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A polyether, acrylic acid and oleic acid were used as raw materials to synthesise oleic acid modified polycarboxylate superplasticiser (OA-PCE) by emulsion polymerisation. The synthesis process was optimised using orthogonal experiments. The colloidal interfacial chemistry results showed that the OA-PCE was more capable of reducing the surface tension of aqueous solutions than an unmodified traditional polycarboxylate superplasticiser (JS-PCE) and its adsorption capacity on cement particles was greater. The isothermal adsorption behaviour of the two kinds of PCEs on cement conformed to the Freundlich isothermal adsorption equation; it was a physical adsorption process by electrostatic action. The effect of OA-PCE dosage on the flowability of cement slurry was preliminarily investigated by rheological behaviour tests. According to the yield stress, plastic viscosity and thixotropic ring area of the slurry, a dosage of 0.35 wt% OA-PCE produced the optimum effect. The compressive strength of concrete made with 0.35 wt% OA-PCE at 4 h and 7 days was, respectively, 117.1% and 88.3% higher than that of the control group and met the standards for the use of concrete in metro pipe sheets. OA-PCE synthesised by emulsion polymerisation is therefore significant for the development of PCEs both in terms of the polymerisation method and practical applications.

In order to graft poly(isoprene) on the surface of fulvic acid (FA), fulvic acid-g-poly(isoprene) grafting polymer (FA-g-PI) was synthesized by reversible addition–fragmentation chain transfer polymerization. Because FA-g-PI became more hydrophobic, the static contact angle of FA-g-PI was 67°, which was increased by 37° compared with FA. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis showed that PI was grafted onto the FA. Furthermore, FA-g-PI was used as a modifier to melt blend with PLA to prepare poly(lactic acid)/fulvic acid-g-poly(isoprene) grafting copolymer composites (PLA/FA-g-PI). The mechanical performance results presented that the impact strength, tensile strength and elongation at break of PLA/FA-g-PI (0.3 wt%) reached 18.8 kJ/m2, 81.5 MPa and 18.47%, respectively, which were increased by 97.8%, 3.6% and 5.0% compared with PLA. The scanning electron microscopy analysis of impact fracture for PLA/FA-g-PI (0.3 wt%) also clearly showed that PLA/FA-g-PI (0.3 wt%) had the typical toughness fracture morphology feature. The results of differential scanning calorimetry and polarized optical microscope analysis indicated that the addition of FA-g-PI reduced the crystallite size during PLA crystallization. The kinetics of thermo-oxygen degradation by Kissinger method showed that the apparent activation energy of PLA/FA-g-PI (0.3 wt%) composites was increased from 153.73 kJ/mol to 179.17 kJ/mol, which was shown that FA-g-PI improved the thermal stability of PLA. Moreover, the reaction order showed that FA-g-PI had little effect on the PLA thermo-oxygen degradation reaction kinetic order under the air atmosphere.

In this work, initiators for continuous activator regeneration atom transfer radical polymerization was adopted to synthesize opal-poly(methyl methacrylate) graft polymer (opal-PMMA) with methyl me...

Both vulcanization reaction and CO2 plasticization play key roles in the temperature rise foaming process of silicone rubber. The chosen methyl-vinyl silicone rubber system with a pre-vulcanization degree of 36% had proper crosslinked networks, which not only could ensure enough polymer matrix strength to avoid bubble rupture but also had enough dissolved CO2 content in silicone rubber for induced bubble nucleation. The CO2 diffusion and further vulcanization reaction occur simultaneously in the CO2 plasticized polymer during bubble nucleation and growth. The dissolved CO2 in the pre-vulcanized silicone rubber caused a temperature delay to start while accelerating further vulcanization reactions, but the lower viscoelasticity caused by either CO2 plasticization or fewer crosslinking networks was still the dominating factor for larger cell formation. There was a sudden increase in elastic modulus and complex viscosity for pre-vulcanized silicone rubbers at higher temperature because of the occurrence of further vulcanization, but CO2 plasticization reduced the scope of change of rheological properties, and the loss factor was close to 1 around 170 °C, which is corresponding to the optimum foaming temperature. The foamed silicone rubber had a higher cell density and smaller cell size at a higher temperature rising rate, which is due to higher CO2 supersaturation and faster vulcanization reaction. These results provide some insight into the coupling mode and effect of CO2 plasticization and vulcanization for regulating cell structure in foaming silicone rubber process.

