Isothermal crystallization kinetics of poly(ethylene terephthalate)-poly(ethylene oxide) segmented copolymer with two crystallizing blocks

The isothermal crystallization kinetics and morphology of poly(ethylene terephthalate)-poly(ethylene oxide) (PET30-PEO6) segmented copolymer, and poly(ethylene terephthalate) (PET) and poly(ethylene oxide) (PEO) homopolymers have been studied by means of differential scanning calorimetry (DSC) and a transmission electron microscope (TEM). It is found that the nucleation mechanism and growth dimension of PEO in the copolymer are different from that in the homopolymer, which is attributed to the effect of the crystallizability of PET-blocks. Furthermore, the crystallization rate of PEO-blocks in the copolymer is slower than that in the homopolymer because the PET-blocks phase is always partially solidified at the temperatures when PEO-blocks begin to crystallize. In contrast, the isothermal crystallization rate of PET-blocks in the copolymer is faster than that in the homopolymer because the lower glass transition temperature of the PEO-blocks (soft blocks) increases the mobility of the PET-blocks in the copolymer.     

Synthesis of block copolymers via redox polymerization

Polymerization and copolymerization of vinyl monomers such as acrylamide, acrylonitrile, vinyl acetate, and acrylic acid with a redox system of Ce(IV) and organic reducing agents containing hydroxy groups were studied. The reducing compounds were poly(ethylene glycol)s, halogen‐containing polyols, and depolymerization products of poly(ethylene terephthalate). Copolymers of poly(ethylene glycol)s‐b‐polyacrylonitrile, poly(ethylene glycol)s‐b‐poly(acrylonitrile‐co‐vinyl acetate), poly(ethylene glycol)s‐b‐polyacrylamide, poly(ethylene glycol)s‐b‐poly(acrylamide‐co‐vinyl acetate), poly(1‐chloromethyl ethylene glycol)‐bpoly(acrylonitrile‐co‐vinyl acetate), and bis[poly(ethylene glycol terephthalate)]‐b‐poly(acrylonitrile‐co‐vinyl acetate) were produced. The yield of acrylamide polymerization and the molecular weight of the copolymer increased considerably if about 4% vinyl acetate was added into the acrylamide monomer. However, the molecular weight of the copolymer was decreased when 4% vinyl acetate was added into the acrylonitrile monomer. Physical properties such as solubility, water absorption, resistance to UV light, and viscosities of the copolymers were studied and their possible uses are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1385–1395, 1999     

Antistatic performance and morphological observation of ternary blends of poly(ethylene terephthalate), poly(ether esteramide), and ionomers

Blends of poly(ethylene terephthalate) (PET) and poly (ether esteramide) (PEEA), which is known as an ion conductive polymer, were prepared by melt mixing using a twin screw extruder. Antistatic performance of the molded plaques and the effects of adding ionomers such as lithium neutralized poly(ethylene‐co‐methacrylic acid) copolymer(E/MAA‐Li), magnesium neutralized poly(ethylene‐co‐methacrylic acid) copolymer(E/MAA‐Mg), and zinc neutralized poly(ethylene‐co‐methacrylic acid) copolymer (E/MAA‐Zn) were investigated. Antistatic effect of adding poly(ethylene‐co‐methacrylic acid) copolymer(E/MAA) and polystyrene, and poly(ethylene naphthalate) (PEN) into PET/PEEA blends were also investigated. Here we confirmed that lithium ionomer worked the most effectively in those blend systems. We also confirmed that E/MAA worked to enhance the antistatic performance of PET/PEEA blends. Morphological study of these ternary blends system was conducted by TEM. Specific interaction between PEEA and E/MAA‐Li, and E/MAA were observed. Those ionomers and copolymer domains were encapsulated by PEEA, which could increase the surface area of PEEA in PET matrix. This encapsulation effect explains the unexpected synergy for the static dissipation performance on addition of ionomers and E/MAA to PET/PEEA blends. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Simultaneous Synthesis of Dimethyl Carbonate and Poly（ethylene terephthalate） Using Alkali Metals as Catalysts

Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carded out under the following conditions： the reaction temperature 250℃, molar ratio of EC to DMT 3 ： 1, reaction time 3h, and catalyst amount 0.004 （molar ratio to DMT）, the yield of DMC was 68.9%.     

