optimal formulation based on 75 wt% Bis-GMA, 25 wt% triethyleneglycoldimethacrylate and 1 wt% camphorquinone/dimethylaminoethylmethacrylate (1/1) was determined. The compatibility between the organic matrix and the fillers was enhanced by grafting a silane coupling agent onto the surfaces of the nanoparticles. This grafting improved the mechanical properties of the final composites without modifying the photopolymerization kinetics. The presence of nanofillers leads to a light-scattering phenomenon that influences the photoinitiated polymerization yield inside the composite. Thus, to characterize this phenomenon, a four-flux radiative transfer theory was applied to calculate the decrease in the light intensity crossing the dental composite. The conversion profiles were then calculated and compared with experimental ones. Photopolymerization of thin layers of a 75/25 (w/w) Bis-GMA/TEGDMA mixture exposed to a 465-nm monochromatic light radiation was first investigated. The final methacrylate conversion was measured by FTIR spectroscopy for different light intensities I0. Then, the variation of the light flux intensity φ inside thick samples of the previous mixture containing mineral nanofillers (Al2O3 or ZrO2) was calculated by means of a numerical model by taking into account the light scattering induced by the fillers. The obtained results permit the determination of the conversion profiles inside the loaded material and the maximal thickness that can be photopolymerized without consequent alteration of the polymerization yield and of the mechanical properties.

Electrical and thermal properties of nylon 6/calcium carbonate composites

AbstractSeveral polymer composites formed from nylon 6/CaCO3 with different ratios and particle sizes were prepared using modified and unmodified CaCO3 as inorganic filler. The modification of CaCO3 surfaces was carried out by adsorption of oleic acid from toluene. TGA and DSC measurements show that the glass transition temperatures reduced by the presence of inorganic filler, whereas the melting temperature did not influenced. In all prepared polymer composites, the presence of filler accelerates the degradation process of the polymer. Dielectric properties of the investigated samples were studied in the frequency range from 45 Hz to 1 MHz and at temperatures ranging between 50 and 200°C. The presence of CaCO3 led to a remarkable decrease in the conductivity of nylon 6. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:257–266, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20165

Biobased Contents of Organic Fillers and Polycaprolactone Composites with Cellulose Fillers Measured by Accelerator Mass Spectrometry Based on ASTM D6866

The biobased contents of raw materials such as starches, sugar, chitin, or wood powders for biomass plastics were measured using Accelerator Mass Spectrometry (AMS) based on ASTM D6866. AMS measures the isotope carbon ratio of 14C to 12C and 13C in graphite derived from sample powders. The biobased contents of starches, sugar or chitin were almost 100% which means that they are fully biobased. The biobased contents of the wood powders were over 140% due to the effect of the post 1950s 14C injection due to nuclear testing. Poly(e-caprolactone) (PCL) composite samples were prepared using the polymerization and direct molding method. The starting compound was the e-caprolactone monomer liquid combined with cellulose and inorganic fillers using aluminum triflate as a catalyst at 80 °C for 6 or 24 h. PCL cylinder-shaped composite samples with a homogeneously dispersed cellulose filler were prepared with Mn = 4,600 (Mw/Mn = 2.9). The biobased content of the PCL composite with 50 wt% cellulose filler (51.67%) measured using AMS was slightly higher than the carbon ratio of cellulose in the starting powder samples (41.3 mol%). This is due to the higher biobased content (112.70%) of the cellulose filler used in this study. The biobased content of the polymer composite powders by AMS was found not to be affected by the presence of inorganic fillers, such as talc.

Elaboration of open‐cell microcellular nanocomposites

AbstractStable water‐in‐oil high internal phase emulsions, containing styrene and divinylbenzene monomers and exfoliated montmorillonite, were prepared and polymerized to obtain nanocomposite microcellular materials. The porous structure was investigated by scanning electron microscopy, mercury intrusion porosimetry, and nitrogen adsorption/desorption analyses. The exfoliation of clay was investigated by X‐ray diffraction and transmission electron microscopy analyses. The presence of inorganic filler did not modify the microcellular structure of the composite, while the use of modified clay significantly enhanced its mechanical properties. No influence on the thermal degradation was noted, except for materials with high clay content that tended to deteriorate at lower temperature than the other materials. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4193–4203, 2007

