Poly1‐hexene: New impact modifier in HIPS technology

Poly1‐hexene was prepared using a conventional heterogeneous Ziegler–Natta catalyst and its stereoregularity was characterized using ¹³C‐NMR analysis. New kind of high impact polystyrene (HIPS) was prepared by radical polymerization of styrene in the presence of different amounts of synthesized poly1‐hexene (PH) as impact modifier (HIPS/PH) and compared with conventional high impact polystyrene with polybutadiene (HIPS/PB) as rubber phase. Scanning electron microscopy (SEM) revealed that the dispersion of poly1‐hexene in polystyrene matrix was more uniform compared with it in HIPS/PB. The impact strength of HIPS/PH was 29–79% and 80–289% higher than that in HIPS/PB and neat polystyrene, respectively. FTIR was used to confirm more durability of HIPS/PH samples toward ozonation. To study the effect of rubber type and amount on the T_gs of polystyrene, differential scanning calorimetry was employed. Results obtained from TGA demonstrated higher thermal stability of HIPS/PH sample in comparison with conventional HIPS/PB one. Our obtained results suggest new high impact polystyrene that in all studied aspects has better performance than the conventional HIPS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43882.     

Dynamic mechanical and thermal properties of fire-retardant high-impact polystyrene

The interaction of a series of fire-retardant additives with high-impact polystyrene (HIPS) has been inferred from their dynamic mechanical and thermal properties. High-melting additives phase separate and act as inert filler in both the rubber and polystyrene phases, while low-melting additives raise the T_g of the rubber phase and plasticize the polystyrene phase. Antimony oxide antiplasticizes the grafted rubber phase but acts as inert filler in the polystyrene phase. The impact strength of these fire-retardant HIPS's shows good correlation with the integrated loss tangent of the rubber T_g peak indicative of large energy dissipation in the rubbery region during impact causing the matrix to craze or flow. It is also suggested that additives which are compatible with, and localized in, the polystyrene phase help retain the impact strength of HIPS.     

Application of magnetic resonance techniques in investigation of hydrocarbons interaction with composite polymers

Composite polymers such as high impact poly stirene (HIPS) or acrylonitrile–butadiene–styrene (ABS) are widely used in manufacturing industry. In special applications, such as refrigerator liners, a good resistance to fluids aggression is required. In this study we have applied NMR and ESR techniques to investigate the effect of diffusion of fluids (light hydrocarbons) used as blowing agents for polyurethanes (thermal insulators) inside selected HIPS materials. The application of NMR relaxation analysis on materials exposed to deuterated hydrocarbons (C₆D₁₂) allowed selective observation of rubber phase modification. Both longitudinal (T₁) and transversal (T₂) relaxation provided information on polymer chain dynamics effects, determined by solvent interactions. In fact, a consistent increase in relaxation times of polybutadiene rubber phase after solvent exposition was observed. Similar results were obtained by using hexachlorobutadiene as solvent. Another confirmation was also obtained by spin‐probe ESR technique. This technique could give useful insight into the molecular mobility of the two phases of HIPS. This experimental investigation provided a clear demonstration of consistent solvent penetration inside the rubbery phase of such composite polymers. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2810–2817, 2006     

Phase morphologies and mechanical properties of high‐impact polystyrene (HIPS) and polycarbonate blends compatibilized with polystyrene and polyarylate block copolymer

Phasemorphology and mechanical properties of blends of high‐impact polystyrene (HIPS) and polycarbonate (PC) blends compatibilized with a polystyrene (PS) and polyarylate (PAr) (PS–PAr) block copolymer were investigated. Over a broad range of composition from 50/50 through 30/70, HIPS/PC blends formed cocontinuous structures induced by the flow during the extrusion or injection‐molding processes. These cocontinuous phases had heterogeneity between the parallel and perpendicular directions to the flow. The micromorphology in the parallel direction to the flow consisted of stringlike phases, which were highly elongated along the flow. Their longitudinal size was long enough to be longer than 180 μm, while their lateral size was shorter than 5 μm, whereas that in the perpendicular direction to the flow showed a cocontinuous phase with regular spacing due to interconnection or blanching among the stringlike phases. The PS–PAr block copolymer was found to successfully compatibilize the HIPS/PC blends. The lateral size of the stringlike phases could be controlled both by the amount of the PS–PAr block copolymer added and by the shear rate during the extrusion or injection‐molding process without changing their longitudinal size. The HIPS/PC blend compatibilized with 3 wt % of the PS–PAr block copolymer under an average shear rate of 675 s^?1 showed a stringlike phase whose lateral size was reduced almost equal to the rubber particle size in HIPS. The tensile modulus and yield stress of the HIPS/PC blends could be explained by the addition rule of each component, while the elongation at break was almost equal to that of PC. These mechanical properties of the HIPS/PC blends can be explained by a parallel connection model independent of the HIPS and PC phases. On the other hand, the toughness factor of the HIPS/PC blends strongly depended on the lateral size of the stringlike phases and the rubber particle size in the HIPS. It was found that the size of the string phases and the rubber particle should be smaller than 1.0 μm to attain a reasonable energy absorbency by blending HIPS and PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2347–2360, 2001     

