2023, 37 (5):
1-8;
Abstract (
456 )
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Ultrahigh molecular weight polyethylene （PE-UHMW） is a polyethylene material with a molecular weight of 1 million or more， and its molecular structure is similar to that of high-density polyethylene. It is an engineering plastic with excellent overall performance. PE-UHMW films are a new type of organic functional polymer films， which are made of PE-UHMW as a polymer matrix with fillers or through structural modification and processed to a certain thickness. PE-UHMW films are mainly divided into non-porous films and microporous films. PE-UHMW films are widely used in textile， packaging， agriculture， food， medical and lithium-ion battery separators thanks to their excellent impact resistance， low-temperature resistance， corrosion resistance and other properties. However， owing to a large molecular weight， a great number of entanglements between molecular chains， and poor flowability in the molten state， it is difficult to prepare film materials with excellent performance through conventional methods. This paper introduces the research progress， performance advantages， common preparation methods， and main applications of PE-UHMW films in recent years in terms of the structural characteristics of PE-UHMW.
2023, 37 (5):
9-14;
Abstract (
232 )
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Using the good distribution， dispersion， and mixing effect of micro-nano lamination extrusion equipment， polyurethane/silicone rubber thermoplastic vulcanized rubber （TPV） was prepared， and the effects of processing methods， dynamic vulcanization temperature， screw speed， rubber-plastic ratio， compatibility agent type， and content on the performance as-prepared TPV were studied. The results indicated that compared to the ordinary blending processing， the tensile strength and elongation at break of the TPV prepared by using micro-nano lamination technology were increased by 12.4 % and 12.1 %， respectively. When the vulcanization temperature was 190 ℃ and the screw speed was 200 r/min， TPV exhibited the optimal mechanical properties， and its tensile strength， elongation at break， hardness and compression set were 6.69 MPa， 363.8 %， 57.6 A and 31.5 %， respectively. The tensile strength， elongation at break， hardness of TPV decreased with an increase in the rubber content， but its elastic recovery performance， aging resistance， and oil resistance were improved. The optimal dosages of silane modified polyurethane （TPSiU） and ethylene methyl acrylate copolymer （EMA） as compatibilizers were 10 phr and 5 phr， respectively. Compared to EMA， the TPV with TPSiU achieved better elastic recovery performance and oil resistance performance was better. However， the use of EMA for TPV increased the elongation at break significantly.
2023, 37 (5):
15-21;
Abstract (
267 )
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27
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Aiming at the localization of deep?sea solid buoyancy materials， epoxy resin/hollow glass microsphere （HGMs） composites were prepared by using independently developed casting molding， compression molding， curing with pressure， vacuum tamping， and isostatic pressing methods with a domestic produced HGMs （H25HS） as a raw material at volume fractions of 60 %~75 %. The density， compressive strength， and hydrostatic resistance of the as?prepared composites were comparatively investigated. The results indicated that when the volume fraction of H25HS was below 68 %， casting molding was a suitable molding method， with which a solid buoyancy material with a safe?using depth of more than 6 000 m and a density of less than 0.58 g/cm3 was obtained. When the volume fraction of H25HS was 68 %~70 %， vacuum tamping and isostatic pressing were the optimal methods to obtain a solid buoyancy material with a safe?using depth of 2 000~4 000 m and a density of 0.48~0.52 g/cm3.
2023, 37 (5):
22-27;
Abstract (
208 )
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17
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At present， the applications of microbial repair materials in engineering are restricted， because the used bacterial solution and calcium source cannot be fixed inside the cracks and the repair process requires repeated grouting. In this paper， the effect of the mass concentration of sodium alginate solution on the performance of repair material and its concrete crack repair effect were studied by using sodium alginate as a carrier for microorganisms. The repair effect of sodium alginate on the concrete cracks was analyzed in terms of the mineral composition and microstructure of repair products. The results indicated that only once grouting repair of concrete cracks using the microbial repair materials based on sodium alginate could seal the cracks of concrete specimens. The 7?day water penetration resistance of this repair material could reach 100 %. Its compressive strength recovery rate reached 63.64 % at a crack width of 1.5 mm.