Degradation of Aliphatic Polyesters in the Presence of Inorganic Fillers

Aliphatic polyesters are melt mixed with bioactive fillers and converted into sheets in order to compare their degradation behavior in a phosphate buffer saline (PBS) solution as a function of processing method, polymer type, and crystallinity and type of filler. The samples are tested for weight changes, pH, intrinsic viscosity (IV), and thermal and mechanical property changes as a function of time. The study establishes that although the fillers appear to enhance the polymer degradation, they also have an effect on crystallinity after several immersion periods. Intrinsic viscosity measurements show degradation in the form of molecular weight reduction even after short periods of immersion.

Biobased Contents of Biodegradable Poly(ε‐caprolactone) Composites Polymerized and Directly Molded Using Aluminium Triflate from Caprolactone with Cellulose and Inorganic Filler

Poly(epsilon-caprolactone) (PCL) composite samples were prepared by polymerization and direct molding. The starting compound was epsilon-caprolactone monomer liquid combined with cellulose and inorganic fillers, using aluminium triflate as a catalyst at 80 degrees C, for 6 or 24 h. Cylinder-shaped PCL composite samples with a homogeneously dispersed cellulose filler were prepared with (-)M(n) = 4 600 ((-)M(w)/(-)M(n) = 2.9). The mechanical properties of the PCL composite samples were studied using compression test methods. The strength of a PCL composite with 50 wt.-% cellulose filler (10.8 MPa) was found to be lower than the PCL sample without fillers (19.2 MPa). The biobased content of the PCL composite with 50 wt.-% cellulose filler (51.67%) measured using accelerated mass spectrometry (AMS) was slightly higher than the carbon ratio of cellulose in the starting powder samples (41.3 mol-%). The biobased content of the polymer composite powders by AMS was found not to be affected by the presence of inorganic fillers, such as talc. The rate and extent of biodegradation, caused by Amano Lipase PS, of the PCL composite sample with cellulose filler (40% degradation in 4 d) was the same as that of a PCL sample without the cellulose filler.

Synthesis and Characterization of Fumarate Copolyesters for Use in Bioresorbable Bone Cement Compositions

Unsaturated amorphous copolyesters of varied composition were prepared by transesterification copolymerization of diethyl fumarate, and two diols, 1,2‐propanediol and 2‐methyl‐1,3‐propanediol. The copolyesters were characterized by IR, 1H‐ and 13C‐NMR, GPC, DSC, and TGA. The glass transition is changing with composition from 0°C to 19°C as the content of 1,2‐propanediol residue in the copolyester increases. The copolyester structure and composition have an impact on the compressive strength and hydrolytic stability of the composites prepared by crosslinking the fumarate double bonds with N‐vinyl pyrrolidone in the presence of inorganic filler, calcium sulfate dihydrate, with the addition of a radical initiator, benzoyl peroxide, at ambient temperatures.

Tensile behavior of Nafion and sulfonated poly(arylene ether sulfone) copolymer membranes and its morphological correlations

AbstractThe tensile stress–strain behavior of Nafion 117 and sulfonated poly(arylene ether sulfone) copolymer (BPSH35) membranes were explored with respect to the effects of the strain rate, counterion type, molecular weight, and presence of inorganic fillers. The yielding properties of the two films were most affected by the change in the strain rate. The stress–strain curves of Nafion films in acid and salt forms exhibited larger deviations at strains above the yield strain. As the molecular weight of the BPSH35 samples increased, the elongation at break improved significantly. Enhanced mechanical properties were observed for the composite membrane of BPSH35 and zirconium phenylphosphonate (2% w/w) in comparison with its matrix BPSH35 film. The stress‐relaxation behavior of Nafion and BPSH35 membranes was measured at different strain levels and different strain rates. Master curves were constructed in terms of plots of the stress‐relaxation modulus and time on a double‐logarithm scale. A three‐dimensional bundle‐cluster model was proposed to interpret these observations, combining the concepts of elongated polymer aggregates, proton‐conduction channels, and states of water. The rationale focused on the polymer bundle rotation/interphase chain readjustment before yielding and polymer aggregate disentanglements and reorientation after yielding. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1453–1465, 2006