Mechanical properties of polyvinyl alcohol (PVA) are of essential importance to the practical application. Much effort has been done to further improve the properties of PVA by modifiers. However, in-depth insight into the role of the modifiers in the properties of PVA at a molecular level still remains rare. Therefore, the Glass transition temperature (Tg) and mechanical properties of PVA, PVA/graphene oxide (GO) and PVA/TRIS functionalized graphene oxide (Tris-GO) are investigated by molecular dynamics (MD) simulation. The results indicate the volume of PVA, PVA/GO and PVA/Tris-GO regularly varies with temperature. The PVA/Tris-GO show a higher Tg compared to the PVA/GO owing to stronger hydrogen-bonding interactions. The Young’s modulus, Shear modulus and Cauchy pressure of PLA/Tris-GO nanocomposites are enhanced by 50%, 46%, and 40% at 2.5 wt% addition amount of Tris-GO. In addition, the introduction of Tris-GO can significantly reduce the mobility and flexibility of the PVA chains in the PVA/Tris-GO. The binding energy between PVA and Tris-GO is larger than that between PVA and GO, which leads to the improved mechanical properties of the PVA/Tris-GO. These simulation results provide a better understanding of the thermomechanical mechanism of PVA/Tris-GO nanocomposites, and an effective guidance for improving their mechanical properties.

Opal-methacryloylpropyltrimethoxysilane-polystyrene graft polymer (opal-MPS-PS) was synthesized using coupling method and solution polymerization. The results of orthogonal experiments showed optimum reaction conditions including: polymerization time of 4 h, catalyst at 0.03 g, reaction temperature of 80 °C, and styrene volume of 4 mL. Moreover, the structure of opal-MPS-PS was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results demonstrated that PS was grafted onto opal-MPS. Furthermore, poly(lactic acid) composites (PLA/opal-MPS-PS) were prepared using opal-MPS-PS as filler by melt blending. The results of mechanical testing showed that the impact toughness of PLA/opal-MPS-PS composites was increased by 50.5%. The rheological behavior and morphological analysis showed that PLA displayed high interfacial compatibility with opal-MPS-PS. The polarized optical microscopic and differential scanning calorimetric results showed that opal-MPS-PS with heterogeneous nucleation effect improved the crystallization properties of PLA, and enhanced toughness of PLA. The flame retardancy test showed that the thermal stability and flame retardancy of the PLA composites material were improved compared with PLA. Enzymatic degradation tests showed that opal-MPS-PS had an inhibitory effect on the degradation of PLA. In all, this study provides a promising method to improve the comprehensive performance of PLA through organic modification using opal as filler.

The ammonium acetate organic vermiculite (A-OVMT) was synthesized with phenylenediamine and ammonium acetate by solution intercalation. Then, poly(lactic acid) (PLA)/A-OVMT nanocomposites were prep...

Fulvic acid (FA) was modified with p-phenylenediamine via iodine and triphenylphosphine as catalyst. The microstructure characterization for modified fulvic acid (MFA) were investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively, which demonstrated that MFA was characteristic of amide derivative. Moreover, poly(lactic acid) (PLA)/MFA composites was prepared with MFA as filler by melt blending. The mechanical tests showed that the impact strength of PLA/(0.5wt%) MFA composites were increased by 97.2%. Scanning electron microscopy demonstrated that the impact fracture of PLA/(0.5wt%) MFA composites were characteristic ductile fracture. The rheological behavior analysis showed that PLA had good interfacial compatibility with MFA. The crystallinity of PLA was increased from 4.9% to 36.9% with the introduction of MFA. The polarized optical microscopy presented that the crystallization nucleation rate of PLA were rapidly increased, which resulted in the increased comprehensive performance of PLA. The results of enzymatic degradation mechanism showed that MFA increased the Km of proteinase K, and had some inhibition to the degradation of PLA, but PLA still remained degraded evidently.

The poly (lactic acid)-fulvic acid graft polymer (PLA-FA) was synthesized with lactic acid and fulvic acid (FA). The optimum parameters were determined by orthogonal experiment. X-ray photo...