Mechanical compatibilization of high density polyethylene–poly(ethylene terephthalate) blends

Blends of high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) exhibit extremely poor mechanical properties owing to the incompatibility of these two polymers. Such blends, however, would result from the reprocessing of certain carbonated beverage bottles. Addition of small amounts of a commercially available triblock copolymer greatly improved the ductility of these incompatible blends, whereas addition of an ethylene–propylene elastomer did not. The results are discussed in terms of phase morphology and interfacial adhesion among the various components.     

The thermal and mechanical behavior of poly(ethylene terephthalate) fibers incorporating novel thermotropic liquid crystalline copolymers

This investigation explores the potential of improving the performance of poly(ethylene terephthalate) fibers by incorporating novel thermotropic liquid crystalline copolymers. Fibers were obtained by melt extrusion and the effect of processing conditions, i.e., spinning temperature, stretch ratio, and post treatment evaluated. The fibers were tested for mechanical performance, dimensional instability (shrinkage), and the development of shrinkage stresses. A segmented block copolymer consisting of rigid-rod, diad, and flexible coil segments was found to improve the performance of poly(ethylene terephthalate) (PET) fibers. At a concentration of 20 wt %, the alternating block copolymer increased the tensile modulus of the fibers by 40% and decreased free shrinkage by 20% compared to neat PET. © 1994 John Wiley & Sons, Inc.     

A Preliminary Investigation on the Use of Poly[(ethylene terephthalate)‐co‐(ε‐caprolactone)] Copolymer as Compatibiliser of HDPE/PET Blends

A preliminary study on the possibility to use the copolymer poly[(ethylene terephthalate)‐co‐(ε‐caprolactone)] as a compatibilising agent in blends of high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) is reported. The copolymer was synthesised by polycondensation of low‐molecular weight PCL precursors, previously end‐capped with reactive isocyanate groups, and oligomers of PET obtained from PET waste through a controlled depolymerisation procedure. HDPE/PET blends at a composition of 70/30 w/w with and without the addition of 10 wt.‐% of compatibiliser were prepared in a single‐screw mixer extruder. The effect of compatibiliser was evaluated by studying the thermal, dynamic‐mechanical and mechanical properties and the morphology of the blends. The compatibiliser was found to be a good emulsifying agent from a morphological point of view. Nevertheless, the mechanical properties of the blend were not improved by the addition of the compatibiliser.     

Recycling of inside upholstery of end‐of‐life cars

A model study for the recycling of the interior upholstery plastic parts of end‐of‐life cars has been carried out by reprocessing the homogenized scraps of an upholstery farm in the presence of different compatibilizer precursors, such as an ethylene‐glycidylmethacrylate copolymer (EGMA), a maleic anhydride functionalized thermoplastic elastomer (SEBS‐MA), etc. The investigated scraps contained recycled polyethylene (from agricultural uses) and poly(ethylene terephthalate), as the main components, plus minor proportions of polypropylene, polyamide‐6, and other additives, including an ethylene copolymer (EC), probably an ethylene‐acrylic acid copolymer, which is used to compatibilize the carpets' backing and increase their flexibility. The reactive blending experiments were carried out using a Brabender Plasticorder static mixer and a Brabender twin‐screw compounder, and the products were characterized by rheometry, differential scanning calorimetry, scanning electron microscopy, stress–strain measurements, etc. It was shown that EGMA was most effective for the reactive compatibilization of the polyolefin and poly(ethylene terephthalate) components of the scraps. It was also found, however, that the EC contained in the upholstery backing neutralizes in part the functional epoxy groups of EGMA, thus reducing its compatibilizing efficiency. The results suggest that substitution of EC with an inert flexibilizing agent, such as an ethylene‐propylene copolymer, and use of small amounts (～ 5%) of an EGMA compatibilizer, might allow recycling of used upholstery into injection moldable plastic articles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1716–1728, 2005     

