Isotactic polypropylene (PP) has been reactively blended with various grades of an ethylene-octene copolymer (EOC) in a twin-screw extruder. Free radical polymerization of styrene and a multifunctional acrylate during melt extrusion has resulted in an enhancement of mechanical properties over the binary blend. The reactive blend exhibits a notched Izod impact strength over 12 times that of pure polypropylene and greater than double the performance of the binary blend. Electron microscopy shows that by grafting onto the polymers, elastomer particle size and interparticle distance decrease, while particle shape becomes less spherical. The acrylate is crucial to achieve superior performance, as infrared spectra correlate an increase in graft yield to improvements in stress-strain behavior and impact strength. In addition, melt flow index (MFI) and melt strength data indicate a reduction in unwanted side reactions of polypropylene and the presence of longchain branching. Dynamic-mechanical analysis reveals that the reaction promotes miscibility between polypropylene and the EOC and reduces molecular mobility at their glass-transition temperatures. Mechanical properties, graft yield, and MFI are shown to be highly dependent upon the elastomer's concentration, density, and molecular weight, initiator and monomer concentration, as well as processing temperature.

Isotactic polypropylene has been reactively blended with an ethylene‐octene copolymer so as to improve mechanical and rheological properties. Free radical polymerization of styrene and a multifunctional acrylate during melt extrusion has resulted in the formation of unique features in both amorphous and crystalline phases. Transmission electron microscopy images show that the elastomer domains are less than 200 nm in diameter, whereas grafting leads to the appearance of clusters of polymeric particles, ranging in size from several nanometers up to 200 nm. Differential scanning calorimetry (DSC) shows that grafting creates lamellar crystals that melt at much lower temperatures and recrystallize at much higher temperatures than binary blends. From wide angle X‐ray diffraction and DSC, grafting has been shown to limit the maximum crystal size and perfection, as well as broaden the size distribution of the crystals. Grafting causes significant changes in the α crystalline phase of polypropylene and promotes the formation of the β phase. Scanning electron microscopy reveals a unique cross‐hatch structure of small crystals in the reactive blend, with tangential and radial lamellae appearing as crosslinked material of about the same aspect ratio. Polarized light microscopy gives evidence that grafting and branching within this blend causes a gelation‐like recrystallization. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

The front cover of Motorola cellular phone housings were ground to the same size as original particles prior to use by a knife mill. The mixtures contained 15.2 wt% metals, 1.9 wt% foams, 1.4 wt% rubbers and 81.4 wt% thermoplastics where the major component was a polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend. The separation of the thermoplastic scraps was performed using the sink-float process in water and salt solution. The impact modification of all housing containing six thermoplastic parts was carried out by the addition of a polyolefin elastomer called as the functionalized polyethylene (PE). Unprinted glass fiber reinforced epoxy circuit boards were size reduced and pulverized using the knife mill and hammer mill. The ground epoxy circuit boards were then classified with a set of testing sieves using Gyro sifter, and their mean diameters were calculated by means of particle size distribution analysis. Izod impact strengths at two temperatures, tensile tests, scanning electron microscopy (SEM) on the fracture surfaces, and dynamic mechanical spectroscopy were performed to characterize the alloys and mixtures compounded by a batch mixer and a twin screw extruder.

The front covers of Motorola cellular phone housings, which were composed of 62.2 wt% of polycarbonate (PC) /acrylonitrile-butadiene-styrene (ABS), were ground and separated from the undesired materials using sink-float methods. The sink-float methods in water and salt were used to remove the floating materials such as the adhesive strips and the foams, and to separate the metal parts where the recovery ratios were 92.8 and 40.5 %, respectively. The separation of residual wires and button rubbers, which could not be done by the sink-float process in water, was preformed using V-Stat Triboelectric Separator (Outokumpu Technology) of a roll separator that also provided the effective methods to separate the ground metals that had existed in the printed circuit boards where the recovery weight ratio of metal parts was 19 wt%. The separated PC/ABS’s could be compounded with the ground circuit boards or the thermoplastic elastomer called Engage®, or the reactive species of glycidyl methacrylate (GMA).