Oligomer sample series

The Tm-values of a series of oligomers are plotted as a function of (Ln[n])/n, extrapolation of (Ln[n])/n to zero results in a value for Tm(o). Five oligomer samples, with the chemical structure ... 

Figure 2.34 shows the results of the curing kinetics of three sample series (see Table 2.5) A. At TH=Const, the value of Xex. varied fix)m 0 minute to 90 d s B. The Xjj, swelling time varied fix)m 8 to 240 hours C. The swollen samples (Xin =8 hours), stored for 240 hours in the air, were put into contact with 4-DMM for the second time. After 8 hours in oligomer, the... 

After the second contact with oligomer (samples of the C series), the swollen films, which were first exposed to oligomer under Xex Xex ", forget about their kinetic stability and their behavior is kinetically similar to the behavior of the samples after... 

The major distribution, centred at approximately 2000 Da as expected, can be assigned as from di-hydroxyl end-capped oligomers of PPG (18). Addition of lithium salts in the MALDI sample preparation procedure leads to the generation of [18 + Li]+ ions as the major species. A series of low-intensity peaks below... 

Materials. A series of a,to-bis(hydroxyphenyl)PSU oligomers with different molecular weights were synthesized and characterized as was previously reported (12). Two samples of PPO (one from Aldrich and one from General Electric Co.) were both purified by precipitation from chloroform solution into methanol. A commercial sample (Dow Chemical) of an isomeric mixture of chloromethylstyrenes (C1MS, 40% para, 60% meta) was used as received. 1-Chloromethoxy-4-chlorobu-tane (CMCB) was prepared according to a procedure developed by Olah et al. (14) and modified by Daly et al. (15), i.e., from paraformaldehyde, tetrahydrofuran and anhydrous HC1. 

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

Figure 2.8—Simulated distillation of lubricating oil (Polvwax). Using a column that can operate at high temperatures, a correlation is made between retention times and boiling temperatures for a series of oligomers. The sample to be distilled is then run under the same chromatographic conditions. Software using the chromatogram reproduces a distribution curve identical to that which would be obtained from the mixture if it were distilled, a much longer process (document SGE 712-0546 and -0547).

FTD chromatograms calculated in this way for a series of samples (Fig. 22) are similar to the experimental ones and thus an unambiguous separation of oligomers according to their molecular weight and functionality is possible. 

The pure TMS and TES polytriacetylene oligomer series were investigated including a polymer sample. The different end groups in the polymer have a negligible influence on the molecular property as the PTA backbone is long enough to dominate the molecular properties. 

The THG experiments of the pure PTA (TMS) series show a power law increase of the second-order hyperpolarizability with an exponent a=2.52 0.10 for the oligomers n=1 to 6. The polydisperse PTA polymer samples exhibit a constant second-order hyperpolarizability per monomer unit of y/ =4.1xl0 48 m5/V2 (300x10 36 esu) indicating an only linear increase for longer PTAs. The... 

Fig. 1.29. Optimised normal-phase gradienl-clution separation of 30 lower oligoslyiencs on two Scparon SGX Cis. 7 pm, silica gel columns in series (150 x mm i.d. each), using the optimised linear and convex gradients of dioxanc in n-hcptanc. Flow rate 1 ml/min. Normalised response relates to the original concenlralions of the oligomers in the sample, to.

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