Structural changes in glassy polymers

It has previously been shown that glassy poly(ethylene terephthalate) gives rise to endothermal peaks in DTA when annealed at temperatures near to the glass temperature. The present work describes results obtained from DTA and DSC on annealing a number of glassy polymers which have been rapidly cooled from above the glass temperature and on slowly cooled samples of the same polymers. The polymers which have been studied are: poly(ethylene terephthalate), poly(methyl methacrylate), atactic and isotactic polystyrene, bisphenol-A polycarbonate, poly(ethyl methacrylate) and poly(vinyl acetate). In every case, evidence of structural reorganization is observed, and the rate at which this takes place is reported. Separate studies on poly(ethylene terephthalate) reflect density changes which also take place upon annealing. These results are discussed in the context of the calorimetric observations.     

One-bath dyeing of poly(ethylene terephthalate)/cotton blends with alkali-clearable azo disperse dyes containing a fluorosulphonyl group

Monoazo disperse dyes containing a fluorosulphonyl group, based on 4-amino-4'-fluorosulphonylazobenzene derivatives, were dyed on poly(ethylene terephthalate)/cotton blends and their dyeing and fastness properties investigated. A one-bath dyeing method was used, as these dyes can be alkali cleared in the same bath. In particular, the cross-staining of cotton was studied in order to assess their suitability for the one-bath dyeing of poly(ethylene terephthalate)/cotton blends.     

Poly(ester-ether) fibres

Ester-ether copolymers were prepared by melt condensation reaction using dimethyl terephthalate (DMT) and different quantities of ethylene glycol (EG) and poly(ethylene glycol) (PEG) (MW 400) in the initial monomer feed. Five copolymer samples were prepared by varying the contents of PEG on the basis of EG from 0.5 to 2.5 mol-%. The polymer samples were characterized by determination of melting points (mp) and intrinsic viscosities. The mp decreased from 258°C to 248°C on increasing the poly(ethylene oxide) segments in the backbone. Thermal stability of the copolymers also decreased by the introduction of PEG units in the backbone. The polymers were melt spun into fibres. With the increase of PEG in the copolymer fibres a decrease in tensile strength and initial modulus was observed while the elongation increased. The dye uptake and moisture regain of the copolyester fibres was considerably enhanced in comparison of poly(ethylene glycol terephthalate) (PET) fibres.     

Melt rheological and thermodynamic properties of polyethylene homopolymers and poly(ethylene/α-olefin) copolymers with respect to molecular composition and structure

Various types of polyethylene homopolymers and copolymers, including linear high-density polyethylene (HDPE), branched low-density polyethylene (BLDPE), poly(ethylene vinyl acetate) copolymer (EVA), heterogeneous linear poly(ethylene/α-olefin) copolymer (het-LEAO) or commonly known as linear low-density polyethylene, homogeneous linear poly(ethylene/α-olefin) copolymer (hom-LEAO), and homogeneous branched poly(ethylene/α-olefin) copolymer (hom-BEAO), were evaluated for their melt rheological and thermodynamic properties with emphasis on their molecular structure. Short-chain branching (SCB) mainly controls the density, but it has little effect on the melt rheological properties. Long-chain branching (LCB) has little effect on the density and thermodynamic properties, but it has drastic effects on the melt rheological properties. LCB increases the pseudo-plasticity and the flow activation energy for both the polyethylene homopolymer and copolymer. Compared at a same melt index and a similar density, hom-LEAO has the highest viscosity in processing among all polymers due to its linear molecular structure and very narrow molecular weight distribution. Small amounts of LCB in hom-BEAO very effectively reduce the average viscosity and also improve the flow stability. Both hom-LEAO and hom-BEAO, unlike het-LEAO, have thermodynamic properties similar to BLDPE. © 1996 John Wiley & Sons, Inc.     

