Blends of poly(ethylene terephthalate) and poly(butylene terephthalate)

Commercial grade poly(ethylene terephthalate), (PET, intrinsic viscosity = 0.80 dL/g) and poly(butylene terephthalate), (PBT, intrinsic viscosity = 1.00 dL/g) were melt blended over the entire composition range using a counterrotating twin‐screw extruder. The mechanical, thermal, electrical, and rheological properties of the blends were studied. All of the blends showed higher impact properties than that of PET or PBT. The 50:50 blend composition exhibited the highest impact value. Other mechanical properties also showed similar trends for blends of this composition. The addition of PBT increased the processability of PET. Differential scanning calorimetry data showed the presence of both phases. For all blends, only a single glass‐transition temperature was observed. The melting characteristics of one phase were influenced by the presence of the other. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 75–82, 2005     

Chain extension of polybutylene adipate and polybutylene succinate with adipoyl‐ and terephthaloyl‐biscaprolactamate

HO‐terminated polybutylene adipate (HO‐PBA‐OH) with molecular weight from 1040 to 3540 and HO‐terminated polybutylene succinate (HO‐PBS‐OH) with intrinsic viscosity of 0.37 dL/g were synthesized through melt condensation polymerization from adipic acid or succinic acid with excess of butanediol. Chain extension of HO‐PBA‐OH or HO‐PBS‐OH with adipoyl biscaprolactamate and terephthaloyl biscaprolactamate was carried out at 200–240°C under reduced pressure. At the optimal conditions, chain‐extended PBA with M_n up to 50,700, and M_w up to 125,700 was synthesized, and the chain‐extended PBS with intrinsic viscosity of 1.25 dL/g was obtained. Meanwhile, p‐toluenesulfonic acid, SnCl₄ and zinc acetylacetonate catalyzed chain‐extending reaction of HO‐PBA‐OH and HO‐PBS‐OH was also studied. The chain‐extended polyesters were characterized by IR spectra, ¹H‐NMR spectra, and differential scanning calorimetry (DSC). The chain extension proceeds through the elimination of caprolactam rings in the chain‐extenders, the adipoyl groups or the terephthaloyl groups couple the hydroxyl‐terminated polyesters together and make the molecular weight of PBA or PBS increased, whether the acid catalyst such as p‐toluenesulfonic acid was present or not. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis of functionalized copolymers and their compatibilization effects on acrylonitrile butadiene styrene/poly(butylene terephthalate) blends

In this study, the copolymers of methyl methacrylate-co-glycidyl methacrylate (MGD) with different epoxy contents and molecular weights, the styrene-co-glycidyl methacrylate (SGD) and methyl methacrylate-co-maleic anhydride (MAD) were synthesized. The synthesized copolymers, styrene-co-maleic anhydride (SMA) and styrene-acrylonitrile-co-glycidyl methacrylate (SAG) were used as compatibilizers to enhance the impact strength of the acrylonitrile butadiene styrene/poly(butylene terephthalate) (ABS/PBT). The effects of differences in the structure, reactive group type, and molecular weight of the compatibilizers on the mechanical properties, phase morphology, melt viscosity, thermal stability, and melting temperature of the blend were studied. The results showed that functionalized copolymers were successfully synthesized with high monomer conversions. Addition of the functionalized copolymers increased melt viscosity but did not considerably affect thermal stability, tensile strength, flexural strength and melting temperature of the ABS/PBT blends. The compatibilizers improved the dispersion of the PBT phase and prevented brittle fracture, thereby increasing the impact strength of the blend. Among the studied compositions, the ABS/PBT/MGD-5 blend exhibited the highest impact strength of 25.8 kJ/m² and an appropriate melt flow index of 19.1 g/10 minutes. The compatibilizer should have an appropriate molecular weight to improve the interface bonding force. Regarding the melting viscosity, the reactive group content and compatibilizer dosage should be adjusted to ensure high impact strength.     

