Marta Worzakowska

Effect of some parameters on the synthesis and the physico-chemical properties of new amphiphilic starch-g-copolymers.

The detailed studies on the graft copolymerization of phenyl methacrylate onto gelatinized potato starch in water using potassium persulfate as radical initiator were presented. The different reaction parameters such as effect of initiator concentration, starch to monomer ratio, reaction temperature and reaction time were studied in terms of grafting efficiency, grafting percent and percent homopolymer formation. It was found that grafting process of aromatic methacrylate monomer onto potato starch backbone allowed obtaining new amphiphilic copolymers with different physicochemical properties as compared to non-modified starch. The influence of the copolymer structure on the swelling behavior in polar and non-polar solvents, moisture absorbance, gelatinization properties, acid and base resistance, surface morphology and thermal properties was discussed.

Thermal properties of citronellyl diesters

Thermal properties of linear citronellyl diesters were studied by TG/DSC/FTIR/QMS-coupled method in inert and oxidative atmospheres. The diesters decompose in one main step in inert atmosphere. As main pyrolysis products, the formation of mainly monoterpene hydrocarbons, acid anhydrides, monoacids, cyclic ketones, aldehyde fragments, carbon dioxide, and water was observed. It was indicated on the ester and O-citronellyl bonds cleavage, partial decarboxylation, and elimination of water from formed dicarboxylic acids during their pyrolysis. The decomposition in air runs in two steps. The first step was connected with the creation of monoterpene hydrocarbons, monoacids, cyclic ketones, aldehydes, carbon dioxide, carbon monoxide, and water. In the second step of decomposition, mainly carbon dioxide and water were produced. It was testified to ester and O-citronellyl bonds cleavage, partial oxygenation, and decarboxylation process of the primary formed decomposition products.

Starch-g-poly(benzyl methacrylate) copolymers

The physicochemical properties such as swelling in polar and non-polar solvents, moisture resistance, chemical resistance, ability for gelatinization and the thermal properties along with the evolution of volatile decomposition products of some starch-g-copolymers obtained through the grafting of benzyl methacrylate monomer onto potato starch have been studied. The chemical structure of copolymers was confirmed using ATR–FTIR analysis. The prepared materials were characterized by completely different properties than unmodified potato starch due to the covalent bonding of poly(benzyl methacrylate) chains onto starch backbone. The copolymers were not able to gelate; however, they exhibited higher swelling in non-polar solvents, lower swelling in polar solvents and higher resistance toward moisture, acid and base conditions than unmodified potato starch. In addition, DSC analysis showed that Tg of copolymers was shifted to a little higher values as compared to Tg of poly(benzyl methacrylate). The thermal stabilities of copolymers and potato starch were comparable. Their decomposition took place in two main stages connected with the emission of various volatile decomposition products (CO2, CO, H2O, CH4, aldehydes, alcohols, furan derivatives, acids, benzyl methacrylate) in inert atmosphere as it was confirmed based on the simultaneous TG/DSC/FTIR analysis.

Thermal and mechanical properties of polystyrene modified with esters derivatives of 3-phenylprop-2-en-1-ol

The thermal and mechanical properties of polystyrene (PS) modified with esters derivatives of 3-phenylprop-2-en-1-ol were investigated. The influence of the content of esters on the glass transition temperature, dynamic mechanical properties, flexural properties, hardness and thermal stability of PS has been examined. It was found that the PS/ester compositions were characterized by lower stiffness, lower values of Tg, lower hardness, lower stress at break, lower thermal stability and higher values of tg delta height and strain at break as compared to pure PS. The obtained results proved that esters derivatives of 3-phenylprop-2-en-1-ol can find their place as an environmentally friendly, external plasticizers of PS.

The effect of starch-g-copolymers structure on the oxidative behavior studied by the TG/DSC/FTIR-coupled method

The effect of starch-g-copolymers structure on the thermal decomposition course under oxidative conditions by using the simultaneous TG/DSC/FTIR technique has been investigated. To those studies, two types of starch-g-copolymers obtained under the graft copolymerization process of aromatic acrylate monomers such as phenyl acrylate and benzyl acrylate onto starch have been chosen. The TG/DSC investigations confirmed that the course of the decomposition process of all studied copolymers under the heating and in the presence of air was similar and run through three large stages. TG/FTIR studies indicated on the same decomposition mechanism under the first decomposition stage, however, on the completely different decomposition mechanism under the second decomposition stage of the copolymers which was directly dependent on the structure of grafted polymer. In addition, it was also proved that the percent grafting of the copolymers has not influenced on its decomposition course and its decomposition mechanism. The grafting percent influenced only on the Δm in each decomposition stage and on the intensity in the emission of the volatile species.