2023, 37 (5):
28-33;
Abstract (
122 )
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21
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Ultra-high molecular weight polyethylene （PE-UHMW）/boron nitride （BN） composites were prepared through high-speed ball milling and hot pressing， and their hardness， mechanical properties and tribological properties were investigated. The results indicated that the addition of BN improved the yield strength of the composites but reduced their tensile fracture stress and elongation at break. When the BN loading was 3 wt%， the increasing effect of BN on the yield strength of the composites was most significant， but there was the least effect on the tensile stress and elongation at break. The addition of BN could reduce the friction coefficient of the PE-UHMW matrix significantly， and the friction coefficient of the composites decreased with an increase in the BN content. The composites obtained the most significant effect of BN on the lubricating performance at a loading of 3 wt%， and their friction coefficient decreased by 60% compared to pure PE-UHMW. The lubrication effect decreased at a BN loading of 7 wt%. The addition of no more than 3 wt% BN can improve the surface hardness of PE-UHMW and therefore increases the wear resistance of the composites effectively. However， the surface hardness of the composites decreased with the addition of 7 wt% BN due to an agglomeration effect. As a result， the wear of the composites increased， but their resistance to wear decreased.
2023, 37 (5):
34-39;
Abstract (
198 )
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22
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In this work， a series of poly（butanediol adipic ester） ［P（BS-co-BA）］ copolyesters were synthesized by using 1，4-butanediol， adipic acid， and succinic acid as raw materials， and their structures and properties were characterized and analyzed by using attenuated total reflection Fourier-transform infrared spectrometer， nuclear magnetic resonance instrument， differential scanning calorimeter， X-ray diffractometer， and thermogravimetric analyzer. The keratin enzyme degradation results indicated that the four copolyesters reached more than 80 wt% after reacting16 h， but the two homopolyesters only reached about 40 wt%. The degradation rate of polyester enzyme increased by a order of P（BS-co-40 % BA） > P（BS-co-60 % BA） > P（BS-co-80 % BA） > P（BS-co-20 % BA） > poly（butylene adipate） （PBA） > poly（butylene adipate） （PBS）. The thermal stability and degradation performance of P（BS-co-40 % BA） were both better than those of pure PBA， indicating that P（BS-co-40 % BA） is an optimal product with the best performance.
2023, 37 (5):
40-47;
Abstract (
194 )
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18
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In this paper， ternary blending modifier （TBM） made of the waste polyethylene （RPE）/waste polypropylene （RPP）/polypropylene grafted maleic anhydride blend with a mass ratio of 6/4/0.7 was prepared through twin?screw extrusion together with a zonal feeding technique. The effect of different mixing time and temperature on the dynamic stability of the modified AC?20?based asphalt was studied. The morphological evolution of TBM in the modified asphalt was analyzed with a variation of mixing time. The effect of TBM content on the high?temperature and low?temperature properties of the modified asphalt was compared at TBM contents of 0， 0.2， 0.3， 0.4， and 0.5 wt%. The results indicated that under the conditions of a dry mixing time of 30 s， a wet mixing time of not less than 180 s， and a wet mixing temperature of 170 ℃， the optimum content of TBM for the modified asphalt was 0.4 wt%. This work provides a theoretical basis for the applications of RPE and RPP blends in the modified asphalt.
2023, 37 (5):
48-54;
Abstract (
193 )
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24
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Acrylate rubber （ACM）， rigid body nano-calcium carbonate （nano-CaCO3）， elastomeric butyl acrylate/methyl methacrylate/butadiene ternary copolymer （AMB） were used as tougheners to blend with poly（vinyl chloride） （PVC）. The impact properties， tensile properties， processing rheology， and dynamic thermomechanical properties of the as-prepared compounds were investigated. The results indicated that when the mass ratio of PVC/ACM/nano-CaCO3/AMB was set to be 100/10/3/9， the compounds obtain low-temperature impact strength of 27.64 kJ/m2， which was 5 times higher than that of pure PVC. Their low temperature impact strength was 14.91 kJ/m2， which was 4.1 times higher than that of pure PVC. The addition of AMB reduced the glass transition temperature （Tg） of the compounding system， resulting in a decrease in Tg from 93.71 to 86.36 oC.
