Enthalpy-Entropy Compensation in Polyester Degradation Reactions

Table 1

Kinetic characteristics of different polyesters.

	PBT-N2						PTT-N2							PET-N2
	β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺	Δ𝐻	β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺		Δ𝐻	β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺	Δ𝐻
Zone 1	5	648	270	−0.015	275	265	5	673	439	−0.022	448		433	5	695	483	−0.169	594	477
	10	669	278	−0.011	280	273	10	693	450	−0.022	458		444	10	710	494	−0.148	593	488
	15	674	295	−0.005	292	289	15	718	429	−0.025	441		423	15	717	480	−0.174	599	474
	20	682	281	−0.010	283	276	20	726	429	−0.025	441		423	20	725	475	−0.182	601	469
Zone 2	5	771	253	−0.016	258	246	5	799	310	−0.027	326		304	5	901	459	−0.031	480	452
	10	793	273	−0.012	276	266	10	822	370	−0.022	381		363	10	972	470	−0.029	490	462
	15	800	295	−0.008	294	288	15	834	379	−0.021	389		372	15	949	443	−0.036	470	435
	20	807	266	−0.013	270	259	20	848	290	−0.031	309		283	20	973	430	−0.042	463	422
	PBT-AIR						PTT-AIR							PET-AIR
	β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺	Δ𝐻	β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺	Δ𝐻		β	𝑇𝑝	𝐸	Δ𝑆	Δ𝐺	Δ𝐻
Zone 1	5	652	304	−0.031	318	298	5	657	328	−0.045	352	323		5	701	397	−0.168	509	391
	10	663	390	−0.015	395	385	10	671	397	−0.033	413	391		10	706	463	−0.151	564	457
	15	670	382	−0.017	388	376	15	679	411	−0.030	426	405		15	719	446	−0.157	552	440
	20	676	407	−0.012	410	402	20	686	389	−0.037	408	383		20	725	402	−0.167	517	396
Zone 2	5	767	184	−0.036	205	178	5	763	274	−0.040	298	268		5	901	309	−0.029	328	302
	10	790	207	−0.021	216	200	10	787	300	−0.036	321	293		10	905	391	−0.019	401	383
	15	805	196	−0.027	212	190	15	803	296	−0.036	318	289		15	928	432	−0.013	436	424
	20	808	179	−0.042	205	172	20	823	280	−0.039	305	273		20	950	382	−0.021	393	374

β: heating rate (°C/min), 𝑇_𝑝: peak degradation temperature (°C), 𝐸: activation energy (kJ/mol), Δ𝑆: change in entropy (kJ/mol), Δ𝐺: change in free energy (kJ/mol), Δ𝐻: change in enthalpy (kJ/mol).