Structure–thermal–morphological correlation in starch–PVA reinforced cactus mucilage bio-based composite films

Structure–Property Relationships of Water‐Free Photocurable Composites Reinforced With Unmodified Starch in an Ionic–Hydrogen‐Bonded Reactive Medium

This study investigates a water‐free photocurable composite system based on an ionic methacrylic acid (MAA)–triethanolamine (TEOA) reactive medium that includes starch as a bio‐based filler. Without pretreating the starch, the system incorporated starch as a physically dispersed filler with limited interfacial bonding in an ionic–hydrogen‐bonded reactive medium via an in situ system. Density, phase separation, mechanical properties, thermal stability, viscoelastic behavior, and morphology were evaluated in relation to starch loading and coupling agents. The findings show that starch improves hardness and density, with tensile strength reaching up to 3.2 MPa. However, it also leads to phase separation, which limits the overall performance of the composite structures. A heterogeneous network structure with broad relaxation behavior is suggested by DMA results, while gel fraction results indicate a high degree of crosslinking. This study suggests how dispersion and network homogeneity influence overall material performance.

Hybrid PLA /Thermoplastic Starch Biocomposites Reinforced With Spent Coffee Grounds: Effect of Maleic Anhydride on Interfacial Compatibility, Mechanical Performance, and Biodegradability

This study developed hybrid poly(lactic acid) (PLA)/thermoplastic starch (TPS) biocomposites reinforced with spent coffee grounds (AK, 0–30 wt%) and compatibilized with maleic anhydride (MA, 5 wt%). The composites were characterized using Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile testing, melt flow rate (MFR), water absorption, and soil‐burial biodegradability. Increasing AK content improved stiffness and biodegradation because of its lignocellulosic structure; however, excessive filler loading caused agglomeration and reduced ductility. MA enhanced interfacial compatibility, filler dispersion, stress transfer, and moisture resistance at low to moderate AK contents. The AK 10% + MA formulation showed the most balanced performance, achieving a tensile strength of 29.86 MPa, low water absorption, favorable melt flow behavior, and 28.03% weight loss after 3 months of soil burial. These results clarify the role of AK and MA in controlling the processing–structure–property–biodegradation relationship of PLA/TPS composites and support the use of spent coffee grounds as sustainable fillers for biodegradable bioplastics.

Structure−Adhesion Relationship in Citric Acid-Crosslinked Cellulose Based Adhesives

Understanding how molecular architecture and rheological properties govern crosslinking behavior of cellulose derivatives is essential for designing high-performance biobased adhesive systems. This study investigates citric acid (CA)-mediated crosslinking in carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC) to elucidate the molecular mechanisms governing bioadhesive performance. High- and low-viscosity grades of both polymers were examined under controlled viscosity and concentration conditions to decouple the effects of molecular architecture from flow behavior. FTIR and XPS results supported curing-induced spectral and thermal changes consistent with possible ester-type interactions and network formation. DSC further showed broad endothermic transitions associated with curing-related thermal processes, while TGA results indicated enhanced thermal stability and higher char yields in all CA-modified samples, particularly for H-CMC, reflecting the formation of thermally stable network-like structures. Lap shear adhesion tests revealed an optimal viscosity window (∼103−104 mPa·s), within which high-viscosity polymers exhibited superior adhesion, achieving shear strengths of ∼4.5−5 MPa, likely due to their greater chain length, higher hydroxyl density, and stronger intermolecular entanglement. Excessive viscosity, however, reduced wood penetration and interfacial bonding, thus reducing the bonding strength. Overall, these results offer new insights into the design of fully biobased, formaldehyde-free wood adhesives.

Synthesis and characterization of CMC–HEC natural polymer hydrogels reinforced with rice husk ash–derived SiO2: swelling kinetics, mechanical performance, and soil water retention

Natural polymer hydrogels derived from renewable biopolymers represent a sustainable alternative to synthetic soil conditioners. This study synthesized amorphous silica (SiO₂) from rice husk ash (RHA) via alkaline dissolution–acid precipitation under four preparation conditions, and incorporated it as a particulate filler into carboxymethyl cellulose–hydroxyethyl cellulose (CMC–HEC) composite hydrogels ionically crosslinked with calcium nitrate. Silica samples were characterized by FTIR, XRD, SEM, and UV–Vis diffuse reflectance spectroscopy. Although all samples were amorphous, sample S1 was selected as the filler for its narrowest, most homogeneous particle-size distribution and preserved surface silanol density, which favors dispersion and interfacial bonding within the polymer matrix. Hydrogels were fabricated at filler loadings of 0, 1, 3, and 5 wt% and characterized by FTIR, SEM, and thermogravimetric–differential thermal analysis. Swelling in distilled water, KOH, NPK + Cu-EDTA fertilizer, and KH₂PO₄ media followed pseudo-second-order kinetics (R² ≥ 0.960); response-surface analysis confirmed that increasing filler content significantly reduced equilibrium swelling (p < 0.001), attributed to densified crosslinking via Si–OH···COO⁻ hydrogen bonding. Tensile stress increased significantly only at loadings ≥ 3 wt% (one-way ANOVA, p < 0.001), with the 1 wt% sample statistically indistinguishable from the unfilled control. Hydrogel H2 incorporating 1 wt% SiO₂ demonstrated an optimal balance of homogeneous filler dispersion, swelling performance, thermal stability, and soil water retention, confirming its potential as a biodegradable soil conditioner for sustainable agricultural applications.

Thermal transport behaviour of glycerol-plasticised cassava starch/PVA composite films: A photoacoustic approach

Influence of TiO\(_2\) Nanoparticles in Enhancing the Structural, Thermal and Electrochemical Properties of PVdF-HFP: NaI based Polymer Electrolyte Systems

This study investigates the influence of TiO₂ nanoparticles on the structural, thermal, and electrochemical properties of PVdF-HFP: NaI based polymer electrolyte films prepared by solution casting. The films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS). XRD analysis showed that incorporation of NaI and subsequent TiO₂ addition altered the crystalline–amorphous balance of the polymer matrix, with the 6 wt.% TiO₂ composition exhibiting enhanced amorphous character relative to the other filler concentrations. FTIR spectra indicated polymer–salt–filler interactions through shifts and changes in characteristic vibrational bands, supporting complex formation within the electrolyte system. DSC measurements further showed a pronounced reduction in melting temperature to 77.11 °C at 6 wt.% TiO₂, consistent with increased chain flexibility and reduced crystalline ordering. Impedance analysis demonstrated that ionic conductivity increased by approximately one order of magnitude compared with the unfilled electrolyte. The optimally filled 6 wt.% TiO₂ sample reached a room-temperature ionic conductivity of 2.24 × 10⁻² S cm⁻¹, whereas further filler addition reduced conductivity. The combined results indicate that TiO₂ concentration strongly influences polymer structure, thermal transitions, and ion transport. Within the investigated compositions, 6 wt.% TiO₂ provided the most favorable balance between amorphous character and ionic conductivity, supporting the suitability of this nanocomposite polymer electrolyte system for electrochemical applications.