2023, 37 (5):
55-61;
Abstract (
202 )
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20
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This research proposed a novel combined glass fiber-reinforced microcellular foaming and double-sided in-mold decoration injection molding （GF-D-MIM/IMD） process. In this process， the mechanical properties of products were enhanced through adding glass fiber-reinforced （GF） matrix into polymer substrate to enhance， and the asymmetric temperature field on both sides of the mold cavity was suppressed and eliminated through applying two decorative films on both sides of plastic parts during single-sided IMD/MIM process（S-IMD/MIM）. This reduced the uneven bubble distribution and the warpage deformation of the molded parts. Taking the tensile test sample as an example， the mechanisms of bubble radius and quantity density were investigated and analyzed. Furthermore， the effects of double-sided decorative films and fiber contents on the warpage deformation and mechanical properties were investigated by using the numerical simulation method through GF with different fiber contents， which were added separately into polymer matrix during the D-MIM/IMD and S-IMD/MIM processes. The result indicated that compared to S-MIM/IMD， the double-sided films in GF-D-MIM/IMD process could balance the asymmetric temperature field effectively. When the fiber content was 20 wt%， the average bubble radius was the smallest， and the average quantity density was the largest in the test sample. Moreover， the tensile modulus and shear modulus of the products increased exponentially with an increase in the fiber content， and their Poisson’s ratio presented a decrease at first and then tended to increase.
2023, 37 (5):
62-68;
Abstract (
236 )
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25
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Ammonium polyphosphate （APP） was modified with chitosan （CS） and then with sodium phytate （PA-Na） to obtain coated APP （MCAPP）. MCAPP was characterized and analyzed by using infrared spectrometer， thermogravimetric analyzer， and cold field emission scanning electron microscope， etc. The as-prepared MCAPP was then used to prepare poly（lactic acid） composites through melt co-extrusion to enhance their flame-retardant performance. The results indicated that the addition of 7.5 wt% MCAPP at a CS/APP mass ratio of 1/2 could improve the flame retardancy and carbon formation capacity of the composites effectively. The peak-heat-release rate of the composites decreased from 654 to 469 kW/m2， and their residual carbon rate increased from 0.37 % to 6.85 %.
2023, 37 (5):
69-75;
Abstract (
203 )
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24
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Poly（vinyl alcohol）/starch composite films were prepared by means of a casting film?forming method using tapioca starch and poly（vinyl alcohol） as basic film-forming materials and sodium lauryl sulfonate as a surfactant. Based on single factor experiments， the effects of the amounts of tapioca starch， poly（vinyl alcohol） and surfactant sodium lauryl sulfonate， molding processing temperature， and molding processing time on the mechanic performance of the composite films were investigated. The three factors of tapioca starch dosage， sodium lauryl sulfonate dosage， and molding processing time were optimized through orthogonal experiments to determine the optimal processing conditions of the composite films. The soil degradation and fresh?keeping properties of the as?prepared composite films were studied. The results indicated that the composite films achieved optimal mechanical properties at a poly（vinyl alcohol） amount of 1 g， a tapioca starch amount of 0.7 g， a sodium lauryl sulfonate amount of 0.5 g， a molding processing temperature of 80 ℃， and a molding processing time of 65 min. The composite films exhibited high elongation at break of 262.58 % and ultimate tensile strength of 24.63 MPa. The developed composite films obtained good degradability. There was no evidence of mold growth for the composite films after storage for 8 h， indicating a certain preservation effect on fresh flowers.
2023, 37 (5):
76-82;
Abstract (
182 )
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16
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There is an urgent demand for degradable high-strength breathable membranes in the fields of food and pharmaceutical packaging. To address this issue， a technology to prepare poly（lactic acid） （PLA） packaging membranes was proposed in this paper. The effects of hot-pressing temperature， pressure， and time on the tensile strength and elongation at break of melt differential electrospun PLA micro-nanofiber membranes were investigated through single factor experiments. The Design-Expert 11 software was used to design experiments and analyze the experimental results. Response surface methodology was used to optimize the process parameters of fiber membrane hot pressing， and the obtained optimal value was verified through experiments. The results indicated that the optimal hot-pressing process parameters were determined to be a hot-pressing temperature of 40 ℃， a hot-pressing pressure of 4 MPa， and a hot-pressing time of 6 s on the basis of the response surface method. The unidirectional average tensile strength of the PLA fiber hot-pressed membrane treated under this condition was 27.613 MPa， which was 149.89 % higher than that of untreated fiber membrane. This datum has a relative error of 0.684 % with the predicted value， indicating a good fitting effect. The hot-pressing treatment can enhance the tensile strength of melt differential electrospun PLA fiber membranes effectively and therefore improve the application potential of PLA fiber membrane products in the field of packaging.