In this work, amino-functionalized nano-SiO2 (m@g-SiO2) was synthesized through coupling reaction on the surface of nano-SiO2. Moreover, the optimum preparation conditions of m@g-SiO2 were selected via orthogonal experiments as follows: reaction temperature of 80 °C, reaction time of 8 h, the mass ratio of stearic acid, N,N′‑carbonyldiimidazole, imidazole hydrochloride and g-SiO2 of 0.5:0.7:0.7:1. Fourier transform infrared spectroscopy, static angle measurement and X-ray photoelectron spectroscopy unanimously confirmed the formation of m@g-SiO2. Furthermore, poly(lactic acid)(PLA)/m@g-SiO2 nanocomposites was prepared with m@g-SiO2 as fillers to improve the comprehensive performance of PLA. Then, the mechanical properties and crystallization behavior of PLA/m@g-SiO2 nanocomposites were studied, which showed that the impact strength and elongation-at-break of PLA/m@g-SiO2 (0.3 wt%) nanocomposites were increased by 78.05% and 1148%, respectively, and its crystallinity was increased by 26.46%. Simultaneously, thermal gravimetric analysis indicated that the thermal stability of PLA/m@g-SiO2 nanocomposites was improved. Eventually, the multi-scale investigation on the phase miscibility of PLA/m@g-SiO2 nanocomposites was probed by rheological behaviors analysis and the molecular dynamics simulations, which confirmed that surface modification of SiO2 greatly enhanced the interaction energy and miscibility between the filler and PLA bulk.

Graphene oxide-polystyrene graft polymer (SGO-PS) was prepared by reversible addition-fragmentation chain transfer radical polymerization method. Orthogonal experiments indicated that the optimum synthesis reaction conditions for SGO-PS were as follows: the millimole ratio of chain transfer agent to initiator was 0.15 : 0.3, and the amount of styrene was 8 mL at 80°C for 12 hours. The products were characterized by Fourier transform infrared spectroscopy and thermal weightlessness analysis, and the highest grafting rate of SGO-PS was 62.46%. Then, PLA/SGO-PS nanocomposites were prepared using SGO-PS as fillers by melt intercalation method, and its crystallinity, mechanical properties, and thermal stability were significantly improved. Compared with pure PLA, the crystallinity of PLA/SGO-PS (0.3 wt%) nanocomposites was increased by 5 times. Multiple melting behavior tests showed that the introduction of SGO-PS caused the PLA molecular chain to be discharged into the unit cell in time, and the melting temperature shifted to a higher temperature, which ultimately made the grain structure of PLA composites more complete and stable than pure PLA. The rheological performance test showed that the uniform dispersion of SGO-PS in the PLA matrix inhibited the free movement of the PLA molecular chain and caused higher flow resistance, resulting in an increase in the complex viscosity, storage modulus, and loss modulus of PLA/SGO-PS.

Zinc oxide pillared organic layered double hydroxides (ZnO-LDHs-S) were synthesized with sodium dodecyl sulfate (SDS) via a intercalation method. Meanwhile, the properties of ultraviolet (UV) absorbance and antibacterial of ZnO-LDHs-S were investigated. To improve the performances of poly (lactic acid) (PLA), PLA/ZnO-LDHs-S nanocomposites were prepared by melt blending using ZnO-LDHs-S as nucleating agent. Structure and properties of PLA/ZnO-LDHs-S nanocomposites were investigated by Fourier transform infrared spectra, transmission electron microscopy, mechanical properties testing, differential scanning calorimetry, polarized optical microscopy and rheological analysis. It was shown that the introduction of ZnO-LDHs-S improved the comprehensive performance of PLA.

