In this study, multi-wall carbon nanotube (MWCNT) reinforced acrylonitrile butadiene styrene (ABS) nanocomposite filaments are produced. Filaments are examined through thermogravimetric analysis (TGA) and definitive scanning calorimetry (DSC) analysis. Produced nanocomposite filaments are used in the fused deposition modeling (FDM) process to manufacture parts. Wear tests are conducted on 3D-printed parts using wear test apparatus with an attached heating module under different ambient temperatures. Hence, the influence of CNT reinforcement, along with different FDM process parameters and varying test conditions on the wear behavior of 3D-printed ABS-CNT parts, are examined. Worn surfaces of the specimens are examined by scanning electron microscopy (SEM). Nonlinear autoregressive exogenous (NARX) models are proposed for the prediction of the wear behavior of 3D-printed ABS-CNT nanocomposites. While wear rate is taken as output, ambient temperature and amount of nanofiller are accounted as input parameters along with the variation of coefficient of friction (COF) which is obtained from measured frictional force and three input-one output model structure is proposed for NARX. The use of multiple input-single output (MISO) model structure and examining the wear behavior of 3D-printed ABS-CNT samples under different wear test conditions with different FDM process parameters are the novelties in this work.

The surface quality of plastic parts produced by the conventional extrusion blow molding (EBM) process is usually poor, especially for those made of engineering thermoplastics. To achieve a high-gloss appearance, some costly and pollutive post-treatments (e.g., painting, polishing, etc.) have to be employed to hide or eliminate surface defects. Herein, a variable mold temperature EBM (i.e., variotherm EBM) technology with electric heating and water cooling, which has the potential to directly yield high-gloss parts, was developed. First, the process principle was designed and presented. Then, an complex industrial plastic part, i.e., automotive spoiler, was selected as a molding case to be studied, in which the variotherm blow mold of the spoiler was designed and especially the design rationality of the mold electric-heating and cooling systems was then examined by numerically evaluating the mold thermal response in the respect of cavity surface heating/cooling efficiencies and uniformity. Finally, the variotherm EBM experiments based on the manufactured prototype spoiler mold were conducted. The results showed that the developed technology can realize high-temperature blow molding with both the molding cycle time and energy consumption in an acceptable range compared with the conventional EBM. Moreover, the surface quality of the molded spoilers is largely improved and the surface defects that are generally appearing in the conventional EBM process can be fully eliminated. Thus, the feasibility and effectiveness of developed technology in yielding high-gloss blow-molded parts are demonstrated.

The framework of the present study is based on investigation of different types of phosphorus based secondary antioxidants and their role in stabilization of polypropylene. Three different chemical entities i.e., Tris (2,4-di-tert-butylphenyl) phosphite, Tetrakis (2,4-di-tert-butylphenyl)-4,4-biphenyldiphosphonite and Bis (2,6-di-tert-butyl-4-methylphenyl pentaerythritol-diphosphite) have been studied for its efficiency as a secondary antioxidants or processing stabilizer. Thermal stability of polymer is predicted using degradation kinetics study and correlated with it’s optical, thermal and rheological response. To further evaluate performance of secondary antioxidants, thermogravimetry analysis was performed for polypropylene at three different heating rates and processed for iso-conversional analysis to get the kinetic parameters. Oxidation induction data and kinetic parameters have been related with efficiency of the stabilizers. Filtration study was also carried out to understand the efficacy of stabilizers during secondary process. Die pressure build up in filtration study is quantified and related with performance of secondary antioxidants.

Friction and wear in a tribological system are directly dependent on the surface structure and roughness of the friction partners involved. In this article, a clear interaction between surface topologies and their roughness depth was identified for the material pairing polyamide 66 – steel. The typical correlation between roughness and wear, initially decreasing and increasing after a wear minimizing roughness, was found for all surface topologies, albeit at different levels. The effect of the surface topology is negligible at low roughness (S z 2.0 µm), the ability of the surface topology to form a stable transfer film determines the tribological behaviour by limiting the effect of abrasive wear processes. A stable transfer film is formed with sufficient roughness and undercuts in the direction of motion, which can be characterised by the average roughness depth, R z , in the direction of motion. Based on these empirical results, an explanatory model for the observed behaviour is presented.

