反应型聚氨酯热熔胶主要性能影响因素研究

采用二苯基甲烷二异氰酸酯(MDI)、不同的低聚物二醇及增黏剂等原料制备了反应型聚氨酯热熔胶。研究了低聚物二醇种类、分子量以及增黏树脂EVA用量对反应型聚氨酯热熔胶的黏度、开放时间、初粘强度和终粘强度的影响。结果表明,相对分子质量为2 000的聚己二酸丁二醇酯二醇(PBA)较适合作为合成聚氨酯热熔胶的低聚物二醇,随着低聚物二醇结晶性的增强、分子量的增加,以及增黏树脂EVA用量的提高,聚氨酯热熔胶的黏度增大、开放时间缩短、初粘强度提高。但是终粘强度则是随着增黏树脂用量的增多而先升高后降低,在增黏树脂添加量10%时最高。     

反应型聚氨酯热熔胶制备及其性能研究

以MDI(二苯基甲烷二异氰酸酯)和不同的低聚物二醇合成了反应型聚氨酯热熔胶,探讨了NCO质量分数、低聚物二醇种类、催化剂用量以及增黏树脂种类对聚氨酯热熔胶性能的影响。研究结果表明:随着NCO质量分数的增加,聚氨酯热熔胶的黏度下降、开放时间缩短、初粘力增大及终粘力先增大后减小,以NCO质量分数为1.6%时较佳;随着低聚物二醇结晶性增强,聚氨酯热熔胶的黏度增大、开放时间缩短、初粘力和终粘力增大;随着催化剂加入及用量的增加,热熔胶的开放时间缩短、终粘力上升速度加快、但初粘力基本不受影响;当催化剂的用量超过0.10%时,施胶经过相同的时间,其粘接强度并无明显区别;增黏树脂的加入,会增大聚氨酯热熔胶的黏度以及粘接力,缩短其开放时间,尤以萜烯酚醛树脂对于粘接力的改善效果最为明显,与聚氨酯热熔胶的相容性也最好。     

梳形聚氨酯丙烯酸酯光固化低聚物的设计及性能研究

光固化低聚物的结构与性能对光固化材料起着决定性的影响。设计合成了一种二羟基丙烯酸酯单体,并以其为原料通过加聚聚合反应制备了一系列梳形结构聚氨酯丙烯酸酯光固化低聚物comb-PUA,监测反应过程并进行基本表征。研究了不同二异氰酸酯对合成comb-PUA的黏度的影响,考察光固化样的热机械性能及固化收缩。结果表明comb-PUA性能的差异依赖于二异氰酸酯结构。与线形低聚物Linear-PUA相比,comb-PUA的综合性能更满足光固化材料在宽温度范围内的稳定应用要求。     

不同软链段对水性聚氨酯性能的影响

以低聚物多元醇、IPDI(异佛尔酮二异氰酸酯)、亲水扩链剂DMPA(2,2-二羟甲基丙酸)和成盐剂三乙胺为主要原料,合成一组软段成分不同的水性聚氨酯乳液。通过测定水性聚氨酯乳液的固含、黏度、结构,以及水性聚氨酯胶膜的耐水性、力学性能、T型剥离强度等,对比了不同类型软段对乳液及胶膜性能的影响。研究结果表明:由含6个碳的聚酯多元醇为软段合成的水性聚氨酯的黏度、耐水性、机械强度、T型剥离强度等数据较好。     

UV固化聚氨酯改性环氧丙烯酸酯的制备

通过聚氨酯丙烯酸酯(PUA)预聚物中的端-NCO与双酚F型环氧丙烯酸酯(BPF-EA)低聚物中的侧-OH反应,制备了一种光活性聚氨酯改性环氧丙烯酸酯(PMEA)低聚物。将两种低聚物与活性稀释剂以及光引发剂均匀混合并进行了UV固化。研究了EA和PMEA低聚物及固化膜的性能。结果表明,制备的BPF-EA低聚物与自制的双酚A型环氧丙烯酸酯低聚物相比黏度大幅下降。EA和PMEA固化膜具有高的交联密度、良好的附着力以及优异的耐化学品性能。由于PUA预聚物的引入,聚合物链中具有一定量的柔性基团,PMEA固化膜的铅笔硬度、热稳定性和拉伸强度略有下降,断裂伸长率明显增加。固化膜的柔韧性变好。其中,以20%(质量分数)TPGDA为稀释剂配制的UV固化涂料,固化膜的综合性能最好。     

UV固化低聚物及其涂料研究进展

综述了UV固化低聚物(主要是环氧丙烯酸酯和聚氨酯丙烯酸酯)的研究进展。环氧丙烯酸酯研究进展包括:降低黏度、改善柔韧性、光敏活性、耐热性、耐磨性和阻燃性能;聚氨酯丙烯酸酯的研究进展包括:紫外光固化的聚氨酯丙烯酸酯预聚物合成方法;聚氨酯丙烯酸酯/无机纳米复合材料;光固化无机/有机杂化材料;水性UV固化聚氨酯丙烯酸酯和UV固化超支化聚氨酯丙烯酸酯。较为详细地论述了氧阻聚的3种作用机理及解决方法(物理和化学2种方法),最后对光固化技术的5大发展趋势进行了展望。     

