PVC Nanocomposites Research Articles

Epoxidized Mesua ferrea L. seed oil‐plasticized thermostable PVC and PVC‐clay nanocomposites

AbstractThe use of vegetable‐oil‐based polymeric plasticizers with nanotechnology can create new applications for plasticized poly(vinyl chloride) (PVC). Epoxidized Mesua ferrea L. (Ceylon Ironwood) seed oil was used as a plasticizer for PVC. Further, nanocomposites were prepared through an ex‐situ technique using epoxidized‐oil‐swelled organically modified montmorillonite (5 wt%) and PVC. Notable improvement in thermal and processing characteristics of the nanocomposites was observed over those of the virgin polymer (in both unplasticized and plasticized PVC), as studied by TGA. The prepared nanocomposites were characterized by FTIR, SEM, TEM, and XRD techniques. A dramatic decrease in viscosity (7‐fold) was observed in THF for a 10% solution of epoxidized‐oil‐modified PVC compared to unplasticized PVC in THF, as measured by Brookfield viscometer. Isothermal analysis at three different temperatures (100, 150, and 200°C) reveals sufficient stability of the epoxidized oil modified PVC nanocomposites, as confirmed by gravimetric and FTIR analysis. Augmentation of thermostability and good retention of mechanical properties of the (Mesua ferrea L.)‐plasticized‐PVC/clay nanocomposites with respect to rigid PVC vouch for the utility of the former as advanced industrial materials. J. VINYL ADDIT. TECHNOL., 18:168–177, 2012. © 2012 Society of Plastics Engineers

Investigation of the addition of nano‐CaCo3 at dry mixing or onset of fusion on the dispersion, torque, and mechanical properties of compounded PVC

AbstractA Brabender torque rheometer equipped with an internal mixer was used to study the influence of compounding method on the properties of (rigid PVC)/(treated and untreated nano‐CaCO3) nanocomposites. Two different methods were studied for the addition of surface treated and untreated nano‐CaCO3 during the melt mixing of rigid PVC. Direct dry mixing of rigid PVC and nano‐CaCO3, and addition of nano‐CaCO3 at the onset of PVC fusion were investigated. Dispersion of treated and untreated nano‐CaCO3 was studied by X‐ray diffraction and scanning electron microscopy. Results showed that using direct dry mixing improved the dispersion of nano‐CaCO3 in the PVC matrix by lowering the fusion time. The mechanical properties of the nanocomposite samples such as impact strength, tensile strength, and elongation at break were improved by using this method. The addition of treated nano‐CaCO3 at the onset of fusion caused a simultaneous decrease in torque. Also, rigid PVC nanocomposites prepared with treated nano‐CaCO3 showed better mechanical properties than those of nanocomposites prepared with the untreated nano‐CaCO3. J. VINYL ADDIT. TECHNOL., 18:153–160, 2012. © 2012 Society of Plastics Engineers

Mechanical Properties and Morphology of Plasticized Poly(vinyl chloride) Nanocomposites Filled with Nanosilica

The mechanical properties (tensile properties, tear strength) and morphology of plasticized poly(vinyl chloride) (PVC) nanocomposites filled with varied loadings of nanosilica (nano-SiO2) (3-9 phr) were investigated. It is found that the addition of nano-SiO2 into the plasticized PVC by melt mixing process results in the increase in the Young’s modulus and tear strength, but the decrease in the tensile strength and elongation at break in a dose dependent manner. The SEM micrographs show ductile fractured surfaces for the neat plasticzed PVC and for the nanocomposites with low nano-SiO2 loadings (3 and 5 phr). As the nano-SiO2 loadings are 7 and 9 phr, SEM images illustrate smoother surfaces, caused by the reduction in the flexibility of the plasticized PVC nanocomposites.