A novel method for the visualization and quantification of the state of dispersion of calcium carbonate particles in thin blown polymer films is described. Particle imaging was achieved by elemental mapping using energy dispersive spectroscopy. This generated outlines of particles and agglomerates located close to the film surface. ImageJ software facilitated the extraction of the corresponding Feret diameters. Finally, the Bootstrap technique was used to estimate confidence intervals for the kurtosis of the Feret particle size distribution. Kurtosis is a statistic that describes the shape of a distribution’s tails in relation to its overall shape. It therefore provides a measure that characterizes the degree of particle agglomeration. The proposed procedure was applied to analyze high-density polyethylene films prepared using different calcium carbonate masterbatches in which formulation parameters were varied.

Microencapsulated phase change material (MPCM) was synthesized by using the in-situ polymerization technique. Dimethyl adipate (DMA) and melamine-formaldehyde were used as core and shell material for polymerization respectively. Sodium laureate sulphate (SLS) is used as a surfactant. The thermal properties were characterized by using a differential scanning calorimeter (DSC) and thermogravimetry analysis (TGA). Fourier transform infrared spectroscopy (FT-IR) was used to confirm the chemical structure. The morphology of microcapsules was studied by using, scanning electron microscopy. DSC result of MPCM has been observed to melt at 10.09 °C with melting latent enthalpy 88 J/g and crystallizes at 4.69 °C with crystallization latent heat 89.50 J/g. TGA analysis confirms increases in the thermal stability of MPCM. The decorative coating was prepared with 0, 5, 10, 15, and 20 % MPCM loading, and the prepared paint was tested for pencil hardness, gloss, and stain resistances. The thermal energy transfer rate was used to measure how much time coated panel took to reach the equilibrium temperature of 25 °C. Coating with 20 % MPCM loading revealed good thermal storage capacity but other general coating properties deteriorate.

Most self-healing hydrogels always exhibited poor mechanical property which largely limited the applications in many fields. In this work, g-C3N4 nanosheets were introduced to the PVA-borax hydrogel to reinforce the network without sacrificing the self-healing ability. The obtained hydrogel displayed remarkable tensile strength (0.98 MPa), Young’s modulus (1.54 MPa) and toughness (4.43 MJ m−3), of which the self-healing efficiency reached to 99 % in 10 min at room temperature. Overall, the strategy proposed in this work provides a simple, operatable and moderate approach to hydrogel with both excellent mechanical property and self-healing ability.

It is challenging to effectively purge wastewater containing heavy metal ions at low concentration. In order to remove trace Cr (VI) from wastewater efficiently, a positively charged microporous membrane was prepared by firstly non-solvent induced phase separation (NIPS) of amphiphilic polymer and secondly surface quaternization modification. The morphologies, surface roughness, surface charge, hydrophilicity, and pore size of membranes were characterized. Based on the dual action of micellar adsorption and charge repulsion, when surfactant is 4 mM and Cr (VI) is 60 ppm, the surface quaternization membrane (Q-MPVD) achieves 99.8 % Cr (VI) rejection simultaneously accompanied by a permeability of 100 LMH/bar. Meanwhile, the effects of STAC concentration, Cr (VI) concentration, pH as well as inorganic salt concentration on the composite micellar size, and Cr (VI) rejection performance were investigated, respectively. Moreover, the Q-MPVD membrane shows an excellent separation stability over a wide pH range, indicating its application perspective in engineering process. In summary, this work provided a positively charged membrane with high-efficiency performance for treating practical trace Cr (VI)-containing industrial wastewater.