Chain extension of poly(butylene terephthalate) by reactive extrusion

The chain extension reaction in poly(butylene terephthalate) (PBT) melt was studied in detail. A high‐reactivity diepoxy, diglycidyl tetrahydrophthalate, was used as a chain extender that can react with the hydroxyl and carboxyl end groups of PBT at a very fast reaction rate and a relatively high temperature. A Haake mixer 600 was used to record the torque during the chain extension reaction. The data show that this chain extension reaction could be completed within 2 to 3 min at temperatures above 250°C, and the reaction time decreased very fast with an increase in the temperature. Shear rate also had some effects on the reaction rate. The effect of the diepoxy chain extender on the flowability, thermal stability, and mechanical properties of PBT were investigated. The melt flow index (MFI) of the chain‐extended PBT dramatically decreased as the diepoxy was added to PBT. In addition, the notched Izod impact strength and elongation‐at‐break of the chain‐extended PBT also increased. The chain‐extended PBT is more stable thermally. Compared with the conventional solid post‐polycondensation method, this approach is simpler and cheaper to obtain high‐molecular‐weight PBT resins. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1827–1834, 1999     

Identification of rheological and structural characteristics of foamable poly(ethylene terephthalate) by reactive extrusion

The reactivity and efficiency of five low molecular weight multifunctional anhydride and epoxy compounds as chemical modifiers of a bottle grade poly(ethylene terephthalate) (PET) resin were evaluated by reactive extrusion under controlled conditions. The two dianhydrides and the three epoxy compounds were used at concentrations based on stoichiometry derived from the measured carboxyl and hydroxyl end group contents of the base resin. Measures of melt viscosity, melt strength, intrinsic viscosity and carboxyl group content were used as criteria of the extent of the modification. Correlations of die pressure with extrudate swell during extrusion, and melt flow index (MFI) with melt strength by off‐line testing of the extrudates permitted the ranking of the modifiers according to their chain‐extending/branching efficiency. For some systems molecular weight increases (related to die pressure/MFI/intrinsic viscosity) accompanied by broadening of the molecular weight distribution (related to die swell/melt strength) were considered excessive. Extrusion foaming experiments with one particular dianhydride modifier that increased the intrinsic viscosity of the resin from 0.71 to 0.9 dl g^?1 indicate that production of low‐density foams by a process involving one‐step reactive modification/gas injection foaming is feasible, at conditions not significantly different from those employed in the simple reactive modification of the PET resin. The rheological and structural parameters determined in this work may be used as criteria to specify PET foamable compositions in terms of types and concentrations of modifiers. Copyright © 2004 Society of Chemical Industry     

聚对苯二甲酸丁二醇酯的化学扩链改性研究

以 2 ,2′ -双 ( 2 -唑啉 ) (BOZ)为扩链剂 ,对聚对苯二甲酸丁二醇酯 (PBT)进行扩链改性 ,考察了反应时间、扩链剂用量对扩链效果的影响 ,测试了扩链后PBT的热失重、力学性能和DSC。结果表明 ,BOZ的用量为 0 .44 % ,反应时间 3～ 5min ,PBT的最大扩链效率可达 72 .9% ,PBT的特性粘数从 0 .83dL/g提高到 1.2 1dL/ g ,扩链后PBT热稳定性和力学性能都得到提高。     

Catalyzed chain extension of poly(butylene adipate) and poly(butylene succinate) with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline)

Low‐molecular‐weight HOOC‐terminated poly(butylene adipate) prepolymer (PrePBA) and poly(butylene succinate) prepolymer (PrePBS) were synthesized through melt‐condensation polymerization from adipic acid or succinic acid with butanediol. The catalyzed chain extension of these prepolymers was carried out at 180–220°C with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) as a chain extender and p‐toluenesulfonic acid (p‐TSA) as a catalyst. Higher molecular weight polyesters were obtained from the catalyzed chain extension than from the noncatalyzed one. However, an improperly high amount of p‐TSA and a high temperature caused branching or a crosslinking reaction. Under optimal conditions, chain‐extended poly(butylene adipate) (PBA) with a number‐average molecular weight up to 29,600 and poly(butylene succinate) (PBS) with an intrinsic viscosity of 0.82 dL/g were synthesized. The chain‐extended polyesters were characterized by IR spectroscopy, ¹H‐NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray scattering, and tensile testing. DSC, wide‐angle X‐ray scattering, and thermogravimetric analysis characterization showed that the chain‐extended PBA and PBS had lower melting temperatures and crystallinities and slower crystallization rates and were less thermally stable than PrePBA and PrePBS. This deterioration of their properties was not harmful enough to impair their thermal processing properties and should not prevent them from being used as biodegradable thermoplastics. The tensile strength of the chain‐extended PBS was about 31.05 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation,characterization and properties of a halogen‐free phosphorous flame‐retarded poly(butylene terephthalate) composite based on a DOPO derivative