Poly(lactic acid)-γ-cyclodextrin inclusion complex-poly(glycidyl methacrylate) (PLA-IC-PGMA) was synthesized with poly(lactic acid) (PLA) and γ-cyclodextrin inclusion complex via surface initiated atom transfer radical polymerization. Then, the PLA/PLA-IC-PGMA composite was prepared by melt blending using PLA-IC-PGMA as additive. Structure and properties of PLA-IC-PGMA and PLA/PLA-IC-PGMA composites were confirmed by X-ray diffraction patterns, 1H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), polarized optical microscopy, rheological analysis, etc. Mechanical testing analysis showed that the tensile strength, elongation at break, and impact strength of PLA/(1 wt%) PLA-IC-PGMA composites were improved by 2.3%, 10.8%, and 52.5%, respectively, compared with pure PLA. Scanning electron microscopy analysis demonstrated that the toughness of PLA/PLA-IC-PGMA composite was improved. The results of DSC and TG showed that the cold crystallization peak of PLA composites after the addition of PLA-IC-PGMA disappeared, and its crystallinity was increased by 25% compared with PLA. Furthermore, the thermal stability of PLA/PLA-IC-PGMA composite was improved. Dynamic mechanical analysis showed that the glass transition temperature of PLA/PLA-IC-PGMA composites decreased by 8 °C, which indicated that the flexibility of the chain of PLA was greatly improved. Therefore, the addition of PLA-IC-PGMA improved the comprehensive performance of PLA.

Humic acid amide (HA-amide) was prepared by amidation of HA and dodecylamine (DDA) with carbonyl diimidazole (CDI) as coupling reagent. Furthermore, HA-amide was added to poly (lactic acid) (PLA) a...

An improved Hummers method was used to prepare graphene oxide (GO). Then, the orthogonal experiment design methods were used to select the optimum conditions of the preparation for amidated graphene oxide (AGO) via amidation. The optimum scheme was followed by: reaction temperature 70 °C, reaction time 5 h and GO: benzohydrazide of 1:3 (g:g). The structure of AGO was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope (TEM) techniques, which demonstrated that the amidation of GO was successful. Furthermore, poly(lactic acid) (PLA)/AGO nanocomposites were prepared by melt blending to improve the comprehensive performance of PLA. Mechanical properties, thermal stabilities, crystallization properties, and rheological behavior of PLA/AGO nanocomposites were investigated, which showed that the addition of 0.3 wt % of AGO increased the tensile strength, elongation-at-break, and impact strength of PLA/AGO nanocomposites by 7.68, 47.32 and 41.27%, respectively, compared with neat PLA. Scanning electron microscopy analysis showed ductile fracture of the PLA/AGO nanocomposites. TEM analysis showed that nano-AGO single layers were evenly dispersed in the PLA matrix, confirming the formation of an exfoliated nanocomposite structure. Differential scanning calorimetry demonstrated that AGO eliminated the cold crystallization of PLA matrix and improved the crystallinity of PLA by 34.1%. In all, this study provided an effective and feasible method for improving the comprehensive performance of PLA.

Nano boron nitride-trimethylolpropane tris (3-mercaptopropionate) grafted poly (L-lactic acid) (BN-TTMP-PLLA) was prepared with nonmetallic organic catalyst by thiol-ene click chemistry. By orthogonal experiment and range analysis, the optimum reaction conditions of BN-TTMP-PLLA were as follows: reaction time of 2.5 h, photoinitiator addition amount of 0.04 g, TTMP addition amount of 0.9 g, and mass ratio of PLLA-AA to BN-570 of 1:1. The product was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which showed that PLLA was successfully grafted onto BN surface. Furthermore, PLA/BN-TTMP-PLLA nanocomposites were prepared by melt blending with BN-TTMP-PLLA as modifier to enhance the performance of PLA. Compared with pure PLA, the impact strength and elongation at break of PLA/BN-TTMP-PLLA (0.5 wt%) nanocomposites were increased by 1.58 times and 7.34 times, respectively. Molecular dynamics simulation calculation showed that EInteraction between PLA and BN before and after functionalization decreased from −177.44 kcal/mol to −516.42 kcal/mol, which proved that intermolecular interactions between them were strengthened. In addition, PLA/BN-TTMP-PLLA (0.5 wt%) nanocomposites during melting and isothermal crystallization were studied by Rheonaut technology for simultaneous rheometry and FTIR, which demonstrated that the crystallization properties of PLA was clearly improved due to the strong hydrogen bonding effect between BN-TTMP-PLLA and PLA.

