Study on enhancement of thermal stability of chlorinated polyvinyl chloride

doi:10.19491/j.issn.1001-9278.2025.11.009

Abstract

Abstract:

Chlorinated polyvinyl chloride （CPVC） suffers from a narrow processing window and poor thermal stability. To address these limitations， this study first established suitable processing conditions based on CPVC's structural characteristics and pyrolysis mechanism， providing a foundation for subsequent compounding modification. The effects of Ca/Zn metal soap， methyl⁃tin， and TiO₂ on the thermal stability， plasticization behavior， and thermal decomposition of CPVC were then investigated. Torque rheology and plasticization analysis determined the optimal processing parameters for TiO₂⁃filled CPVC to be a temperature of 145 ℃， a shear rate of 45 r/min， and a processing time of 10 minutes， with TiO₂ found to promote rapid plasticization. Based on yellowness index and thermogravimetric⁃infrared analysis， methyl⁃tin significantly improved thermal stability， increasing the initial pyrolysis temperature from 240 to 250 ℃. Furthermore， torque rheological curves revealed that the thermal decomposition of pristine CPVC commenced at approximately 810 s， a process that was substantially delayed by the addition of methyl⁃tin. The results demonstrated that methyl⁃tin was a highly effective stabilizer for enhancing the long⁃term thermal stability of CPVC.

Key words: chlorinated polyvinyl chloride, methyl tin, thermal stability, modification

CLC Number:

TQ325.3

DU Haojie, ZHANG Ying, HUANG Jian, SUN Huali, XU Haiyun, ZHAO Xiaoying, XIANG Aimin. Study on enhancement of thermal stability of chlorinated polyvinyl chloride[J]. China Plastics, 2025, 39(11): 53-58.

Figures/Tables 11

序号	1	2	3	4	5	6
加工温度/℃	160	165	170	175	180	185
转速设置/r·min^-1	60	60	60	60	60	60
加工时间1/min	5	5	5	5	5	5
加工时间2/min	10	10	10	10	10	10
加工时间3/min	20	20	20	20	20	20
加工时间4/min	30	30	30	30	30	30
加工时间5/min	40	40	40	40	40	40

Tab.1. Pure CPVC processing temperature exploration experiment

序号	1	2	3	4	5
加工温度/℃	145	145	145	145	145
转速设置/r·min^-1	45	60	80	100	120

Tab.2. Inquiry experiments exploring CPVC shear rate

序号	CPVC/份	Ca/Zn金属皂/份	甲基锡/份	TiO₂/份
1	100	0	1.2	-
2	100	0	1.5	-
3	100	0	1.5	0.2
4	100	0	1.5	0.5
5	100	0	1.5	1.0
6	100	0	1.5	1.5
7	100	2	-	-

Tab.3. Experimental scheme design of the CPVC/heat stabilizer composite system

Fig.1. The degree of plasticization of pure CPVC at different processing temperatures

Fig. 2. The degree of plasticization of CPVC with added methyltin at different processing temperatures

Fig. 3. The degree of plasticization of CPVC in the experimental group with added methyltin at different processing times

Fig. 4. The degree of plasticization of CPVC in the methyltin experimental group at different shear rates

Fig.5. The change in CPVC yellowness index with processing time

Fig.6. TGA⁃IR spectral diagrams at different stages of thermal decomposition of CPVC with 1.5phr of methyltin

Fig.7. TGA curves of CPVC with different contents of heat stabilizers

Fig.8. Torque curves for the CPVC mixing system with different TiO2 content

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