Construction of chain segment structure models, and effects on the initial stage of the thermal degradation of poly(vinyl chloride)

Lv, Yin; Liu, Jia; Luo, Zhidong; Wang, Heyun; Wei, Zhong

doi:10.1039/c7ra07615k

Cited by 10 publications

(5 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our previous work confirmed the negligible effect of the conjugated sequences and internal allylic chloride structures on the initial thermal stability of the PVC resin, and the dehydrochlorination reaction of the PVC resins was predominantly initiated at the internal allylic chlorine sites . Also, such reaction could be found in the process of UV photo degradation and have a certain effect on the photo aging properties and transparency of materials .…”

Section: Introductionsupporting

confidence: 80%

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

Geng

Wang

et al. 2018

Vinyl Additive Technology

Self Cite

View full text Add to dashboard Cite

The suspension polymerization of polyvinyl chloride (PVC) was carried out at two different constant temperature conditions (52.5°C and 57.5°C) and at two‐stage variable temperature conditions (52.5–57.5°C). The molecular weight and molecular weight distribution were characterized by gel permeation chromatography (GPC). The unstable chlorine content, total double bond content, and conjugated diene content were explored via phenol substitution, catalytic bromine addition, and ultraviolet–visible spectroscopy (UV–Vis). pH meter and thermogravimetric analyzer (TGA) were used for the determination of the thermal stability. According to the results, due to the gradual consumption of the impurities and the effect of the local high temperature in the early stage of polymerization, which caused more molecular chain‐transfer and more structural defects, a large number of oligomers generated. A rapid increase in the molecular weight could be found until the conversion was close to 23%. A lower temperature should be conducive to reducing the structural defects in molecular segments. Based on these observations, we applied two‐stage variable temperature polymerization and compared the PVC resin at a similar molecular weight at a constant temperature of 56°C. The PVC resin produced by the two‐stage variable temperature polymerization process obtained a similar Polydispersity index (PDI), reduced the unstable chlorine content by 15.11%, reduced the total double bond structure content by 8.81%, reduced the conjugated diene structure content by 13.86%, and increased the thermal stability time by 13.91%, thereby improving the thermal stability of the PVC resin. J. VINYL ADDIT. TECHNOL., 25:E80–E87, 2019. © 2018 Society of Plastics Engineers

show abstract

Section: Introductionsupporting

confidence: 80%

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

Geng

Wang

et al. 2018

Vinyl Additive Technology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover, new peaks appeared around 874–472 cm −1 due to the REE adsorption. Furthermore, the peaks of C=S appeared at 747 and 700 cm −1 in the spectrum of REEs/DdTC/PVC [ 39 , 40 ]. This means that the rare-earth ions were adsorbed and reacted with the DdTC/PVC.…”

Section: Resultsmentioning

confidence: 99%

“…Thermogravimetric examination (TGA) was used to study the thermal stability at a 10 °C/min temperature rate between 25–900 °C under an N 2 environment. Figure 3 e,f present the TGA thermograms of DdTC/PVC and REEs/DdTC/PVC with three stages of weight loss [ 39 , 40 ]. The first stage of weight loss at 100–115 °C was due to the loss of H 2 O.…”

Section: Resultsmentioning

confidence: 99%

Rare Earth Group Separation after Extraction Using Sodium Diethyldithiocarbamate/Polyvinyl Chloride from Lamprophyre Dykes Leachate

et al. 2022

View full text Add to dashboard Cite

This study presents the first application of sodium diethyldithiocarbamate/polyvinyl chloride (DdTC/PVC) as a novel adsorbent for rare earth element (REE) sorption from leach liquors. DdTC/PVC has higher adsorption properties than other sorbents, the synthesis of DdTC/PVC is more accessible than other resins, and it is considered a more affordable sorbent. The three-liquid-phase extraction technique (TLPE) was applied to separate REEs into light, middle, and heavy rare earth elements as groups. The TLPE is an excellent achievable technique in the separation of REEs. DdTC/PVC was prepared as a sorbent to sorb rare-earth ions in chloride solution. It was described by XRD, SEM, TGA, and FTIR. The factors pH, initial rare-earth ion concentration, contact time, and DdTC/PVC dose were also analyzed. The ideal pH was 5.5, and the ideal equilibration time was found to be 45 min. The rare-earth ion uptake on DdTC/PVC was 156.2 mg/g. The rare-earth ion sorption on DdTC/PVC was fitted to Langmuir and pseudo-2nd-order models. The rare-earth ions’ thermodynamic adsorption was spontaneous and exothermic. In addition, rare-earth ion desorption from the loaded DdTC/PVC was scrutinized using 1 M HCl, 45 min time of contact, and a 1:60 S:L phase ratio. The obtained rare earth oxalate concentrate was utilized after dissolving it in HCl to extract and separate the RE ions into three groups—light (La, Ce, Nd, and Sm), middle (Gd, Ho, and Er), and heavy (Yb, Lu, and Y)—via three-liquid-phase extraction (TLPE). This technique is simple and suitable for extracting REEs.

show abstract

“…The first weight loss step occurred in the range of 220–332 °C and was related to removing the HCl consecutive reaction and forming a conjugated polyene structure. The second step appeared within the range of 445–535 °C due to the thermal degradation of the PVC carbon chain, which yields flammable volatiles [ 46 , 47 ].…”

Section: Resultsmentioning

confidence: 99%

Cetylpyridinium Bromide/Polyvinyl Chloride for Substantially Efficient Capture of Rare Earth Elements from Chloride Solution

et al. 2022

View full text Add to dashboard Cite

A new sorbent cetylpyridinium bromide/polyvinylchloride (CPB/PVC) was prepared and tested to extract rare earth elements (REEs) from their chloride solutions. It was identified by FTIR, TGA, SEM, EDX, and XRD. The impact of various factors such as pH, RE ion initial concentration, contacting time, and dose amount via sorption process was inspected. The optimum pH was 6.0, and the equilibrium contact time was reached at 60 min at 25 °C. The prepared adsorbent (CPB/PVC) uptake capacity was 182.6 mg/g. The adsorption of RE ions onto the CPB/PVC sorbent was found to fit the Langmuir isotherm as well as pseudo-second-order models well. In addition, the thermodynamic parameters of RE ion sorption were found to be exothermic and spontaneous. The desorption of RE ions from the loaded CPB/PVC sorbent was investigated. It was observed that the optimum desorption was achieved at 1.0 M HCl for 60 min contact time at ambient room temperature and a 1:60 solid: liquid phase ratio (S:L). As a result, the prepared CPB/PVC sorbent was recognized as a competitor sorbent for REEs.

show abstract

Construction of chain segment structure models, and effects on the initial stage of the thermal degradation of poly(vinyl chloride)

Abstract: Comparing two models, the dehydrochlorination reaction of PVC was predominantly initiated at the internal allylic chlorine sites, further promoting degradation.

Cited by 10 publications

References 45 publications

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

Rare Earth Group Separation after Extraction Using Sodium Diethyldithiocarbamate/Polyvinyl Chloride from Lamprophyre Dykes Leachate

Cetylpyridinium Bromide/Polyvinyl Chloride for Substantially Efficient Capture of Rare Earth Elements from Chloride Solution

Contact Info

Product

Resources

About