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Internal corrosion and perforation of metal pipelines is the main reason for failure of gathering and transportation pipelines in a western oil field. The content of Cl-in the transport medium of the oilfield is between 24910-118051mg/l, the total salinity is between 65404-39363mg/l, the reduced sulfur content is between 6-36mg/l, and the number of SRBS is between 20-300 /ml, which are the main factors leading to corrosion in the pipeline. Through investigation, demonstration and field test, the internal corrosion control technology system of pipeline has been formed, which includes internal extrusion coating, internal penetration, 32MPa high pressure flexible composite pipe, polyethylene lined FRP composite pipe technology. The internal corrosion control strategy has been popularized in oil field, and the effect is good.

During the production of medical thin-walled tubes, a thin coating layer is required. This requirement reduces the cross-sectional clearance area of the straight section flow channel formed by the mandrel and the die, leading to excessive pressure of the polymer melt at the shaping section, elevated die pressure, and backflow of the material melt, all of which directly impact the quality of the coating layer. To address these issues, this study conducted a non-isothermal numerical simulation of coating models both with and without a shaping section. It analyzed the impact of the coating model without a shaping section on the coating layer’s thickness and the stability of the coating flow field under varying drag velocities, inlet flow rates, and die temperatures. Furthermore, it compared these results with those of coating extrusion using shaping section runners and investigates how different flow channel parameters affect the extrusion characteristics of the coating layer. The results showed that the setting of the shaping section could not eliminate the extrusion expansion in wrap extrusion. In comparison to coating extrusion utilizing a shaping section die, the process without a shaping section die reduced die pressure drop by 35% to 40%, decreased energy consumption, and enhanced the quality of the coating layer. Finally, an amorphous segment-coating extrusion die was designed based on the simulation results, and coating extrusion experiments were carried out using the designed and fabricated die.

Depending on the type and application, the coatings of power, electric, telecommunication cables as well as other types of conduits are made of various kinds of polymer plastics. However, most often, because of good mechanical properties and many other advantages, they are first of all made from polyvinyl chlorine (PVC). This paper contains characteristics of the developed cellular extrusion of cable coatings, as well as specification of the blowing agent (BA) used and selected research results of the obtained cellular extrusion product. In technological tests the coating extrusion technological line was used. The material was modified with a new blowing agent of exothermic distribution of process characteristics, which was introduced into the material in quantities from 0.2 to 0.6% wt. The amount of blowing agent used has a direct impact on the density and structure of the received result for the extrusion of modified polymers. The cellular structure of the cellular coatings was presented. The results of the study are thin-walled properties of single- and double-layer cellular outer coatings, forming an outer surface on a steel wire. The research on the structure of manufactured materials, density and the degree of porosity, water and oil absorptivity, mechanical strength is presented.

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.

Most fruits and vegetables are susceptible to spoilage after harvest, the transportation and preservation conditions can further decrease the product quality. As one of the main food preservation technologies, edible films/coatings are made of eatable materials to form thin layers that can maintain food freshness during transport and storage. This review summarizes different films/coating materials, including proteins (soy, whey, wheat gluten, gelatin), polysaccharides (chitosan, starch, cellulose) and lipids. However, the films/coatings prepared by single material have many deficiencies which can be made up by the combination of composite films/coatings. Moreover, several prepared methods (electrospinning, casting, extrusion, dipping, fluidized-bed, spraying, panning) used for films/coatings are introduced. Finally, the application and future directions of films/coatings in the preservation of fruits, vegetables and other food products are also presented. Graphical Abstract

Microencapsulation is an advanced food processing technology, using which any compound can be encapsulated inside a particular material, making a tiny sphere of diameter ranging from 1 μm to several 100 μm. Microencapsulation is done for protecting the sensitive compounds and, hence, ensuring their safe delivery. The compound or active material which is encapsulated is called the core and the material which is used for encapsulating is called the encapsulant. Encapsulants can be either polymeric or nonpolymeric materials like cellulose, ethylene glycol, and gelatin. There are several techniques used for microencapsulation. Fluidized bed coating, spray cooling, spray drying, extrusion, and coacervation are few to be named. The selection of a particular technique depends upon the properties of the core material, encapsulant, and different properties and morphology of the capsules desired. The characterization and optimization of efficient and successful encapsulation can be done by studying the encapsulation efficiency and various properties of the capsules like morphology, size, hydrophobicity, hygroscopicity, solubility, surface tension, thermal behavior, and mechanical properties. Microencapsulation is a technology that is extensively used in foods, whether as a fortifying tool or as a mode for the development of a functional food. Based on the fundamental understanding of encapsulation and latest research and findings from literature, this review critically analyses and brings together the utilization of this particular technique in foods, different methods used for encapsulation, different properties of the capsules which result from the different techniques adopted for microencapsulation and different release mechanisms used for delivering the compounds. Different techniques of microencapsulation: (a) spray drying; (b) fluidized bed coating; (c) coacervation; (d) extrusion

