- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Understanding the oxygen barrier property of highly transparent poly(lactic acid)/benzoxazine composite film by analyzing the UV-shielding performance
摘要： This work reports a new composite film from poly(lactic acid) (PLA) and benzoxazine (BOZ). Introduction of BOZ to PLA simultaneously improves the ultraviolet (UV)-shielding and oxygen barrier properties, which show strong dependence on the content of BOZ. The PLA film demonstrates almost no UV-shielding capacity, but the PLA/BOZ composite film can reach UV-shielding capacity of 98.3% at 350 nm. The corresponding average oxygen permeability coefficient of the composite film is as low as 1.168 × 10^{-18} m^3 m m^{-2} s^{-1} Pa^{-1}, which is significantly lower than that of PLA (5.540 × 10^{-17} m^3 m m^{-2} s^{-1} Pa^{-1}). Meanwhile, the composite film retains visible transparency ≥90.0% at 550 nm. The relationship and its implication between the oxygen barrier performance and UV-shielding capacity are discussed, which propose new guidelines for the development of high barrier PLA film.
关键词： thermosets,films,blends,thermoplastics
更新于2025-09-23 15:23:52
-
Submicron laser-textured vents for self-cleaning injection molds
摘要： Clogging of venting slots in injection molds is a common maintenance problem caused by the degradation and the accumulation of gaseous and volatiles by-products of polymer melting. In this work, the effect of laser-induced periodic surface structures on the self-cleaning properties of venting slots is investigated. The degradation of poly(ethylene terephthalate) (PET) over different surfaces is characterized by reproducing the mechanisms that occurs in mold cavities when the air is pushed through the venting channel. An imaging technique is developed for the quantification of the sediment that deposits on sample surfaces due to condensation of by-products of PET melting. The experimental results indicate that the use of a multiscale texture minimizes the deposition of residues on the vent surface reducing it from 17.2 to 3.1%. A linear dependency between contact angle and clogging ratio indicates the efficacy of the model that explains vent self-cleaning properties considering their wetting properties.
关键词： applications,surfaces and interfaces,thermoplastics
更新于2025-09-23 15:21:01
-
Influence of the laser-based surface modification on the bond strength for friction press joining of aluminum and polyethylene
摘要： Friction press joining is an innovative joining process for the production of plastic-metal joints without additives, in an overlap configuration. In order to achieve a high bond strength, the metallic joining partner is pretreated with laser radiation. Subsequently, heat is induced by friction and pressure during the joining process, causing the thermoplastic material to melt and adhere to the metallic joining partner. In this work, the temperature distribution during the process in the composite is analyzed and characterized. It was found that the occurring temperatures and temperature differences are not only dependent on the rotational speed, but also on the feed rate. It is also shown that the friction surface temperature can be used as an indirect control variable for a model-based, closed-loop control. Based on these findings, various surface modifications for the metallic joining partner were investigated and analyzed with regard to the maximum strength of the joint. It was observed that the highest tensile shear strength can be achieved with a quasi-chaotic nano structure. In addition, the joining compound was characterized by a thin section, facilitating the identification of specific zones in the joint. These investigations show the high potential for friction press joining of plastics and metals, and form the basis for a model-based control of the joining zone temperature.
关键词： Polymer metal joining,Dissimilar material joining,Aluminum,Hybrid bonds,Thermoplastics,Friction press joining
更新于2025-09-12 10:27:22
-
Laser transmission welding of polymers – Irradiation strategies for strongly scattering materials
摘要： In laser transmission welding of thermoplastics the optical properties of the transparent part have great influence on the weld seam quality. Especially scattering, for example at crystalline structures or additives, can significantly affect the intensity distribution of the radiation in the joining zone. Since scattering is a strongly wavelength dependent process the right choice of the laser wavelength can enable laser transmission welding even for challenging materials. It is shown that the necessary optical material properties needed to assess the weldability of scattering materials can be directly obtained from NIR-spectroscopy.
关键词： thermoplastics,spectroscopy,optical properties,laser transmission welding,scattering
更新于2025-09-12 10:27:22
-
3-D FE heat transfer simulation of quasi-simultaneous laser transmission welding of thermoplastics
摘要： Laser transmission welding of thermoplastics is a non-contact welding process for producing aesthetically and qualitatively high-grade joints with low thermal and mechanical stresses. In this research work, a three-dimensional heat transfer model is developed to simulate the quasi-simultaneous variant of laser transmission welding of thermoplastics. The thermal analysis is implemented to acquire the temperature history in this multi-pass welding process. The transient temperature field is computed using ANSYS? finite element code. The multi-pass movement of laser beam is realized by implementing a subroutine in ANSYS? Parametric Design Language (APDL). The effect of process variables namely laser power, welding speed, number of welding passes and line energy on temperature field during welding is investigated. The predicted outcomes of the temperature profiles, weld pool and time–temperature history are useful for optimizing the process parameters in the quasi-simultaneous laser transmission welding process.
关键词： Thermal analysis,Laser transmission welding,Thermoplastics,Quasi-simultaneous welding,Finite element model
更新于2025-09-12 10:27:22
-
A sol-gel polymerization method for creating nanoporous polyimide silsesquioxane nanostructures as soft dielectric materials
摘要： A sol–gel polymerization method was developed to make polyimide (PI) silsesquioxane (SSQ) nanoparticles as functional, soft dielectric materials. The surface functionalization of the polymer chain backbone and chain ends of poly(trimellitic anhydride chloride-co-4,40-methylenedianiline), PMR-15 resin, with para-(chloromethyl)-phenylethyltrimethoxy silane yielded a novel sol–gel reactive sites functionalized PMR-silane precursor. Upon base-catalyzed hydrolysis and condensation of the PMR-silane precursor, spherical, raspberry-like PMR-SSQ nanoparticles were obtained in considerably good yield. Controlling the particle size distribution was attempted upon adjusting the molar ratio between the silane precursor and the base, as well as in the presence of a catalytic amount of silica sols. Particle composition, thermal stability, and morphology were confirmed from Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy analyses. Nanoparticles, visualized under transmission electron microscopy exhibit a nanoporous structure. The Brunauer–Emmett–Teller analysis confirmed that the average pore dimension is ranged from 2 to 5 nm. The dielectric constant of PMR-SSQ nanoparticles was as low as 1.95, compared to dielectric constants of 3.05 and 3.13 for PMR-15 and PMR-silane, respectively. Thus, the base-catalyzed sol–gel polymerization of alkoxysilylated PI offers a novel synthetic path to make functional nanoporous PI nanostructures that possess ultralow dielectric constants.
关键词： resin,polyimides,polymer functionalization,soft dielectric materials,thermoplastics
更新于2025-09-04 15:30:14