High-impact Polystyrene Nanocomposites Research Articles

Sol–gel synthesis and physical characterization of high impact polystyrene nanocomposites based on Fe2O3 doped with ZnO

Manufacturing of organic–inorganic composites with enhanced properties particularly, Fe2O3–ZnO/high impact polystyrene (HIPS) nanocomposites promising candidates for many requests. The presence of nanoparticles enhances the structural, thermal, and chemical stabilities, mechanical and operational performance of the nanocomposite matrices. Modified HIPS nanocomposites based on Fe2O3 doped by (0.0–0.6) ZnO were synthesized using the sol–gel method and gel casting approach. The structures, spectroscopic, dielectric and mechanical properties of the synthesized polymeric nanocomposites were investigated by XRD, TEM, FT-IR, UV–vis-DRs, terahertz (THz), dielectric and mechanical analysis. From chemical structural results, it can be confirmed the existence of ZnO in Fe2O3 and the internal structure rearrangement of iron oxide before dispersion into the HIPS matrix. The UV–Vis DRs show that the optical band gap decreases significantly with the increase of ZnO content in the nanocomposite. THz spectra in the spectral range of 0.2–2.5 THz showed an increase in the refractive indices and absorption coefficients for the prepared nanocomposites. Besides, the mechanical properties were affected by the addition of ZnO to HIPS-Fe2O3 where the elongation at break %, Young’s modulus, and maximum strength varied values relying on the applied ratio of ZnO especially for the ratio of 0.4. Finally, the produced nanocomposites can find widespread applications in optoelectronic, chemical, and biological applications besides their feasibility to apply on a large scale.

Study on the flame retardancy of high impact polystyrene composites filled with organic-modified carbon nanotubes

ABSTRACTCarbon nanotubes (CNTs) were organic modified by the synthesized flame retardant (FR) named as spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride/10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (SPDH). CNTs-g-SPDH with a core-shell microstructure was successfully obtained, and its grafting efficiency was calculated to be about 65%. Effects of pristine CNTs and modified CNTs on flame retardation, structure and mechanical properties of high impact polystyrene (HIPS) were investigated. Cone calorimeter results showed that the heat release rate (HRR) and smoke production rate (SPR) of HIPS nanocomposites filled with CNTs or CNTs-g-SPDH were reduced. Moreover, addition of CNTs-g-SPDH resulted in better charring performance than that of pristine CNTs. Modification of CNTs improved compatibility and dispersion in the polymer matrix. Mechanical measurements showed that the Young’s modulus increased, while the tensile strength and elongation at break decreased. The negative effect of CNTs-g-SPDH on tensile strength of HIPS resin was obviously minimized by organic modification of CNTs.

Estimation of Mechanical Performance, Thermal Stability and Flame Retardancy of High-Impact Polystyrene/Surface-Modified APP/Carboxylic-Functionalized MWCNTs Nanocomposites.

An ammonium polyphosphate (APP) surface-modified by silane coupling agent was used as flame retardant in high-impact polystyrene (HIPS). A series of HIPS nanocomposites containing different mass fractions of APP (k-APP) surface-modified by silane coupling agent (3-aminopropyl triethoxysilane, KH 550) and carboxylic-functionalized MWCNTs (COOH–MWCNTs) were prepared by the melt blending method. A composite only containing APP was also prepared as a reference material. Scanning electron microscopy (SEM) was employed to investigate the dispersion of the fillers into the HIPS matrix, and it was found the hydrophobic groups on the k-APP surface would greatly enhance the dispersion and prevent agglomerations compared with APP. Furthermore, the COOH–MWCNTs also showed good dispersibility into the matrix. Mechanical tests of the nanocomposites revealed that k-APP exhibits a more beneficial effect on both tensile and flexural properties compared with APP. Thermogravimetric analysis (TGA) and cone calorimeter tests (CCT) were conducted to probe the thermal and flammability properties of the nanocomposites, respectively. The synergistic effects of k-APP and COOH–MWCNTs on mechanical, thermal and flammability properties were examined as well.

