Cosupported Tandem Catalysts for Production of Linear Low-Density Polyethylene from an Ethylene-Only Feed

Linear low-density polyethylene (LLDPE) is produced from an ethylene-only feed over a tandem catalyst system consisting of a phenoxy–imine titanium trimerization catalyst and a silylene-linked cyclopentadienyl/amido titanium polymerization catalyst cosupported on the same methylaluminoxane/silica particles. The level of 1-hexene incorporation can be controlled by varying the ethylene pressure

Highlight on the Mathematical Modeling of Controlled Free Radical Polymerization

Over the last quarter century, controlled free radical polymerization (CFRP) has received great attention by the researchers of polymer science and engineering. In addition to the experimental studies, many publications in the literature dealt with the modeling of CFRP processes. A review of acknowledged and well-received researches on mathematical modeling in the area of CFRP is presented in this work. Three main categories of CFRP (namely, ATRP, RAFT, and NMP) are taken into consideration in the review. The different techniques used in modeling CFRP processes are also enumerated with more emphasis on Monte Carlo simulation and the method of moments. The review provides a better understanding of the processes and the recent efforts to model CFRP

Effect of Fabrication Method on the Thermo Mechanical and Electrical Properties of Graphene Doped PVDF Nanocomposites

Nanocomposites of poly (vinylidene fluoride) PVDF with graphene nanoflakes (GNF) were prepared using two different routes. Initially, a mix-melting method was used to prepare composites, and their thermal and mechanical properties were evaluated to choose the better method for future experiment and properties investigation. Then, nanocomposite films were prepared by a simple solution-casting technique using a PVDF/graphene solution. In both cases, the amount of graphene was varied to observe and to compare their thermal and mechanical properties. The addition of graphene to the PVDF matrix resulted in changes in the crystallization and melting behaviors as confirmed by DSC analyses. Increasing the graphene content led to improved thermal stability of the PVDF nanocomposites prepared using both methods. Improvements in mechanical properties by the addition of graphene were also observed. Better performance was observed by the nanocomposites prepared by a mix-melting technique suggesting better dispersion and strong interface bonding between PVDF and graphene particles. Thermal and electrical conductivity were measured and compared. Microstructure and morphology were characterized using FTIR, XRD, and SEM analyses

Mechanical Properties of Polyethylene-Carbon Nanotube Composites Synthesized by In Situ Polymerization Using Metallocene Catalysts

The influence of multiwalled carbon nanotubes (MWCNTs) on the properties of polyethylene prepared by in situ polymerization using metallocene catalyst (Cp2ZrCl2) in combination with methylaluminoxane has been studied. The MWCNT was incorporated in the polymer matrix adopting a stirring method. Incorporation of MWCNT causes a drop in molecular weight of the polymer along with an increase in number of branches and increase in crystallinity. It was also observed that addition of MWCNT during metallocene-catalyzed polymerization caused a drop in both the dynamic modulus and Young’s modulus of polyethylene. But the drop in tensile strength was minimal, and there was an increase in elongation at break along with consequent increase in energy at break

Thermal Degradation Kinetics Analysis of Ethylene-Propylene Copolymer and EP-1-Hexene Terpolymer

LLDPE is a less crystalline polymer with vast industrial and domestic applications. It is imperative to understand the synthesis, processing conditions, and thermal degradation mechanism of the co- as well as terpolymers. This paper reports the in-situ synthesis and thermal degradation studies of the ethylene-propylene copolymer and ethylene-propylene-1-hexene terpolymer and its nanocomposite with ZnAL LDH sheets. The 1-hexene dosing during the in-situ process influenced the product yield and immensely affected the thermal stability of the resultant polymer. One milliliter 1-hexene in-situ addition increased the product yield by 170 percent, while the temperature at 10 percent weight loss in TGA was dropped by about 60 °C. While only 0.3 weight percent ZnAL LDH addition in the terpolymer improved the thermal stability by 10 °C. A master plot technique and combined kinetics analysis (CKA) were deployed to access the thermal degradation mechanism of the synthesized polymers