Comparison with PBT

It should be taken into account that all of the aspects described above are of a general nature and therefore more or less valid for any kind of industrially relevant polyester resin. Upon closer examination, the experiences gained with PET are particularly applicable to poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate) (PTT) and polyethylene naphthalate) (PEN). These polymers have gained major industrial importance as a result of a number of different properties in comparison with PET. 

To improve the notched impact strength and to prevent hydrolysis induced embrittlement of PBT, PBT-styrenic blends have been thoroughly investigated. In comparison with ASA-PC, blends of ASA and PBT generally have to be compa-tibilized in order to yield acceptable mechanical properties. In the case of glass fibre reinforced PBT-ASA blends, an added and important bonus is reduced warpage properties on injection moulding in comparison with reinforced PBT. 

Summarizing, it can be concluded that a relatively sharp (within 2-4% of deformation) drop in H is observed for copolymers of PBT but in comparison with homo-PBT this transition occurs at much higher deformations (between 25 and 30%). This difference as well as the following increase and decrease of H are related to the structural peculiarities of thermoplastic elastomers - the presence of a soft amorphous phase which first deforms and the existence of a physical network. The very low H values obtained for PEE are related to the fact that the PBT crystallites are floating in an amorphous matrix characterized by a low viscosity. 

Table 5.15. Mechanical properties of the PBT/ABPBI molecular composites in comparison with the phase-separated composites. ...

Hoechst Vectra A950) / EEA-GMA (0-100) mechanical properties / comparison vs. properties of ternary EEA-GMA blends with PBT or LCP + PP 1995... 

No systematic study of the use of HALS as UV stabilisers in aromatic polyesters has been found in the literature very few articles even touch on the subject, and these are limited to PBT [157-159]. Without comparisons with other stabiliser types, it is difficult to assess the true capability of the HALS tested by these authors in PBT. It was noted by Borukaev and co-workers [159] that poly[[6[(l,l,3,3-tetramethylbutyl)amino]-s-triazine-2,4-diyl]-[(2,2,6,6-tetramethyl-4-piperidyl)imino]-l,6-hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]] (Chimmasorb 944 Ciba) was a better UV stabiliser than the dimethylsuccinate polymer with 4-hydroxy-2,2,6,6-tetramethyl-l-piperidineethanol (Tinuvin 622 Ciba). 

Kanomata et al. (2011) prepared compatibilized blends of either PBT or PET and polyethersulfone using PES having hydroxyphenyl end-groups. Blends prepared in a Brabender mixer were characterized using TEM and torque rheometry in comparison with control blends. 

The specific gravity of the unfilled, well-crystalline polymer is 1.320 g/cml Quenching of the melt leads to a fully amorphous polymer with the density of 1.256 g/cm Typical recrystallization occurs when PBT heats above its T. The crystalline portion of the polymers can be raised up to 60 % by annealing [57-59]. The faster crystallization of PBT in comparison with that of either polyamides or PET is of great importance, since it leads to low mould temperatures and short cycle times, and therefore, to economical processing. Slow cooling of the melt causes crystallization to large spherulitic forms [17]. 

The enhanced compatibility of the MAH modified EVA or EMA with PBT in comparison with non-MAH EVA or EMA may be expected because of the intermolecular dipole-dipole interaction between the carbonyl oxygen in MAH of the EVA-g-MAH or the EMA-g-MAH and the hydrogen in the hydroxyl group ( +) of PBT. The enhanced compatibility may be also ascribed... 

Saturated complex polyesters, particularly, poly (butylene terephthalate) (PBT) are used as engineering thermoplastics possesing good thermo - and wearstability, excellent moulding. These properties also allow to use them as matrix material for polymer composites [1], One of the perspective ways of search of effective catalysts for such systems is kinetic study of the reesterification model reaction, performed in the presence of various catalysts and comparison it with the results of the similar reaction without catalyst. Clarification on the example of model system of the most effective catalysts list allows to use them for obtaining both filled and nonfilled PBT and compare catalytic activity of various catalysts. The purpose of the... 

It seems reasonable that polyester cyclics could be prepared by an extension of the /wendo-high-dilution [17] chemistry used for the preparation of cyclic carbonate oligomers [18, 19] however, such proved not to be the case. Brunelle et al. showed that the reaction of terephthaloyl chloride (TPC) with diols such as 1,4-butanediol did not occur quickly enough to prevent concentration of acid chlorides from building up during condensation [14]. Even slow addition of equimolar amounts of TPC and butanediol to an amine base (triethylamine, pyridine or dimethylaminopyridine) under anhydrous conditions did not form cyclic oligomers. (The products were identified by comparison to authentic materials isolated from commercial PBT by the method of Wick and Zeitler [9].)... 

Table 11.4 Comparison of the mechanical and physical properties of PTT with those of PET and PBT [67, 68]...

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