Conductive and Mechanical Properties of Graphite Nanoplatelets/PVC Nanocomposites Prepared by Melt Blending

Graphite nanoplatelets (Nano-Gs) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution, and then the Nano-Gs/ PVC nanocomposites were fabricated by way of melt blending. The structure of Nano-Gs was characterized by FTIR and SEM, the conductive and mechanical properties of the Nano-Gs/ PVC nanocomposites were also studied. Results show that with a small amount of functional groups distributing on the surface, Nano-Gs have a thickness ranging 30-100nm and a diameter ranging 3-20μm, and disperse randomly in PVC resin matrix. The Nano-Gs/ PVC nanocomposites exhibit low volume resistivity of 104Ω•cm when the mass fraction of Nano-Gs goes beyond 10%, and the percolation threshold of the nanocomposites is as low as 6wt%. Furthermore, with the increase of the filled Nano-Gs, both the tensile strength and notched impact strength of the nanocomposites increase first and then decrease, and achieve the maximal value simultaneously with the addition of 1 wt% Nano-Gs, which increase by 8% and 29% respectively compared with the pristine PVC.

Preparation of organoclay, its copolymerization with MMA, and use to produce PVC nanocomposites

Two quaternary ammonium compounds with polymerizable vinyl group were designed and synthesized for use as clay modifiers. Copolymerization of quaternary ammonium compounds modified MMT platelets with methyl methacrylate was studied under a range of different reaction conditions and two kinds of polymeric surfactant-modified MMTs were prepared. These polymeric surfactant-modified MMTs were introduced to produce a series of PVC/MMT composites by melt compounding. XRD, TEM, and TGA confirmed that the better organic coverage of the platelets and the bigger interlayer spacing could be obtained for the copolymer of long-chain quaternary ammonium compounds modified MMT and methyl methacrylate (PMMA-H-MMT). The platelet fillers with better organic coverage represented much more useful functional fillers than the conventional ammonium-treated fillers due to their potential to exfoliate to a greater extent when melt-compounded with the PVC matrices. The experiment proved that PMMA-H-MMT shows better performance in increasing thermal stability of PVC/MMT composites.

Structure and Properties of Poly(vinyl chloride)/Halloysite Nanotubes Nanocomposites

Poly(vinyl chloride)(PVC)/halloysite nanotubes (HNTs) nanocomposites were prepared by melt blending. The effects of HNT content on the mechanical properties, morphology, and rheological properties of the nanocomposites were investigated. The results showed that HNTs were effective in toughening and reinforcing PVC nanocomposites. The notched impact, tensile and flexural strength, and flexural modulus of the nanocomposites were remarkably increased compared with those for the pure PVC. Scanning electron microscopy (SEM) results illustrated the ductile behavior of the nanocomposites, with a possible cavitation mechanism. Transmission electron microscopy (TEM) results showed that HNTs were uniformly dispersed in the PVC matrix. Interfacial interaction of hydrogen bonding between the HNTs and PVC matrix was substantiated. The plasticization times of PVC/HNTs nanocomposites were found to be shorter and the equilibrium torque was higher than that for the pure PVC.

Influence of surface modification of montomorillonite on properties of PVC nanocomposites

Column chromatographic technique was used for improvement in d-spacing of montomorillonite using quaternary ammonium salt as an intercalent with a cation exchange capacity of 110 meq/100 g. The modified clay was then referred as organically modified montomorillonite (OMMT). Poly(vinyl chloride) (PVC) nanocomposites were prepared through direct melt compounding on a conventional twin screw extruder with variation in mass percentage of loadings (3–12%). Due to improved d-spacing of OMMT the polymer chains get exfoliated in between the plates of clay and dispersed uniformly. The properties of the nanocomposites were found to be appreciable up to 12 mass% loading of OMMT. Rheological data like torque, fusion time, viscosity, and shear rate were also recorded on Brabender Plasticorder. The improvement in properties with increase in amount of OMMT loading was evidenced from reduction in shear viscosity and torque. Also nanoclay is acting as a lubricating agent with packing effect, which reduces the torque with decrease in viscosity. Moreover, a strong interaction between PVC molecules and nanolayers, which leads to greater nucleation with, improved d-spacing. Due to the soft nature of OMMT and improvement in d-spacing, the processing of PVC becomes easier. Also it is noteworthy that nanoclay may be attributed as a nucleating agent.