Novel methods for synthesis of high‐impact polystyrene with bimodal distribution of rubber particle size

By using in situ prepolymerization and radiation curing, high‐impact polystyrene (HIPS) with a bimodal distribution of the size of the rubber particles (bimodal HIPS) was synthesized in the presence of ultrafine full‐vulcanized powdered styrene–butadiene rubber (UFPSBR) and polybutadiene rubber (BR). TEM photographs indicated that UFPSBR was dispersed uniformly as a single particle with a diameter of about 100 nm. On the other hand, bimodal HIPS with different rubber particle size distributions could also be obtained by blending HIPS and UFPSBR grafting styrene (UFPSBR‐g‐St) with different grafting yields. The bimodal HIPS with the smallest rubber particle size, at about 100 nm, could be prepared by blending the monomodal HIPS containing big rubber particles with polystyrene/UFPSBR. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Toughness enhancement of high‐impact polystyrene based on γ‐radiation vulcanized natural rubber latex by using block copolymer

Polyisoprene‐block‐polystyrene‐block‐polyisoprene (ISI) was synthesized by the iniferter route and its use, as compared to a commercial polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS), in the enhancement of the toughness of high‐impact polystyrene (HIPS), prepared by the γ‐radiation vulcanized natural rubber (RVNR) latex/phase transfer/bulk polymerization technique, was investigated. Addition of 5% SIS was adequate as an interfacial agent, which effectively increased the unnotched Izod impact energy of HIPS, whereas use of 10% of ISI was required. A long polyisoprene block with two polystyrene segments of SIS was favorable for compatibilization of HIPS. Transmission electron micrographs revealed the uniform distribution of the block copolymer at the shell region of the rubber particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1307–1316, 2002     

Toughness and morphology of radiation‐crosslinked natural rubber modified polystyrene

γ‐Radiation vulcanized natural rubber (RVNR)/phase transfer/suspension polymerization technique was used to prepare high‐impact polystyrene (HIPS) in bead form. The high notched Izod impact resistance of HIPS based on RVNR was observed and compared with that of unmodified PS. The impact resistance of HIPS based on RVNR was further enhanced by addition of 10% of polystyrene‐block‐polyisoprene‐block‐polystyrene copolymer. A mesh structure of all crosslinked rubber particles containing polystyrene and long crazes in HIPS were observed under electron microscopy. Copyright © 2003 Society of Chemical Industry     

Synthesis and mechanical properties of high impact polystyrene with in situ bulk polymerization toughened by one‐pot Nd‐based styrene–isoprene–butadiene terpolymer rubber

High impact polystyrene (HIPS) resins were obtained with in situ bulk polymerization toughened by styrene–isoprene–butadiene terpolymer rubber (SIBR). SIBR prepolymer was prepared through selective polymerization of styrene (St), isoprene (Ip), and butadiene (Bd) in St with [Nd]/[Al]/[Cl] catalyst. Nd‐based catalyst exhibited more favorable activity toward conjugated diene other than St, resulting in St solution of random SIBR with high cis‐1,4 stereoregularity and low St content, which was directly exposed to the free radical polymerization of St to generate HIPS. Effect of toughened rubber and the initiators [difunctional (D2) and trifunctional (T3)] were examined to attain HIPS possessing mechanical properties as follow: impact strength, 0.9–24.8 kJ/m²; tensile strength, 16.0–27.5 MPa; and elongation at break, 7.4–107.0%. Increasing SIBR matrix in HIPS improved the impact strength and decreased tensile strength. The fracture surface morphologies of HIPS specimens were studied by notched impact tests and scanning electron microscopy (SEM), illustrating that the incremental SIBR matrix presented synergistic toughening effect of crazing to enhance the ductile fracture behavior. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43979.     

