A Comparative Study on the Post-Buckling Behavior of Reinforced Thermoplastic Pipes(RTPs)Under External Pressure Considering Progressive Failure

The collapse pressure is a key parameter when RTPs are applied in harsh deep-water environments.To investigate the collapse of RTPs,numerical simulations and hydrostatic pressure tests are conducted.For the numerical simulations,the eigenvalue analysis and Riks analysis are combined,in which the Hashin failure criterion and fracture energy stiffness degradation model are used to simulate the progressive failure of composites,and the“infinite”boundary conditions are applied to eliminate the boundary effects.As for the hydrostatic pressure tests,RTP specimens were placed in a hydrostatic chamber after filled with water.It has been observed that the cross-section of the middle part collapses when it reaches the maximum pressure.The collapse pressure obtained from the numerical simulations agrees well with that in the experiment.Meanwhile,the applicability of NASA SP-8007 formula on the collapse pressure prediction was also discussed.It has a relatively greater difference because of the ignorance of the progressive failure of composites.For the parametric study,it is found that RTPs have much higher first-ply-failure pressure when the winding angles are between 50°and 70°.Besides,the effect of debonding and initial ovality,and the contribution of the liner and coating are also discussed.

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Sustainable, thermoplastic and hydrophobic coating from natural cellulose and cinnamon to fabricate eco-friendly catering packaging

Non-degradable polymers cause serious environmental pollution problem,such as the widely-used while unrecyclable coatings which significantly affect the overall degradation performance of products.It is imperative and attractive to develop biodegradable functional coatings.Herein,we proposed a novel strategy to successfully prepare biodegradable,thermoplastic and hydrophobic coatings with high transparence and biosafety by weakening the interchain interactions between cellulose chain.The natural cellulose and cinnamic acid were as raw materials.Via reducing the degree of polymerization(DP)of cellulose and regulating the degree of substitution(DS)of cinnamate moiety,the obtained cellulose cinnamate(CC)exhibited not only the thermalflow behavior but also good biodegradability,which solves the conflict between the thermoplasticity and biodegradability in cellulose-based materials.The glass transition temperature(T_(g))and thermalflow temperature(T_(f))of the CC could be adjusted in a range of 150–200℃ and 180–210℃,respectively.The CC with DS<1.2 and DP≤100 degraded more than 60%after an enzyme treatment for 7 days,and degraded more than 80%after a composting treatment for 42 days.Furthermore,CC had no toxicity to human epidermal cells even at a high concentration(0.5 mg mL^(-1)).In addition,CC could be easily fabricated into multifunctional coating with high hydrophobicity,thermal adhesion and high transparence.Therefore,after combining with cellophane and paperboard,CC coating with low DP and DS could be used to prepare fully-biodegradable heat-sealing packaging,art paper,paper cups,paper straws and food packaging boxes.

Overview of Jute Fibre as Thermoplastic Matrix Polymer Reinforcement

Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberreinforced composites have been investigated as a sustainable alternative to synthetic materials to reduce the usage of hazardous waste and environmental pollution.Among the natural fibre,jute fibre obtained from a bast plant has an increasing trend in the application,especially as a reinforcement material.Numerous research works have been performed on jute fibre with regard to reinforced thermoset and thermoplastic composites.Nevertheless,current demands on sustainable materials have required new developments in thermoplastic composites.In this paper,the author reviews jute plants as reinforcement materials for thermoplastic matrix polymers.This review provides an overview of the sustainability of jute plants as reinforcement material for thermoplastic matrix polymers.The overview on jute based thermoplastic composites focused on the thermal behavior and mechanical properties.Apart from physical,chemical,and mechanical properties,the study also covers the current and perspectives for future research challenges faced by the researchers on jute fibre reinforced thermoplastic composites.

Acetylation of Chinese bamboo flour and thermoplasticity

Chinese bamboo flour was chemically modified by acetylation with acetic anhydride by using trichloroacetic acid as an activation agent and the optimized condition for acetylation of bamboo flour was determined as the trichloroacetic acid amount 6.0 g per 1.5-g bamboo flour, ultrasosonication duration 40 min and the reaction time 1 h at 65℃. The composition, microstructure and thermal behavior of acetylated bamboo flour were preliminarily characterized by FT-IR, DSC and SEM etc. The acetylated bamboo flour can be molded into sheets at 130℃ and 10 MPa, indicating the modified bamboo flour possesses thermalplastic performance.

PROPERTIES OF BIODEGRADABLE THERMOPLASTIC STARCH

Thermoplastic starch is a kind of modified starch produced by mixing starch with additives and processing the mixture in an extruder. The mechanical properties, including tensile strength and elongation at break, biodegradability and rheological properties were studied. Glycerol and urea, to some extent, can both decrease the tensile strength and increase percentage elongation at break, because the former acts as a plasticizer and the latter can break down interactions among starch macromolecules. Thermoplastic starch shows thermoplasticity and its melt behaves as a pseudoplastic liquid at a low shear rate. Its biodegrading extent is slightly higher than that of native starch. The molecular weight of starch displays a decreasing tendency after thermoplastic modification.

