Thermal degradation of polymer systems having liquid crystalline oligoester segment

Matroniani, Renato; Wang, Shu Hui

doi:10.1590/0104-1428.2423

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Original Article • Polímeros 27 (4) • Oct-Dec 2017 • https://doi.org/10.1590/0104-1428.2423 copy

Thermal degradation of polymer systems having liquid crystalline oligoester segment

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Block copolymers and blends comprised by liquid crystalline oligoester and polystyrene were prepared and their thermal stability were characterized by thermogravimetric analysis (TGA). The samples have shown three main decomposition temperatures due to (1) lost of flexible chain and decomposition of mesogenic segment, (2) decomposition of polystyrene and (3) final decomposition of oligoester rigid segment. Both copolymers and polymer blends presented lower thermal stability compared to polystyrene and oligoester. The residual mass after heating at 600 °C in copolymers and polymer blends were lower than those found in the oligoesters. A degradative process of aromatic segments of oligoester induced by decomposition of polystyrene is suggested.

Keywords:
blends; liquid crystalline oligoester; thermal degradation; thermal stability

Sample	Type	Oligoester	Polystyrene
		(%)	(%)
1	homopolymer	100	0
2	copolymer	63	37
3	copolymer	39	61
4	copolymer	29	71
5	copolymer	16	84
6	homopolymer	0	100^a a Comercial polystyrene PS1380 used in the blends.
7	blend	70	30^a a Comercial polystyrene PS1380 used in the blends.
8	blend	50	50^a a Comercial polystyrene PS1380 used in the blends.
9	blend	30	70^a a Comercial polystyrene PS1380 used in the blends.

Sample	Oligoester	Block copolymer		Polystyrene block
	(%)	M_w	M_w/M_n	M_w	M_w/M_n
1	100	4500	1.61	-	-
2	63	10000	1.72	8000	1.39
3	39	21000	2.22	17500	1.73
4	29	54500	1.52	28500	1.71
5	16	110500	1.48	69500	1.63
6^a a Comercial polystyrene PS1380 used in the blends.	-	-	-	228000	1.47

Sample	%	T_d1	wt-loss-1	T_d2	wt-loss-2	residue
	oligoester	°C	%	°C	%	%
1	100	353	62	426	23	15
2	63	352	81	402	23	0
3	39	336	68	412	32	0
4	29	338	77	419	23	0
5	16	361	100	-	0	0

Sample	%	T_d1	wt-loss-1	T_d2	wt-loss-2	residue
	oligoester	°C	%	°C	%	%
6	0	372	100	-	0	0
7	70	335	71	417	16	13
8	50	349	86	415	12	2
9	30	361	84	413	13	3

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