Some considerations on the second phase structure in high impact polystyrene and on the related measurement methods

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.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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

Grassi¹,

Pizzol²,

Forte

et al. 2011

“…10 Characteristic properties of investigated polymers, such as swelling index and rubbery phase fraction content (reported on Table I) were determined according to the procedures previously reported. 11 The absorption of solvents was performed on HIPS rods (4 mm O.D.). These samples were immersed in standard cyclohexane (C 6 H 12 ) for NMR imaging observation and in deuterated cyclohexane (C 6 D 12 ) (Aldrich 99.6% w/w) for NMR relaxation measurements.…”

Section: Methodsmentioning

confidence: 99%

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

Maddinelli

Montanari

Ferrando³

et al. 2006

Composite polymers such as high impact polystirene (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 (C 6 D 12 ) allowed selective observation of rubber phase modification. Both longitudinal (T 1 ) and transversal (T 2 ) 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.

“…The influence of particle morphology on the mechanical properties of HIPS has been extensively reported in the literature. [1][2][3][4] It is well known that the optimum diameter of rubber particles in high-impact polystyrene (HIPS) with a monomodal distribution of rubber particle size (monomodal HIPS) is 1-2 mm. 5,6 However, a few studies showed that better impact toughness could be obtained in bimodal HIPS than in monomodal HIPS with the same rubber content.…”

Section: Introductionmentioning

confidence: 99%

“…HIPS is basically a blend of polystyrene (PS) and a graft copolymer of butadiene and styrene that owes its high toughness to the unique “salami” domains of BR, which contains many PS subdomains. The influence of particle morphology on the mechanical properties of HIPS has been extensively reported in the literature 1–4…”

Section: Introductionmentioning

confidence: 99%

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

Peng

Zhai

et al. 2008

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