A phosphorous flame retardant (DOPO‐MAH) was synthesized through the reaction between of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and maleic anhydride (MAH) and confirmed by FT‐IR, ¹H NMR, and ³¹P NMR techniques. The obtained flame retardant was then melt blended with poly(butylene terephthalate) (PBT) to prepare flame retardant PBT/DOPO‐MAH composites. The composites were characterized by LOI, UL‐94, and mechanical tests as well as scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry analysis. On adding 20 wt % DOPO‐MAH, LOI increased from 20.9 to 25.7 and the UL‐94 V‐0 rating was achieved, whereas the tensile and flexural properties were notably improved. Torque‐time profile during the melt blending and intrinsic viscosity of the composite indicated that DOPO‐MAH acted as both flame retardant and chain extender for the PBT matrix. The results showed that PBT/DOPO‐MAH composite is a promising material for its good comprehensive properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1301‐1307, 2013     

Kinetic studies of POSS–DGEBA precursors derived from monoamine functional POSS using dynamic dielectric sensing and nuclear magnetic resonance

Incorporation of pre‐reacted monofunctional polyhedral oligomeric silsesquioxane (POSS)–epoxy adducts dramatically improves dispersion of POSS in epoxy–amine networks. The relationship between reaction kinetics and mechanism for formation of POSS–epoxy adducts versus reaction temperature was investigated. Reactivities of epoxy–monoamine functional POSS molecules were determined using in situ reaction monitoring by dynamic dielectric sensing and ²⁹Si NMR spectroscopy. The amine‐functional POSS–epoxy isothermal reaction showed reduced reactivity due to reduced molecular mobility, that is, diffusion limitations. Kinetic parameters were determined by fitting ²⁹Si NMR data to the model of Kamal that was extended to include diffusion. Fitting of this model to experimental data showed very good agreement over the entire conversion range for pre‐reaction between amine‐functionalized POSS and epoxy. An autocatalytic mechanism, the same as that for the neat epoxy–amine systems, was indicated. Gel permeation chromatography, scanning electron microscopy and transmission electron microscopy were used to investigate molecular weight evolution and morphology of final networks cured by 4,4′ diaminodiphenyl sulfone using pre‐reacted POSS–epoxy adducts. POSS aggregate size decreased with increased pre‐reaction temperature; more homogenous POSS dispersion was observed with higher pre‐reaction temperature. Dynamic mechanical analysis demonstrated that T_g of composites decreased slightly compared to that of the neat matrix and there appeared to be little change in microstructural heterogeneity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45994.     

Effects of reactive and nonreactive POSS types on the mechanical,thermal, and morphological properties of plasticized poly(lactic acid)

The aim of this study is to investigate the effects of the reactive and nonreactive polyhedral oligomeric silsesquioxane (POSSs) types and their composition on the mechanical, thermal, and morphological properties of poly(ethylene glycol) plasticized poly(lactic acid) (PLA) composites prepared with melt compounding. The results showed that the incorporation of POSS decreased the melt viscosity of the compounds regardless of POSS type. The lowest viscosity was obtained with epoxy‐POSS, which is the only one that is liquid at processing temperature in comparison to the others. It was revealed from the mechanical tests that the toughness‐related properties such as impact strength and elongation at break improved by the addition of POSS without remarkable deterioration in stiffness. The chemical structure of the POSS influenced the level of dispersion and hence the mechanical performance of the composites. Octaisobutyl‐POSS, being the nonreactive and nonpolar one, had the best dispersion among the other reactive and polar POSS types. The glass transition temperature of the matrix decreased in the presence of POSS types. In addition, the POSS particles also had an impact on the crystallization of PLA. The thermal stability of the composites improved in the presence of POSS particles with respect to the POSS content and the POSS type. POLYM. ENG. SCI., 54:264–275, 2014. © 2013 Society of Plastics Engineers     

不同特性粘数PBT切片的流变性能研究

采用毛细管流变仪研究了5种不同特性粘数的聚对苯二甲酸丁二醇酯(PBT)的流变性能,计算得到了PBT的非牛顿指数和粘流活化能。结果发现:不同特性粘数的PBT熔体能够达到的最大剪切速率不同,随着特性粘数的增大,PBT熔体的非牛顿指数逐渐减小,粘流活化能先是逐渐减小,然后又变大。     

Chain extension of poly(ethylene terephthalate) by reactive blending using diepoxides

