低挥发环保增塑剂对苯二甲酸二（2⁃丙基庚）酯的应用研究

以对苯二甲酸和2?丙基庚醇为原料,在钛酸异丙酯为催化剂的条件下制备对苯二甲酸二（2?丙基庚）酯（DPHTP）,并将DPHTP作为增塑剂用于制备聚氯乙烯（PVC）柔性薄膜,与市售DOP和DOTP进行应用性能的比较。通过傅里叶变换红外光谱和核磁共振氢谱对产物进行结构分析;通过热失重分析、拉伸测试、耐迁移测试和耐挥发性测试等比较DPHTP、DOP以及DOTP增塑的PVC薄膜在力学性能等方面的差异。结果表明,相比DOP和DOTP,DPHTP具有更低的挥发性,其增塑的薄膜有着更优异的热稳定性以及更高的体积电阻率;其中,DPHTP的加热减量为0.031 90 %,DPHTP增塑的薄膜的热失重5 %的温度为272 ℃,体积电阻率为6.5×10⁹ Ω·m;DPHTP具有更低的挥发性且可以赋予PVC材料优异的电绝缘性能,在包装材料和电线电缆行业具有广阔的开发前景。     

Use of carbon fibril additives to reduce the dc resistivity of elastomer-based composites

We have prepared insert model solid rocket propellants of two kinds, polycaprolactone (PCP) networks highly (60%) plasticized with triacetin and hydroxyl-terminated polybutadiene (HTPB) cross-linked with isophorone diisocyanate, both filled with over 65% NaSO₄ and Al powders as well as traces of fine carbon fibrils 100 Å thick and several micrometers long. Sheets of these dieletric composites were used for dc surface and volume electrical resistivities near room temperature. Addition of less than 1% fibrils in the PCP composites reduces volume resistivity by a factor of 10. The amount required for HTPB is only 0.1% leaving processability unaffected; resistivity reduction rises from one to nearly four orders of magnitude as potential differnce in increased from 10 to 500 V. Addition of fibrils to HTPB composites is a promising candidate for minimizing the incidence of dangerous electric discharge events. © 1995 John Wiley & Sons, Inc.     

Rheological and thermodynamic interaction effects in plasticized polyvinyl chloride compounds

Earlier work reported the superposition of flow curves for plasticized compounds of vinyl chloride homopolymer with corresponding curves for unplasticized resin. Viscosity shift factors for three plasticizer systems plotted against temperature define an apparent fusion temperature for the bulk polymer. A Brabender Plasticorder, used as a temperature-scanning rheometer, determined fusion temperatures for various plasticized PVC compounds. These data confirm a fusion temperature for bulk polymer near 205°C, and permit calculation of Flory-Huggins χ parameters over substantial ranges of composition and temperature. The thermodynamic parameter correlates well with viscosity shift factors for compounds with polymer volume fractions below 0.6. The possibility is therefore raised of calculating flow characteristics for plasticized PVC compounds from knowledge of χ only. The temperature and composition dependence of χ, estimated for the system PVC-diiso-octyl phthalate, is similar to reported variations in simpler polymer-diluent systems. Thus, PVC-plasticizer systems may follow analogous thermodynamic rules.     