The thermal shrinkage of the drawing poly(ethylene isophthalate terephthalate) copolyester films

The objective of this study is to use the copolymerization method to improve the thermal shrinkage property of poly(ethylene terephthalate) (PET), so that the resultant copolyester can be used for the application of thermal shrinkage packing materials. The poly(ethylene isophthalate terephthalate) (PEIT) copolyester films were prepared and studied. The thermal shrinkage rate of PET films and the thermal shrinkage rate of the copolyester films were measured by using a thermomechanical analyzer (TMA). The thermal shrinkage of copolyester was found to be dependent on such factors as composition, molecular weight, and draw temperature. The highest thermal shrinkage was obtained when the copolymer contained 40 mol % of ethylene isophthalate. Its shrinkage ratio and shrinkage rate were consistently 1.3 and 2.4 times those of PET. The increase of molecular weight and decrease of drawing temperature resulted in the increase of the thermal shrinkage. The best drawing temperature range was between glass transition temperature and soft temperature of the copolymer. The relationship of shrinkage rate and temperature indicate that the shrinkage mechanism of the copolyester belongs to two-step thermal shrinkage.     

Synthesis and evaluation of biodegradable segmented multiblock poly(ether ester) copolymers for biomaterial applications

Based on 1,4‐succinic acid, 1,4‐butanediol, poly(ethylene glycol)s and dimethyl terephthalate, biodegradable segmented multiblock copolymers of poly[(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol)] (PTSG) were synthesized with different poly(butylene succinate) (PBS) molar fractions and varying the poly(ethylene glycol) (PEG) segment length, and were evaluated as biomedical materials. The copolymer extracts showed no in vitro cytotoxicity. However, sterilization of the copolymers by gamma irradiation had some limited effect on the cytotoxicity and mechanical properties. A copolymer consisting of PEG‐1000 and 20 mol% PBS, assigned as 1000PBS20 after SO₂ gas plasma treatment, sustained the adhesion and growth of dog vascular smooth muscle cells. The in vivo biocompatibility of this sample was also measured subcutaneously in rats for 4 weeks. The assessments indicated that these poly(ether ester) copolymers are good candidates for anti‐adhesion barrier and drug controlled‐release applications. Copyright © 2004 Society of Chemical Industry     

Thermal,rheological, mechanical,and dyeing property studies of poly(ethylene‐co‐trimethylene terephthalate) copolymer filaments

The thermal and rheological properties of poly(ethylene‐co‐trimethylene terephthalate) (PETT) copolymer are investigated. The thermal behavior of PETT copolymers is dependent on the composition. The PETT‐15 and PETT‐85 copolymers can crystallize, whereas the PETT‐30 copolymer cannot crystallize at 5°C/min cooling rate. The copolymers have a good thermal stability, even though the addition of poly(trimethylene terephthalate) (PTT) chain causes a disadvantage to the thermal stability of the copolymers. Moreover, the PETT copolymers are a typical pseudoplastic fluid exhibiting shear thinning. With increasing the shear rate or the content of PTT units, the flow activation energy decreases and the sensitivity of the shear viscosity to the melt temperature declines. The PETT copolymer filaments have intermediate elastic recovery and dyeability between poly(ethylene terephthalate) (PET) and PTT filaments. With increasing the PTT content, the elastic recovery and dyeability of PETT copolymer filaments increase. That is to say, introducing PTT units as a minor component into the macromolecular chains is an available means to improve the properties of PET filament. The obtained PETT copolymer filaments blend the advantage of the mechanical property of PET and the elastic and dyeability of PTT filament together into one polymer and possess a softer feeling and a higher extension. POLYM. ENG. SCI., 50:1689–1695, 2010. © 2010 Society of Plastics Engineers     