In this study, vacuum-assisted material extrusion (~ 1 Pa) is performed to eliminate matrix voids and improve the bonding quality of deposited layers by reducing heat loss and entrapped air during manufacturing. Continuous flax fibers with short polyester fibers/polylactic acid matrix sandwich composites (skin/core thicknesses of 2 and 25.4 mm, respectively) are fabricated via vacuum-assisted material extrusion. Compared with material extrusion, vacuum-assisted material extrusion yields higher bending and short-beam shear strengths by 36.6% and 27.2%, respectively; higher bending and short-beam shear stiffnesses by 12.3% and 9.5%, respectively; and higher averaged loading cycles at the failure stage by 47.3% and 101.5% in the three-point bending and short-beam shear loads, respectively. Vacuum-assisted material extrusion with surface coating is convenient, low cost, high in dimensional accuracy, and does not require reduced printing speed compared with conventional methods, thus satisfying the industrial targets of carbon emission reduction and high-volume production cleaning.

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. This review article uniquely highlights the use of green composites from natural fiber, particularly with regard to the development and characterization of chitosan, natural-fiber-reinforced chitosan biopolymer, chitosan blends, and chitosan nanocomposites. Natural fiber composites have a number of advantages such as durability, low cost, low weight, high specific strength, non-abrasiveness, equitably good mechanical properties, environmental friendliness, and biodegradability. Findings revealed that chitosan is a natural fiber that falls to the animal fiber category. As it has a biomaterial form, chitosan can be presented as hydrogels, sponges, film, and porous membrane. There are different processing methods in the preparation of chitosan composites such as solution and solvent casting, dipping and spray coating, freeze casting and drying, layer-by-layer preparation, and extrusion. It was also reported that the developed chitosan-based composites possess high thermal stability, as well as good chemical and physical properties. In these regards, chitosan-based “green” composites have wide applicability and potential in the industry of biomedicine, cosmetology, papermaking, wastewater treatment, agriculture, and pharmaceuticals.

Two polyethylene (PE) resins (samples A and B) are synthesized as high-speed extrusion coatings with similar minimum coating thickness and neck-in performance but different maximum coating speeds. Both samples are separated into seven fractions using preparative temperature rising elution fractionation. The microstructures of the original samples and their fractions are studied by high-temperature gel permeation chromatography, Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and successive self-nucleation/annealing thermal fractionation. Compared with sample B, sample A has a broader MWD, more LCB contents, and less SCB contents. Moreover, sample A contains slightly more 30 °C and 50 °C fractions with lower molecular weights, and more fractions at 75 °C and 85 °C with higher molecular weight. The chain structure and its distribution in the two PE resins are studied in detail, and the relationship between the chain structure and resin properties is also discussed.

To address the issue of cracking in aluminum extrusion dies during operation, this study employs laser cladding technology to modify the surface of these dies. This modification aims to enhance their hardness and friction resistance. Laser cladding technology was utilized to coat the surface of H13 steel with Stellite 12, a cobalt-based alloy, at varying laser power levels. The surface formation quality, microstructural organization, phase composition, microhardness, and wear resistance of the coatings were investigated using optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction (XRD), microhardness testing, and confocal microscopy. The results indicated that as the laser power increased, the surface formation quality of the coating gradually improved, while the dilution rate of the coating increased. Changes in the phase composition and microstructure were not significant, and both microhardness and wear resistance initially increased before decreasing. Optimal process parameters for achieving good surface formation quality, high microhardness, and strong wear resistance were found to be a laser output power of 2200 W, scanning speed of 10 mm/s, feeding rate of 1.2 r/min, and overlap rate of 40%. The results indicate that the coating applied to the surface of H13 steel using Stellite 12 enhances the performance of aluminum extrusion dies.