The degradation behavior of poly(lactic-co-glycolic acid) (PLGA) under natural seawater conditions has been less systematically described than that in buffered laboratory media. In this study, PLGA copolymers with different lactic acid/glycolic acid (LA/GA) ratios were prepared at two molecular-weight levels and immersed in natural seawater. Water uptake, mass retention, molecular weight changes, glass transition temperature (T g) changes, and surface morphology were analyzed. PLGA-9010 exhibited limited hydration, modest T g variation, and relatively slow molecular-weight reduction, whereas PLGA-5050 showed pronounced T g depression toward seawater temperature accompanied by accelerated molecular-weight decay and earlier surface disruption. PLGA-7030 displayed intermediate behavior. Within the investigated molecular weight range, lower molecular weight samples showed slightly faster decreases in molecular weight and T g during the early stage of immersion; however, the relative degradation behavior among different PLGA compositions remained unchanged. These results provide comparative information on the degradation behavior of PLGA copolymers with different compositions and molecular weights under natural seawater conditions.

Poly(lactic-co-glycolic acid) (PLGA) is a widely used biodegradable polyester; however, its inherently glassy nature limits its applicability in systems requiring large and reversible deformation. In this work, segmented PLGA-based biodegradable thermoplastic elastomers (BTPEPLGA) were developed by incorporating highly flexible, amorphous aliphatic polyester soft segments with a low glass transition temperature (approximate to-55 degrees C) through chain extension with hexamethylene diisocyanate (HDI). The resulting materials exhibit microphase-separated morphologies characterized by distinct glass transitions associated with soft- and PLGA-rich domains. By varying the PLGA/soft-segment ratio, mechanical properties can be systematically tuned, with tensile strengths ranging from approximately 5 to 15 MPa and elongations at break exceeding 900% at intermediate compositions. Cyclic tensile tests demonstrate elastic recovery above 90% under repeated loading. Dynamic mechanical analysis reveals composition-dependent modulus and a stable rubbery plateau region. Enzymatic degradation studies further show that the mass-loss behavior can be regulated through segmental composition while maintaining the thermoplastic elastomer characteristics. These results demonstrate that segmented structural design provides an effective strategy for balancing elasticity and degradation behavior in PLGA-based thermoplastic elastomers.

Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable aliphatic polyester with tunable composition and degradation behavior, but its intrinsic brittleness limits its broader use as a structural material. In this work, a highly flexible polyester macroinitiator (FPM) was introduced into PLGA through bulk ring-opening copolymerization of L-lactide and glycolide, followed by chain extension with hexamethylene diisocyanate (HDI), to construct PLGAFPM multiblock copolymers. FPM incorporation weakened the ordered packing of PLGA and progressively changed its tensile behavior from brittle fracture to pronounced ductile deformation. With increasing FPM content, PLGAFPM copolymers showed a gradual transition from brittle fracture to ductile deformation, accompanied by markedly improved elongation at break and tensile toughness. Among the investigated samples, PLGAFPM10 provided the most favorable balance between strength retention and toughness improvement, retaining a tensile strength of 55.6 MPa together with an elongation at break of 182.9 % and a toughness of 45.3 MJ/m3. Further increasing FPM content promoted extensibility but reduced tensile strength. Seawater immersion further showed a composition-dependent aqueous degradation response, with mass retention decreasing from 94.5 % for neat PLGA to 74.8 % for PLGAFPM20 after 126 d. This result indicates that FPM incorporation retained the hydrolyzable PLGA-based polyester framework while increasing water-related structural evolution. These results provide a chain-structure design strategy for toughening PLGA while maintaining its degradable polyester framework.

Copper is a versatile material, commonly utilized in power transmission and electronic devices, but its relative high reactivity necessitates a long-lasting protective technique. Here, we report a method that combines plasma-enhanced non-equilibrium magnetron sputtering physical vapor deposition (PEUMS-PVD) and anodization to construct a self-healing three-dimensional Ti/Al-doped TiO2 nanotubes/Ti3AlC2 coating on the surface of Cu substrates. This novel strategy enhances the corrosion resistance of copper substrates in marine environments, with corrosion current densities of up to 4.5643×10−8 A/cm2. Among them, the doping of nano-aluminum particles makes the coating self-healing. The mechanistic analysis of the corrosion behaviors during early immersion experiments was conducted using electrochemical noise, and revealed that during the initial stages of coating immersion, uniform corrosion predominates, with a minor occurrence of localized corrosion.

