Characterization of Engineering Plastics Plasticized Using Supercritical CO2

Watanabe, Masaki; Hashimoto, Yoshihide; Kimura, Tsuyoshi; Kishida, Akio

doi:10.3390/polym12010134

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…Corresponding Vickers hardness values (HV) are summarized in Figure 6 . Lower HV values are attributed to a plasticization effect [ 96 , 97 , 98 , 99 , 100 ] and reduction of the glass transition temperature ( T g ) due to the sorption of CO 2 into the amorphous, unstructured regions in PMMA, as previously discussed. These conditions can promote localized rearrangements in pockets of free volume within the polymer network.…”

Section: Resultsmentioning

confidence: 68%

“…Sorption of CO 2 into a polymer matrix is also reported to promote plasticization and reduction of the glass transition temperature ( T g ) [ 96 , 97 , 98 , 99 , 100 ], as well as the formation of a cellular/porous structure [ 67 , 87 , 101 , 102 , 103 ]. The formation of bubbles might occur during the depressurization stage, and bubbles are more likely to form when the operational conditions are of high temperature and/or high pressure and the depressurization to ambient conditions is performed very quickly [ 104 ].…”

Section: Resultsmentioning

confidence: 99%

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Assessing the Impact and Suitability of Dense Carbon Dioxide as a Green Solvent for the Treatment of PMMA of Historical Value

et al. 2023

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Surface cleaning of plastic materials of historical value can be challenging due to the high risk of inducing detrimental effects and visual alterations. As a result, recent studies have focused on researching new approaches that might reduce the associated hazards and, at the same time, minimize the environmental impact by employing biodegradable and green materials. In this context, the present work investigates the effects and potential suitability of dense carbon dioxide (CO2) as an alternative and green solvent for cleaning plastic materials of historical value. The results of extensive trials with CO2 in different phases (supercritical, liquid, and vapor) and under various conditions (pressure, temperature, exposure, and depressurization time) are reported for new, transparent, thick poly(methyl methacrylate) (PMMA) samples. The impact of CO2 on the weight, the appearance of the samples (dimensions, color, gloss, and surface texture), and modifications to their physicochemical and mechanical properties were monitored via a multi-analytical approach that included optical microscopy, Raman and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopies, and micro-indentation (Vickers hardness). Results showed that CO2 induced undesirable and irreversible changes in PMMA samples (i.e., formation of fractures and stress-induced cracking, drastic decrease in the surface hardness of the samples), independent of the conditions used (i.e., temperature, pressure, CO2 phase, and exposure time).

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Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Assessing the Impact and Suitability of Dense Carbon Dioxide as a Green Solvent for the Treatment of PMMA of Historical Value

et al. 2023

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“…However, with the addition of CO 2 , the composite hydrogels exhibited lower G′ and G″ values. This might result from the plasticizing effect of CO 2 40 . Additionally, the formation of small bubbles and pores in the composite hydrogels may further reduce both G′ and G″ values.…”

Section: Resultsmentioning

confidence: 99%

Novel CO2-encapsulated Pluronic F127 hydrogel for the treatment of Achilles tendon injury

Yu,

Lee,

Hsu

et al. 2023

Sci Rep

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Nonsurgical treatment and surgical repairment of injured Achilles tendons seldom restore the wounded tendon to its original elasticity and stiffness. Therefore, we hypothesized that the surgically repaired Achilles tendon can achieve satisfactory regeneration by applying multi-drug encapsulated hydrogels. In this study, a novel bupivacaine-eluting carbon dioxide-encapsulated Pluronic F127 hydrogel (BC-hydrogel) was developed for the treatment of Achilles tendon injuries. The rheological properties of BC-hydrogel were measured. A high-performance liquid chromatography assay was used to assess the release characteristics of bupivacaine in both in vitro and in vivo settings. Furthermore, the effectiveness of BC-hydrogel in treating torn tendons was examined in a rat model, and histological analyses were conducted. Evidently, the degradable hydrogels continuously eluted bupivacaine for more than 14 days. The animal study results revealed that the BC-hydrogel improved the post-surgery mobility of the animals compared with pristine hydrogels. Histological assay results demonstrated a significant reaction to high vascular endothelial growth factor in the surrounding tissues and expression of collagen I within the repaired tendon. This demonstrates the potential of this novel BC-hydrogel as an effective treatment method for Achilles tendon injuries.

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“…Utilizing supercritical fluids in the process of polymer foaming offers many benefits. Fluids in supercritical conditions combine the viscosity of a gas and the density of a liquid, therefore, performing as an excellent solvent and plasticizer and enhancing the expansion of the polymer [50]. Supercritical CO 2 (scCO 2 ) is a nontoxic, nonflammable, chemically inert, and reasonably low critical point.…”

Section: Process Related Factors Influencing Polymer Foamsmentioning

confidence: 99%

Production and Application of Polymer Foams Employing Supercritical Carbon Dioxide

Lima¹,

Bose²

2022

Advances in Polymer Technology

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Polymeric foams have characteristics that make them attractive for different applications. However, some foaming methods rely on chemicals that are not environmentally friendly. One of the possibilities to tackle the environmental issue is to utilize supercritical carbon dioxide ScCO2 since it is a “green” solvent, thus facilitating a sustainable method of producing foams. ScCO2 is nontoxic, chemically inert, and soluble in molten plastic. It can act as a plasticizer, decreasing the viscosity of polymers according to temperature and pressure. Most foam processes can benefit from ScCO2 since the methods rely on nucleation, growth, and expansion mechanisms. Process considerations such as pretreatment, temperature, pressure, pressure drop, and diffusion time are relevant parameters for foaming. Other variables such as additives, fillers, and chain extenders also play a role in the foaming process. This review highlights the morphology, performance, and features of the foam produced with ScCO2, considering relevant aspects of replacing or introducing a novel foam. Recent findings related to foaming assisted by ScCO2 and how processing parameters influence the foam product are addressed. In addition, we discuss possible applications where foams have significant benefits. This review shows the recent progress and possibilities of ScCO2 in processing polymer foams.

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Characterization of Engineering Plastics Plasticized Using Supercritical CO2

Cited by 9 publications

References 27 publications

Assessing the Impact and Suitability of Dense Carbon Dioxide as a Green Solvent for the Treatment of PMMA of Historical Value

Assessing the Impact and Suitability of Dense Carbon Dioxide as a Green Solvent for the Treatment of PMMA of Historical Value

Novel CO2-encapsulated Pluronic F127 hydrogel for the treatment of Achilles tendon injury

Production and Application of Polymer Foams Employing Supercritical Carbon Dioxide

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