Chemical modification of unsaturated polyesters influence of polyester's structure on thermal and viscoelastic properties of low styrene content copolymers

2011

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The thermal, viscoelastic, and mechanical properties of cured dicyclopentadiene (DCPD)-containing polymers prepared from novel DCPD-modified unsaturated epoxypolyesters and styrene were evaluated. This was accomplished using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, threepoint bending test, and Brinell's hardness. The thermal, viscoelastic, and mechanical properties of DCPD-containing polymers were strongly dependent on chemical structure. The cross-linking density (t e ) of obtained networks increased with increasing content of carbon-carbon double bonds in the poly(ester) structure. In addition, the introduction of DCPD rings into the poly(ester) structure increased the rigidity of the molecular backbone. It resulted in obtaining polymers which showed great improvement in mechanical properties including remarkably higher storage modulus (E 0 20 C ), flexural modulus at bending (E mod ), hardness, lower extension at maximum force (e-F max ), as well as higher thermal stability. These good properties make these materials highly promising as potential candidates for structural applications.

Section: Discussionsupporting

confidence: 73%

Thermal, viscoelastic, and mechanical properties of DCPD-containing polymers

2011

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“…Unsaturated epoxy polyesters (UEP) were prepared by chemical modification of unsaturated polyesters based on cyclohex-4-ene-1,2-dicarboxylic anhydride, maleic anhydride (MA), Merck-Schuchardt (Germany), and suitable glycol: ethylene glycol (EG) or 1,4-butanediol (BDO) or 1,6-hexanediol (HDO), Fluka, Chemika (Switzerland) according to procedure described in [17]. Styrene was delivered by Polish Chemical Reagents-POCH.…”

Section: Methodsmentioning

confidence: 99%

The influence of tertiary aromatic amines on the BPO initiated cure of unsaturated epoxy polyesters with styrene studied by non-isothermal DSC

2011

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The influence of tertiary aromatic amines on the course of BPO initiated cure reaction of unsaturated epoxy polyesters with different styrene content has been studied by non-isothermal differential scanning calorimetry. Unsaturated epoxy polyesters prepared from cyclohex-4-ene-1,2-dicarboxylic anhydride, maleic anhydride and suitable aliphatic glycol: ethylene glycol or 1,4-butanediol or 1,6-hexanediol were dissolved in vinyl monomer (styrene) resulting in a styrene content of 20-80% by weight. The styrene solutions of polyesters were subjected to the cure reaction with suitable curing agent: benzoyl peroxide (BPO) used in various concentration (0.5-3.0 wt%) or the mixture of BPO/stoichiometric ratio of chosen tertiary aromatic amines: (N,N-dimethylbenzylamine (BDMA) or 2,4,6-tri(dimethylaminomethyl) phenol (DMP-30). The curing characteristic such as: temperature of the cure initiation (T onset ), peak maximum temperature (T max ), final cure temperature (T end ), heat generated during the cure reaction (DH) were evaluated. It has been found that the course of the cure reaction depended on the styrene content in prepared compositions and the initiating system used. The performed investigations confirmed that one of the applied tertiary aromatic amine: BDMA was an effective promoter for BPO decomposition process, causing a decrease in characteristic curing temperatures of unsaturated epoxy polyesters with styrene. The organic peroxide-amine interactions caused the promotion of BPO decomposition to benzoyloxy radicals at lower temperatures and thus accelerated the copolymerization process. However, DMP-30 was a very sluggish promoter for BPO decomposition, probably due to the presence of both hydroxyl group, their ortho-position to two of three amine groups and their branched structure. The redox reaction between BPO and DMP-30 probably resulted in non-radical products or radical formation which was incapable of initiating the polymerization reaction.

“…The copolymers prepared in the presence of polyesters based on diethylene or triethylene glycols exhibited lower values of cross-linking density (v e ), glass transition temperature identified as a tgd max , storage modulus (E 0 20°C ), and higher values of tgd max height than those ethylene glycol-based copolymers. It indicated on formation of more flexible polymer networks for copolymers based on polyesters with longer glycol's chain length in their structure [22,23]. Moreover, as the styrene content in the copolymers is varied from 20 to 80 mass%, the significant increase in molecular mobility of the polymer chains (tgd max height), decrease in cross-linking values (v e ) and the storage modulus (E 0 20°C ) and almost constant tgd max were observed.…”

Section: Thermal and Viscoelastic Properties Of Styrene Copolymersmentioning

confidence: 96%

Thermal and viscoelastic properties of novel epoxy-dicyclopentadiene-terminated polyesters-styrene copolymers

2012

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This article presents the studies on the thermal and viscoelastic properties of novel epoxy-dicyclopentadiene-terminated polyesters-styrene copolymers. The novel materials were prepared during a three step process including the addition reaction of maleic acid to norbonenyl double bond of dicyclopentadiene; polycondensation of acidic ester of dicyclopentadiene, cyclohex-4-ene-dicarboxylic anhydride, maleic anhydride, and suitable glycol: ethylene, diethylene, or triethylene glycol; and the epoxidation process of prepared polyesters. It allowed obtaining novel epoxy-dicyclopentadiene-terminated polyesters which were successfully used as a component of different styrene content (10-80 mass%) copolymers. The influence of the structures of polyester and styrene content on the cross-linking density (v e ), tgd max , tgd max height, storage modulus (E 0 20°C ), FWHM values as well as the thermal stability of copolymers was evaluated by TG, DSC, and DMA analyses and discussed.