The formation of a stable gas layer is to have a significant effect on polymer gas-assisted extrusion (GAE). Previously, for vertical extrusion forming, the gap intake method was used, which tends to result in very short stabilization times for the gas layer. In this study, the effect of two gas intake modes was compared based on horizontal sheet extrusion. The results show that stabilization of the gas layer is easily achieved in the vertical gas-assisted die by introducing gas first. However, when using parallel die, the gas distributes the melt uniformly along the surrounding velocity and the gas layer can be stable for a long time. Moreover, disrupting the process sequence also makes it easy to achieve gas layer stability without affecting the tability of the gas layer in the subsequent extrusion. And, during low-speed extrusion, the flow inertia of the polymer melt is used to extend the flow channel of the gas-free–assisted section into the gas-assisted section to overcome the gravity of the polymer melt and smoothly extrude it in the parallel gas-assisted die. The parallel die can be considered for the production of GAE of daily profiles and can be used to improve quality.

Carrageenan fibers crosslinked with trivalent metal ions (Al3+ or Fe3+) were prepared into carrageenan fiber paper (Al/CAP, Fe/CAP) by the Rapid Kothen method, and their flame-retardant mechanism and flame retardancy were studied through LOI, VF, SEM, CONE, and TGA testing. The results showed that Al/CAP exhibited good flame retardancy and thermal stability, and its LOI value reached 52%. Meanwhile, the afterflame time and afterglow time of Al/CAP were 0 and 1 s, respectively, which indicated that it was not ignited and almost had no smoldering phenomenon. The flame-retardant performance of Fe/CAP is inferior to that of Al/CAP, with LOI of 32, but the total smoke emission (TSP) of Fe/CAP is lower in cone calorimetry test. Thus, CAPs (especially Al/CAP) can be widely used in the flame-retardant paper industry, due to their flame retardancy and environmental protection.

In this research work, waste plastic bottle caps made of high-density polyethylene (HD-PE) were reincorporated as a matrix and reinforced by alfa short fibers and natural pozzolan particles. Using different weight percentages of both fillers of 5 wt% up to 30 wt%, three types of bio-composite materials have been produced; alfa short fibers/HDPE, pozzolan particles/HDPE, and alfa fibers pozzolan/HDPE. Specimens for each type of the biocomposites were prepared through the compression molding method. The objective of this study is to investigate the effect of different content of alfa short fibers and pozzolan particles on the mechanical and morphological properties of the recycled HDPE matrix. Tensile test results revealed an enhancement in the mechanical properties for the three types of the biocomposites, an increase in tensile strength reached the maximum of 3573 MPa plus an interesting improvement in Young’s modulus with a maximum value of 3696 MPa. The toughness of the neat recycled HD-PE decreased by 212% by adding the natural filler whereas the modulus of resilience exhibited an increase of 138% compared to the neat recycled HD-PE. Therefore, the good rheological behavior of these bio-composites makes it possible to produce competitive materials and allows the reduction of plastic waste in the environment.

Ultrahigh molecular weight polyethylene (UHMWPE) has been extensively used in various tribological systems because of its outstanding tribological properties and excellent overall performance. Compression molding is the main molding method for UHMWPE, and the process parameters of molding have a profound effect on its material properties. In this study, three groups of UHMWPE samples were prepared, and their physical, mechanical, and tribological properties under different molding process parameters were examined—with a particular focus on the frictional and wear behavior of the material under various heating-temperatures, pressing-temperatures and pressures—and the friction and wear mechanisms of UHMWPE were analysed. Studies have shown that the rise in heating-temperature promotes the diffusion of polymer chains, resulting in an increased friction coefficient and wear loss of UHMWPE. The main wear mechanism switches from plastic deformation to fatigue wear. With an increase in the pressuring-temperature, the friction coefficient first increases and then decreases, while the wear loss increases, and the dominant wear mechanism switches from fatigue wear and plastic flow to plastic flow. With an increase in pressure, the friction coefficient and wear loss first decrease and then increase, and the prime wear mechanism changes from plastic deformation and fatigue wear to fatigue wear.