Poly(L-lactic acid) (PLLA), one of the most prosperous bio-derived synthetic polymers, has garnered significant attention due to its biodegradability and origin from renewable resources. However, its practical applications are limited by its inherent brittleness. In this study, a novel highly flexible polyester macromolecule (FPM) was synthesized via stepwise polycondensation, employing bio-based diols and diacids. The macromolecular initiator (FPM) was subsequently used to prepare PLLA(FPM) multiblock copolymers through ring-opening polymerization (ROP) of L-lactide, followed by chain extension with hexamethylene diisocyanate (HDI). The chemical structures were investigated by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (H-1 NMR). The differential scanning calorimetry and tensile testing revealed that increasing FPM content reduced crystallinity while dramatically improving ductility-PLLA(FPM20) exhibited a 367% elongation at break, similar to 74 times higher than neat PLLA (5%). These results demonstrate a viable and scalable strategy for producing ultra-tough PLLA-based materials via incorporation of bio-based flexible macroinitiators, offering a tunable balance between mechanical strength and toughness.

Improving the wet skid resistance of tire tread is very important for the safety of vehicle driving. Using a novel ultrafine full-vulcanised powdered styrene-butadiene rubber (UFPSBR), this work prepared an advanced UFPSBR/nature rubber (NR)/styrene-butadiene rubber (SBR) composites used for the tire tread. On one hand, the UFPSBR improves the loss factor (tanδ) values of the UFPSBR/NR/SBR composites in temperature range from 0 °C to 10 °C, indicating that the UFPSBR modified tire tread has better wet skid resistance. On the other hand, the UFPSBR increases the surface roughness and complex modulus of the UFPSBR/NR/SBR composites while decreasing the water contact angle of the UFPSBR/NR/SBR composites, which is conducive to increasing the wet skid resistance of tire tread by puncturing the water film or leading a thinner water film between tire tread surface and road surface. Above researches are more comprehensive and benefit for studying the advanced green tire with high wet skid resistance.

In this article, aliphatic diols (1,3-propylene glycol and 1,4-butanediol), aliphatic dibasic acids (succinic acid, sebacic acid, and fumaric acid), and graphene oxide (GO), were used as raw materials to prepare the advanced biodegradable thermoplastic elastomer (BTPE)/reduced GO (rGO) nanocomposites through reactions of in situ melting condensation, chemical reduction, and chain extension. The rGO is well dispersed in BTPE matrix by means of its predispersion in aliphatic diols before the polycondensation of the polyester prepolymers. Tensile strength of the BTPE/rGO nanocomposite with GO dosage of 0.6 wt% increase from 8.2 MPa of BTPE to 15.6 MPa, and its elongation at break also increases simultaneously. Meanwhile, biodegradability and electrical conductivity of the BTPE/rGO nanocomposites with GO dosage of 1.0 wt% increase greatly compared with those of BTPE. The advanced BTPE/rGO nanocomposites have great potential values in the fields of biodegradable medical materials, antistatic and conductive materials, among other applications.

应用超细全硫化粉末丁苯橡胶粒子(UFPSBR)制备了应用于轮胎胎面胶的UFPS-BR/溶聚丁苯橡胶(SSBR)/顺丁橡胶(BR)/白炭黑复合材料,并重点研究了UFPSBR粒子对胎面胶复合材料抗湿滑性能的影响.动态热机械性能研究表明,UFPSBR粒子能够明显提高轮胎胎面胶的抗湿滑性能,且不增加其滚动阻力;胎面胶表面微观形貌研究表明,UFPSBR粒子增加了胎面胶表面的微观粗糙度,提高了胎面胶的浸润性,有利于湿滑地面水膜的刺破,进而丰富了UFPSBR/SSBR/BR/白炭黑复合材料的高抗湿滑性能作用机制.UFPSBR/SSBR/BR/白炭黑复合材料还具有良好的力学性能.