The modified saponite (SASAP) was prepared with 3-aminopropyl triethoxysilane, stearic acid, 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 1-hydroxybenzotriazole and triethylamine. The structure of SASAP was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and static contact angle, which confirmed that SASAP had been successfully prepared. To improve the crystallization rate of poly (lactic acid) (PLA), PLA/SASAP nanocomposites was melt intercalation with SASAP as fillers. The mechanical properties showed that the elongation at break of PLA/SASAP nanocomposites was increased from 9.8% of PLA0 to 45.5%, its impact strength was increased from 9.1 kJ/m2 to 13.5 kJ/m2, and its tensile strength was increased from 23.25 MPa to 28.79 MPa. The interface tension testing demonstrated that the interface tension of PLA/SASAP nanocomposites decreased to 0.24 ( mN·m−1), which was due to the fact that amide groups of SASAP formed stronger intermolecular interactions with the PLA chains. Moreover, rotation rheology demonstrated that the interface compatibility of PLA/SASAP nanocomposites was significantly improved. Rheonaut technology analysis for simultaneous rheology and FTIR investigated the isothermal crystallization and chemical structure of PLA/SASAP nanocomposites, which indicated that SASAP accelerated the crystallization rate of PLA.

Amidated humic acid (AHA) was prepared by amidation of humic acid (HA) and its structure was verified by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Then poly(lactic acid)/amidated humic acid composites (PLA/AHA) were prepared using AHA as the nucleating agent. The mechanical properties, thermal stability, and crystallization behavior of the PLA/AHA composites were investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheological analysis. The mechanical properties and thermogravimetric analysis showed that the tensile properties, impact resistance, and thermal stability of the PLA/AHA composites were improved. The cross-sectional morphology of the fractured surface showed that the addition of the nucleating agent significantly changed the crystallinity of PLA. The DSC results showed that the crystallinity of PLA/AHA composites increased from 4.19 to 35.36% after introduction of the nucleating agent. The POM of PLA/AHA composites demonstrated that AHA increased the crystallization rate of PLA. The maximum torque of PLA/AHA composites was 75.0% higher than that of PLA and the apparent viscosity was increased by 172.5%. This proved that the AHA changed the crystalline lattice structure and stiffness of PLA matrix. Non-isothermal crystallization kinetics showed that HA provided a large number of heterogeneous nucleation sites and improved the crystallization rate of PLA.

In this study, novel star-shaped polymers of I²-cyclodextrin (I²-CD)–poly (glycidyl methacrylate) (PGMA) were prepared by atom transfer radical polymerization (ATRP), formed from GMA and I²-CD. In addition, the structure, properties and hydrophilicity of the I²-CD-PGMA polymers thus prepared were systematically analyzed. 1,10-phenanthroline monohydrate (Phen)/I²-CD-PGMA drug-loaded microspheres were prepared by emulsion solvent evaporation. The optimum preparation conditions were determined by orthogonal tests. Analysis results indicated that the performance of star-shaped polymers of I²-CD-PGMA clearly changes, resulting in the increase of the contact angle from 17° to 72.5°, and their thermal degradation temperature was enhanced from 260 °C to 401 °C. Moreover, I²-CD-PGMA drug-loaded microspheres with a smooth, spherical surface were successfully prepared, and the drug-loading capacity and average particle size of drug-loaded microspheres were 26.67 % and 10 I¼m, respectively. Drug release tests indicated that the release behavior of I²-CD-PGMA drug-loaded microspheres conformed to Higuchi release kinetics, which exhibited a significant drug delivery capability. The release rate and utilization of I²-CD-PGMA were greater than that of I²-CD, demonstrating that I²-CD-PGMA was more suitable as a drug delivery material.

Fulvic acid–poly(methylmethacrylate) graft copolymers were synthesized by surface-initiated atom transfer radical polymerization with fulvic acid. The result demonstrated that the hydrophobicity of fulvic acid–poly(methylmethacrylate) was improved after modification by surface-initiated atom transfer radical polymerization. Furthermore, poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites were prepared to improve the performances of poly(lactic acid) by blend melting. Compared to poly(lactic acid) with Xc of 5.38%, the Xc of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was 19.94%. Moreover, the impact strength of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was increased by 5.19% compared to poly(lactic acid). In all, this study provided an effective and feasible method for optimizing interface performance and enhancing the thermal stability of poly(lactic acid).