NH3 gas sensors with good sensing performance including wide detection range at room temperature are highly desirable for a large variety of applications. In this work, multi-walled carbon nanotubes grafted with sodium polystyrenesulfonate (PSSNa-MWCNTs) are prepared via a controlled radical polymerization and show good dispersibility in water. The composite of polypyrrole with PSSNa-MWCNTs (PPy/PSSNa-MWCNT) is prepared by in situ vapor phase polymerization of pyrrole to fabricate NH3 gas sensors. Effects of the content of PSSNa-MWCNTs, the concentration of the oxidant, polymerization time and temperature on the gas sensing properties of the composite are investigated at room temperature. It is revealed that the composite shows much higher response magnitude than the single components. Under optimal conditions, PPy/PSSNa-MWCNT exhibits very wide detection range from 5 to 2000 ppm, and good sensing linearity over 5–20 ppm and 20–100 ppm, respectively. Moreover, the electrical responses of the composite towards NH3 gas are fast (response and recovery time to 1000 ppm NH3 gas are 16.7 s and 143.6 s, respectively), reproducible and highly selective. The interactions between PPy and MWCNTs promote the charge transfer in the composite, leading to good sensing performance and exhibiting a synergetic effect.

This paper aims to investigate the crystallization and barrier properties of oxygen-scavenging polyethylene terephthalate films (OSP) at different stretching ratios and stretching rates. The results show that with the increase of the stretching ratio, more regular lamellar crystal was formed in the biaxially stretched OSP films, and the amorphous phase thickness between lamellae and the long period decreased. The presence of oxygen scavenger acted as heterogeneous nucleation, further promoting the crystallization of the OSP films. This was conducive to prolong the diffusion path of gas molecules through the film. Furthermore, the increase of the stretching ratio expanded the “active” oxygen barrier area of the oxygen scavengers. Thus, the barrier performance of the biaxially stretched OSP films was improved significantly. In addition, the variation of crystallinity and properties of OSP films with the stretching ratio was consistent with the variation with the stretching rate, but the stretching ratio had a greater impact. It was also found that the increase of the stretching ratio and the introduction of oxygen scavenger both increased the stretching strength of the OSP films, while the biaxially stretched OSP film maintained good optical properties.

In this work, glycidyl methacrylate (GMA) and trimethylol propanetriacrylate (TMPTA) are employed to adjust the branching structure of poly L-lactide acid (PLLA) during reactive extrusion induced by UV irradiation. The reaction of GMA epoxide with terminal carboxyl or hydroxyl groups at PLLA chain end can introduce C=C groups onto PLLA molecular chains. Chain branching reaction occurred via the free-radical grafting reaction of the vinyl group in TMPTA with both PLLA backbone and the C=C group terminated PLLA induced by UV irradiation. As a result, varied branching levels can be obtained by changing the ratio of GMA and TMPTA. The characterizations of rheological properties and size exclusive chromatograph correlated to the chain branches were performed to evaluate the chain branching extent. The increases in shear viscosity and storage modulus at terminal zone, and the reduced branching degree were observed in the branched PLLA samples. The results from 1H-NMR and FIRT indicate that the grafting reaction of GMA onto PLLA take place successfully. Thus, this study proposes a strategy to adjust LCB-PLA structure using GMA and TMPTA as co-agents, which is of great importance for the industrialization of PLA products.

Fluorine free analogues of three commercially available rigid contact lens materials were prepared by replacing the fluorinated component, hexafluoroisopropyl methacrylate (HFPM), with the widely used, non-fluorinated monomers methyl methacrylate (MMA) and 3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS). The properties of the commercial materials and analogues were measured and compared. The oxygen permeabilities of the MMA analogues were found to be significantly lower than those of the commercial materials, decreasing by 87 % on average, while the TRIS analogues lacked sufficient hardness, dimensional stability and lipid deposit resistance to be viable for use in rigid contact lenses. Analogues prepared using a 1:1 mixture of MMA and TRIS had the best overall combination of properties, but were still on average 47 % less permeable to oxygen and also significantly less resistant to lipid deposition. The analogues prepared in this study did not adequately replicate the performance of marketed, fluorine containing rigid contact lens materials. These observations give an indication of the challenges that would face contact lens material manufacturers in preparing rigid lens polymers without the use of fluorinated species. A reduction in effectiveness would be almost inevitable, and would be expected to have a negative impact on the safety and eye health of rigid contact lens patients.

