Preparation and properties of polyether pentaerythritol mono-maleate grafted linear low density polyethylene by reactive extrusion

A reactive type nonionic surfactant, polyether pentaerythritol mono-maleate (PPMM) was synthesized in our laboratory. PPMM was adopted as functionalizing monomer and grafted onto linear low density polyethylene (LLDPE) with a melt reactive extrusion procedure. FT-IR was used to characterize the formation of grafting copolymer and evaluate their degree of grafting. The effects of monomer concentration, reaction temperature and screw run speed on the degree of grafting were studied systematically. Isothermal crystallization kinetics of LLDPE and LLDPE-g-PPMM samples was carried out using DSC.

Grafting acrylic acid onto polypropylene by reactive extrusion with pre-irradiated PP as initiator

In this paper, the modification of polypropylene (PP) with acrylic acid (AA) by reactive extrusion using pre-irradiated PP (rPP) as initiator was investigated. It was found the relatively high graft degree (Gd) and slight degradation of modified PP was obtained when 20 wt% rPP was used. This result can be explained in terms of effective concentration of free radicals.

Improved Melting Strength of Polypropylene by Reactive Compounding With Ultrafine Full-Vulcanized Polybutadiene Rubber (UFBR) Particles

Ultrafine full-vulcanized polybutadiene rubber (UFBR) in particle sizes of ca. 50-100 nm has been used for modifying mechanical and processing performances of polypropylene (PP), and PP-g-maleic anhydride (PP-MA) has been used as a compatibilizer for enhancing the interfacial adhesion between the two components. The results show that PP/UFBR possesses rheological behaviors such as highly branched PP when UFBR content in blends reaches 10 wt%, while in contrast, the much low content of UFBR combining small amount of PP-MA endows the material with rheological characteristics of high melt strength materials like highly branched PP.

Novel Method for Preparation of Polypropylene Blends with High Melt Strength by Reactive Compounding

Ultrafine full-vulcanized polybutadiene rubber(UFBR) with particle sizes of ca. 50-100 nm were used for modifying mechanical and processing performances of polypropylene(PP) with PP-g-maleic anhydride(PP-g-MA) as a compatibilizer for enhancing the interfacial adhesion between the two components. The morphology, dynamical rheology response and mechanical properties of the blends were characterized by means of SEM, rheometer and tensile test, respectively.

Reactive Mold Filling in Resin Transfer Molding Processes with Edge Effects

Reactive mold filling is one of the important stages in resin transfer molding processes, in which resin curing and edge effects are important characteristics. On the basis of previous work, volume-averaging momentum equations involving viscous and inertia terms were adopted to describe the resin flow in fiber preform, and modified governing equations derived from the Navier-Stokes equations are introduced to describe the resin flow in the edge channel. A dual-Arrhenius viscosity model is newly introduced to describe the chemorheological behavior of a modified bismaleimide resin. The influence of the curing reaction and processing parameters on the resin flow patterns was investigated.

Reactive compatibilization of LLDPE/PS blends with a new type of Lewis acid as catalyst

The reactive compatibilization of LLDPE/PS (50/50 wt%) was achieved by Friedel-Crafts alkylation reaction with a combined Lewis acids (Me3SiCl and InCl3 center dot 4H(2)O) as catalyst. The graft copolymer at the interface was characterized by Fourier transform infrared spectroscopy and the morphology of the blends was analysized by scanning electron microscopy. It was found that the combined Lewis acids had catalytic effect on Friedel-Crafts alkylation reaction between LLDPE and PS, and the catalytic effect was maximal when the molar ratio of InCl3 center dot 4H(2)O to Me3SiCl was 1:5. The graft copolymer LLDPE-g-PS was formed via the F-C reaction and worked as a tailor-made compatibilizer to reduce the interfacial tension. The mechanical properties of reactive blend with combined Lewis acids as catalyst was notably improved compared to that of physical LLDPE/PS blend and serious degradation had been decreased compared to the reactive blend system with AlCl3 as catalyst; we interpreted the above results in term of acidity of combined Lewis acids.

Analysis of chemical calorific effect during reactive extrusion processes for free radical polymerization

In the reactive extrusion process for polymerization, the chemical calorific effect has a great influence on the temperature. In order to quantitatively analyze the polymerization trend and optimize the processing conditions, the phenomena of the chemical calorific effect during reactive extrusion processes for free radical polymerization were analyzed. Numerical computation expressions of the heat of chemical reaction and the reactive calorific intensity were deduced, and then a numerical simulation of the reactive extrusion process for the polymerization of n-butyl methacrylate was carried out. The evolutions of the heat of chemical reaction and the reactive calorific intensity along the! axial direction of the extruder are presented, on the basis of which reactive processing conditions can be optimized.

Investigation of the gel effect in reactive extrusion processes for free radical polymerization

The gel effect in the reactive extrusion process for free radical polymerization in a closely intermeshing co-rotating twin screw extruder was investigated. First the reaction kinetic model was constructed mainly on the basis of entanglement theory. Next, numerical calculation expressions for the initiator and monomer concentrations, monomer conversion, average molecular weight and apparent viscosity were deduced. Finally, the evolution of the above variables were shown and discussed for the example of butyl methacrylate. The simulated results of the monomer conversion are in good agreement with experimental results.