Molecular weight increase via chain extension reactions of poly(ethylene terephthalate) with commercially available diepoxides was studied in a custom‐made laboratory scale reactor and a Brabender rheomixer under reactive blending conditions. The products were characterized by carboxylic end group analysis, intrinsic viscosity, and differential scanning calorimetry. PET was effectively modified in the laboratory‐scale reactor using cyclic diepoxides because the resulting polymers show intrinsic viscosities that are comparable to virgin PET (0.68–0.75 dL/g vs. 0.74 dL/g) and much higher than processed PET (0.55), while carboxyl contents were reduced to a third of that of the virgin PET. Diglycidyl ethers produced polymers displaying decreased viscosity values, increased carboxyl content, and lower melting points. Low concentrations of extender and short reaction times generally favored chain extension. In addition, purging with nitrogen resulted in chain extended polymers having the highest values of intrinsic viscosity ([η] = 0.79, 0.82). Similar trends were observed with modified products in the rheomixer having somewhat smaller viscosity values, larger carboxyl contents, and increased melting points. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2121–2127, 1999     

Synthesis,spectral, and thermal characterization of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain derived from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone

A series of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain were synthesized from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone (BHPMBCH) and aliphatic and aromatic diacid chlorides. The diol precursor, BHPMBCH, was synthesized from 2,6‐bis(4‐hydroxy‐3‐methoxybenzylidene)cyclohexanone and 3‐bromo‐1‐propanol. The solubility of the polymers was tested in various solvents. The intrinsic viscosity of the synthesized polymers, determined by an Oswald viscometer, was found to be 0.06–0.80 g/dL. The molecular structures of the monomer and polymers were confirmed by Fourier transform infrared, ultraviolet–visible, ¹H‐NMR, and ¹³C‐NMR spectral analyses. The thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. The thermogravimetric analysis data revealed that the polymers were stable up to 220°C and started degrading thereafter. The thermal stability initially increased with increasing spacer length and then decreased due to negative effects of the spacer. The self‐extinguishing properties of the synthesized polymers were studied by the determination of the limiting oxygen index values with Van Krevelen's equation. In addition, the photocrosslinking properties of the polymer chain were studied with UV spectroscopy, and we observed that the rate of photocrosslinking increased significantly with increasing methylene carbon chain length of the acid spacer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

扩链改性聚对苯二甲酸丁二酯的力学性能研究

利用熔体流动速率测定仪、动态粘弹仪和电子拉力试验机等手段,考察了扩链改性对聚对苯二甲 酸丁二酯(PBT)的拉伸性能、熔体流动指数和动态力学性能的影响。实验结果表明:PBT经扩链改性后,随 其特性粘数增加,相对分子质量提高,熔体流动指数大幅度下降,玻璃化转变温度有所增加;改性后PBT的 储能模量和耗能模量提高2.6-4.6倍,拉伸强度提高50％以上,断裂伸长率提高1倍以上,表明扩链改性起 到了增粘增韧作用。     

Effect of octa(epoxycyclohexyl) POSS on thermal,rheology property,and foaming behavior of PLA composites

Foams of poly(lactic acid) (PLA)/octa(epoxycyclohexyl) polyhedral oligomeric silsesquioxanes (ePOSS) composite were prepared by melt‐mixing and solid‐state foaming methods. A systematic and accurate method was applied to evaluate the effects of epoxy‐based POSS on the structure of dispersion, thermal behavior, and rheological properties of PLA composites. The application of secondary electron–electron back‐scattered diffraction technique was used to observe the cellular micromorphology and micro‐phase dispersion in composite foams, simultaneously. The results indicated that secondary dispersion of POSS aggregates occurred in foaming process. The enhanced melt elasticity, dispersity of POSS, and crystallization morphology of PLA/POSS composite had a significant effect on the controlling foaming behavior. Thus, a homogeneous and finer cellular morphology of PLA/POSS composite foam with high expansion ratio was obtained with a proper content of POSS in the composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46399.     

Peroxide vulcanized EPDM rubber/polyhedral oligomeric silsesquioxane nanocomposites: Vulcanization behavior,mechanical properties,and thermal stability

Effects of two different polyhedral oligomeric silsesquioxane (POSS), an acrylisobutyl POSS (AIBuPOSS) containing an acrylate group along with seven isobutyl group on its cage and an octaisobutyl POSS where the acrylate group is absent, on vulcanization behavior, mechanical properties, and thermal stability of peroxide vulcanized ethylene‐propylene‐diene rubber (EPDM) were investigated. The POSS was incorporated into the EPDM by melt mixing with POSS content of 0–10 part per hundred of rubber (phr). Oscillating disk rheometer analysis revealed that the acrylate group of the POSS are activated by dicumyl peroxide and improves the peroxide crosslinking efficiency of EPDM rubber. Solid state ²⁹Si‐nuclear magnetic resonance spectroscopy analysis and field emission scanning electron microscopy with energy dispersive X‐ray analysis of the EPDM/POSS vulcanizates showed that the AIBuPOSS are covalently grafted onto the EPDM chain during vulcanization and are dispersed uniformly at the nanometer scale in the rubber matrix. The EPDM/AIBuPOSS nanocomposites exhibit great improvement in tensile, tear strength, and modulus with a concurrent increase in elongation‐at‐break. Enhanced thermal stability in the nanocomposite was also observed. POLYM. ENG. SCI., 55:2814–2820, 2015. © 2015 Society of Plastics Engineers     