以不同粒径的羧基封端生物降解聚酯弹性体粒子(CBEP)改性聚乳酸(PLA)制备了CBEP/PLA复合材料,对复合材料的力学、结晶与降解等性能进行了测试,并研究了CBEP对PLA性能的影响及作用机理.结果 表明,CBEP可显著提高PLA的韧性,复合材料样条在拉伸时出现了颈缩现象,尤其是添加了7.5％(与PLA的质量比)粒径在200 nm的CBEP-a的复合材料的断裂伸长率由纯PLA的4.6％提高至155％,而复合材料的缺口冲击强度最高达到了纯PLA的2倍.同时CBEP可提高PLA的结晶性能,其中添加7.5％粒径在200 nm的CBEP-a的复合材料的等温结晶半结晶时间较纯PLA缩短了21.4％.而降解实验结果表明,添加了10％粒径在200 nm的CBEP-a的复合材料在脂肪酶环境下与土壤掩埋环境下的降解质量损失率分别由纯PLA的0.34％与0.25％,提高至2.52％与1.20％.CBEP/PLA复合材料在生物医药与环保材料等领域具有广阔的发展与应用前景.

Solving the problems involved in processing wet mixing coprecipitated rubber is of great importance to develop high-performance green tires. In this work, the concept of polyester ball plasticized rubber is proposed to eliminate these processing difficulties using novel radiation-crosslinked polyester particles (REP). This paper describes a study of the effects of REP on the processability of wet mixing coprecipitated rubber compound and the mechanical properties of vulcanized rubber composites. Results indicate that REP lubrication untangles the rubber macromolecule during coprecipitated rubber processing; thus, reducing the Mooney viscosity and improving processability. Using 200 nm REP, the Mooney viscosity is reduced by 24% and the processing energy consumption is reduced by 10%. Additionally, REP can improve vulcanization efficiency and the mechanical properties of the vulcanized rubber composites. The application of REP in plasticizing coprecipitated rubber and reinforcing vulcanized rubber composites has theoretical importance in solving the problems of processing coprecipitated rubber and addressing the challenge of silica dispersal in tire tread composites for green tires.

提高轮胎胎面胶的抗干滑性能对提高汽车的安全驾驶性具有重要意义.文中应用平均粒径为160 nm的辐射交联型丁苯橡胶粒子(UFPSBR)制备了轮胎胎面胶用UFPSBR/天然橡胶(NR)/丁苯橡胶(SBR)复合材料.动摩擦系数实验、动态力学性能分析(DMA)和橡胶加工分析(RPA)等研究结果显示,与NR/SBR复合材料相比,15 phr UFPSBR粒子改性后的UFPSBR/NR/SBR复合材料的动摩擦系数增加了27％,同时,UFPSBR/NR/SBR复合材料在30℃的损耗因子(tanδ)值增大了30％,表明UFPSBR粒子具有显著提高轮胎胎面胶抗干滑性的作用.RPA研究结果发现,与NR/SBR复合材料在60℃时的tanδ值相比,UFPSBR/NR/SBR复合材料在60℃时的tanδ值显著降低,表明UFPSBR粒子也具有降低轮胎胎面胶滚动阻力的作用.

Using novel biodegradable elastomer particles (BEP) prepared by the technologies of melt polycondensation, emulsification, and irradiation vulcanization, we successfully prepared advanced poly(lactic acid) (PLA)/BEP composites with higher toughness, higher biodegradability, and better cytocompatibility than neat PLA by means of the melt blending technology. The experimental results revealed that the elongation at break of the PLA/BEP composites containing 8 parts per hundred rubber (phr) by weight BEP increased dramatically from 2.9% of neat PLA to 67.1%, and the notched impact strength increased from 3.01 to 7.24 kJ/m(2). Meanwhile, the biodegradation rate of the PLA/BEP composites increased dramatically in both soil environment and lipase solution, and the crystallization rate and crystallinity of the PLA/BEP composites increased significantly compared to those of neat PLA. The methyl thiazolyl tetrazolium (MTT) assay also showed that the viability of L929 cells in the presence of extracts of PLA/BEP composites was more than 75%, indicating that the PLA/BEP composites were not cytotoxic and had better cytocompatibility than neat PLA. Research on advanced PLA/BEP composites opens up new potential avenues for preparing advanced PLA products, especially for advanced biomedical materials.

