Hydroxyapatite-lignin hybrid systems as improved poly(vinyl chloride) fillers: From preparation to application.

In this study, new, functional hydroxyapatite-lignin hybrid systems were designed and characterized. The efficacy of the mechanical method utilized to obtain these systems was confirmed by Fourier transform infrared spectroscopy. The hybrid materials were also noted for their good electrokinetic stability and thermal stability. The introduction of 2.5 to 10 wt% hydroxyapatite-lignin systems into an unplasticized PVC blend using a two-step kneading and pressing method resulted in composites with relatively homogeneous distribution, as confirmed by SEM observations. The processing properties of the filler-containing blends were investigated using plastographometric analysis and MFR tests. The introduction of a lignin-predominant hybrid system into the PVC matrix results in a significant improvement of thermal stability, softening temperature, and tensile strength, while maintaining sufficient impact strength for numerous applications. Hybrid materials containing higher amounts of added lignin are promising materials with bacteriostatic properties. This can be utilized to stabilize and prevent the deposition of microorganisms, as well as the formation of biofilms, on material surfaces, thereby limiting the spread of pathogens. New eco-composites based on PVC and a hybrid filler containing lignin show promise in producing components with surfaces resistant to bacterial colonization. Hence, these materials could be used in medical and hospital equipment.

Plasticized Poly(vinyl chloride) Modified with Developed Fire Retardant System Based on Nanoclay and L-histidinium Dihydrogen Phosphate-Phosphoric Acid.

The current work assessed the burning behavior of plasticized poly(vinyl chloride) (PVC-P) modified with a two-component composition, consisting of L-histidinium dihydrogen phosphate-phosphoric acid (LHP) and nanoclay (n). The thermal and thermodynamical properties of the PVC-P containing from 10 to 30 wt% of the fire retardant system (FRS) were determined by thermogravimetric analysis (TG) as well as by dynamic mechanical thermal analysis (DMTA). In contrast, fire behavior and smoke emission were studied with a cone calorimeter (CC) and smoke density chamber. The research was complemented by a microstructure analysis, using a scanning electron microscope, of the materials before and after burning CC tests. The effects were compared to those achieved for PVC-P, PVC-P with a commercially available fire retardant, the substrate used for the produced LHP, and the mixture of LHP and zinc borate, both of which contained the same share of nanoclay. Based on a notable improvement, especially in smoke suppression suggests that the n/LHP system may be a candidate fire retardant for decreasing the flammability of PVC-P.

Composites of Poly(vinyl chloride) with Residual Hops after Supercritical Extraction in CO2.

The common applications of poly(vinyl chloride) (PVC) in many industries mean that the topic of recycling and disposal of post-consumer waste is still very important. One of the methods of reducing the negative impact of PVC waste on the natural environment is to use technological or post-consumer waste of this polymer to produce new composite materials with favorable utility properties, with the addition of natural fillers, among which agro-waste, including hop residue, is deserving of special attention. In this study, the effect of the addition of residual hops (H) on the mechanical and physicochemical properties of poly(vinyl chloride) was investigated. PVC blends containing 10, 20 and 30 wt % of hop residue were mixed in an extruder, while the specimens were obtained by the injection molding method. It was observed that the addition of H increased their thermostability, as shown by a Congo red test. Furthermore, thermogravimetric analysis showed that the degradation rate of PVC/H composites in the first and second stages of decomposition was lower in comparison with unmodified PVC. In turn, composite density, impact strength and tensile strength decreased significantly with an increasing concentration of filler in the PVC matrix. At the same time, their Young's modulus, flexural modulus and Rockwell hardness increased. Flame resistance tests showed that with an increasing residual hop content, the limiting oxygen index (LOI) decreased by 9.0; 11.8 and 13.6%, respectively, compared to unfilled PVC (LOI = 37.4%). In addition, the maximum heat release rate (pHRR) decreased with an increasing filler content by about 16, 24 and 31%, respectively. Overall, these composites were characterized by a good burning resistance and had a flammability rating of V0 according to the UL94 test.

Poly(vinyl chloride) Composites with Raspberry Pomace Filler.

This study examined, the effect of chemically extracted raspberry pomace on the thermal stability, mechanical properties, flammability, chemical structure and processing of poly(vinyl chloride). It was observed that the pomace in this study was used to extract naphtha, thereby permitting the removal of bio-oil as a factor preventing the obtaining of homogeneous composites. Furthermore, adding 20% raspberry pomace filler after extraction extended the thermal stability time for the composites by about 30%. It was observed that composite density, impact strength, and tensile strength values decreased significantly with increasing concentrations of filler in the PVC matrix. At the same time, their modulus of elasticity and Shore hardness increased. All tested composites were characterized by a good burning resistance with a flammability rating of V0 according to the UL94 test. Adding 20 to 40% of a natural filler to the PVC matrix made it possible to obtain composites for the production of flame resistant elements that emitted less hydrogen chloride under fire conditions while ensuring good rigidity.