Zolfaghari Ehsan, Infurna Giulia, Alessi Sabina, Dispenza Clelia, Dintcheva Nadka Tz
Dipartimento di Ingegneria, Università degli Studi di Palermo, Viale delle Scienze, ed. 6, 90128 Palermo, Italy.
Polymers (Basel). 2024 Oct 18;16(20):2922. doi: 10.3390/polym16202922.
In order to limit the ever-increasing consumption of new resources for material formulations, regulations and legislation require us to move from a linear to a circular economy and to find efficient ways to recycle, reuse and recover materials. Taking into account the principles of material circularity and waste reuse, this research study aims to produce thermoplastic composites using two types of industrial waste from neighbouring companies, namely waste polypropylene (wPP) from household production and carbon-fibre-reinforced epoxy composite scrap from a pultrusion company. The industrial scrap of the carbon-fibre-reinforced epoxy composites was either machined/ground to powder (pCFRC) and used directly as a reinforcement agent or subjected to a chemical digestion process to recover the carbon fibres (rCFs). Both pCFRC and rCF, at different weight ratios, were melt-blended with wPP. Prior to melt blending, both pCFRC and rCF were analysed for morphology by scanning electron microscopy (SEM). The pCFRC powder contains epoxy resin fragments with spherical to ellipsoidal shape and carbon fibre fragments. The rCFs are clean from the matrix, but they are slightly thicker and corrugated after the matrix digestion. Further, the morphologies of wPP/pCFRC and wPP/rCF were also investigated by SEM, while the thermal behaviour, i.e., transitions and changes in crystallinity, and thermal resistance were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The strength of the interaction between the filler (i.e., pCFRC or rCF) and the wPP matrix and the processability of these composites were assessed by rheological studies. Finally, the mechanical properties of the systems were characterised by tensile tests, and as found, both pCFRC and rCF exert reinforcement effects, although better results were obtained using rCF. The wPP/pCFRC results are more heterogeneous than those of the wPP/rCF due to the presence of epoxy and carbon fibre fragments, and this heterogeneity could be considered responsible for the mechanical behaviour. Further, the presence of both pCFRC and rCF leads to a restriction of polymer chain mobility, which leads to an overall reduction in ductility. All the results obtained suggest that both pCFRC and rCF are good candidates as reinforcing fillers for wPP and that these complex systems could potentially be processed by injection or compression moulding.
为了限制用于材料配方的新资源的不断增长的消耗，法规要求我们从线性经济转向循环经济，并找到有效的方法来回收、再利用和回收材料。考虑到材料循环性和废物再利用的原则，本研究旨在使用来自邻近公司的两种工业废料生产热塑性复合材料，即家庭生产中的废聚丙烯（wPP）和拉挤成型公司的碳纤维增强环氧复合材料废料。碳纤维增强环氧复合材料的工业废料要么被加工/研磨成粉末（pCFRC）并直接用作增强剂，要么经过化学消化过程以回收碳纤维（rCFs）。将不同重量比的pCFRC和rCF与wPP进行熔融共混。在熔融共混之前，通过扫描电子显微镜（SEM）对pCFRC和rCF的形态进行分析。pCFRC粉末包含球形至椭圆形的环氧树脂碎片和碳纤维碎片。rCFs不含基体，但在基体消化后它们稍厚且有波纹。此外，还通过SEM研究了wPP/pCFRC和wPP/rCF的形态，同时分别通过差示扫描量热法（DSC）和热重分析（TGA）评估了热行为，即转变和结晶度变化以及热阻。通过流变学研究评估了填料（即pCFRC或rCF）与wPP基体之间的相互作用强度以及这些复合材料的加工性能。最后，通过拉伸试验表征了体系的力学性能，结果发现，pCFRC和rCF都发挥了增强作用，尽管使用rCF获得了更好的结果。由于存在环氧树脂和碳纤维碎片，wPP/pCFRC的结果比wPP/rCF的结果更不均匀，这种不均匀性可能被认为是导致力学行为的原因。此外，pCFRC和rCF的存在导致聚合物链迁移率受到限制，从而导致延展性整体降低。所有获得的结果表明，pCFRC和rCF都是wPP的良好增强填料候选物，并且这些复杂体系有可能通过注塑或压缩成型进行加工。