Clay Platelet Partition within Polymer Blend Nanocomposite Films by EFTEM

Transmission electron microscopy (TEM) is the main technique used to investigate the spatial distribution of clay platelets in polymer nanocomposites, but it has not often been successfully used in polymer blend nanocomposites because the high contrast between polymer phases impairs the observation of clay platelets. This work shows that electron spectral imaging in energy-filtered TEM (EFTEM) in the low-energy-loss spectral crossover region allows the observation of platelets on a clear background. Separate polymer domains are discerned by imaging at different energy losses, above and below the crossover energy, revealing the material morphology. Three blends (natural rubber [NR]/poly(styrene-butyl acrylate) [P(S-BA)], P(S-BA)/poly(vinyl chloride) [PVC], and NR/starch) were studied in this work, showing low contrast between the polymer phases in the 40-60 eV range. In the NR/P(S-BA) and P(S-BA)/PVC blend nanocomposites, the clay platelets accumulate in the P(S-BA) phase, while in the P(S-BA)/PVC nanocomposites, clay is also found at the interfaces. In the NR/starch blend, clay concentrates at the interface, but it also penetrates the two polymer phases. These observations reveal that nanostructured soft materials can display complex morphochemical patterns that are discerned thanks to the ability of EFTEM to produce many contrast patterns for the same sample.

Morphology, mechanical properties, and thermal stability of rigid PVC/clay nanocomposites

AbstractPVC/Poly(ε‐caprolactone) (PCL)/organophilic‐montmorillonite (OMMT) and PVC/Polylactide (PLA)/OMMT nanocomposites were prepared by a two‐step process. PCL/OMMT and PLA/OMMT master batches were prepared by melt blending using a two‐roller mill first, and then they were blended with PVC via extrusion. PVC/OMMT nanocomposites were also prepared using a two‐roller mill. Morphology, mechanical properties, and thermal stability were investigated. The formation of exfoliated or intercalated nanocomposites was confirmed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Only the PVC/PCL/OMMT nanocomposite showed both higher tensile strength and stiffness than unfilled PVC. Atomic force microscopy (AFM) indicated dependency of this behavior not only on the clay dispersion, but also on the adhesion between the OMMT and the polymer matrix. Furthermore, scanning electron microscopy (SEM) showed that the large plastic deformation of the PVC/PCL matrix also contributed to the strength increase of the PVC nanocomposites. The effect of PCL/OMMT on the improvement of the thermal stability of PVC was remarkable while the effect of PLA/OMMT was moderate. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.

Performance properties of pigmented polyvinyl chloride nanocomposites

This work highlighted the role of blue CoO·MgO·Al 2O 3 pigments in changing some properties of PVC composites such as electrical, mechanical and thermal properties. The pigments were prepared by doping different ratios of magnesium in cobalt aluminate crystals using solid–solid interaction. The prepared pigments were characterized by different instrumental analysis (e.g. XRD, SEM and TEM). The influences of different concentrations of nanosized CoO·MgO·Al 2O 3 pigment on PVC prepared by solution blending were studied. The obtained data revealed that PVC nanocomposites containing 1CoO·1MgO·Al 2O 3 pigments show the most promising results. The composites containing 5 wt% of the three compositions of pigments exhibit the optimum electrical, mechanical as well as thermal properties. The relation between tan δ and temperature indicates that T g is not affected by increasing pigment content till 5 wt%, after this concentration, it begins to shift towards higher temperatures. The above investigation led to a conclusion that the optimum recommended concentration of 1CoO·1MgO·Al 2O 3 pigments is 5 wt%. This finding was confirmed by TEM micrographs indicated that inspite that the pigments were prepared in the nano-scale, they tend to agglomerate in the composite reaching the micron-size.