Effect of partitioning of monomer on the reactivities of monomers in microemulsion

Copolymerization of styrene and 2‐hydroxyethyl methacrylate (2‐HEMA) was carried out in a microemulsion medium. The composition of the copolymers was estimated using proton ¹H‐NMR. The reactivity ratios of styrene and 2‐HEMA in ternary microemulsions were observed and were considerable different from those reported for solution and bulk polymerization. In monomer pairs with a considerable difference in polarity, partitioning of a monomer between the aqueous phase and the microemulsion droplets develops a concentration gradient, which can be calculated from the distribution coefficient of the monomer between the two phases. This approach has led to more reliable reactivity ratios for the monomers. The study of styrene–2‐HEMA copolymerization in a sodium dodecylsulfate‐based microemulsion resulted in r_S = 3.79 and r_H = 0.17 as apparent reactivity ratios and r_S = 0.57 and r_H = 23.24 as true reactivity ratios for styrene and 2‐HEMA, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1832–1837, 2002; DOI 10.1002/app.10401     

Influence of small rubber particles on the environmental stress cracking of high impact polystyrene

This article exploits the influence of rubber particle size (RPS) and rubber crosslinking on environmental stress cracking resistance (ESCR) of high impact polystyrene (HIPS), with special interest on the influence of small rubber particles fraction. Three commercial HIPS of high ESCR were selected and four batches of HIPS were prepared in‐house, including samples based on high cis and very high viscosity polybutadiene (PB). Their morphologies were analyzed by low angle laser light scattering, optical microscopy, and transmission electron microscopy, and the samples were submitted to flexural ESCR tests with fatty agents. The ESCR to sunflower oil was found to increase with the reduction of the rubber particles fraction smaller than 1–2 micron. Results have also confirmed that an increase in RPS is the key parameter to promote ESCR, although there is limit for RPS to be effective on ESCR improvement. The reduction of small rubber particles fraction in HIPS was achieved by using a high cis PB, that promotes low grafting efficiency of polystyrene onto PB backbone because of the low content of 1,2 vinyl isomer. Besides the ESCR improvements, HIPS with high cis PB showed higher elastic modulus and impact resistance than HIPS containing medium cis PB, which is desired for thickness reduction in food packaging and refrigeration cabinets. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of absorbent polymers for the removal of volatile hydrophobic pollutants from air

BACKGROUND: An emerging innovation for the treatment of polluted air consists in using a liquid–solid biphasic system, in which the sequestering phase contains inert polymer beads. The different polymers tested here for this purpose were; Hytrel^® G3548L, Hytrel^® G4078W, styrene butadiene copolymer, 28% and 31%, silicone rubber, PEBAX^® 2533, and rubber tires. The selection of the most effective polymer(s) first requires a determination of the uptake of the pollutants by the solid phase in terms of key polymer properties such as partition coefficient, diffusion coefficient and biodegradability. RESULTS: A significant difference was found in the uptake levels of α‐pinene from the gas phase for the different polymers tested. Based on partition coefficient measurements, relatively non‐polar polymers such as Kraton^® tend to uptake α‐pinene better than polar ones, such as Hytrel^®. A reduction in the partition coefficient of α‐pinene into polymers in the presence of water has also been observed. It was also proven that the tested polymers are not biodegradable. CONCLUSIONS: The uptake of α‐pinene by the different polymers tested was determined and it was shown that such polymers could be used for air pollution control. Furthermore, their non‐biodegradability justifies their use as absorbents. This paper provides a new opportunity to work with biofilters (BFs)/biotrickling filters (BTFs) using polymers as a sequestering phase. Copyright © 2010 Society of Chemical Industry     

Blends of polyamide1010 with unmodified and maleic‐anhydride‐grafted high‐impact polystyrene

The crystallization behaviors, dynamic mechanical properties, tensile, and morphology features of polyamide1010 (PA1010) blends with the high‐impact polystyrene (HIPS) were examined at a wide composition range. Both unmodified and maleic‐anhydride‐(MA)‐grafted HIPS (HIPS‐g‐MA) were used. It was found that the domain size of HIPS‐g‐MA was much smaller than that of HIPS at the same compositions in the blends. The mechanical performances of PA1010–HIPS‐g‐MA blends were enhanced much more than that of PA1010–HIPS blends. The crystallization temperature of PA1010 shifted towards higher temperature as HIPS‐g‐MA increased from 20 to 50% in the blends. For the blends with a dispersed PA phase (≤35 wt %), the T_c of PA1010 shifted towards lower temperature, from 178 to 83°C. An additional transition was detected at a temperature located between the T_g's of PA1010 and PS. It was associated with the interphase relaxation peak. Its intensity increased with increasing content of PA1010, and the maximum occurred at the composition of PA1010–HIPS‐g‐MA 80/20. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 857–865, 1999     