Thermal behavior, decomposition mechanism and some physicochemical properties of starch-g-poly(benzyl acrylate) copolymers

TG/FTIR/QMS-coupled method to study the thermal behavior along with the evolution of volatile decomposition products and thus the decomposition mechanism under inert conditions of some starch-g-poly(benzyl acrylate) copolymers was applied. Starch-g-poly(benzyl acrylate) copolymers under K2S2O8-initiated copolymerization process of benzyl acrylate monomer with gelatinized potato starch were prepared. The ATR-FTIR and 13C CP/MAS NMR confirmed the successful formation of grafted polymers with different grafting parameters such as grafting percent (%G) and grafting efficiency (%GE). The evolution of some physicochemical properties such as swelling, moisture resistance and chemical resistance allowed certifying that the copolymers obtained were more resistant toward polar solvents, moisture and acidic medium due to the incorporation of more hydrophobic chains into starch backbone as compared to unmodified potato starch. The TG/FTIR/QMS studies confirmed their similar thermal stability, two stage decomposition process but different and more complex decomposition mechanism under the second decomposition stage as compared to the previously presented starch-g-poly(benzyl methacrylate) copolymers.

Physical sorption and thermogravimetry as the methods used to analyze linear polymeric structure

An increased interest in polymer optical fibers can be observed in the last years. One of the main problems in the technology of these fibers is achieving good optical and thermal stability of used polymer materials. This paper presents a series of manufactured poly(methyl methacryalte) samples which quality was investigated using the physical sorption and the thermogravimetry methods. Studies were carried out to optimize the composition of the starting mixtures used to obtain proper polymer optical fibers.

Thermal properties of neryl long-chain esters obtained under microwave irradiation

Abstract Thermal properties of novel, neryl long-chain esters obtained through the esterification process of nerol, different chain lengths acidic components such as succinic anhydride, glutaric anhydride, adipic acid or sebacic acid and diol components such as ethylene glycol or diethylene glycol in solvent-free conditions under microwave irradiation were studied by TG/FTIR-coupled method. The studies confirmed that the use of microwave irradiation allowed obtaining flavor esters in absolutely shorter reaction time (only minutes) with high purity and yield compared to conventional method. The prepared novel, neryl long-chain esters were high thermal stable compounds and decomposed at three stages under air conditions including the breaking of ester bonds, oxidation and decarboxylation processes of formed intermediate products in a gaseous phase and thus the emission of various gaseous products. It was indicated on the same, complex and parallel decomposition mechanism under oxidative conditions for the present and previously studied long-chain esters of primary order terpene alcohols showing it independence on the type of alcohol used for their synthesis.

Pyrolysis of cyclo-aromatic diesters

Studies on the pyrolysis of cyclo-aromatic diesters derivatives of 3-phenylprop-2-en-1-ol are presented. The diesters are obtained during catalyzed esterification process of a stoichiometric ratio of 3-phenylprop-2-en-1-ol with suitable cycloaliphatic or aromatic acid anhydride in the solvent-free medium. As an acid anhydrides cyclohexane-1,2-dicarboxylic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic anhydride, and phthalic anhydride were applied. The thermal properties of obtained compounds under inert atmosphere were tested by means of differential scanning calorimetry and thermogravimetry coupled with FTIR analysis. The pyrolysis products were determined and the probable mechanism of their decomposition was proposed.

Novel DCPD-modified polyester containing epoxy groups: thermal, viscoelastic, and mechanical properties of their wood flour filled copolymers

In this article, the synthesis of novel DCPD-modified polyesters containing epoxy groups and their possible utilization as polar matrices for wood flour filled copolymers have been studied. The novel DCPD-modified polyester containing epoxy groups was prepared during three-step process. First, the addition reaction of maleic acid to DCPD norbonenyl double bond has been performed. Then, the polyesterification of acidic ester of DCPD, cyclohex-4-ene dicarboxylic anhydride, and ethylene glycol (ethane-1,2-diol, EG) or neopentyl glycol (2,2-dimethyl-1,3-propanediol, NP) in the presence of catalyst was carried out using melt condensation technique. Finally, the oxidation process of prepared DCPD-modified polyesters led to obtain DCPD-modified polyesters containing epoxy groups. The structural characterization of prepared DCPD-modified polyesters containing epoxy functionality has been carried out using FTIR and HNMR spectroscopic methods. The thermal, viscoelastic, and mechanical properties of their unfilled and wood flour filled copolymers have been studied by DSC, DMA, TGA analyses, three-point bending test, and Brinell’s hardness. The performed investigations indicated that novel DCPD-modified polyesters containing epoxy groups can be successfully applied as polar matrices for preparation wood flour filled copolymers due to their “compatibility” with hydrophilic wood flour surface which resulted with stronger interactions between wood and polymer surface and thus producing copolymers which were characterized by improved thermo-mechanical properties compared to unfilled copolymers.