Back Injection Molding of Sub-Micron Scale Structures on Roll-to-Roll Extrusion Coated Films

Roll-to-roll extrusion coated films were bonded onto polymer parts by back injection molding (BIM). The polypropylene (PP) coated polyethylene terephthalate (PET) films were pre-patterned with microstructured V-shaped grooves with 3.2 µm and 53 µm width, and other geometries. Bonding on PET and poly(methyl methacrylate) (PMMA) parts was facilitated by either higher tool or melt temperatures but was particularly enhanced by applying a mild oxygen plasma to the backside of the PET film prior to injection of the polymer melt. Silver wires from conductive nanoparticle ink were embedded into the PP coating during the BIM process by controlled collapse of the V-grooves. Thus, the feasibility of combining standard carrier film materials for printed flexible electronics and packaging into a non-flat polymer part was demonstrated, which could be a helpful step towards the fabrication of polymer parts with surface functionality.

Chitosan-Based Coating with Antimicrobial Agents: Preparation, Property, Mechanism, and Application Effectiveness on Fruits and Vegetables

Chitosan coating is beneficial to maintaining the storage quality and prolonging the shelf life of postharvest fruits and vegetables, which is always used as the carrier film for the antimicrobial agents. This review focuses on the preparation, property, mechanism, and application effectiveness on the fruits and vegetables of chitosan-based coating with antimicrobial agents. Chitosan, derived by deacetylation of chitin, is a modified and natural biopolymer as the coating material. In this article, the safety and biocompatible and antimicrobial properties of chitosan were introduced because these attributes are very important for its application. The methods to prepare the chitosan-based coating with antimicrobial agents, such as essential oils, acid, and nanoparticles, were developed by other researchers. Meanwhile, the application of chitosan-based coating is mainly due to its antimicrobial activity and other functional properties, which were investigated, introduced, and analyzed in this review. Furthermore, the surface and mechanical properties were also investigated by researchers and concluded in this article. Finally, the effects of chitosan-based coating on the storage quality, microbial safety, and shelf life of fruits and vegetables were introduced. Their results indicated that chitosan-based coating with different antimicrobial agents would probably have wide prospect in the preservation of fruits and vegetables in the future.

Investigation of a Polishing Pad and a Carrier Film for Decreasing Edge Roll Off of Workpiece

Demand for diminishing edge roll off of workpiece has rapidly increased, especially in polishing silicon wafers and glass disks. However, the conventional polishing technologies cannot meet the demand. To address this problem, the influence of carrier film properties and that of polishing pad properties on the stress distribution near the workpiece edge were investigated using finite element methods. Based on the analytical results, double-layered polishing pads having an extra-fine fiber thin layer and a hard polymer layer were developed. Polishing experiments on silicon wafers and glass plates showed that the developed polishing pads achieved high finishing efficiency and extremely flat surface near the edge.

Tensile Testing of Ultra-Thin-Film Materials Deposited on Polyimide for Mems Applications

A newly developed approach to thin-film tensile testing has been utilized for evaluating ultra-thin-films of about 60-100 nm in thickness. Thin sputtered metal films deposited on 3.5 gm thick polyimide film substrates were tested using a Mesotronix nanotensiometer. Modifications to sample handling and zero strain calibration helped to improve testing reproducibility. The response of a thin-film metal was determined by subtracting the response of the polyimide carrier film from that of the metal-on-polyimide composite. Stress-strain curves for two amorphous alloys sputtered from Al-25 at% Ti and Nb-25 at% Al targets exhibited well-defined elastic regions followed by brittle behavior. The ultimate tensile strengths (UTS) were about 1200 MPa for the Al-Ti and 1700 MPa for the Nb-Al, both of which occurred near the elastic strain limit of about 2%. After recrystallization at 280°C for an hour, the Al-Ti film showed what appears to be an upper and lower yield point, in addition to strain hardening. Initial yielding occurred at a strain of about 1.2% and a stress of about 800 MPa, while the UTS of about 1000-1060 MPa occurs at strains as high as 9%. Stress relaxation measurements performed on both the amorphous and the recrystallized films showed lower values of stress relaxation at 1% strain compared to low alloy polycrystalline Al films.