Theoretical and Experimental investigation of PVMQ/ EPDM-g-MA/CR blends: Rheological, Compatibility and Mechanical Properties

The main problem of uncompatibilize rubbers nano-composites in polymeric matrix are accumulation and agglomeration of graphene oxide. In this study, EPDM-g-MA was used as a compatibilizer for better dispersion of graphene oxide (GO) in the phenyl-vinyl-methyl-polysiloxane/chloroprene rubber (PVMQ/CR) matrix. To achieve this purpose mechanical characterizations, rheology, morphology and curing characterizations of nano-composite was investigated. SEM and TEM were used to assess surface characteristics, morphology and dispersion of EPDM-g-MA in PVMQ/CR nano-composite, which showed the size of EPDM-g-MA in the blends became smaller, denser and more uniform. Also, the results showed that, by increasing the GO nano-platelets in PVMQ/CR matrix during the reaction with EPDM-g-MA, curing properties was improved such a way that optimum curing time and scorch time were decreased and also MH–ML and cure rate index (CRI) were increased and also toughness strength enhanced. In addition, the mechanical properties indicated that tensile strength, fatigue strength, hardness, elongation-at-break and modulus increased by the incorporation with GO nano-platelets.

Equilibrium Swelling of Biocompatible Thermo-Responsive Copolymer Gels

Biomedical applications of thermo-responsive (TR) hydrogels require these materials to be biocompatible, non-cytotoxic, and non-immunogenic. Due to serious concerns regarding potential toxicity of poly(N-isopropylacrylamide) (PNIPAm), design of alternative homo- and copolymer gels with controllable swelling properties has recently become a hot topic. This study focuses on equilibrium swelling of five potential candidates to replace PNIPAm in biomedical and biotechnological applications: poly(N-vinylcaprolactam), poly(vinyl methyl ether), poly(N,N-dimethyl amino ethyl methacrylate), and two families of poly(2-oxazoline)s, and poly(oligo(ethylene glycol) methacrylates). To evaluate their water uptake properties and to compare them with those of substituted acrylamide gels, a unified model is developed for equilibrium swelling of TR copolymer gels with various types of swelling diagrams. Depending on the strength of hydrophobic interactions (high, intermediate, and low), the (co)polymers under consideration are split into three groups that reveal different responses at and above the volume phase transition temperature.

Sustainable Synthesis of Vinyl Methyl Ether from Biomass-derived Ethylene Glycol Dimethyl Ether over Solid Base Catalysts

Vinyl methyl ether (VME) is an important chemical intermediate for the production of functional polymers and fine chemicals. It is primarily produced in industry via the addition of methanol to...

Energy Dependent XPS Measurements on Thin Films of a Poly(vinyl methyl ether)/Polystyrene Blend in Dependence on Film Thickness – Concentration Profile on a Nanometer Resolution to Understand the Behavior of Nanofilms

The composition of the surface layer in dependence from the distance of the polymer/air interface in thin films with thicknesses below 100 nm of miscible polymer blends on a spatial...

Phase Equilibrium and Interdiffusion in Poly(Vinyl Methyl Ether)-Water System

The phase state diagram of the poly(vinyl methyl ether)-water system in a wide concentration range was obtained by the optical interferometry method. It was shown that this system was characterized by a complicated phase equilibrium with two lower critical solution temperatures, one of which was located in the concentrated region at 21 °C, and the other one in the region of a dilute solution at 31 °C. In the framework of the Flory–Huggins theory, pair interaction parameters were calculated for different parts of the binodal curves, and an attempt was made to reverse simulate the diagram in different conditions. It was suggested that the unusual character of the diagram was associated with the formation of a complicated complex between PVME and water in the middle region of the compositions. Concentration profiles for different temperatures were constructed. For the first time for this system, the numerical values of the diffusion coefficients of poly(vinyl methyl ether) (PVME) into water and water in PVME were obtained. Concentration and temperature dependences of diffusion coefficients were constructed and analyzed. The kinetics of water sorption in PVME was plotted, the clustering integral was calculated, and the approximate number of molecules in a water cluster was estimated. It was shown that in the dilute solution region upon passing through the binodal curve, the interphase disappeared immediately, and the remaining fluctuation of the concentration decreased in size with time. The kinetics of this process was estimated from the change in the size of such a particle.