THE STRUCTURE OF THERMOPLASTIC STARCH

The granular structure, crystal structure and gelatinization temp. of thermoplastic starch were studied with a polarized light microscope and a scanning electron microscope, and the crystallinity and crystalline patterns were determined through X ray diffraction. The results indicate that the original granular structure and spherical crystalline structure of starch were disrupted by the action of pressure, heat and shear force with the help of additives. The starch can be melted during extrusion, and part of the spheric crystal was destroyed and changed into a continual amorphous with a few crystalline fractions dispersed in it. The configuration of starch molecules changed from double helices to single helix, which indicated the formation of the complex.

Synthesis of aliphatic amidediol and used as a novel mixed plasticizer for thermoplastic starch

In this paper,aliphatic amidediol was synthesized and mixed with glycerol used as a plasticizer for preparing thermoplastic starch（AGPTPS）.The yield of aliphatic amidediol was 91%.FF-IR expressed that the mixture of aliphatic amidediol and glycerol formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch.By scanning electron microscope（SEM）native cornstarch granules were proved to transfer to a homogeneous continuous system.After being stored for a period time at room temperature,the mechanical properties of AGPTPS were also studied.As a mixed plasticizer,aliphatic amidediol and glycerol would be practical to extend TPS application scopes.

EPOXY RESIN TOUGHENED BY THERMOPLASTICS

Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated. The fractography of PSF, particle modified epoxy was examined in detail with SEM. The contribution of every possible energy absorption process has been discussed. Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.

Effect of microwave treatment on tensile properties of sugar palm fibre reinforced thermoplastic polyurethane composites

The effect of microwave treatment on the tensile properties of treated sugar palm fibre with 6% NaOH reinforced thermoplastic polyurethane composites was investigated. Firstly, the sugar palm fibres were treated by 6% alkali solution. Then, microwave treatment was used to treat the alkali treated sugar palm fibres. Three types of temperatures(i.e. 70, 80 and 90℃) were applied in microwave treatment. The extruder and hot press machines were used to mixing the sugar palm fibres and polyurethane resin, and fabricate the composites. Tensile properties(i.e. tensile strength, tensile modulus and elongation at break) were studied by following the ASTM D-638 standard. The highest tensile strength was recorded 18.42 MPa with microwave temperature at 70℃ and 6% alkali pre-treatment. Therefore, the temperature 70℃ of microwave treatment may consider the best degree cent grate.

Blends of Poly(lactic acid) with Thermoplastic Acetylated Starch

Blends of poly（lactic acid）（PLA） and thermoplastic acetylated starch（ATPS） were prepared by means of the melt mixing method. The results show that PLA and ATPS were partially miscible, which was confirmed with the measurement of Tg by dynamic mechanical analysis（DMA） and differrential scanning calorimetry（DSC）. The mechanical and thermal properties of the blends were improved. With increasing the ATPS content, the elongation at break and impact strength were increased. The elongation at break increased from 5% of neat PLA to 25% of the blend PLA/ATPS40. It was found that the cold crystallization behavior of PLA changed evidently by addition of ATPS. The cold crystallization temperature（Tcc） of each of PLA/ATPS blends was found to shift to a lower temperature and the width of exothermic peak became narrow compared with that of neat PLA. The thermogravimetry analysis（TGA） results showed that the peak of derivative weight for ATPS moved to higher temperature with increasing PLA content in PLA/ATPS blends. It can be concluded that PLA could increase the thermal stability of ATPS. The rheological measurement reveals the melt elasticity and viscosity of the blends decreased with the increased concentration of ATPS, which was favorable to the processing properties of PLA.

Thermoplastic Starch Prepared with Different Plasticizers: Relation between Degree of Plasticization and Properties

Ethylene glycol, glycerol, sorbitol, formamide, and urea were used as plasticizers for the preparation of thermoplastic starch（TPS） from corn starch. The properties of TPS were tested by analysis method. The results showed that TPSs were more highly plasticized with amines than alcohols. For the same type of plasticizer, the degree of plasticization decreased as the molecular weight of plasticizer increased. The relationship between plasticization degree and TPS properties was characterized and described by mechanical properties and water absorption. The experimental results showed that when the degree of plasticization increased, the tensile strength decreased and the elongation at breakage and water absorption increased.

MICROMOLDING ON CURVED SURFACES WITH THERMOPLASTICS

Microstructures were produced on curved surfaces and micro-protrusions by using direct micromolding with fourthermoplastic polymers. This method is simpler and more convenient than micromolding with liquid prepolymer or using theμTM method. By repeated molding, crossed structures were produced with a stamp prepared only with lines. The processingvariables including the softening temperature of the polymers and heating time were discussed. The result shows that theoptimal molding temperature is preferably slightly higher than the melting temperature of the thermoplastic polymers, atwhich polymers are in the critical states of being melted. This method can be applied to many polymers except those with high softening temperatures or high rate of shrinkage upon temperature change.