In this paper, using some bio-based aliphatic diols (1,3-propanediol and 1,4-butanediol) and dibasic acids (succinic acid, adipic acid and sebacic acid), we successfully prepared a novel biodegradable thermoplastic elastomer (BTPE) blocked by crystalline aliphatic hard-segment prepolyester (HPE) and amorphous aliphatic soft-segment prepolyester (SPE) by means of polymerization technologies of melt polycondensation and chain extension reaction. Experimental results showed that the BTPE had glass transition temperature of about –50 °C, melt temperature of about 105 °C, and initial thermal decomposition temperature of above 340 °C. The elongation at break of the BTPE was up to 1100%, and the recovery rate of 100% tensile deformation of the BTPE was above 85%, meanwhile the recovery rate of cycle stretch with 300% strains was above 75%. The BTPE had controllable hardness between 56 and 73 HA, while the tensile strength was between 7.5 and 9.6 MPa. Notably, mass of the BTPE lost up to 68% after 15-d degradation in lipase buffer solution at 37 °C. Also, mass of the BTPE lost up to 57% after 120-d degradation in natural soil. Methyl thiazolyl tetrazolium (MTT) colorimetric assay showed that the relative growth ratio of L929 cells cultured in BTPE extract for 72 h was above 80%, and the cell growth morphology was good, indicating that the BTPE had no obvious cytotoxicity and the evaluation result was first-class qualified. Above results show that the novel BTPE has great development prospects in the fields of environment-friendly materials and biomedical materials.

A series of different contents of glycidyl methacrylate (GMA)-grafted natural rubber (GNR) copolymers were fabricated via green bulk melt-grafting reactions, and super-tough bio-based poly (lactic acid) (PLA)/GNR thermoplastic vulcanizates (TPVs) were achieved by in-situ dynamic vulcanization. Increasing the graft yield, gel fraction, and crosslinking density of GNR vulcanizates effectively improved the ductility of the PLA/GNR TPVs, while prolonging the dynamic vulcanization time and increasing the GMA graft yield led to a notable enhancement in the impact toughness of the PLA/GNR TPVs. PLA/30 wt % GNR TPVs exhibited a significantly increased elongation (410%) and notched impact strength (73.2 kJ/m2), which were 40 and 15 times higher than those of the PLA/30 wt % NR TPVs, respectively. The new bio-based PLA/GNR TPVs offer promise as replacements for petroleum-based polymers in the automotive, 3D printing, and packaging fields.

Using the melt polycondensation of five bio-based aliphatic monomers (succinic acid, sebacic acid, fumaric acid, 1,3-propanediol, and 1,4-butanediol), we first synthesized the more flexible and biodegradable polyester diols (BPD) with an average molecular weight of 3825. Then, the BPD was polymerized with excessive 4,4′-diphenylmethane diisocyanate (MDI). Finally, the molecular chain extender of 1,4-butanediol (BDO) was used to fabricate the biodegradable thermoplastic polyurethane elastomer (BTPU), comprising the soft segment of BPD and the hard segment polymerized by MDI and BDO. Atomic force microscope (AFM) images showed the two-phase structure of the BTPU. The tensile strength of the BTPU containing 60% BPD was about 30 MPa and elongation at break of the BTPU was over 800%. Notably, the BTPU had superior biodegradability in lipase solution and the biodegradation weight loss ratio of the BTPU containing 80% BPD reached 36.7% within 14 days in the lipase solution.