Online monitoring of the influence of the chemical structure of hindered amines on the hydrolysis of polycarbonate in a polycarbonate/poly(acrylonitrile–butadiene–styrene) blend by ultraviolet–visible spectroscopy

Without stabilization, polycarbonate (PC)/poly(acrylonitrile–butadiene–styrene) (ABS) blends are susceptible to a loss of mechanical properties after a few days of exposure to weathering conditions. ABS can be stabilized against terrestrial light by the use of hindered amines in combination with a UV absorber; such hindered amines cannot be used when PC is present in the polymer blend. The hydrolysis of PC is accelerated when a small amount of a hindered amine light stabilizer (HALS) is incorporated into the resin and is exposed to elevated temperatures. In this study, three different HALSs (Tinuvin 123, Tinuvin 770, and Tinuvin 765, Ciba, Basel, Switzerland) were used as UV stabilizers for PC/ABS blends, and their effects on the PC phase were observed with online ultraviolet–visible spectroscopy on extruded flat films. These stabilizers were compounded with the blends in a corotating twin‐screw extruder at 240°C. The molecular weight of the compounded samples was determined by gel permeation chromatography. The extent of degradation induced by the HALSs on the PC phase was found to be a function of its chemical structure. Tinuvin 123 with an amino ether functional group enhanced degradation in comparison with Tinuvin 770 and Tinuvin 765. Tinuvin 770, a secondary amine, was apt to be more reactive than Tinuvin 765, a tertiary amine, because less steric hindrance was experienced by the former. Accelerated aging of the compounded samples was performed. Decreased degradation was observed for the samples containing hindered amines; however, the HALSs alone were not effective in protecting the PC/ABS blends against harmful UV light. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and mechanical properties of polypropylene/high‐impact polystyrene blends from postconsumer plastic waste

The compatibilizing effect of the triblock copolymer poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) on the morphological and mechanical properties of virgin and recycled polypropylene (PP)/high‐impact polystyrene (HIPS) blends was studied, with the properties optimized for rigid composite films. The components of the blend were obtained from municipal plastic waste, PP being acquired from mineral water bottles (PP_b) and HIPS from disposable cups. These materials were preground, washed only with water, dried with hot air, and ground again (PP_b) or agglutinated (HIPS). Blends with three different weight ratios of PP_b and HIPS (6:1, 6:2, and 6:3) were prepared, and three different concentrations of SEBS (5, 6, and 7 wt %) were used for investigations of its compatibilizing effect. Scanning electron microscopy showed that SEBS reduced the diameter of dispersed HIPS particles in the globular and fibril shapes and improved the adhesion between the disperse phase and the matrix. However, SEBS interactions with PP_b and HIPS influenced the mechanical properties of the compatibilized PP_b/HIPS/SEBS blends. An adequate composition of PP/HIPS, for both virgin and recycled blends, for applications in composite films with characteristics similar to those of synthetic paper was obtained with a minimal amount of SEBS and a maximal HIPS/PP ratio in the range of concentrations studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2861–2867, 2003     

Ionic mechanisms in pulse irradiated poly(vinyl chloride) system containing stabilizing additives

The pulse radiolysis studies of poly(vinyl chloride), PVC, film containing stabilizers i.e., Tinuvin P, Irgastab PVC 11, and Irganox 1076 have been carried out with the main aim of investigating ionic reactions in these systems. The evidences are presented concerning the formation of ionic transients in model solvents i.e. 2‐propanol and sec‐butyl chloride as well as in PVC film. In PVC‐stabilizer system under consideration the additives can contribute to the positive charge transfer processes whereas Tinuvin P, in addition may scavenge effectively electrons (the rate constant for e^?_solv scavenging in 2‐propanol equals 5.9 × 10⁹ mol^?1 dm³ s^?1) influencing the negative charge scavenging by PVC matrix itself and the HCl formation during the radiolysis of PVC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Deformation mechanism of polystyrene toughened with sub‐micrometer monodisperse rubber particles