环氧油酸新戊二醇酯的制备及应用性能研究

以油酸和新戊二醇为原料,通过酯化反应和环氧化反应制备了新型环保增塑剂环氧油酸新戊二醇酯（ENDO）,采用红外光谱仪（FTIR）和核磁共振仪对ENDO的结构进行了表征,并通过转矩流变仪、超低温脆化试验仪、老化试验机和万能试验机测试对比了ENDO、邻苯二甲酸二辛酯（DOP）、已二酸二辛酯（DOA）或偏苯三酸三辛酯（TOTM）增塑的聚氯乙烯（PVC）样品的流变性能、低温脆化性能、耐溶剂抽出性能和耐老化性能。结果表明,本实验成功制备了预期增塑剂产品ENDO;增塑PVC混合物料扭矩由大到小对应的增塑剂为TOTM、ENDO、DOP、DOA,能耗由大到小对应的增塑剂为TOTM、ENDO、DOA、DOP;ENDO增塑PVC样品的低温脆化性能可通过-30 ℃测试;当溶剂为正己烷时,DOP、ENDO、DOA和TOTM增塑PVC样品的断裂伸长率残留率依次为88.24 %、87.99 %、1.69 %和0.71 %,当溶剂为无水乙醇时,为79.00 %、96.22 %、72.76 %和74.52 %;ENDO增塑PVC样品老化后的断裂伸长率残留率、拉伸强度变化率及热老化质量损失均小于TOTM增塑的PVC样品。     

Thermal,kinetic, and mechanical properties of glycerol‐plasticized wheat gluten

Glycerol‐plasticized wheat gluten was prepared by mixing in an internal mixer equipped with sigma rotors, and then thermally compression‐molded to form a sheet for crosslinking and tensile tests. Referring to rubber vulcanization process, rotorless curemeter was applied to test the vulcanization characteristic parameters of the molded round samples, which could be used to calculate the activation energy and reaction rate of crosslinking occurring in wheat gluten when heated. Vulcanizing curves obtained show that the optimum temperature for processing glycerol‐plasticized wheat gluten is 150°C, and that activation energy and reaction rate of crosslinking in wheat gluten plasticized with 20 wt % glycerol reach minimum and maximum values, respectively. In addition, glycerol content, plasticizing time, and temperature have significant effects on the mechanical properties of thermomolded wheat gluten plastics. The factors are closely related to the establishment of a covalent network resulting from the formation and rearrangement of disulfide bridges in wheat gluten. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrical resistivity of pitch during heat treatment

The d.c. electrical resistivity of coal-tar pitch has been measured from ambient temperature to 450 °C. The change in resistivity with temperature up to 200 °C has been found to be consistent with viscosity-controlled diffusion of current carriers. In an isothermal study at 450 °C, the start of mesophase formation was found to be accompanied by a rapid rise in the pitch resistivity, which subsequently levelled off and remained nearly constant until the onset of mesophase coalescence and phase inversion. The resistivity of the resultant mesophase pitch was found to be less temperature susceptible than that of the parent pitch.     

Molecular orientation behaviour of uniaxially stretched poly(vinyl chloride) film: 1. Birefringence: effect of plasticizers and draw ratio above and below Tg

In order to investigate the orientation behaviour of a non-crystalline chain polymer, plasticized and unplasticized poly(vinyl chloride) films (PVC) are chosen for investigation. The following two orientation distribution functions are postulated to calculate the second moment of the molecular orientation: (a) for the unplasticized film drawn below the glass transition temperature the distribution function derived from an affine deformation mechanism is applied; (b) for the all plasticized films or for the films drawn above the glass transition temperature a compound distribution function derived from the affine deformation mechanism and that of a rubber-like chain (Langevin model) proposed by Roe et al is applied. The parameters which are included in the distribution function, viz. the ratio of the affine part to the Langevin part, the ratio of polyene to carbonyl in a heat treated film and the segment number of the Langevin chain, can be evaluated experimentally. The intrinsic birefringences of normal and heat treated unplasticized and plasticized films are estimated theoretically on the basis of additivity of band polarizabilities. The calculated birefringences and orientation distribution functions show good agreement with measured values.     

