Study on thermal, mechanical and morphological properties of recycled poly(vinyl chloride)/fly ash composites

Study on the Physical, Thermal and Mechanical Properties of SEBS/PP (Styrene-Ethylene-Butylene-Styrene/Polypropylene) Blend as a Medical Fluid Bag

The presence of DEHP in PVC-based medical bags poses a significant health risk to patients undergoing blood transfusion. In order to fabricate safer medical fluid bag materials, the use of SEBS/PP polymer blend as a potential material was investigated. Polymeric blends with varying weight percentages of styrene-ethylene-butylene-styrene/polypropylene (SEBS/PP) were fabricated by melt mixing using an internal Haake mixer. The physical properties of the SEBS/PP polymer blends were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and inductively coupled plasma–mass spectrometry (ICP-MS). In addition, measurements of the mechanical strength (tensile strength and Young’s modulus) as per ASTM 638, polymer hardness was tested using a durometer and swelling was analysed through water absorption and compared with commercial PVC-based blood bags. The results indicate that the SEBS/PP 50/50 blend has approximately similar characteristics as PVC-based blood bags. The SEBS/PP polymer blend possesses approximate tensile strength and Young’s modulus with values of 23.28 MPa and 14.42 MPa, respectively, to that of the conventional PVC blood bags. The results show that the SEBS/PP polymer blends have negligible zinc and aluminium migration with values of 1.6 and 2.1 mg/kg, respectively, and do not elute any harmful leachates, while the thermal studies indicate that the studied SEBS/PP materials are capable of withstanding steam sterilisation at 120 °C and cold storage below −40 °C. The investigated material can be utilized for medical fluid bags and contributes towards sustainable development goals, such as SDG 3 to ensure healthy lives and promote well-being, as well as SDG 12 to ensure sustainable consumption and production patterns.

A Brief Review of Poly(Vinyl Chloride) (PVC) Recycling

Bearing in mind the aspiration of the world economy to create as complete a closed loop of raw materials and energy as possible, it is important to know the individual links in such a system and to systematise the knowledge. Polymer materials, especially poly(vinyl chloride) (PVC), are considered harmful to the environment by a large part of society. The work presents a literature review on mechanical and feedstock recycling. The advantages and disadvantages of various recycling methods and their development perspectives are presented. The general characteristics of PVC are also described. In conclusion, it is stated that there are currently high recycling possibilities for PVC material and that intensive work is underway on the development of feedstock recycling. Based on the literature review, it was found that PVC certainly meets the requirements for materials involved in the circular economy.

Co-pyrolysis of Fe3O4-poly(vinyl chloride) (PVC) mixtures: Mitigation of chlorine emissions during PVC recycling

A systematic investigation was conducted onthe co-pyrolysisof Fe₃O₄and PVC mixtures in temperatures as high as 1373 K upon the development of PVC recycling technology that mitigates chlorine emission. Central to our investigation, PVC decomposition plays the leading role in the co-pyrolysis of Fe₃O₄and PVC mixtures following a two-stage pattern bifurcated at a temperature of 673 K. In Stage 1, at temperatures 673 K and lower, Fe₃O₄is chlorinated by chlorine from PVC, resulting in FeCl₂. The composition of the final solid residue of Stage 1,conjugated polyene, FeCl₂and Fe₃O₄/Fe₂O₃, depends on the initial Fe₃O₄content in the mixture. When the temperature is increased to be higher than 673 K, decomposition of conjugated polyene occurs simultaneously with the stepwise reduction of Fe₃O₄/Fe₂O₃: Fe₂O₃ → Fe₃O₄ → FeO → Fe. However, in mixtures containing Fe₃O₄that is less than 39.6% of the mass, Fe₃O₄can coexist with Fe; therefore, the FeO formation step is skipped. Most FeCl₂escapes from the reaction system as vapor, showing the necessity of removing FeCl₂at the end of Stage 1 to avoid harmful substance emission. The presence of Fe₃O₄can significantly suppress gaseous emissions, especially HCl originating from PVC decomposition. There was only 0.6% HCl by mass (2.4% PVC base by mass) released when co-pyrolyzing the PVC + 75% Fe₃O₄mixture due to the complete consumption of PVC and its decomposition products by Fe₃O₄. After separating FeCl₂,which is a valuable chemical feedstock, by water-leaching the solid residue obtained at 673 K, the filtered residue,which is a mixture of Fe₃O₄/Fe₂O₃and polyene, was confirmedto be suitable for iron-making. The results clearly show the possibility of developing a PVC recycling technology with mitigated chlorine emissions by manipulating the amount of Fe₃O₄added.