封端异氰酸酯对低粘度PBT改性的研究

以封端异氰酸酯(BMDI)作低粘度聚对苯二甲酸丁二酯(PBT)的改性剂,考察改性前后PBT的特性粘度、端基含量、力学性能的变化。结果表明,改性后PBT的特性粘度从0．82dL／g提高到1．3dL／g以上;端羟基含量从84．2mmol／kg降至35．1mmol／kg;端羧基含量从31．3mmol／kg降至21mmol／kg;BMDI用量在理论用量之内时,PBT的力学性能得到明显提高,超过理论用量,由于产生凝胶其力学性能降低;随着BMDI用量的增加,玻纤增强低粘度PBT的力学性能也得到提高,基本达到玻纤增强正品PBT的性能指标。     

r-PET扩链增粘工艺及其单丝力学性能

在废旧聚对苯二甲酸乙二酯(r-PET)泡泡料中分别加入2,2'-(1,3-亚苯基)二恶唑啉(BOZ)、均苯四甲酸二酐(PMDA)扩链剂,利用双螺杆反应挤出进行扩链试验,并经熔融纺丝后多级拉伸制得r-PET单丝。通过改变扩链剂含量、挤出温度、停留时间以及抽真空条件,对扩链后的r-PET特性黏度以及单丝力学性能等进行了测试。结果表明,抽真空可显著提高扩链效果;BOZ质量分数为2.5%时,在250℃下停留60 s,特性黏度上升最高为0.77 dL/g,单丝断裂强度为4.9 cN/dtex,断裂伸长率为21.4%;PMDA质量分数为1.25%时,在260℃下停留60 s,特性黏度上升最高为0.82 dL/g,单丝断裂强度为5.2 cN/dtex,断裂伸长率为15.6%;BOZ与PMDA联用时,其含量应比各自单独扩链时的最佳含量低,当联用体系中BOZ质量分数为2%,PMDA质量分数为0.75%时,在270℃下停留60 s,r-PET特性黏度可达0.88 dL/g,单丝断裂强度为5.8 cN/dtex,断裂伸长率为18.2%。     

扩链改性对聚对苯二甲酸乙二酯挤出吹膜成型的影响

通过添加多官能团环氧扩链剂对聚对苯二甲酸乙二酯(PET)进行扩链改性,然后用改性PET进行吹膜成型,研究了扩链剂含量对PET特性黏度、膜泡稳定性及薄膜力学性能和透明度的影响。结果表明,扩链剂的添加显著提升了PET的特性黏度;随着扩链剂含量的增加,薄膜膜泡稳定性以及表面质量、最大吹胀比、拉伸强度得到显著改善,断裂伸长率呈先增大后减小的趋势。当扩链剂质量分数为0.7%时,PET的特性黏度由纯PET的0.71 d L/g上升至0.94 d L/g,最大吹胀比则由1.9提高至4.5,横纵向拉伸强度分别为61.7 MPa和64.4 MPa,横纵向断裂伸长率达到最高,分别为12%和12.45%,较扩链剂质量分数为0.2%时提高了105.5%以及125.1%,而透光率仅下降1.4%,得到了性能较优的吹塑薄膜制品。     

熔融反应扩链制备高黏度PA6及其力学性能研究

采用熔融反应挤出作为聚酰胺6(PA6)的扩链方法,以不同马来酸酐含量的苯乙烯-马来酸酐共聚物(SMA)为扩链剂,对PA6进行了扩链研究。对扩链后产物的特性黏度、熔体质量流动速率、氨基含量、凝胶含量及力学性能进行了表征。结果表明,马来酸酐摩尔分数为50%的SMA对PA6扩链效果较好,可使其特性黏度由2.0dL/g增大至4.2 dL/g,熔体质量流动速率则从115 g/10min减小至0.5 g/10min;通过扩链后的PA6氨基滴定测试表明,SMA在熔融挤出过程中与PA6末端氨基官能团进行反应从而引发PA6扩链。经扩链改性,PA6的力学性能得到明显改善,拉伸强度由62 MPa提高至85 MPa,缺口冲击强度则从3.8 kJ/m2提高至7.5 kJ/m2。