Rheological behavior and mechanical properties of PVC/MAP‐POSS nanocomposites

AbstractThe polyhedral oligomeric silsesquioxanes which contains methylacryloylpropyl groups (MAP‐POSS) was synthesized. The MAP‐POSS/PVC nanocomposites were prepared. The influences of composition, shear rate' shear stress on melting rheological behavior of MAP‐POSS/PVC nanocomposites were discussed. The dynamic mechanical properties, mechanical properties, and morphology were determined by DMA, material tester and SEM, respectively. The result shows that the plastic times decreases and melt viscosity increases with increasing MAP‐POSS content. The n has a maximal value at 5 wt% MAP‐POSS content, but have best impact strength at 3%. MAP‐POSS can use as process aid and impact aid of PVC at appropriate contents. POLYM. COMPOS., 31:1822–1827, 2010. © 2010 Society of Plastics Engineers.

Preparation of Modified Montmorillonite with Benzethonium and Benzalconium Chloride for Nanocomposites Preparation

Modified clays were intercalated with benzethonium chloride and benzalkonium chloride by exchanging the sodium ions. The organoclays obtained were characterized by X-ray diffraction (XRD); thermogravimetric analysis (TGA) and low field nuclear magnetic resonance (NMR), through proton spin-lattice relaxation time measurements (T1H). From the characterization data, the formation of organically modified clays was confirmed. These products can probably be used to prepare PVC nanocomposites with superior processing characteristics due to better chemical structure of clay surfactants.

Preparation, Characterization and Properties of Poly(vinyl chloride)/CaSO4 Nanocomposites

Poly(vinyl chloride)/CaSO4 nanocomposites were prepared on Brabender plasticorder. Moreover, for comparison PVC/ commercial CaSO4 composites was prepared. The amount of loadings of nano CaSO4 and commercial CaSO4 was in the range of 0–12 wt%. Nano CaSO4 was synthesized by matrix-mediated growth technique. The size and shape of nano CaSO4 were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). These PVC nanocomposites were then subjected to mechanical, thermal analysis on UTM, and TGA respectively. Morphology studies of PVC nanocomposites were done on scanning electron microscope (SEM). The morphology study showed that nano CaSO4 get exfoliated and intercalated with the PVC matrix. Notched Charpy impact strengths of PVC nanocomposites was drastically improved compared to that of pristine PVC and commercial CaSO4 composites. PVC/CaSO4 nanocomposites showed higher values of tensile strength, elongation at break and impact strength than PVC/CaSO4 (commercial) composites. Impact strengths also gives some drastic dependence on nano CaSO4 content and give a maximum value at certain CaSO4 loadings.

Effect of montmorillonite treatment on the thermal stability of poly(vinyl chloride) nanocomposites

The aim of this research was to study the effect of different intercalants on the thermal degradation/dehydrochlorination of poly(vinyl chloride) (PVC). PVC nanocomposites were prepared containing 2 phr of montmorillonite clay. The montmorillonite was treated with different organic intercalants and analysed by thermogravimetric analysis and X-ray diffraction. All intercalants were found to intercalate the clay. The nanocomposites were prepared on a two-roll mill and pressed into 0.7 mm thick plates. The degradation was analysed by yellowness index, Congo red test and UV–visible spectroscopy. All cationic intercalants were found to accelerate the dehydrochlorination of PVC whereas the non-ionic did not affect thermal degradation. On the other hand, some non-ionic intercalants showed poor dispersion.

Rigid PVC/(layered silicate) nanocomposites produced through a novel melt‐blending approach

AbstractOn the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+‐MMT) and organically modified montmorillonite (Org.‐MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X‐ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+‐MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.‐MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers

Latest advancements in PVC/clay nanocomposites: potential applications in plastisols

A PVC nanocomposite has been obtained by exploiting the exfoliation of Na–bentonite in water and the fact that vinyl chloride is usually polymerised as a water suspension or emulsion. An exfoliated clay aqueous dispersion is prepared and blended with PVC latex before the latter is dried, leading to intimate mixing and the desired morphology. The nanocomposite has useful properties in PVC paste applications, exhibiting shear thinning rheology, improved thermal stability and transparency. Possible applications are mainly for plasticised PVC but also rigid applications such as pipes, profiles or films. The PVC nanocomposite also shows good dispersion in plasticiser and may be used instead of a paste resin, so extending the range of PVC pastes towards very high plasticiser ratios. These plastisols have been shown to be more stable against sedimentation or decantation during storage and very soft articles can be produced by coating technologies. The very high low shear viscosities make it possible to produce thick films in only one coating step.

