Regulation of supramolecular additives on conformation and crystallization behaviors of syndiotactic polystyrene

doi:10.19491/j.issn.1001-9278.2024.12.001

Abstract

Abstract:

Syndiotactic polystyrene （sPS）/N，N'⁃diphenylterephthalamide （DPHT） blends were prepared through melt blending， and the conformation and crystallization behaviors of sPS were regulated by utilizing the π⁃π interactions between sPS and DPHT. The results indicated that there were two dispersion states for DPHT， i.e.， free molecule or as self⁃assemblies， existing in the sPS matrix. The addition of DPHT increased the content of the all⁃trans conformation （TTTT） of sPS and reached a maximum when the self⁃assemblies were formed for DPHT. Moreover， the self⁃assembled structures of DPHT effectively increased the content of β⁃crystals in sPS. The proportion of the β⁃crystals was higher than that of the α⁃crystals in the sPS/DPHT blends at a slow cooling rate of 5 or 2 ℃/min. However， the α⁃crystal content in sPS was higher when the cooling rate was increased to 10 ℃/min. When DPHT was molecularly dispersed in the sPS matrix， the π⁃π interaction between DPHT and sPS restricted the crystallization ability of sPS， resulting in a decrease in the degree of crystallinity from 41 % to 35.9 %）. When DPHT was in the self⁃assembly state， the self⁃assemblies of DPHT acted as a nucleating agent to promote the crystallization of sPS， leading to an increase in the degree of crystallinity from 36.1 % to 38.2 %. Therefore， the conformation and crystallization behaviors of sPS were successfully regulated during melt processing through the π⁃π interactions between DPHT and sPS.

Key words: syndiotactic polystyrene, conformation, crystallization behavior, π?π interaction

CLC Number:

TQ325.2

SHEN Yingzhou, LIU Lei, CHONG Jinxuan, ZHANG Kai, YIN Bo. Regulation of supramolecular additives on conformation and crystallization behaviors of syndiotactic polystyrene[J]. China Plastics, 2024, 38(12): 1-7.

Figures/Tables 10

Fig.1. FTIR and XRD results of different proportions of sPS/DPHT materials after isothermal crystallization at 260 ℃

Fig.2. FTIR and XRD results of sPS / DPHT materials at different cooling rates

Fig.3. Isothermal crystallization results of sPS/DPHT system at 258 ℃ and 260 ℃ were obtained

样品	等温温度 /℃	Avrami 指数（n）	lnK	t_1/2/min
sPS⁃PURE	258	2.05	-1.31	1.58
sPS+DPHT⁃1.11	258	2.04	-0.75	1.22
sPS+DPHT⁃11.1	258	2.16	2.41	0.28
sPS⁃PURE	260	2.27	-0.99	1.32
sPS+DPHT⁃1.11	260	2.37	-1.69	1.73
sPS+DPHT⁃11.1	260	2.18	-2.72	2.95

Tab.1. Isothermal crystallization kinetic parameters of sPS/DPHT materials

Fig.4. Non⁃isothermal crystallization results of sPS/DPHT system

样品	降温速率/℃·min^-1	T_c/℃	T_m/℃	ΔH_m/J·g^-1	X_c/%
sPS⁃PURE	2	258.2	271.5	21.8	41.0
sPS+DPHT⁃1.11	2	257.7	271.8	19.1	35.9
sPS+DPHT⁃11.1	2	257.4	272.0	18.8	35.3
sPS⁃PURE	5	252.4	270.7	19.8	37.2
sPS+DPHT⁃1.11	5	253.9	271.7	17.8	33.5
sPS+DPHT⁃11.1	5	253.8	271.2	20.8	39.1
sPS⁃PURE	10	248.7	270.7	19.2	36.1
sPS+DPHT⁃1.11	10	250.2	271.5	17.9	33.6
sPS+DPHT⁃11.1	10	250.0	271.5	20.3	38.2

Tab.2. Tc，Tm， ΔHm and Xc of sPS/DPHT materials

Fig. 5. FTIR results of pure sPS cooling from 320 ℃ at 2 ℃/min to 50 ℃

Fig.6. FTIR results of sPS/DPHT material at 320 ℃ at 2 ℃/min cooling to 50 ℃

Fig. 7. Conformation and crystal form results of isothermal crystallization cooling to 50 ℃

Fig.8. The results of conformation and crystal form at different cooling rates to 50 ℃

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