GR-1聚氨酯树脂研发成功

山西省化工研究院合成材料厂成功开发出了隔热铝合金门窗用GR - 1聚氨酯树脂。它用于铝合金门窗材的灌注以阻止热量的散发。工业试验表明 ,该树脂各项物理性能、工艺性能及机械性能均达到了美国亚松公司聚氨酯树脂的水平。GR - 1聚氨酯树脂采用一步法反应体系 ,甲组分由低聚物多元醇和功能助剂混合而成 ,乙组分为多异氰酸酯或改性多异氰酸酯 ,室温下均为低黏度液体。该体系的初固时间为 6 0～180s ,硬度大于邵D80 ,弯曲强度大于 6 0MPa ,拉伸强度大于 5 0MPa ,热导率小于 0 .2 3w(m·k) - 1,阻燃性能达到Ⅴ - 0级 ,热形变温度为 5 0～ 6…     

聚氨酯预聚物制备及影响因素分析

聚氨酯预聚体是由多异氰酸酯和低聚物多元醇制备而成。对于聚氨酯预聚物的制备,预聚反应温度的最佳温度应控制在70℃;预聚反应的最佳反应时间应控制在70-90min;参加预聚反应的聚乙二醇的含水量必须控制在0．03％以下。这样才能控制好制备聚氨酯预聚体的质量。     

山西开发出隔热用聚氨酯树脂

日前 ,一种隔热材料GR 1聚氨酯树脂由山西省化工研究院合成材料厂开发成功。该树脂用于铝合金门窗材的灌注 ,用于隔断热量的散发。工业试验表明 ,该树脂各项物理性能、工艺性能及机械性能均达到了美国亚松公司聚氨酯树脂的水平。GR 1聚氨酯树脂采用一步法反应体系 ,甲组分由低聚物多元醇和功能助剂混合而成 ,乙组分为多异氰酸酯和改性多异氰酸酯 ,室温下均为低黏度液体。该体系的凝胶时间为 6 0～ 180s ,硬度大于邵D80 ,弯曲强度大于 6 0MPa ,拉伸强度大于 5 0MPa ,热导率小于 0 2 3W·m- 1·K- 1,阻燃性能达到FV O ,热变形温度为 5 …     

NIPU低聚物的合成及多重固化塑胶涂料研究

采用环保材料合成可紫外光-热-潮气(多重)固化的性能优越的非异氰酸酯聚氨酯(NIPU)低聚物,并制备了数码电子产品(塑胶)涂料.对自合成NIPU低聚物用FT-IR、DSC和GPC进行分析表征,考察了合成配方及工艺对NIPU固化物力学性能、漆膜等性能的影响.在0.5%四丁基溴化铵催化作用下,用聚乙二醇二缩水甘油醚和CO,在100℃、1.2 MPa下反应8 h,其转化率达84.3%;在50℃时用聚乙二醇二环碳酸酯、甲基丙烯酸环碳酸酯、异佛尔酮二胺和氨基硅氧烷所合成的Si-NIPU低聚物黏度(25℃)为89 mPa·s,Mn为1 249,d为1.35.用Si-NIPU低聚物配制的多重固化涂料黏度低、流平性达10级,漆膜附着力0级,硬度2H,热稳定性显著提高.     

Rheological and chemorheological studies of cyclic aryl ether ketone and aryl ether thioether ketone oligomers containing the 1,2-dibenzoylbenzene moiety

The melt stability, shear rate, and temperature dependence of steady-state shear viscosity of molten cyclic aryl ether ketone and thioether ketone oligomers containing the 1,2-dibenzoylbenzene moiety have been investigated. The isothermal chemorheology of the ring-opening polymerization of cyclic oligomers 4 and 9 in the presence of a nucleophilic initiator was also conducted. The cyclic aryl ether ketone oligomers are thermally stable in the melt, and their melt viscosity is several orders of magnitude lower than their high molecular weight linear counterparts. At a given temperature, the steady-state shear viscosity of the molten cyclics initially undergoes shear thinning as the shear rate increases, and once the shear rate is above 10 s⁻¹, the molten cyclic oligomers behave like Newtonian fluids. For the amorphous cyclic oligomers studied, the steady-state shear viscosity at 100 s⁻¹ at a given temperature only depends on their glass transition temperature. The cyclic aryl thioether ketone oligomers are thermally unstable in the melt and undergo ring-opening polymerization in the absence of an initiator to form high molecular weight linear polymers with a concomitant rapid increase in viscosity. The rate of change in viscosity increases with temperature and is promoted by the addition of a catalytic amount of elemental sulfur or a disulfide such as 2,2-dithiobis(benzothiazole). It is hypothesized that the ring-opening polymerization is initiated by the in situ generated thiyl radical(s) and proceeds via a free radical route. © 1996 John Wiley & Sons, Inc.     

