Structure of N-Layer Film Obtained by Developed Blow Molding Process

Aim of the work was obtaining of the composite in form of n-layer polymer film and investigation of the structure. Manufacturing of the film combine the advantages of individual layers in one production process to achieve multilayer composite. In the experiment LDPE was used as main material. Processing of material was done using blow molding process and final product was obtained if the form of thin film. Conventional blown film line contains one extruder, die head, cooling ring and calibration basket, collapsing frame and winding rolls. To develop structure unique blow film line has been used. Two another extruder were joined to existing one transferring material simultaneously to the die head where 3 materials were joined together to combine 3-layered film. This process gives possibility to design final product and control the structure in many various combinations.

Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

Interferometric Instrument for Thickness Measurement on Blown Films

Real-time measurement of plastic film thickness during production is extremely important to guarantee planarity of the final film. Standard techniques are based on capacitive measurements, in close contact with the film. These techniques require continuous calibration and temperature compensation, while their contact can damage the film. Different optical contactless techniques are described in literature, but none has found application to real production, due to the strong vibration of the films. We propose a new structure of low-coherence fiber interferometer able to measure blown film thickness during productions. The novel fiber-optic setup is a cross between an autocorrelator and a white light interferometer, taking the advantages of both approaches.

Biodegradable Polymer Compounds Reinforced with Banana Fiber for the Production of Protective Bags for Banana Fruits in the Context of Circular Economy

Bags used to protect and accelerate the ripening of bananas are a clear example of the environmental problem of packaging waste. Small pieces of these non-biodegradable bags are frequently disposed on the soil by accident (environmental conditions and poor handling during the harvest) and remain there for years. This work focuses on the development of protective biodegradable bags reinforced with banana fiber, obtained from waste of the banana plants, thus promoting a circular economy and a more environmentally friendly process. To achieve this, different bio-based composites were tested (processability) by compounding extrusion (biopolymer and banana fiber with different process steps) and blown film extrusion. The bags produced were tested in field and sequentially improved in three generations of biofilms. The results showed that the maximum processable fiber content was 5 wt %. Additionally, the micronizing of the compounds was crucial to simplify the blown film extrusion and improve the smoothness of the bags (scratches avoidance on the banana surface). The final bags (Mater-Bi biopolymer, 5% combed and sieved banana fiber, and 2.5 wt % TiO2 for ultraviolet light filtration), performed better than the conventional ones (faster maturing, i.e., earlier harvest, and easier handling) and fulfilled the biodegradability, composting and ecotoxicity test requirements.

Comparing the elasticity of the melt and electrical conductivity of the solid of PP-HDPE copolymer CNT composites obtained by direct compounding versus dilution of a PP masterbatch

Composites of multiwall carbon nanotubes (CNT) at 1, 2, and 3 wt.% on a polypropylene–polyethylene random copolymer matrix were prepared by melt compounding CNT powder and by dilution of a commercial polypropylene masterbatch (PMB). While the shear viscosity shows similar behavior for both dilution modes, the differences in their elastic properties clearly show the effect of the addition method and the presence of the PMB. This also indicates the relevance of having a difficult to mix masterbatch to enhance the elongational viscosity of the composites for free wall applications such as fiber spinning and blown film. On the other hand, the 2 and 3 wt.% CNT composites from both addition modes have similar electrical conductive behavior, with values near the semiconductors’ range. TEM and SEM images show different states of dispersion for each source of CNT. The immiscibility observed in those images is the simplest explanation for the differences in the molten composites’ elastic properties due to direct CNT addition versus CNT addition by dilution of a PMB.

Flow analysis of conical spiral mandrel dies

Spiral dies are divided into three categories, namely: Flat Spiral Die (FSD), Cylindrical Spiral Mandrel Die (SMD), and Conical Spiral Mandrel Die (CSD). These dies are used to produce films via blown film extrusion and multilayer films via co-extrusion. The goal is to improve the flow distribution and to decrease the pressure drop which will result in uniform film thickness and reduced energy dissipation. A viscous power-law fluid model shows that low-pressure drop and proper flow distribution can be achieved in a CSD simultaneously. As the number of grooves and the initial channel depth increases, the flow distribution becomes more uniform and the pressure drop decreases. Also, there is an optimum initial clearance and clearance increment angle. The model results show that the pseudo-plastic fluid has more appropriate performance than the Newtonian and dilatant fluids in improving the flow distribution and reducing the pressure drop.

Plasticization Effect of Poly(Lactic Acid) in the Poly(Butylene Adipate–co–Terephthalate) Blown Film for Tear Resistance Improvement

The mechanical properties and tear resistance of an ecofriendly flexible packaging film, i.e., poly(lactic acid) (PLA)/poly (butylene adipate–co–terephthalate) (PBAT) film, were investigated via a blown film extrusion process. The application of PLA and PBAT in product packaging is limited due to the high brittleness, low stiffness, and incompatibility of the materials. In this study, the effects of various plasticizers, such as adipate, adipic acid, glycerol ester, and adipic acid ester, on the plasticization of PLA and fabrication of the PLA/PBAT blown film were comprehensively evaluated. It was determined that the plasticizer containing ether and ester functionalities (i.e., adipic acid ester) improved the flexibility of PLA as well as its compatibility with PBAT. It was found that the addition of the plasticizer effectively promoted chain mobility of the PLA matrix. Moreover, the interfacial adhesion between the plasticized PLA domain and PBAT matrix was enhanced. The results of the present study demonstrated that the plasticized PLA/PBAT blown film prepared utilizing a blown film extrusion process exhibited improved tear resistance, which increased from 4.63 to 8.67 N/mm in machine direction and from 13.19 to 16.16 N/mm in the transverse direction.