Resistivity relaxation behavior of carbon black filled high‐density polyethylene conductive composites

The variation of resistivity for high‐density polyethylene (HDPE) conductive composites filled with carbon black (CB) with time was investigated under the excitation of different temperature field. The movement of CB particles in the HDPE matrix was not a momentary equilibrium process, but a relaxation process. The relaxation of resistivity of the composites was monotonic, and it could be described by an exponential form above melting temperature. However, the relaxation of resistivity was nonmonotonic below melting temperature, herein a parameter t₀ which was the beginning time of the resistivity attenuation could be introduced into the exponential equation. The attenuation of resistivity at constant temperature was limited for the composites with certain content of CB. The resistivity of the composites would incline to a constant value with the prolongation of time no matter what the heat treatment temperature was. Heating rate had influence on the relaxation of resistivity of the composites, and the lower heating velocity resulted in less time to approach to the equilibrium resistivity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties and weldability of plasticized polylactic acid films

The objectives of the presented work were to investigate films based on polylactic acid (PLA) and polyethylene glycol (PEG) in order to improve ductility and weldability of PLA films. The effect of plasticizer amount on the thermal, rheological, and mechanical properties of PLA plasticized films was investigated. The PEG content does affect the glass transition and the cold crystallization temperature of PLA in blends, while the melting temperature was not affected by the addition of PEG. The complex viscosity of the neat PLA granules and of plasticized films showed strong temperature and angular velocity dependence. The Young's modulus and tensile strength of plasticized films were improved with increasing plasticizer concentration, while the elongation at break stays rather constant. Plasticized PLA films were furthermore heat welded. These investigations showed that plasticized PLA films can be welded by heat welding. The obtained weld strength is strongly depending on the PEG amount as well as on selected welding parameters. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40394.     

The plasticization of an epoxy resin by dibutylphthalate and water

The glass-transition temperature of an epoxy resin cured at two different temperatures and plasticized with water and dibutylphthalate has been studied. Both modulus of elasticity and yield stress were measured as a function of temperature to determine the glass-transition temperature. Drying a saturated material appeared to restore the glass-transition temperature to its original value but some broadening of the transition occurred. The behavior of an undercured epoxy when saturated with water could not be predicted by theory. A substantial increase in the transition temperature was observed which may have been caused by the presence of water and an expanded structure.     

Film extrusion and film weldability of poly(lactic acid) plasticized with triacetine and tributyl citrate

Film extrusion and welding of biodegradable polymer films are important processes that must be considered in the development of compostable packaging materials. Film extrusion of poly(lactic acid) (PLA) has proved to be rather difficult because of its brittleness, but the flexibility of PLA can be improved by incorporation of a plasticizer in the material. PLA was plasticized with triacetine (TAc) and tributyl citrate (TbC). The blended materials and neat PLA were film extruded and the films were welded with constant heat (CH) welding. The films were analyzed by means of gas chromatography (GC), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), contact angle measurements, and tensile testing. Storage of the plasticized films resulted in an increased crystallinity and changes in the film properties, rendering CH welding difficult. The welding process had no influence on thermal properties, such as cold crystallization temperature, melting temperature, crystallization temperature, and degree of crystallinity, of neat PLA but caused significant changes in the crystallinity of the plasticized materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3239–3247, 2003     

Measurement and simple equation models of the specific heats of neat and glycerol‐plasticized poly(vinyl alcohol)

The specific heats (C_sp) of neat and glycerol‐plasticized poly(vinyl alcohol) (PVOH) were studied by differential scanning calorimetry at 330–530 K. Glycerol‐plasticized poly(vinyl alcohol) was prepared by a melt‐blending method. The outcomes were modeled into mathematical functions. Incorporation of glycerol increased the specific heat of PVOH. Glycerol provided internal lubrication to the PVOH system, giving a smoother and lower‐amplitude melting curve. As a result, glycerol‐plasticized PVOH had a lower melting‐temperature range than neat PVOH. However, higher energy was required to increase the temperature of glycerol‐plasticized PVOH. The modeling functions showed a best fits regression range of 0.967–0.999. Neat PVOH and glycerol‐plasticized PVOH required 1166.05 J/g and 2113.09 J/g, respectively, to increase the temperature from 330 to 530 K. J. VINYL ADDIT. TECHNOL., 18:198–203, 2012. © 2012 Society of Plastics Engineers     

