Structure and properties of an hybrid system based on bisphenol A polycarbonate modified by A polyamide 6/organoclay nanocomposite

Blends of poly(carbonate of bisphenol A) (PC) with minute amounts of a nanocomposite based in polyamide 6 (PA6) with a layered organoclay (nPA6) were obtained upon melt mixing by varying the contents of both nPA6 and organoclay. The ternary nanocomposites (NC) were composed of a PC-rich matrix with some mixed PA6 present, and by a neat nPA6 dispersed phase. Upon dissolution of the matrix of the NC’s, the dispersed phase showed a highly fibrillar morphology that resembled that of thermoplastic/liquid crystalline polymer (LCP) blends. The cryogenically fractured surfaces observed by SEM showed a very fine particle size that was attributed to the presence of PA6 in the matrix and indicated a low interfacial tension. The Young’s modulus behaviour is proposed to be a consequence of the slight orientation of the PC-rich matrix and the highly fibrillated and oriented nPA6 dispersed phase. The important reinforcement effect of the dispersed phase is attributed to the additive effects of its large degree of orientation, and the reinforcing effect of the organoclay.     

ESC resistance of commercial grade polycarbonates during exposure to butter and related chemicals

Three commercial grades of polycarbonates (Lexan^® 144, Lexan^® 104 and Makrolon Rx1805) were studied with respect to resistance to environmental stress cracking (ESC) when exposed to butter and related chemicals. The polycarbonates (PCs) were extensively characterised to determine whether differences in ESC resistance could be related to their structural or chemical properties. MALDI-TOF mass spectrometry revealed that Makrolon Rx1805 contains a low molar mass material characterised as poly(propylene glycol)p, which was confirmed by ATR-FTIR and ¹H NMR. Some “non-absorbing” chemicals, such as butter, cause the PCs to be less resistant to ESC under stress. The reason for this is that these chemicals and the PCs have sufficiently similar Hansen solubility parameters to allow surface conformational changes even though absorption is non-existent or extremely small. ATR-FTIR was used to detect changes in molecular structure in the PC surfaces.     

Morphology and Compatibility of Compatibilized Polyethersulfone and Polycarbonate Blends

A PES-PC （polyethersulfone-polycarbonate） multi block random copolymer was synthesized with two oligomers, polyethersulfone and polycarbonate. The effects of the copolymer, as a compatibilizer, on the morphology and compatibility of the PES-PC blends were investigated. It was found that the addition of this copolymer to the PES-PC blends could improve their compatibility.     

PC/PET/EPDM共混体系的结晶与熔融行为

本文用解偏振光法与DSC法分别测定并研究了PC/PET/EPDM共混体系的结晶速度、结晶度、Avrami指数(n)和熔融温度及其影响因素,共混物中PET的结晶速度、结晶度均随PC含量增加而下降;EPDM用量不超过10%时,可提高PET的结晶速度,但不影响结晶度和成核与增长方式,n值不变。当EPDM为5%时,结晶速度呈现极大值。经退火处理的共混物呈现熔融双峰,PC量增加,高温熔融峰略移向高温方向;热处理温度升高或时间延长,则低温熔融峰移向高温方向。     

Bibliometric analysis and an overview of the application of the non-precious materials for pyrolysis reaction of plastic waste

Huge plastic consumption and depletion of fossil fuels are at the top of the world's environmental and energy challenges. The scientific community has tackled these issues through different approaches. Catalytic pyrolysis of plastic wastes to valuable products has been proved as a sustainable route which fits with the circular economy aspects. The design of catalytic materials is the central factor for performing the catalytic conversion of plastic wastes. This review aims to conduct a Bibliometric analysis of the pyrolysis of plastic wastes and non-precious-based catalysts by mapping research studies over the last fifty years. The analysis was developed via VOSviewer and RStudio tools. It showed the historical progress regarding plastic waste pyrolysis to produce valuable products and chemicals worldwide. The research shows that the top five countries with the highest citations and publications in this field were Spain, China, England, the USA and India. The Journal of Analytical and Applied Pyrolysis had the most comprehensive coverage of plastic waste. The relationship between the catalyst and the mechanism of plastic waste can influence the production yield and selectivity. The research gap and underrepresented research topics were identified, and previous research studies on developing non-precious-based catalysts that were most relevant to the current topic were reviewed and discussed. The challenges and perspectives on catalyst preparation and development for material complexity were critically discussed. Challenges of previous studies and directions for future research were provided. This report might guide the reader to take a general look at plastic waste valorization by pyrolysis and easily understand the main challenges.