PVC nanocomposites—Nanoclay chemistry and performance

AbstractNanoclay applications in poly(vinyl chloride) (PVC) have been limited, as the organic modifier of conventional nanoclays can promote PVC degradation. Novel nanoclays designed for enhanced PVC compatibility were compounded with PVC. Hectorite and bentonite clays were studied as nanoclay fillers. Two incorporation methods were evaluated to determine the effect on nanoclay dispersion and composite performance. A two‐stage method, in which the nanoclay was predispersed in plasticizer, resulted in good nanoclay dispersion at both the micrometer and nanometer scales. The nanocomposites were characterized by using a wide range of analytical tools. They exhibited significantly improved heat stability, an increase of up to 200% in storage modulus, and a decrease of up to 77% in oxygen permeation, as compared to unfilled PVC. Bentonite nanoclays provided a greater increase in barrier and mechanical properties. No change was seen in the PVC glass transition temperature. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers

Effect of flexibility of grafted polymer on the morphology and property of nanosilica/PVC composites

In this study, poly(methyl methacrylate)-grafted-nanosilica (PMMA-g-silica) and a copolymer of styrene (St), n-butyl acrylate (BA) and acrylic acid (AA)-grafted-nanosilica (PSBA-g-silica) hybrid nanoparticles were prepared by using a heterophase polymerization technique in an aqueous system. The grafted polymers made up approximately 50 wt.% of the resulted hybrid nanoparticles which showed a spherical and well-dispersed morphology. The silica hybrid nanoparticles were subsequently used as fillers in a poly(vinyl chloride) (PVC) matrix to fabricate PVC nanocomposite. Morphology study of PVC nanocomposites revealed that both PMMA- and PSBA-grafted-silica had an adhesive interface between the silica and PVC. The tensile strength and elongation to break were found to be improved significantly in comparison with that of untreated nanosilica/PVC composites. Finally our results clearly demonstrated that the properties (e.g. chain flexibility, composition) of the grafted polymer in the hybrid nanoparticles could significantly affect the dispersion behavior of hybrid nanoparticles in PVC matrix, dynamic mechanical thermal properties and mechanical properties of the resulted PVC composites.

Flame Retardancy of Tpu and Pvc Nanocomposites

Flame Retardancy of Tpu and Pvc Nanocomposites

Preparation and characterization of poly(vinyl chloride)/layered double hydroxides nanocomposite via in situ suspension polymerization

AbstractPoly(vinyl chloride)/layered double hydroxides (PVC/LDHs) composite resins were prepared by in situ suspension polymerization of vinyl chloride monomer in the presence of LDHs intercalated with dodecyl sulfate anions (LDH‐DS), and were further processed to obtain PVC/LDH‐DS nanocomposites. It was found that the mean particle size of PVC composite resins decreased as LDH‐DS was added in the polymerization system. The 5 and 10% weight loss temperatures of PVC resins significantly increased with the increase of LDH‐DS weight fraction in the composite resins. The transmission electron microscopy images showed that LDH‐DS particles were partially intercalated and partially exfoliated, and well distributed in the PVC nanocomposites. The storage modulus below the glass transition region and the glass temperature of the PVC/LDH‐DS nanocomposites are greater than that of the pristine PVC. The mechanical properties of PVC/LDH‐DS nanocomposites indicate that LDH‐DS nanoparticles stiffen and toughen PVC. The tensile strength, Young's modulus, and Charpy notched impact strength of the PVC/LDH‐DS nanocomposites are greater than those of the pristine PVC and PVC/LDH‐DS composites prepared by the melt blending. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1471–1477, 2006