Thermal Decomposition Of Copolymers Research Articles

Comparative Analysis of Thermal Decomposition Kinetics of Copolymers Based on Polyethylene Glycol Fumarate with Methacrylic Acid

The thermal properties of a copolymer based on polyethylene glycol fumarate with methacrylic acid in a nitrogen atmosphere were studied in this paper. Four various heating rates and two types of a polyester resin composition were used. The analysis of thermal decomposition kinetics was implemented. Three kinetics methods namely Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Friedman were applied. Curves of a thermogravimetric analysis demonstrated that the thermal decomposition of copolymers with different molar ratios was observed. It was determined that the kinetic data depends on the studied copolymers’ composition. The obtained data showed a good convergence in various heating rates. Also, the thermodynamic characteristics were calculated namely the changes in the Gibbs energy (ΔG), enthalpy (ΔH) and entropy of activation (ΔS). The Achar-Brindley-Sharp method was used to find the invariant kinetic parameters of decomposition. Thus, the the kinetic compensation effect was applied to define a reaction model and a pre-exponential factor. A main phase of the copolymer decomposition in a narrow temperature range was determined. It was attested by a peak on the differential curve. An insignificant mass loss of the volatile-matter yield was observed in the range of 30–150 °C.

Sunflower and Linseed Oils with Decyl Methacrylate Based Copolymers as Green Lubricating Additives

During the last few years, the greener additives prepared from bio-raw materials with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In the present work, copolymers derived from sunflower and linseed oils with decyl methacrylate were synthesized by a thermal method using benzoyl peroxide (BPO) as a radical initiator. Direct polymerization through the double bonds of the fatty acid chain in the presence of a free radical initiator leads to the formation of ecofriendly copolymeric additives (P1 and P2). The copolymers were characterized by Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (1H-NMR). Thermal decomposition of copolymers was determined by thermogravimetric analysis. The average molecular weight was measured by gel permeation chromatography (GPC) method. Different concentrations of prepared copolymer as additives vis 1, 2, 3, and 4 (w/v) were used to examine the rheological behavior and performance evaluation of the formulated base oil. The copolymer acts as an excellent viscosity improver and better pour point depressant.

Copolymers of Castor and Corn Oils with Lauryl Methacrylate as Green Lubricating Additives

During the last few years, the greener additives prepared from bio-raw materials with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In the present work, copolymers derived from sunflower and linseed oils with decyl methacrylate were synthesized by a thermal method using benzoyl peroxide (BPO) as a radical initiator. Direct polymerization of fatty acid double bonds in the presence of a free radical initiator results in the development of environmentally friendly copolymeric additives (Co-1 and Co-2). Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (1H-NMR) were used to characterize the resulting copolymers. Thermal decomposition of copolymers was determined by thermogravimetric analysis. The average molecular weight was measured by gel permeation chromatography (GPC) method. Different concentrations of prepared copolymer as additives vis 1, 2, 3, and 4 (w/v) were used to examine the rheological behavior and performance evaluation of the formulated base oil. The prepared copolymers show good thermal stability. Both prepared polymeric additives (Co-1 and Co-2) are evaluated as pour point depressant and excellent viscosity improver. The base oil blended with Co-1 has higher viscosity index value than the base oil blended with Co-2. The pour point values for the base oil blended with Co-1 and Co-2 are ranging from (-11 to -15 oC) and (-12 to -15 oC), respectively.

Evaluation of renewable feedstock-derived copolymers of stearyl methacrylate-co-triglyceride as multifunctional green additives in lubricant

The greener additives synthesized from bio-sources with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In this study, the synthesis of novel multifunctional green additives of stearyl methacrylate-co-triglyceride polymeric architectures MGA-1 and MGA-2 has been reported by incorporating the stearyl methacrylate on the sunflower oil and soybean oil, respectively. Direct polymerization through the double bonds of the fatty acid chain in the presence of a free radical initiator leads to the formation of ecofriendly copolymeric additive. The synthesized copolymers have been characterized by routine spectroscopic analysis, and the molecular weight and thermal decomposition of copolymers were determined by gel permeation chromatography and thermogravimetric analysis, respectively. The rheological behavior and performance evaluation of the formulated base oil were examined in different concentrations of additive viz. 1%, 1.5%, and 2% (w/v). Both MGA-1 and MGA-2 additives act as pour point depressant, viscosity modifier, viscosity index (VI) improver, and rheology modifier to the base oil. However, MGA-1 additive acts as an excellent viscosity modifier and VI improvers, whereas MGA-2 copolymer acts as better pour point depressant (PPD). The rheological study established the shear-thickening behavior for both the additive. The significance of this study lies in the fact that the increment in viscosity occurs with shear rate which make the formulated lubricant feasible at extreme conditions. Along with this, these vegetable oils derived additives MGA-1 and MGA-2 can be considered as good alternative to conventional synthetic homo- and copolymeric lubricant additives for environmentally benign lubricant formulations.