Influence of nanoparticle geometry on the thermal stability and flame retardancy of high-impact polystyrene nanocomposites

Nanocomposites of high-impact polystyrene (HIPS) with three types of nanoparticles, namely layered organically modified montmorillonite (OMMT), tubular multi-walled carbon nanotubes (MWNTs) and spherical silica nanoparticles, were prepared by melt blending method. The influence of nanoparticle geometry on the thermal stability and flame retardancy of HIPS nanocomposites was investigated by transmission electron microscopy, thermo-gravimetric analysis, cone calorimeter method and scanning electron microscopy. The results show that the presence of three types of nanoparticles with varying geometries does not change the degradation mechanism of the nanocomposites, but greatly decreases the heat release rate and mass loss rate of the materials due to the fire residue formed in the condensed phase. The layered structure of OMMT exhibits the best flame-retarded effect, and the tubular structure of MWNT obtains a weaker flame-retarded effect and the spherical structure of silica nanoparticles the weakest. The effectiveness of flammability reduction is varied with nanoparticle geometries due to the discrepancies in featured structures of fire residues formed in real fire conditions. The idealized models of the featured structures of fire residues from the nanocomposites studied are put forward to explain the flame-retardant mechanism of the nanoparticles with different geometries.

Kinetic Study of Thermal Degradation of High-impact Polystyrene Nanocomposites with Different Flame Retardants using Isoconversional and Model Fitting Methods

The non-isothermal degradation of pure high- impact polystyrene (HIPS) and flame retarded HIPS nanocomposites was investigated in the temperature range 25–550 °C at four heating rates in an inert atmosphere. Three different phosphate and polyphosphate based flame retardants were used, while nanosilica and montmorillonite clay were used as nanofillers. Kinetic analysis was performed using isoconversional and model fitting non-linear regression method. Activation energy (Ea) was determined by isoconversional methods of Friedman and Kissinger- Akahira-Sunose while true kinetic triplets (Ea, A, f(α)) were determined by one step and two-step non-linear regression with various reactions mechanisms. It was found that flame retarded samples exhibit complex degradation which cannot be satisfactorily described by single reaction model fitting. Instead, when each distinctive degradation step was modelled individually it was possible to obtain good fit with Reaction order and Avrami-Erofeev proposed mechanisms while the same was not possible for Diffusion and Autocatalytic mechanisms

Flame retardant and smoke suppression mechanism of multi-walled carbon nanotubes on high-impact polystyrene nanocomposites

Nanocomposites of high-impact polystyrene (HIPS) with multi-walled carbon nanotubes (MWNT) were prepared by melt blending method. The flame retardant and smoke suppression mechanism of MWNT on HIPS were intensively investigated by transmission electron microscopy (TEM), thermogravimetric (TG) analysis, cone calorimeter method, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that the addition of MWNT has no marked effect on the degradation mechanism of the nanocomposites, but it significantly reduces the smoke production rates, total smoke release, smoke factor, heat release rates and mass loss rates of the material and forms a considerable volume of residue after burning. The flame retardant and smoke suppression mechanism are due to the formation of residue with featured structure during combustion. The fine morphology of the residues for the composites showed that the residues of HIPS/MWNT nanocomposites assume a two-layer structure in sub-microscale and micro network structure in nanoscale. The two-layer structure includes a thin skin layer at the surface of the residue and an expanded cellular layer beneath the skin layer. It is the skin-cellular layer structure which considerably enlarges the thickness and volume of residue. Both the skin layer and cellular layer are constituted of MWNT, which are interconnected to form a network-like structure in nanoscale. It is a well combination of the skin-cellular layer and the nanoscale network structure that acts as a good insulation barrier to reduce flammability and smoke production of the composites.