Computer simulation of reactive extrusion processes for free radical polymerization

The reactive extrusion for polymerization is an integrated polymer processing technology. A new semi-implicit iterative algorithm was proposed to deal with the complicated relationships among the chemical reaction, the macromolecular structure and the chemorheological property. Then the numerical computation expressions of the average molecular weight, the monomer conversion, and the initiator concentration were deduced, and the computer simulation of the reactive extrusion process for free radical polymerization was carried out, on basis of which reactive processing conditions can be optimized.

Study on reactive extrusion processes of block copolymer

The anionic copolymerization process of styrene-buradiene (S/B) block copolymer in a closely intermeshing co-rotating twin screw extruder with butyl-lithium initiator was studied. According to the anionic copolymerization mechanism and the reactive extrusion characteristics, the mathematical models of monomer conversion, average molecular weight and fluid viscosity during the anionic copolymerization of S/B were constructed, and then the reactive extrusion process was simulated by means of the finite volume method and the uncoupled semi-implicit iterative algorithm. Finally, the influence of the feeding mixture composition on conversion was discussed. The simulated results were nearly in agreement with the experimental results.

Numerical simulation of reactive extrusion processes of PA6

To analyze the complicated relationships among the variables during the reactive extrusion process of polyamide 6 (PA6), and then control the chemical reaction and the material structures, the process of continuous polymerization of caprolactam into PA6 in a closely intermeshing co-rotating twin screw extruder was simulated by means of the finite volume method, and the influences of three key processing parameters on the reactive extrusion process were discussed. The simulated results of an example were in good agreement with the experimental results.

Free radical grafting of polyethylene with vinyl monomers by reactive extrusion

The free radical grafting of polyethylene with vinyl monomers by reactive extrusion was studied numerically. Numerical computation expressions of key variables, such as the concentrations of the initiator and polymer, grafting degree, average molecular weight and apparent viscosity, were deduced. The evolutions of the above variables were predicted by means of an uncoupled semi-implicit iterative algorithm. The monomer conversion monotonically increases with decreasing throughput or increasing initial initiator concentration; with increasing barrel temperature, the monomer conversion first increases then decreases. The simulated results are nearly in good agreement with the experimental results.

Preparation and properties of a reactive type nonionic surfactant grafted linear low density polyethylene

A reactive type nonionic surfactant, monostearic acid monomaleic acid glycerol diester (MMGD) was synthesized in our laboratory. Grafting-copolymerization of linear low density polyethylene ( LLDPE) with MMGD was carried out by using beta ray irradiation in air in a twin-screw extruder. Evidence of the grafting of MMGD as well as its extent was determined by Fourier-transformed infrared (FT-IR) spectroscopy. The effects of monomer concentration, reaction temperature and screw run speed on degree of grafting were studied systematically. The thermal behavior of LLDPE-g-MMGD was investigated by using differential scanning calorimety ( DSC). Compared with neat LLDPE, the crystallization temperature ( Tc) of LLDPE-g-MMGD increased about 3 degrees C, and the melting enthalpy (Delta H-m) decreased with increase of MMGD content. It showed that the grafted MMGD monomer onto LLDPE acted as a nucleating agent. The tensile properties and light transmission of blown films were determined. Comparing with neat LLDPE film, no obvious changes could be found for the tensile strength, elongation at break and right angle tearing strength of LLDPE-g-MMGD film. The wettability is expressed by the water contact angle. With an increasing percentage of MMGD, the contact angles of water on film surface of LLDPE- g-MMGD decrease monotonically.

Synthesis, reactive mechanism and thermal stability of W1-xAlxC (x=0.33, 0.5, 0.75, 0.86) nanocrystalline

W1-xAlxC (x = 0.33, 0.50, 0.75, 0.86) solid solutions have been synthesized directly by ball-milling tungsten powder, aluminum powder and activated carbon. The structural development of W0.5Al0.5C phase with the milling times up to 160 h has been followed using X-ray diffraction. X-ray photoelectron spectra demonstrate that Al atom takes the place of W. High temperature annealing experiment reveals that Al is stable in hexagonal structure to 1873 K. Transmission electron microscopy image shows that the grain size of the prepared powders is about 5 nm.

Synthesis of novel maleimide-terminated thioetherimide oligomer and its bulk copolymerization with reactive solvents

This paper reports the synthesis of a novel maleimide-terminated thioetherimide oligomer and its copolymefization with reactive solvents bearing vinyl. Starting from 3-chlorophthalic anhydride and 4-chlorophthalic anhydride, 2,2',3,3'-thiodiphenyl tertracaboxylic dianhydride (3,3'-TDPA) and 3,3',4,4'-thiodiphenyl tertracaboxylic dianhydride (4,4'-TDPA) were synthesized. Thereby, a novel maleimide-terminated thioetherimide oligomer was prepared from. 3,3-TDPA, 4,4'-TDPA, 3,3'-dimethyl-4,4-diaminodiphenylmethane (DMMDA) and maleic anhydride. Binary and ternary copolymer resin were derived from corresponding binary and ternary homogeous solution consisting of thioetherimide oligomer, reactive solvent N-vinylpyrrolidone (NVP) or N,N'-dimethylacrylamide (DMAA) and divinylbenzene (DVB) as modifier, initiated either by gamma ray irradiation or by benzoyl peroxide (BPO). Thermal and mechanical properties of copolymer resin are determined and compared in terms of the kind of reactive solvent, addition of modifier DVB. The effect of initiation approach on property of final copolymer resin were studied. Phase separation and sub-transition of ternary copolymer resin induced by BPO are observed, which could be accounted for by thermal movement of DMAA molecules during thermal initiation.