Thermal decomposition of copolymers from ethylene with some vinyl derivatives

The thermal degradation of ethylene-vinyl acetate (EVA), ethylene-vinyl-3,5-dinitrobenzoate (EVDNB) and ethylene-vinyl alcohol (EVAL) copolymers have been studied using differential thermal analysis (DTA) and thermogravimetry (TG) under isothermal and dynamic conditions in nitrogen. Thermal analysis indicates that EVA copolymers are thermally more stable than EVDNB samples. The degradation of the copolymers considered occurs as an additive degradation of each component polyethylene (PE) and poly(vinyl acetate) (PVA), poly(vinyl-3,5-dinitrobenzoate) (PVDNB) or poly(vinyl alcohol) (PVAL). The apparent activation energy of the decomposition was determined by the Kissinger and Flynn-Wall methods which agree well.

Thermal decomposition of copolymers used in dental resins formulations photocured by ultra blue IS

Kinetics of thermal decomposition of acrylates copolymers used in dental resins formulations were studied with dynamic thermogravimetric analysis experiments. The kinetic parameters, including activation energy, pre-exponential factor, and 60 min half-life temperature, which were calculated by the Flynn and Wall method, are presented. The results indicate that thermal decomposition of the material occurred in three different stages characterized by different mechanism. These three events were separated and the kinetics parameters were determined. The loss mass was observed in the onset of the thermal decomposition for the all of copolymers studied. When the copolymers were submitted to thermal treatment before of thermal analysis was not observed the loss mass in the beginning of the process. The analysis of intermediates by GC of the condensed material extracted after thermal treatment at TB copolymers showed the presence of the methacrylic acid and 2-hydroxyethyl methacrylate, which are products of decomposition of BisGMA and triethyleneglycol dimethacrylate monomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Grafting of Polymers Having Pendant Peroxycarbonate Groups Onto Carbon Black and Postpolymerization of Vinyl Monomers

Postpolymerization of vinyl monomers initiated by pendant peroxycarbonate groups of grafted polymer chains on carbon black (CB) was investigated. The grafting of polymers having pendant peroxycarbonate groups onto CB was achieved by the trapping of polymer radicals formed by the thermal decomposition of copolymers of t-butylperoxy-2-methacryloyloxyethyl-carbonate (HEPO) with vinyl monomers such as vinyl acetate (VAc), styrene (St) and methyl methacrylate (MMA). The copolymers having pendant peroxycarbonate groups were prepared by copolym-erization of HEPO with vinyl monomers using azo initiator under irradiation of UV light at room temperature. The amount of remaining pendant peroxycarbonate groups of the poly(VAc-co-HEPO)-grafted CB obtained from the reaction at 90°C was maximum and decreased above the temperature. Furthermore, the postpolymerization of vinyl monomers, such as St, MMA, and VAc was initiated in the presence of poly(VAc-co-HEPO)-grafted and poly(St-co-HEPO)-grafted CB and the corresponding polymers were postgrafted onto CB to give branched polymer-grafted CB. The percentage of poly(St)-postgrafting (proportion of post-grafted poly(St) to poly(MMA-co-HEPO)-grafted CB used) increased with increasing polymerization time, but became constant at 20% after 4 hours.

Thermal decomposition of copolymers of methyl methacrylate and alkyl methacrylates obtained from a CSTR

Thermal decomposition of the copolymers of methyl methacrylate (MMA) with ethyl methacrylate (EMA) or n-butyl methacrylate (BMA) were investigated. The copolymers were obtained in a continuous stirred tank reactor (CSTR) using toluene and benzoyl peroxide, as solvent and initiator, respectively, at 80C. The volume was 1.2 litters and residence time was 3 hours. The thermal decomposition followed the second order kinetics for both MMA/EMA and MMA/BMA copolymers, which were almost in accordance with the order of copolymerization in a CSTR. The activation energies of thermal decomposition were in the ranges of 32-37 kcal/mol and 27-37 kcal/mole for MMA/EMA and MMA/BMA copolymers, respectively and a good additivity rule was observed against each composition for both copolymers. The thermogravimetric trace curve agreed well with the theoretical calculation.