2023, 37 (5):
83-89;
Abstract (
229 )
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22
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Carbon-fiber （CF）-reinforced polyamide 10T （PA10T） composites were prepared by using PA10T as a matrix， and the effect of parameters for injection molding process on the mechanical properties of the composites were investigated. Based on the analysis of the average fiber-retention length of each samples， the optimal fiber-retention length for the PA10T/CF composites was about 295 μm. The optimized injection parameters were determined to be an injection temperature 330 oC， an injection pressure of 50 % corresponding to the maximum injection pressure， an injection rate of 70 % corresponding to the maximum injection rate， a maintaining pressure of 50 MPa， and a module temperature of 30 oC. Scanning electron microscopy showed that the cross-section of the composites with different contents of CF presented ductile fracture， and the carbon fibers were uniformly dispersed in the matrix when the optimized process parameters were adopted.
2023, 37 (5):
90-97;
Abstract (
225 )
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23
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Taking blueberry as a research object， poly（glycolic acid） （PGA）/poly（butylene terephthalate） （PBAT） biodegradable composite films were prepared by using a twin-screw extruder and a film blowing mechanism. The effects of different composite films on the fresh-keeping quality of blueberry were investigated by taking enzyme activity， bioactive compounds， fruit quality and sensory evaluation as assessment indicators. The results indicated that the PGA/PBAT composite film at a weight ratio of 60/40 could effectively inhibit an increase in the H2O2 content and delay a decrease in the total phenol content， total flavonoids content， soluble solids content and sensory score. Therefore， the biodegradable preservative films based on the PGA and PBAT compounds are very advantageous to the preservation of blueberries， especially for the PGA/PBAT composite film at a weight ratio of 60/40.
2023, 37 (5):
98-103;
Abstract (
180 )
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17
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In this paper， the current product standard and manufacturing technology of polyethylene （PE） gas valve were described briefly， and the common problems in production quality and failure modes as well as the reasons for quality problems in the gas valves were analyzed. The quality control technologies and requirements of the gas valves， such as promoting the research and development of valve manufacturing， testing and evaluation technologies， and strengthening the production quality control management of the gas valve were proposed， which provided a reference for the development of manufacturing technology of gas valves and the improvement of their product quality.
2023, 37 (5):
104-109;
Abstract (
215 )
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21
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A novel flame retardant， methyl diphenyl phosphine oxide （DPMP）， was compounded with polyurethane （PU） to obtain flame-retardant PU composites by using flake clay as a synergist. The effects of DPMP and clay on the flame retardancy of the composites were investigated through ultimate oxygen index （LOI）， vertical combustion （UL 94）， and micro calorimetry. The crystallization properties and thermal degradation behaviors of the composites were analyzed by using differential scanning calorimetry and thermogravimetric analyzer. The results indicated that DPMP could promote the cold crystallization of PU， thus improving its modulus and mechanical properties. The addition of 10 wt% DPMP increased the LOI value of PU from 23 to 28.3 vol%， and the resultant composite obtained a modulus， elongation at break， and tensile strength of 1.37 MPa， 1 042 % and 13.84 MPa， respectively， while the corresponding values for pure PU were 1.17 MPa， 811 % and 11.32 MPa， respectively. With a further addition of 1 wt% clay， the dripping phenomenon of the composites could be eliminated， enabling the composites to achieve a UL 94 V-0 classification in the vertical burning test.
2023, 37 (5):
110-115;
Abstract (
497 )
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27
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This paper overviewed the general situation and the latest development status in the plastics industry of China in 2022. The development situation in 2023 was prospected. Based on the data of plastics industry， the apparent consumption and waste amounts of plastics and the utilization and rate amounts of recycled plastics in 2022 were analyzed.
2023, 37 (5):
116-122;
Abstract (
274 )
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31
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This paper reviewed the working principle， influence conditions of electrospinning technology and the development status of polymer nanofiber separators for the use in lithium batteries by this technology at home and abroad， mainly including polymethylmethacrylate， polysulfonamide， polyacrylonitrile， polyvinylidene fluoride， and other polymer nanofiber separators. The characteristics and properties of various polymer separators were also introduced. Finally， the development direction of separators prepared through electrospinning was prospected.
