Degradation polyester resin

UNSATURATED POLYESTER RESINS ON THE BASE OF CHEMICAL DEGRADATION PRODUCTS OF PET WASTE FOR VARNISHES... 

Table V. Analysis of Gases Evolved During Thermal Degradation of Brominated Polyester Resin Samples...

As it is both inexpensive and easy to handle, steam is a potential candidate carrier gas for waste plastic recycling in chemical plants. Furthermore, as mentioned in Section 2.1, the degradation temperatures for polyester resins are remarkably shifted to low-temperature regions, and the amount of carbonaceous residue produced in the degradation process is reduced in a steam atmosphere, as compared with that in a nitrogen atmosphere. Accordingly, the preparation of a catalyst that could demonstrate both stable activity for the catalytic cracking of PE-derived heavy oil, but that would also remain stable in a steam atmosphere, was examined [16],... 

Thermoset plastics have also been pyrolysed with a view to obtain chemicals for recycling into the petrochemical industry. Pyrolysis of a polyester/styrene copolymer resin composite produced a wax which consisted of 96 wt% of phthalic anhydride and an oil composed of 26 wt% styrene. The phthalic anhydride is used as a modifying agent in polyester resin manufacture and can also be used as a cross-linking agent for epoxy resins. Phthalic anhydride is a characteristic early degradation product of unsaturated thermoset polyesters derived from orf/io-phthalic acid [56, 57]. Kaminsky et al. [9] investigated the pyrolysis of polyester at 768°C in a fiuidized-bed reactor and reported 18.1 wt% conversion to benzene. 

As in polyester resins, reactive halogens containing fire-retardant chemicals are most often used in epoxy materials. Tetrabromobisphenol A is perhaps the most widely used component for flame-retarding epoxy resins. Nara and Matsuyama (24) and Nara et al. (25) described the thermal degradation and flame retardance of tetrabrominated bisphenol A diglycidyl ether compared to the nonbrorainated structure. Their results indicate that bromine acts by vapor-phase as well as condensed-phase mechanisms of flame inhibition. 

Blends of PAS, poly(phenylene ether), with a polyester resin and a compatibilizer have been described. The polyester should be aromatic, e.g., poly(ethylene terephthalate), poly(cyclohexylenedimethanol tere-phthalate), and poly(butylene terephthalate) (PBT). Because of the tendency of polyesters to undergo hydrolytic degradation at the high extrusion and molding temperatures encountered by the compositions, it is preferred that the polyester be substantially free of water. Orthoesters or epoxide-functionalized compounds are suitable compatibilizers [49]. 

Polyester resin in which dicyclopentadienol (DCPD) is present as grafts on chain ends is more stable than those without. In a fire scenario, ignition takes place more or less at the same time in both cases. Material degradation, at first, takes place faster in the DCPD tipped resins. This lasts a brief period, as the consumed material becomes a char that keeps the subsequent rate of heat release at a lower level than pertains in the non-tipped versions for the remaining duration of a fire. No char is seen in the non-tipped resins. No other flame retardants were present in these formulations. 

Cusack,P.A.,Heer, M.S., andMonk,A.W. (1997) Zinc Hydrorgfstarmate as an Alternative Synergist to Antimony Trioxide in Polyester Resins. Polym. Degrad. Stab., 58, 229. 

Huntite (Mg3Ca(C03)4) was used as reinforcement for an unsaturated polyester resin [53]. A content of 3 % huntite had a reinforcing effect for the resin, which caused an improvement of the mechanical and thermal properties. Regarding the thermal behavior, the onset temperature of composites thermal degradation was increased with approximately 50 °C, while the maximum degradation temperature was improved with 16 °C, compared to the polyester matrix. 

Bora et al. [63] prepared nanocomposites based on graphene oxide (GO) and unsaturated polyester resin (UPR). They verified that the incorporation of 3 wt% of GO improved the major degradation temperature of polyester from 230 to 285 °C. This improvement in thermal stability was attributed to the strong interaction between GO and UPR which restricts the mobility of the polymer matrix segments at the interface. The interaction may be attributed to the formation of hydrogen bonding between oxygen functionality on reinforcement and polymer or probably dipolar interactions between the two components. 

Jash and Wilkie [86] reported that even when the fraction of clay was as low as 0.1 wt% the PBQiR in a cone calorimeter was lowered by 40 %. Lee et al. [87] demonstrated that incorporation of 6, 8 and 10 wt% of MMT into epoxy resin increased linearly the char yield firom 9.1 to 15.4 % reducing the thermal degradation of the epoxy matrix. Nazare et al. [88] studied the flammability properties of unsaturated polyester resin with nanoclays using cone calorimetry. The authors verified that the incorporation of 5 wt% of nanoclays reduces the PHRR by 23-27 % and THR values by 4-11 %. While incorporation of condensed-phase flame retardants (such as ammonium polyphosphate, melamine phosphate and alumina trihydrate) reduce the PHRR and THR values of polyester resin, the inclusion of small amounts of nanoclay (5 % w/w) in combination with these char promoting flame retardants causes total reductions of the PHRR of polyester resin in the range 60-70 %. Ammonium polyphosphate, in particular and in combination with polyester-nanoclay hybrids show the best results compared to other flame retardants. 

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