Two asymmetric diamines [1,1′-biphenyl]-4-yl(3,5-diaminophenyl) methanone (BPDAM) and (3,5-diaminophenyl)(4′-(naphthalen-1-yl)-[1,1′-biphenyl]-4-yl) methanone(DANPBPM) were synthesized by Suzuki coupling reaction from (4-bromophenyl)(3,5-diaminophenyl) methanone (BDAM) and corresponding arylboronic acid. A series of polyimides exhibiting organic solubility were prepared from 2,2′,3,3′-biphenyl tetracarboxylic dianhydride(BPDA) and these above three new diamines via a two-stage process. The obtained polymers showed outstanding organic solubility and high thermal stability. And studies have shown that the storage device with a sandwich type configuration of Al/polyimide/ITO was prepared by the traditional liquid spin coating technology, which showed the storage capacity of flash memory type. All the polyimide-based devices showed bistable conductivity switching and nonvolatile memory behavior that had long preservation period and high ON/OFF electric current, the rate of which was 104.

To overcome the lack of dissolved oxygen in high-density aquaculture water, a hydrogen peroxide-acrylic resin inclusion complex with sustained oxygen releasing effect was designed and prepared. The resin was synthesized by emulsion polymerization of acrylic acid, methyl methacrylate and butyl acrylate in a mass ratio of 2: 3: 5, and neutralized with sodium hydroxide solution by 50%. The resin solution was mixed in a mixture of urea and 30% hydrogen peroxide solution (CO(NH2)2: H2O2, 1: 1, mol: mol), and dried at 40 °C for 4 h to obtain the hydrogen peroxide-acrylic resin inclusion complex. The product with 4.0% resin by mass of hydrogen oxygen solution, could release oxygen for 92 h in pond water. After optimization by adding a small amount of NaCl, Na2SO4, and EDTA, it was mixed with calcium carbonate and magnesium stearate in a mass ratio of 5: 4: 0.9, and pressed into tablets (1.2 × 0.6 cm, 0.99 g). One tablet in 50 L simulated micro ecosystem aquaculture water with 20 of Carassius auratus fish could release oxygen for 116 h and brought fish with 83.3% of survival rate higher than 51.7 and 70.0% of blank and sodium percarbonate groups.

In this work, a new model is developed by modifying the existing Maxwell–Wagner–Sillars (MWS) model to predict the gas separation properties of mixed matrix membranes (MMMs). The new modified MWS model, for the first time, provides the simultaneous exploration of the role of nanofillers/matrix interface voids and the exact geometrical shape of nanofillers in predicting the gas separation properties of MMMs. To unveil the crucial role of nanofillers/matrix interface voids, a mixed matrix membrane is considered a three-component system composed of the polymer matrix as the continuous component, nanofillers as the dispersed component and the interface voids between the two components. Moreover, the new model elucidates the role of the exact ellipsoidal shape of nanofillers within the membrane on the gas separation of MMMs by considering the shape factor of nanofillers. The newly developed modified MWS model is accurately able to predict the gas permeation of MMMs with a lower average absolute relative error (%AARE) of around 8% compared with the around 30% for conventional models such as the Maxwell model, Bruggeman model, Lewis–Nielsen model and Pal model and even compared with the modified Maxwell model (∼24%).

The blended composites with ultra-high molecular weight polyethylene (UHMWPE) as the matrix polymer, sodium polyacrylate (PAANa), and tetraphenyltin (Ph4Sn) as fillers were prepared by hot compression molding process. The friction and wear behavior of GCr15 balls with composites mating pairs under the seawater environment was explored, and the friction and wear mechanism was analyzed. The results show that adding PAANa, a polyelectrolyte material, can effectively reduce the friction coefficient of UHMWPE/PAANa/Ph4Sn composites. The wear resistance of composites increased significantly with increasing Ph4Sn content compared with pure UHMWPE, and the best wear resistance was observed at 1% content. The primary wear mechanism of UHMWPE/PAANa/Ph4Sn composites changed from adhesive wear of pure UHMWPE to plastic deformation at lower PAANa and Ph4Sn contents and finally to adhesive wear and spalling. This work provides a theoretical basis for preparing and applying other polymer blend composites.