Improved flame-retardant properties of HIPS/ATH system by organo Fe-montmorillonite

High-impact polystyrene nanocomposites (HIPS) with aluminium trihydroxide (ATH) and organo-modified Fe-montmorillonite (Fe-OMT) were prepared by melting intercalation. The nanocomposite structures were characterized by X-ray diffraction and transmission electron microscopy. The results show that the intercalated and exfoliated nanocomposites were formed. Accordingly, the thermal stability and flame-retardant properties were evaluated by thermogravimetric analysis, limiting oxygen index, UL94 and the cone calorimeter test. The results indicated that the nanocomposites had excellent thermal stability and the char yield was also improved. When 4 wt% organo-modified Fe-MMT was added in the HIPS/ATH (46 wt%) composites, the nanocomposites were able to achieve UL94 V-0 grade. The heat release rate, total heat release, and mass loss rate of the nanocomposites were reduced. Furthermore, the addition of Fe-OMT could further improve the smoke suppression property of HIPS composites. The improved flame-retardancy caused by Fe-OMT in the HIPS/ATH matrix maybe due to a reinforced char layer which prevents the diffusion of the oxygen and decomposed organic volatiles in the flame during combustion.

Improved flame-retardant properties of HIPS/ATH system by organo Fe-montmorillonite

High-impact polystyrene nanocomposites (HIPS) with aluminium trihydroxide (ATH) and organo-modified Fe-montmorillonite (Fe-OMT) were prepared by melting intercalation. The nanocomposite structures were characterized by X-ray diffraction and transmission electron microscopy. The results show that the intercalated and exfoliated nanocomposites were formed. Accordingly, the thermal stability and flame-retardant properties were evaluated by thermogravimetric analysis, limiting oxygen index, UL94 and the cone calorimeter test. The results indicated that the nanocomposites had excellent thermal stability and the char yield was also improved. When 4 wt% organo-modified Fe-MMT was added in the HIPS/ATH (46 wt%) composites, the nanocomposites were able to achieve UL94 V-0 grade. The heat release rate, total heat release, and mass loss rate of the nanocomposites were reduced. Furthermore, the addition of Fe-OMT could further improve the smoke suppression property of HIPS composites. The improved flame-retardancy caused by Fe-OMT in the HIPS/ATH matrix maybe due to a reinforced char layer which prevents the diffusion of the oxygen and decomposed organic volatiles in the flame during combustion.

Preparation of high-impact polystyrene nanocomposites with organoclay by melt intercalation and characterization by low-field nuclear magnetic resonance

Recycled high-impact polystyrene nanocomposites with organoclay were prepared. Clay of the smectite group (montmorillonite) with two types of intercalated compounds was used (Viscogel S4 and Viscogel S7). The polymer nanocomposites were prepared by melt intercalation, applying two shear intensities in a twin screw extruder. The nanostructured materials obtained were characterized by NMR relaxometry, X-ray diffraction, thermogravimetric analysis, melt flow index and mechanical analyses. The results showed that the nanostructured materials presented a mixed intercalated/exfoliated morphology. The organophilic clay, Viscogel S7, generated polymer nanocomposites with better dispersion and distribution (at low concentrations) than those produced with the Viscogel S4. The shear rate was effective for dispersion of the nanoparticles. The materials processed at 600rpm showed better dispersion than those processed at 450rpm. The characterization techniques chosen were effective. They were complementary and permitted comparison among the polymer nanocomposites. The use of low-field NMR relaxometry allowed measurement of the spin–lattice relaxation time of hydrogen (T1H), which provided more precise information on the mobility of the materials, thus complementing and explaining the results obtained by X-ray diffraction.