Epoxidized soybean oil‐plasticized poly(lactic acid) films performance as impacted by storage

This study examined the effect of storage time at room temperature on the melt viscosity, thermal, and tensile properties of epoxidized soybean oil plasticized poly(lactic acid) (PLA) films manufactured through a cast extrusion process. Infrared results indicate that plasticizer migration to the surface of the film occurred after only 30 days of storage, which significantly affected the performance of plasticized films. While the melt viscosity, glass transition temperature, degree of crystallinity, tensile strength, and modulus increased, the elongation at break and energy to break decreased with storage time up to 30 days and all properties remained constant thereafter. However, the ability of stored plasticized film to cold crystallize remained unaffected since both the cold crystallization temperature and melting temperature were not affected during storage. Although plasticized film lost some flexibility after only 30 days of storage due to plasticizer migration to the surface of the film, sufficient plasticization performance still remained in plasticized PLA films for flexible packaging application even after a long storage period at ambient conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43201.     

Crystallization behavior and mechanical properties of crosslinked plasticized poly(L‐lactic acid)

Enhancing the stability of plasticized poly(L ‐lactic acid) (PLLA) with poly (ethylene glycol) (PEG) is necessary for its practical application. In this study, plasticized PLLA (PLLA/PEG 80/20 wt/wt) was crosslinked under γ‐ray (Co⁶⁰) in the presence of triallyl isocyanurate (TAIC) as crosslinking agent. FTIR analysis revealed that PLLA, PEG, and TAIC formed a cocrosslinking structure. Crystallization behavior and mechanical properties of the crosslinked plasticized PLLA were investigated by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), and tensile tests. Experimental results indicated that the crystallization behaviors of both PEG and PLLA in the blends were restrained after irradiation. The melting peak of PEG in the crystallized samples disappeared at a low irradiation doses about 10 kGy. Although PLLA still owned the behavior of crystallize, its cold crystallization temperature and glass transition temperature shifted to higher temperature. Mechanical properties of the plasticized PLLA were strengthened through crosslinking. Both yield strength and elastic modulus of the samples increased after crosslinking. Elongation at break of the crosslinked plasticized PLLA decreased with the increase of crosslinking density but remained a high value over 200%. SEM images of fracture surfaces confirmed that the ductile fracture behavior of plasticized PLLA was kept after suitable crosslinking. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Instability of the Characteristics of the Positive Temperature Coefficient of Resistivity in High-Curie-Point Barium-Lead Titanate Ceramics and Their Grain Structures

A significant isothermal increase in resistivity with time has been observed in high-Curie-point barium-lead titanate ceramics in the temperature region of the Curie points, giving rise to an instability of the characteristics of the positive temperature coefficient of resistivity (PTCR). The isothermal increase in resistivity (ρ) with time (t) observed at various temperatures can be expressed by the equation log ρ=A+B√t, where A and B are both temperature-dependent constants. The temperature dependence of A gave the usual PTCR characteristics because A is log ρ at t=0, while the temperature dependence of B was found to show a characteristic curve with a peak around the Curie point. Observation by SEM revealed a considerable difference between the grain structure of a sample showing a significant resistivity change and that of a sample showing little resistivity change.     

Tri‐(butanediol‐monobutyrate) citrate plasticizing poly(lactic acid): Synthesis,crystallization, thermal,and mechanical properties