Flame-retarded poly(lactic acid) (PLA) biodegradable materials are viewed as promising as sustainable alternatives to petroleum-based commodity polymers. A new highly efficient flame retardant, poly(phenylphosphoryl phenylenediamine) (PPDA), was synthesized by the condensation of phenylphosphoryl dichloride with p-phenylenediamine and its structure was confirmed by H-1 nulear magnetic resonance and Fourier-transform infrared spectroscopy. When 3 wt% PPDA was incorporated into PLA, the limited oxygen index increased from 20.0% of neat PLA to 25.5% and its UL-94 vertical burning testing achieved V-0 rating. Moreover, the total heat release and peak heat release rate values of PLA/3 wt% PPDA material were decreased from 109.1 MJ/m(2) and 643.7 kW/m(2) of PLA to 98.3 MJ/m(2) and 570.0 kW/m(2), respectively, and the fire performance index increased from 0.081 of PLA to 0.132 m(2) s/kW. The high fire safety of PPDA in PLA is mainly attributed to the combined effects of the phosphorous-containing radical inhibition and inert gases and the barrier action of the formed char layer. The addition of less than 3 wt% PPDA has little influence on the tensile and impact properties of PLA. The flame retardant PLA blends have great application potential in electrical casing, automobile interiors and three-dimensional printing materials.

Using melt polycondensation of bio-derived dicarboxylic acids and diols, followed by polyester emulsification and radiation, we fabricate the bio-based elastomer nanoparticles with controllable biodegradability, which can be used in biomedical fields.

Some aliphatic dibasic acid and dibasic alcohol were applied to synthesize the soft prepolyester and hard prepolyester by melting polycondensation, followed with chain extender methods to fabricate a series of biodegradable thermoplastic polyester elastomer (BTPE), which was identified by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR) and atomic force microscope (AFM). Experimental results showed that the BTPE has good mechanical properties with tensile strength up to 13 MPa while the elongation at break above 800%; the BTPE has good thermal stability with thermal decomposition temperature over 300°C and its melting point ( T m) over 100°C. Notably, the BTPE has good degradation properties, and the degree of degradation in lipase solution increases with the content of soft polyester increasing.

ABSTRACT How to improve the wet skid resistance of rubber composites for tire tread while decreasing the rolling resistance is very important for both rubber researchers and industry. The irradiation-vulcanized elastomer particles, ultrafine fully-vulcanized powder nitrile butadiene rubber (UFPNBR), having the diameter of about 80 nm, were studied on modifying the dynamic mechanical properties of styrene butadiene rubber/natural rubber (SBR/NR) composites for tire tread. It is notable that the UFPNBR particles can improve the tanδ values of SBR/NR composites in a temperature range from −10 to 20 °C and decrease the tanδ values in the temperature range from 50 to 70 °C simultaneously, which indicates that the UFPNBR particles not only can improve the wet skid resistance but also can reduce the rolling resistance of the SBR/NR composites. On the other hand, the UFPNBR-modified SBR/NR composites also have good dynamic properties for safety operation of tires at high temperature and good tensile strength, tear strength, and fatigue properties in the range of 8 phr UFPNBR loadings.

In this paper, the electron beam irradiation technology being more suitable for the industry application is explored to fabricate the acrylic acid (AAc) monomer-grafted polyvinyl alcohol (PVA-g-AAc) hydrogels. ATR-IR spectra of the PVA-g-AAc hydrogels shows an obvious absorption peak of the CO group at 1701cm−1, indicating that the AAc monomers were grafted onto the PVA macromolecules. This paper also studied some effects of the mass ratio of PVA/AAc, pH of buffer solution and irradiation dosage on the water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels. The water swelling ratio of PVA-g-AAc hydrogels decreases with increased irradiation dosage and mass ratio of PVA/AAc, whereas swelling ratio increases with increased pH of buffer solution and soaking time. The water-swelling behavior of PVA-g-AAc hydrogels occurred easily in an alkaline environment, particularly in a buffer solution with pH 9.2. Both PVA-g-AAc hydrogels (PVA/AAc=1/5, w/w) irradiated with 5kilogray (kGy) and PVA-g-AAc hydrogels (PVA/AAc=1/1, w/w) irradiated with 15kGy could easily absorb water and lead to high water swelling ratios (up to about 600%), which are potential candidates to meet the requirements for some biomedical applications.