Nano-Calcium carbonate (CaCO3)/Polystyrene (PS) core-shell nanoparticle: It’s effect on physical and mechanical properties of high impact polystyrene (HIPS)

Rheological, thermal, mechanical and morphological properties of core-shell [Calcium carbonate (CaCO3)/Polystyrene (PS)]/High impact polystyrene (HIPS) as well as bare nano-CaCO3/HIPS nanocomposites with different wt% loading were investigated in this paper. All composites were prepared individually by incorporating nano-CaCO3/PS hybrid nanoparticles and bare nano-CaCO3 with 0.10–5.0 wt% loading on Brabender Plastograph. It was shown from the experimental results that rheological, thermal, mechanical and morphological properties were improved as hybrid nano-CaCO3/PS particles reinforced in HIPS matrix. The interaction between nano-CaCO3 particles and HIPS matrix was significantly improved when the nano-CaCO3 nanoparticles were grafted with PS. FESEM (field emission scanning electron microscope) and AFM (atomic force microscope) images showed a perfect dispersion of nano-CaCO3 particles in polypropylene (PP) matrix.

The effects of processing and using different types of clay on the mechanical, thermal and rheological properties of high-impact polystyrene nanocomposites

High-impact polystyrene (HIPS) nanocomposites were prepared by melt compounding two grades of organoclays (Cloisite 10A (C10A) and Cloisite 30B (C30B)) in a Haake internal mixer or a corotating twin screw extruder. The nanocomposites were characterized by transmission electron microscopy, small-angle X-ray diffraction, thermogravimetric analysis, rheometer analysis and tensile and impact testing. The correlation between the morphological and the rheological properties of the nanocomposites was also investigated. As the exfoliation of the samples processed by the twin screw extruder was greater than the exfoliation of the samples processed by the Haake internal mixer, the extruded samples were of better quality than the samples subjected to internal mixing. Furthermore, the HIPS nanocomposite material that was prepared with C10A showed better mechanical properties and thermal stability than the HIPS nanocomposite material that was prepared with C30B. By increasing the clay content, it was observed that the zero shear viscosity increased, whereas the initial slope of the storage modulus decreased. A high degree of clay dispersion was obtained for HIPS samples containing a concentration of 2 wt% C10A with an aspect ratio of 177.1, whereas the exfoliated nanocomposite material had an aspect ratio of approximately 300.

Study of flammability and thermal properties of high-impact polystyrene nanocomposites

To increase thermal stability and flammability of high-impact polystyrene (HIPS) nanocomposites with silica nanoparticles and two types of polyphosphate flame retardants were prepared by extrusion. Nanocomposites were characterized by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, limiting oxygen index (LOI) analysis and the evaluation of mechanical properties. It was found that organic polyphosphate in combination with silica increased thermal stability and fire retardancy by 50% in LOI test. Morphology characterization revealed existence of crystalline order which affected mechanical properties; tensile strength was approximately the same as virgin HIPS while elasticity was sharply decreased. Ammonium polyphosphate did not affect mechanical properties as much as the organic material but was not equally efficient in flame retardancy which was just marginally increased.

Comparison Between Effects of Two Different Cationic Surfactants on Structure and Properties of HIPS/OMT Nanocomposites

The high impact polystyrene (HIPS)/organophilic montmorillonite (OMT) nanocomposites were prepared by melt-mixing. The hexadecyl triphenyl phosphonium bromide (P16) and cetyl pyridium chloride (CPC) were used to modify montmorillonite (MMT). The structure and thermal stability property of the OMT were respectively characterized by Fourier transfer infrared (FTIR) spectra, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results indicated that the cationic surfactants intercalated into the gallery of the MMT and the OMT had higher thermal stability. The influences of two different OMT on the structures and properties of the HIPS nanocomposites were characterized by XRD, TGA, Cone calorimeter and dynamic mechanical analysis (DMA), respectively. The increased basal spacing showed that HIPS intercalated into the gallery of the OMT. The TGA showed that onset temperature of thermal degradation, temperature of maximal weight loss and char residue at 700°C of the HIPS nanocomposites had remarkable enhancements compared to pure HIPS. The Cone calorimeter tests showed that the peak of heat release rate (PHRR) decreased significantly. The DMA indicated that the loading of silicate clays improved the storage modulus of HIPS.

