Plastic‐rubber composite, 1. The polymer‐polymer interdiffusion at the phase boundary of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) and polystyrene

Abstract

SUMMREThe interdiffusion of poly(oxy-2,6-dimethyl-l,4-phenylene) (PPE) and polystyrene (PS) sequences is the key step in the formation of the commonly called plastic-rubber composite (Kunststoff-Kautschuk-Verbund, K&K-V). This new process bonds PPE and poly(styrene-co-butadiene) rubber (SBR) during the vulcanization of the rubber, without the aid of any adhesive. As PPE and PS are f d y mutually compatible polymers, polymer-polymer interdiffusion takes place readily. PS was therefore used as a model system. Electron microscopy clearly demonstrates that the kinetics of the diffusion process are determined by the faster diffusing PS. This was studied in the temperature range of 180°C to 260OC. The interdiffusion coefficients are of the order of lo-" to lo-'' cm2 * s-'. These are significantly higher than the selfdiffusion coefficients of PPE and PS, which are lo-'' and lo-'' cm2s-', respectively. The interdiffusion coefficients are dependent on temperature and inversely proportional to the PS molecular weight. for PS molecular weights higher than the entanglement value. The diffusion process follows Fick's law. The interdiffusion coefficient is not, or is only weakly, dependent on the concentration. The interdiffusion of PS samples of molecular weights below the entanglement value is observed by a newly developed method based on Fourier transform infrared spectroscopy with attenuated total reflection technique (FT'IR-ATR). In this low-molecular-weight region, interdiffusion coefficients as high as lo-' cm2 * s-' are obtained. 0 1990, HUthig & Wepf Verlag, Basel CCC 0025-1 16X/90/%03.00

Direct bonding between poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) and rubber with radicals

“…In 1990, Machate et al investigated a combination of PXE and polystyrene 16, 17. According to their results, polystyrene would diffuse into PXE above 180°C.…”

“…According to AFM, a specific layer in which viscoelasticity is between that of PPE‐1 and that of rubber was observed. In the case of PPE‐1 and SBR‐1, the AFM observation shows an ∼96‐nm‐thick layer (i.e., the diffusion layer) between PPE‐1 and SBR‐1, because PPE‐1 and SBR‐1 can interdiffuse each other 16, 17. Figure 2 shows the interface between PPE‐1 and E‐03 using AFM observation.…”

Experimental and simulative investigation of a multistage 2K injection molding process of PA6 and EPDM

“…Subsequent crosslinking of the SBR fixes these interdiffusions. 1,2 Covalent bonds are possible between PPE and special peroxide-crosslinked ethylene-propylene-diene rubber (EPDM). 3 Direct adhesion between polyamide (PA) or polybutylene terephthalate (PBT) and liquid silicone rubber (LSR) has also been the subject of various research papers in the past.…”

“…This material combination results in the interdiffusion of styrene segments and the formation of a distinct interdiffusion zone. Subsequent crosslinking of the SBR fixes these interdiffusions 1,2 . Covalent bonds are possible between PPE and special peroxide‐crosslinked ethylene‐propylene‐diene rubber (EPDM) 3 .…”

Flexible and flame‐retardant S‐SEB‐S triblock copolymer/PPE nano‐alloy

“…Due to its unprocessability, modified PPE, a blend of PPE and PS, is usually used for industrial products, but the flame retardancy of modified PPE is insufficient without including flame retardant additive . The mechanical properties and processability of PPE have been improved frequently by blending it with thermoplastic styrenic elastomers (TPSs) consisting of outer glassy polystyrene (PS) block segments and middle rubbery blocks such as polystyrene‐ block ‐polybutadiene‐ block ‐polystyrene (S‐B‐S triblock copolymer) and its hydrogenated version, polystyrene‐ block ‐poly(ethylene‐ co ‐butylene)‐ block ‐polystyrene (S‐EB‐S triblock copolymer), because PPE is solubilized by PS block segments in TPS . However, these blends are usually limited to PPE‐rich compositions to maintain the toughness, the inherent heat resistance and flame retardancy, whereas these blends are inflexible and inferior processability.…”