Application of biodegradable polylactic acid (PLA) is limited by its poor toughness and processability. This research focused on modifying PLA using butadiene rubber (BR) and epoxy butadiene rubber (EBR) as a toughening material. To enhance the compatibility between PLA and BR, and dicumyl peroxide (DCP) and acetyl tributyl citrate (ATBC) was introduced into the BR/PLA or EBR/PLA system to prepare BR/PLA-S or EBR/PLA-S by melt blending. The results showed that the optimal composition of modified-BR/PLA was that the mass ratio of PLA/BR/DCP/ATBC was 80/20/0.15/4. The impact strength and elongation at break of the BR/PLA-S and EBR/PLA-S were 8.73 kJ/m 2 and 105.6%; and 11.18 kJ/m 2 and 157.9% respectively. It improved the toughness of PLA, and the toughening effect of EBR was better than that of BR. The peak intensity of the C=C bond (3006 cm -1 ) in the FTIR spectra of the modified-BR/PLA weakened, and the peak area of the CH 2 bond (2918 cm −1 ) increased, occurring a cross-linking reaction between BR (or EBR) and PLA. Tg, Tc and Tm of the BR/PLA-S and EBR/PLA-S were 58.44°C, 92.53°C and 170.13°C; 55.0°C, 87.5°C and 167.66°C respectively, lower than Tg and Tc of PLA, and higher than Tm of PLA, suggesting that modified-BR improved processability and thermal stability of PLA composites. The successful preparation of BR-based toughening agent using an environmental-friendly system broadened the use of BR and PLA with the truly-sustainable developments.
Natural rubber constitutes a critical and largely irreplaceable raw material for the tire industry due to its sustainability, its broad applicability across diverse compound formulations in various tire components, and its relatively lower cost compared to alternatives. In recent years, the demand for natural rubber has steadily increased, primarily driven by rising production and consumption in the tire sector as well as in related industries. However, the environmental challenges associated with this growing demand have intensified concerns. Consequently, research efforts aimed at sourcing natural rubber from alternative and locally available resources have gained significant momentum and prominence. The rubber-based material used in this study was obtained from Gundelia tournefortii , which is an endemic herb raised mainly in the eastern part of Türkiye. Initially, the latex from Gundelia tournefortii was collected from the cut body, the impurities were removed, and it was dried till solid form remained. The remaining solid form, as a rubber-based material, was then analyzed by various instrumental techniques and compared with commercial natural rubber obtained from the latex of the Hevea Brasiliensis tree. In the second part of the study, the rubber-based material was used in a standard compound recipe (ASTM D3184) by partially replacing natural rubber in varying proportions. Trial compounds containing the rubber-based material were evaluated in terms of their curing, mechanical and dynamic mechanical properties and compared with the control compound prepared by natural rubber only. Although amorphous, likely resinous, secondary structures reduce the reinforcement imparted by the rubber -based material, DMA analysis showed that rubber -based material at 10–20 phr levels in the standard compound recipe provided improvements in grip and structural response, while maintaining or reducing tan δ at 60°C did not worsen rolling resistance.
Silica-reinforced natural rubber composites cured with sulfur and phenolic resin were prepared in this study. The properties were monitored through the rheological characteristics, mechanical strength, and dynamic mechanical analysis of the composites. Maximum torque and torque difference increased with silica loading in all cases, but the composites cured with phenolic resin showed greater changes. The composites cured with the phenolic resin also showed greater swelling resistance, crosslink density, stress at different strains, and tensile strength compared to composites with the sulfur system. The highest tensile strength was observed at 30 phr silica loading, with about 38% improvement for phenolic resin and about 6% for sulfur systems compared to their unfilled controls. Hydrogen bonding or condensation reactions possibly took place between phenolic resin and silica filler in the phenolic cured composites, whereas such interactions were absent in the cases with the sulfur system. This was confirmed by monitoring the silica aggregation and Payne effect. Although the phenolic resin is considered the second-choice system for silica-reinforced natural rubber composites. However, this study has demonstrated their performance as a system of choice for silica-based rubber composites.
Recent research has focused on the use of natural fiber/recycled plastic composites for industrial waste recycling and the reduction of environmental pollution. This study examines the development of recycled polyvinyl chloride-styrene-co-acrylonitrile copolymer blend (rPVC-SAN) filled with date palm fiber (DF). The composites were produced using a co-rotating twin-screw micro-extruder at processing temperatures ranging from 165 to 175 degrees C, followed by hot compression molding at 170 degrees C under a pressure of 300 bar for 10 min. The impact of fiber surface modification (alkali and silane treatments) on the mechanical, morphological, and water absorption properties of the composites was investigated. The rPVC-SAN-DF composites exhibited superior interfacial characteristics following surface treatment. Then, the impact of DF surface treatment on composite characteristics was assessed. In addition, the adhesion of rPVC-SAN-DF composites after various treatments was investigated. Due to its strong interfacial interaction and the interaction involving the alkoxy group of silane coupling agents and the nitrile group in SAN, the combined alkali-silane composite (BC-NaSi) outperformed other composites in mechanical properties. This resulted in the SAN accumulating at the interface between components and diminished the hydrophilicity of DF. Specifically, compared to the untreated composite, the BC-NaSi composite exhibited maximum improvements of 30% in tensile strength, 40% in tensile modulus, 24% in flexural strength, and 38% in flexural modulus. Scanning electron micrographs (SEM) revealed that the BC-NaSi composite has a rough surface with many exposed fibers, supporting the hypothesis that alkali-silane-treated fibers may improve interfacial bonding. The rheological properties of the composites were tested using dynamic shear rheology. The treated fiber composite demonstrated improved rheology. At low frequencies both the complex viscosity (3.06 & times; 105 Pa. s) and the storage modulus (13.24 GPa) were increased in the BC-NaSi composite. Finally, the water uptake performance of the composites was studied. After 2, 4, and 6 weeks, the BC-NaSi composite still had the lowest water uptake at 4.02%, 4.22%, and 4.37%, respectively. The results illustrate the potential of using agricultural waste fibers in recycled polymer composites to produce sustainable materials with enhanced performance for structural, electrical, and packaging applications.
This study elucidates in situ reactive compatibilization of polystyrene (PS) and polymethyl methacrylate (PMMA) blends using styrene-maleic anhydride (SMA) as a compatibilizer and benzoyl peroxide (BPO) as a free-radical initiator. Various PS/PMMA blends with weight ratios of 90/10, 80/20 and 70/30 were melt-processed using a co-rotating twin-screw extruder, incorporating 5, 7 and 10 wt.% SMA to evaluate the effects of composition and compatibilizer loading on blends' performance. Reactive compatibilization with 7 wt.% SMA 90/10 PS/PMMA composition significantly enhanced tensile strength (up to similar to 25%), impact strength (by similar to 30%), and heat deflection temperature (up to similar to 11%), compared with uncompatibilized blends of same composition, owing to improved interfacial adhesion and refined phase morphology. FTIR and DSC analyses confirmed improved interfacial interactions whereas, TGA demonstrated enhanced thermal stability, with the onset degradation temperature (Tonset) increased by similar to 20 degrees C. A 7 wt.% SMA threshold was identified for optimal properties, beyond which agglomeration adversely affected performance. A compatibilization model based on various reactions has been proposed that explains enhanced mechanical and thermal properties particularly in the presence of benzoyl peroxide acting as a free-radical initiator.