Study on the combustion behavior of high impact polystyrene nanocomposites produced by different extrusion processes

The combustion behavior of a blend made of high impact polystyrene (HIPS) with sodium montmorillonite (MMT-Na+) and triphenyl phosphite (TPP), as a halogen-free flame retardant, is analyzed in detail in this work. The blend is processed through various extrusion methods aimed to improve clay dispersion. The UL94 method in vertical position, oxygen index and cone calorimetric measurements assess HIPS blend behavior in combustion. TGA, FTIR, SEM and X-ray measurements, together with mechanical and rheological tests evaluate the thermal degradation, morphology, intercalation and degree of dispersion of particles. The use of a static-mixing die placed at the extreme of a single screw extruder improves clay platelets distribution and reduces the peak heat release rate better than employing a twin screw extrusion process. In addition, mechanical and rheological properties are affected substantially by changing the extrusion process. A correlation between clay dispersion and HIPS fire retardant properties is found, as the peak heat release rate decreases with good clay dispersion in cone calorimetric tests.

Unusual Extensional Rheology and Dispersion Behavior of High Impact Polystyrene/TiO2 Nanocomposites Prepared by Melt‐Compounding

The extensional rheology and dispersion behavior of high impact polystyrene (HIPS) and HIPS/TiO2 nanocomposites prepared by melt‐compounding were investigated. The influence of ethylene‐vinyl acetate (EVA) copolymer on the extensional rheology of HIPS/TiO2 masterbatches was also researched. The rheological experiments investigated with Rosand Presicion Rheometer confirmed that the HIPS/TiO2 masterbatches, the HIPS/EVA/TiO2 masterbatches and the HIPS/TiO2 nanocomposites with low TiO2 loading shown different extensional rheology in comparison to the pure HIPS. Field‐emission scanning electron microscopy (FE‐SEM) shown the dispersion morphology of TiO2 nanoparticles in HIPS based nanocomposites and indicated the influence of TiO2 dispersion behavior on the unusual extensional rheology of HIPS nanocomposites.

Styrenic nanocomposites prepared using a novel biphenyl-containing modified clay

Montmorillonite was organically modified using an ammonium salt containing 4-acetylbiphenyl. This clay (BPNC16 clay) was used to prepare polystyrene (PS), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) nanocomposites. Polystyrene nanocomposites were prepared both by in situ bulk polymerisation and melt blending processes, while the ABS and HIPS nanocomposites were prepared only by melt blending. X-ray diffraction and transmission electron microscopy were used to confirm nanocomposite formation. Thermogravimetric analysis was used to evaluate thermal stability and the flammability properties were evaluated using cone calorimetry. By thermogravimetry, BPNC16 clay was found to show high thermal stability, and by cone calorimetry, a decrease in both the peak heat release rate and the mass loss rate was observed for the nanocomposites.

Exfoliated high-impact polystyrene/MMT nanocomposites prepared using anchored cationic radical initiator–MMT hybrid

High-impact polystyrene (HIPS)/montmorillonite (MMT) nanocomposites were prepared via in-situ polymerization of styrene in the presence of polybutadiene, using intercalated cationic radical initiator–MMT hybrid. Incomplete exfoliation of the silicate layers in the HIPS nanocomposites was observed when a bulk polymerization was employed. On the other hand, the silicate layers were efficiently exfoliated in the PS matrix during a solution polymerization, due to the low extra-gallery viscosity, which can facilitate the diffusion of styrene monomers into the clay layers. The resulting exfoliated HIPS/MMT nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, particle size analysis, gel permeation chromatography, and dynamic mechanical analysis. The nanocomposites exhibited significant improvement in thermal and mechanical properties. For example, about 50% improvement in Young’s modulus was achieved with 5 wt% of clay, compared to the unmodified polymer counterpart.