Tri‐(butanediol‐monobutyrate) citrate (TBBC) as a new plasticizer for poly(lactic acid) (PLA) was synthesized via a two‐step esterification. The chemical structure of TBBC was characterized by ¹H‐nuclear magnetic resonance. The studies on solubility parameters, transparence, and storage stability indicated the good miscibility between PLA and TBBC. The glass transition, crystallization, thermal, and mechanical properties of PLA plasticized by TBBC were evaluated. With an increase in TBBC content, the glass transition temperature (T_g), melting point (T_m), and the cold crystallization temperature (T_cc) of plasticized PLA gradually shifted to a lower temperature. The elongation at break and flexibility were greatly improved by the addition of TBBC. After 30 days of storage, PLA plasticized with up to 20 wt% of TBBC exhibited good storage stability and remained the original transparence and mechanical properties. The flexibility of PLA/TBBC films can be tuned by changing TBBC content. The corresponding crystalline morphology and structure were investigated by Polarizing optical microscope and X‐ray diffraction as well. This study revealed that TBBC was miscible with PLA and may therefore be a promising plasticizer for PLA‐based packaging materials. POLYM. ENG. SCI., 55:205–213, 2015. © 2014 Society of Plastics Engineers     

Low environmental sensitive antistatic material based on poly(vinyl chloride)/quaternary ammonium salt by blending with poly(ethylene oxide)

A quaternary ammonium salt (QAS) was synthesized and characterized by ¹H NMR. A low environmental sensitive antistatic plasticized poly(vinyl chloride) (PPVC) was prepared by blending with QAS and poly(ethylene oxide) (PEO). The structure and properties of PPVC/QAS/PEO blend were studied by scanning electronic microscope (SEM), surface resistivity, and mechanical properties tests. The results show that the surface resistivity of PPVC/QAS/PEO (100/4.5/0) blend without PEO component can be reduced to less than 3.0 × 10⁸ Ω at 65% environmental humidity, which satisfied the antistatic property requirement related to MT113‐1995 of China. However, QAS, similar to other commercial antistatic agents, is much sensitive to environmental humidity. When a small amount of PEO is added, the surface resistivity of PPVC/QAS/PEO blend has a quite low sensitivity to environmental humidity and further reduces. An excellent antistatic property of PPVC/QAS/PEO blend under low humidity can be achieved. Its tensile strength and elongation at break are also improved with PEO addition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(citrate glyceride): a hyperbranched polyester for starch plasticization

Hyperbranched polyesters (HBPETs), terminated with either hydroxyl or carboxyl groups, were prepared from citric acid and glycerol in simple one‐step syntheses. The HBPET structure and degree of branching were investigated using Fourier transform infrared and ¹H NMR spectroscopies and gel permeation chromatography. The HBPET plasticizers were combined with a maize starch via cooking and film formation. The mechanical, thermal, paste and structural properties of the plasticized starch composites were studied in detail using differential scanning calorimetry, thermogravimetric analysis, rapid viscosity analysis and X‐ray diffraction. The HBPETs reduced the pasting viscosity but slightly increased the pasting temperature of the starch. The smaller breakdown and setback values of the plasticized starch pastes relative to those of native starch suggested weaker retrogradation. Compared with glycerol/starch plasticized films, HBPET/starch composite films had lower crystallinity, lower glass transition temperature and better mechanical and thermal properties. The properties of the plasticized starch samples strongly depended on the terminal groups and the molecular weight of the HBPET plasticizers. © 2017 Society of Chemical Industry     

Cooperation between chemical and physical networks in crosslinked and plasticized PVC

The effect of crosslinking of plasticized PVC on the mechanical properties has been investigated. Crosslinking was performed by using a dithioltriazine, and penetration as a function of temperature was used to follow the changes in mechanical properties. Changes in the melting behavior were detected by differential scanning calorimetry. Even rather low levels of gel content gave a substantial reduction in penetration in the interval 60–110°C, while a more complete reaction prevented major penetration up to at least 200°C. The penetration curve of heavily crosslinked materials showed several plateaus and the transitions could be related to melting of different crystallites formed by annealing at different temperatures. The physical network formed by the crystallites constitutes an important complement to the chemical network in plasticized PVC crosslinked by dithioltriazine. Both the amount and the melting temperature of the crystallites increased after annealing. The introduction of the chemical network further improved the heat resistance of the crystallites. The presence of the two networks will therefore show a synergistic effect with respect to the mechanical properties at increased temperatures.