Core–shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core‐shell rubber particles were then blended with polystyrene to prepare PS/PB‐g‐PS blends with a constant rubber content of 20 wt%. PB‐g‐PS particles with a lower PB/PS ratio (≤70/30) form a homogeneous dispersion in the polystyrene matrix, and the Izod notched impact strength of these blends is higher than that of commercial high‐impact polystyrene (HIPS). It is generally accepted that polystyrene can only be toughened effectively by 1–3 µm rubber particles through a toughening mechanism of multiple crazings. However, the experimental results show that polystyrene can actually be toughened by monodisperse sub‐micrometer rubber particles. Scanning electron micrographs of the fracture surface and stress‐whitening zone of blends with a PB/PS ratio of 70/30 in PB‐g‐PS copolymer reveal a novel toughening mechanism of modified polystyrene, which may be shear yielding of the matrix, promoted by cavitation. Subsequently, a compression‐induced activation method was explored to compare the PS/PB‐g‐PS blends with commercial HIPS, and the result show that the toughening mechanisms of the two samples are different. Copyright © 2006 Society of Chemical Industry     

Dynamic mechanical behavior of atactic and high‐impact polystyrene

Results of the dynamic mechanical behavior of atactic polystyrene (PS) and high‐impact polystyrene (HIPS) for temperatures between 300 and 425 K at a frequency of the order of 50 kHz are presented. The storage Young's modulus, (E′), of the HIPS is lower than the PS value, being the relationship between them a function of the rubber phase volume fraction, independent of the measurement frequency. The glass transition temperature (T_g) of HIPS is shifted to lower temperature in respect to the PS. The γ relaxation appears at 308 K in PS at 50 kHz, while it seems to move toward lower temperatures in the HIPS. Both shifts are attributed to the presence of mineral oils in the HIPS. The values of E′, T_g, and the temperature of the γ relaxation at 50 kHz are discussed within the scope of the theory of viscoelasticity. Finally, the effect of thermal treatments, using different annealing times, on the behavior of both materials is shown. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 865–873, 2000     

Effect of tensile strain rate on the mechanical properties of polystyrene and high-impact polystryene

The dependency of the mechanical properties (Young's modulus, maximum load, breaking strain, and breaking energy) of polystyrene (PS) and high-impact polystyrene (HIPS) on the tensile deformation speeds was examined without changing the mode of deformation or the shape of the test specimen. It was found that HIPS has an excellent mechanical balance compared with PS for both low (1.7 × 10^?4 to 2.9 × 10^?2 m/sec) and high (1.3–16m/sec) speeds. This is due to the following two mechanisms ( which have different time responses) originating from the dispersed rubber particles: (1) at low speeds, the generation of large numbers of microcrazes, and (2) at high speeds, tensile-orientation hardening of the rubber and cold-drawing of the PS matrix resulting from the rise in temperature accompanied by the abrupt eleongation of the rubber phases.     

13C‐NMR study on cure‐accelerated phenol–formaldehyde resins with carbonates

Both liquid‐ and solid‐state ¹³C‐NMR spectroscopies were employed to investigate the cure‐acceleration effects of three carbonates [propylene carbonate (PC), sodium carbonate (NC), and potassium carbonate (KC)] on liquid and cured phenol–formaldehyde (PF) resins. The liquid‐phase ¹³C‐NMR spectra showed that the cure‐acceleration mechanism in the PC‐added PF resin seemed to be involved in increasing reactivity of the phenol rings, while the addition of both NC and KC into PF resin apparently resulted in the presence of ortho–ortho methylene linkages. Proton spin‐lattice rotating frame relaxation time (T_1ρH) measured by solid‐state ¹³C‐CP/MAS‐NMR spectroscopy was smaller for the cure‐accelerated PF resins than for that of the control PF resin. The result indicated that cure‐accelerated PF resins are less rigid than the control PF resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 841–851, 2000     

13C‐NMR study on cure‐accelerated phenol‐formaldehyde resins with carbonates

Both liquid‐ and solid‐state carbon‐13–nuclear magnetic resonance (¹³C‐NMR) spectroscopies were used to investigate the cure acceleration effects of three carbonates (propylene carbonate, sodium carbonate, and potassium carbonate) on liquid and cured phenol‐formaldehyde (PF) resins. The liquid‐phase ¹³C‐NMR spectra showed that the cure acceleration mechanism in the propylene carbonate‐added PF resin seemed to be involved in increasing reactivity of the phenol rings, whereas the addition of both sodium carbonate and potassium carbonate into PF resin apparently resulted in the presence of ortho–ortho methylene linkages. Proton spin‐lattice rotating frame relaxation time (T_1ρH) measured by solid‐state ¹³C cross polarization/magic‐angle spinning NMR spectroscopy was smaller for the cure‐accelerated PF resins than that of the control PF resin. The result indicated that the cure‐accelerated PF resins are less rigid than the control PF resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1284–1293, 2000