Fluorenone polyesters

The synthetic fiber Industry is only about fifty years old yet the annual production Is In billions of lbs. The development of fibers resulted due to advances In polymer synthesis and new spinning methods. At the present time nylons, polyesters, acrylics and polyolefins are major classes of synthetic fibers. Fibers have also been made from polymers, e.g., polyvinylIdene chloride and polyvinyl alcohol but their commercialization has not materialized. Recently, we have made fibers from fluorenone polyesters which have good potentials and should be further developed. 

Fluorenone polyesters are made from Isophthallc acid or terephthallc acid/Isophthallc acid and blsphenol fluorenone and a typical formula Is as follows ... 

In this paper we will describe the chemistry and characterization of blsphenol fluorenone polyesters and copolyesters that were found to be suitable for conversion Into fiber. We will also describe the synthesis and utility of acetylene terminated fluorenone to Improve deficient properties of fluorenone polyesters. 

Fire relstance,chemical composition by infrared (IR) and nuclear magnetic resonance (Mlffit) spectroscopy, thermal analyses, Clash-Berg moduli determination and dynamical mechanical analyses were determined. The fluorenone polyesters were spun as fibers from solution. They were blended with an acetylene terminated fluorenone monomer for plasticization and crosslinking at high temperatures to form an improved thermally stable product. 

A reversed phase high performance liquid chromatography (RP-HPLC) was run on ATF. It revealed that besides ATF other low molecular weight blfunctlonal oligomers were also formed In small amounts. Formation of reactive oligomer does not reduce utility of ATF as a reactive plasticizer for fluorenone polyesters. 

Fire Resistance. Fluorenone polyester fibers were tested for fire resistance and compared against a polycarbonate control. FPE-2, -3, and -4 had good flame resistance. They did not support combustion, did not drip, and were nearly self-extinguishing. When they burned, black soot was given off. FPE-1 was slightly inferior to the others in flame resistance. The control polycarbonate burned with excessive dripping and considerable black soot. Thus the fluorenone polyesters... 

Solubility and Intrinsic Viscosity. Fluorenone polyesters are readily soluble in methylene chloride, dlmethylformamide, dimethylaceta-mlde, and tetrahydrofuran. Intrinsic velocities [q] in methylene chloride were determined at 25 C (see Table I). 

Table I. Intrinsic Viscosities of Fluorenone Polyesters in Ifethy-...

Preparation of Fibers from Solution. Fibers can be spun (wet or dry) from 10% polymer solution in methylene chloride or tetrahydrofuran (THF). An advantage of THF is that it is a good solvent for the ethylene terpolymer (E/VA/VOH) as well, which we used to modify the fluorenone polyesters. The fluorenone polyester fibers formed were transparent (Figure 5). The polyesters can be blended with 10% E/VA/VOH and they formed slightly cloudy films. Blending In this case was carried out with FPE-4 in an attempt to toughen the polymer. However, the cloudy appearance of the films indicates that some phase separation occurs and toughening is not likely to occur. Tensile data determination confirmed our speculation. 

ATF. ATF has ether linkages and will plasticize fluorenone polyesters at moderately elevated temperatures. At high temperature (300 C), ATF will form a crossllnked network and thereby improve thermal stability. In Figure 10 thermogravlmetrlc analysis (TGA) of ATF is shown and compared with a fluorenone polyester. The superior thermal stability of ATF is evident. 

The fluorenone polyesters have very good thermal and flame resistance and produce medium char yields in the 30-60% range. They do not drip at high temperatures and will not ignite under sustained external flame exposure. Fibers can be spun from solutions of these polymers (wet or dry). They can be blended with 10% ethylene terpoly-mer without much loss in heat resistance properties, althougih not much toughening is achieved. 

We have successfully synthesized ATF which can be used with FPE up to 80% but no less than 20%. ATF improves processability. Cross-linked ATF provides flexibility and thermal stability to the fluorenone polyester. The fact that the polyester structure does not contain nitrogen is a potential advantage in fire-resistant fiber applications, since there is no likelihood of HCN generation during burning. Because of high glass transition temperature of fluorenone polyesters, these polymers can be used as heat-resistant fibers. 

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