透明塑料件注射成型的缺陷和解决的办法

分析采用聚甲基丙烯酸甲酯、聚碳酸酯、聚对苯二甲酸乙二酯、聚苯乙烯、(丙烯腈／苯乙烯)共聚物、聚砜等生产透明塑料件时产生缺陷的原因,并提出通过调整成型工艺条件(温度、压力、时间、注射速率等)、修改模具结构、原料使用前进行处理等措施来克服成型缺陷。     

Powdered poly(ethylene terephthalate)

The influence of the conditions of preparation on the properties of powdered poly(ethylene terephthalate) was followed from the point of view of its specific surface. The powdered poly(ethylene terephthalate) prepared by reprecipitation from the melt of 6-caprolactam has a porous and structured surface, and consequently, also a large specific surface in comparison with the powedered poly(ethylene terephthalate) prepared by mechanical milling. The specific surface value is influenced by the cooling rate of the initial homogeneous melt of poly(ethylene terephthalate)-6-caprolactam, by the concentration of poly(ethylene terephthalate) in this melt and by its molecular weight, by the water temperature at the extraction of 6-caprolactam from the tough mixed melt, by the drying temperature of the powdered poly(ethylene terephthalate), and by the content of residual 6-caprolactam in the powdered product. In the examined area, the specific surface value of the powdered poly(ethylene terephthalate) prepared by reprecipitation from the melt of 6-caprolactam ranged from 10 to 110 m²·g^?1.     

Supramolecular structures and dyeing properties of poly(ethylene terephthalate) industrial yarns for seat‐belt webbings

The effects of spinning conditions and additives on the physical and dyeing properties of poly(ethylene terephthalate) industrial yarns were investigated by analysing their supramolecular structures. Four poly(ethylene terephthalate) yarns for seat‐belt webbing were prepared with different formulations and under different spinning conditions. Instrumental characterisation of the internal morphologies and physical properties confirmed that the structural characteristics are influenced by the draw ratio, heat‐setting temperature and copolymer added, and that there are close correlations between the supramolecular structure and the physical and dyeing properties. In particular, the draw ratio was the most dominating factor, influencing both the mechanical properties and the dyeability.     

Preparation and characterization of poly(trimethylene terephthalate)‐poly(ethylene oxide terephthalate) segmented copolymer/multiwalled carbon nanotubes composites by in situ polymerization

Poly(trimethylene terephthalate)‐poly(ethylene oxide terephthalate) block copolymer (PTG)/multiwalled carbon nanotubes (MWCNTs) composites were prepared via in situ polymerization. To improve the dispersion of MWCNTs in the PTG matrix, the poly(ethylene glycol)‐grafted multiwalled carbon nanotubes (MWCNT‐PEG) were produced by the “graft to” method. The transmission electron microscopy observation demonstrated that a homogeneous dispersion of MWCNT‐PEG was obtained. As a consequence, the percolation threshold for the rheology was around 0.5 wt% and the conductivity was ～1 wt%, respectively. Differential scanning calorimetry and polarized optical microscopy results confirmed that MWCNT‐PEG can act as an effective heterogeneous nucleating agent. Interestingly, the effects of MWCNT‐PEG on crystallization and melting of the poly(ethylene oxide terephthalate) blocks were more pronounced than on those of the PTT blocks. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Polycarbonate-polystyrene block copolymers and their application as compatibilzing agents in polymer blends

The synthesis of a block copolymer with polystyrene (PS) and polycarbonate (PC) segments is described. It is produced by anionic polymerization of the styrene and endcapping with a hydroxyl group followed by subsequent reaction with phosgene and bisphenol-A. The polystyrene/polycarbonate block copolymer was used as a compatibilizing agent for blends of poly(ethylene terephthalate) (PET) and poly(p- phenylene oxide) (PPO). The block copolymer reduced the dimensions of the dispersed phase. The uniaxial mechanical properties of the compatibilized blends were improved by 5 to 10 wt% loadings of the copolymer.