Highly Ordered Thermoplastic Polyurethane/Aramid Nanofiber Conductive Foams Modulated by Kevlar Polyanion for Piezoresistive Sensing and Electromagnetic Interference Shielding

Highly ordered and uniformly porous structure of conductive foams is a vital issue for various functional purposes such as piezoresistive sensing and electromagnetic interference(EMI) shielding. With the aids of Kevlar polyanionic chains, thermoplastic polyurethane(TPU) foams reinforced by aramid nanofibers(ANF) with adjustable pore-size distribution were successfully obtained via a nonsolvent-induced phase separation. In this regard, the most outstanding result is the in situ formation of ANF in TPU foams after protonation of Kevlar polyanion during the NIPS process. Furthermore, in situ growth of copper nanoparticles(Cu NPs) on TPU/ANF foams was performed according to the electroless deposition by using the tiny amount of pre-blended Ti_(3)C_(2)T_(x) MXene as reducing agents. Particularly, the existence of Cu NPs layers significantly promoted the storage modulus in 2,932% increments, and the well-designed TPU/ANF/Ti_(3)C_(2)T_(x) MXene(PAM-Cu) composite foams showed distinguished compressive cycle stability. Taking virtues of the highly ordered and elastic porous architectures, the PAM-Cu foams were utilized as piezoresistive sensor exhibiting board compressive interval of 0–344.5 kPa(50% strain) with good sensitivity at 0.46 kPa^(-1). Meanwhile,the PAM-Cu foams displayed remarkable EMI shielding effectiveness at 79.09 dB in X band. This work provides an ideal strategy to fabricate highly ordered TPU foams with outstanding elastic recovery and excellent EMI shielding performance, which can be used as a promising candidate in integration of satisfactory piezoresistive sensor and EMI shielding applications for human–machine interfaces.

A Mixed Plasticizer for the Preparation of Thermoplastic Starch

In this paper, formamide was firstly used as plasticizer to prepare thermoplastic starch (TPS), which could suppress the retrogradation of TPS by X-ray diffractometry (XRD) and show a good flexibility, but was weaker than conventional glycerol-plasticized TPS (GPTPS). When urea was introduced into plasticizer, both the retrogradation and mechanical properties were ameliorated. The tensile stress, strain and energy break of TPS plasticized by urea (wt. 20%) and formamide (wt.10%), respectively, reached 4.83 MPa, 104.6 % and 2.17 N-m (Newton-meter) after it had been stored at relative humidity (RH) 30% for one week.

A Novel Plasticizer for the Preparation of Thermoplastic Starch

in this paper, ethylenebisformamide was synthesized and used as a novel plasticizer for cornstarch to prepare thermoplastic starch （TPS）. FT-IR expressed that ethylenebisformamide formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch. X-ray diffraction （XRD） showed that the typical A-style crystallinity in the native starch has been destructed. By scanning electron microscope （SEM） native cornstarch granules were proved to transfer to a homogeneous system. After being stored for one week at RH=33%, the mechanical properties of EPTPS was also studied. The elongation reached to 264% utmost. As a novel plasticizer, ethylenebisformamide would be practical to extend TPS application scopes.

Effect of Accelerated Xenon Lamp Aging on the Mechanical Properties and Structure of Thermoplastic Polyurethane for Stratospheric Airship Envelope

This study aimed to investigate the effect of artificial weathering test on the photoaging behavior of TPU films. Changes in mechanical properties, morphology and chemical structures are studied by tensile test, scanning electron microscopy, atomic force microscopy, Fourier-transformed infrared, and X-ray photoelectron spectroscopy. The results show that the photoaging negatively affects the initial modulus and stress at break values of TPU films. The surface of the specimen that is exposed to irradiation becomes rough, and some visible micro-defects such as blisters and voids can be detected. The morphology of the fracture surfaces illustrates that irradiation reduces the plasticity but increases the brittleness of the TPU films. The chemical structure analyses of the accelerated aged films prove that chemical structural changes in TPU films occur. The irradiation may break the long molecular chains on the surface of the specimens and form the lowmolecular weight oxygen-containing groups. The number of chain scissions increases with the increase in exposure time.

Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites

The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/thermoplastic polyurethane(TPU) composites.The treated kenaf fiber,NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine.The polymer composites were then fabricated using the hot press to form a sample board.The sample was cut and prepared and water absorption,density,thickness swelling and DMA tests were performed.As far as physical properties are concerned,composites with the highest NR amount of shows the best results,which indicates good fiber bonding adhesion.The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature.

The Friction Wear Properties and Application of Thermoplastic Polyester Elastomer and Polyoxymethylene

The experiment of injection molding, Dais-simulating test, morphological structure investigation(Scanning Electron Microscopy, SEM),X-ray photoelectron spectroscopy(XPS)were performed on mini-automobile spherical seat which was made of thermoplastic polyester elastomer(TPEE)and oiled polyoxymethylene(POM),respectively. The friction-wear properties between the frictionl pair of polymer spherical seat and metallic(iron)spherical pin were studied. The test results indicate that the antifriction property of TPEE is superior to that of POM, while its surface chemical effect is inferior to that of POM.

Synthesis and Properties of Non-isocyanate Crystallizable Aliphatic Thermoplastic Polyurethanes

A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.