Main-chain benzoxazine oligomers: A new approach for resin transfer moldable neat benzoxazines for high performance applications

A new approach has been developed to enhance the processability of main-chain benzoxazine polymers by synthesizing benzoxazine main-chain oligomers that are low in viscosity while maintaining the major part of the advantages of main-chain type polybenzoxazines. A series of main-chain benzoxazine oligomers have been synthesized using bisphenol-F isomers. The structure of the oligomers has been characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The molecular weight has been evaluated using size exclusion chromatography (SEC). For a viscosity study, a mixture of benzoxazine monomers derived from the same bisphenol-F isomers has been used as control and a reactive diluent to control the viscosity.     

Star oligomers for low VOC polyurethane coatings

Conclusion  Hydroxyl functional star oligomers prepared by ring-opening polycondensation have a narrow molecular weight and composition distribution. Such oligomers give a solids/viscosity advantage over linear structures at the same molecular weight and can be used in low VOC two component polyurethane coatings. The solids/viscosity advantage is a combination of the highly branched structure and the narrow molecular weight distribution. Acrylic polyols formulated at the same molecular weight/polarity/average functionality and hydroxyl value give poorer drying properties. This difference can be explained by the fact that the free radical polymerisation technique leads to polymer compositions having a broad molecular weight and functionality distribution and high fractions of polymer with a low functionality. The potlife of acrylic polyols based formulations is adversely affected by the higher fractions of high molecular weight material and with a high average functionality. In low VOC polyurethane formulations star oligomers need to be formulated within a narrow range of compositions (TG, polarity), functionality and molecular weight to get an optimum balance of drying properties and potlife.     

Novel phenylethynyl‐endcapped polyimide oligomers: Synthesis and characterization

A series of novel phenylethynyl‐endcapped polyimide oligomers were prepared by polycondensation of an aromatic diamine mixture of 1,3‐bis(4‐aminophenoxy) benzene (1,3,4‐APB) and 3,4′‐oxydianiline (3,4′‐ODA) with different aromatic dianhydrides including 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐(hexafluoro isopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA), and 4,4′‐[2,2,2‐trifluoro‐1‐(3′,5′‐bis‐(trifluoro‐methyl)phenyl)ethylidene]diphthalic anhydride (9FDA) in the presence of 4‐phenyl‐ethynylaniline (PEA) as endcapping agent in aprotic solvent at elevated temperature. The chemical structures, thermal behavior, and melt rheological properties of the synthesized polyimide oligomers were investigated. Experimental results indicated that the fluorinated polyimide oligomers derived from 6FDA (PI‐2) and 9FDA (PI‐4) are amorphous solid resins and exhibited lower melt viscosities than those prepared from the unfluorinated aromatic dianhydrides such as BPDA and ODPA. The BPDA‐based polyimide oligomers with a molar ratio of 1,3,4‐APB/3,4′‐ODA = 50:50 (PI‐5) showed lower melt viscosity than those derived from a mixture of 1,3,4‐APB and 3,4′‐ODA with molar ratios of 75:25 and 100:0, respectively. In addition, the melt viscosity of the polyimide oligomers increased obviously with increasing of the polymer calculated molecular weights. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

含苯乙炔基的酰亚胺低聚物及其复合材料研究

制备了一种侧链含苯乙炔基的二胺单体2,4-二氨基[4'-(4-苯乙炔基酞酰亚胺基)]二苯醚(DPED),并合成了基于2,3',3,4'-联苯四甲酸二酐(3,4'-BPDA)和DPED的酰亚胺低聚物,通过热重分析,示差扫描量热分析,1H NMR,熔点和力学性能测试研究了DPED的结构及固化行为,低聚物和其固化物及其碳纤维增强复合材料的性能。结果表明:在主链化学结构相同的情况下,将DPED引入到分子质量约为5 000 g/mol的低聚物中,低聚物熔体粘度会有显著降低,侧链苯乙炔基含量越高,其熔体粘度越低,含侧链苯乙炔基的树脂基复合材料的压缩强度高于不含侧链苯乙炔基复合材料,其值分别为570 MPa和415 MPa。     

Synthesis of UV‐curable hyperbranched polyurethane (meth)acrylate oligomers via thiol‐ene “click” chemistry

First, the second‐generation hyperbranched poly(amine‐ester) (G2‐OH) was successfully prepared by thiol‐ene “click” chemistry. Subsequently, a series of photosensitive hyperbranched oligomers (G2‐ORs) were synthesized by facile modifications of the G2‐OH with acryloyl chloride, methacryloyl chloride, IPDI‐HEA, and IPDI‐HEMA, respectively. The structures of hyperbranched oligomers were characterized by element analysis, FT‐IR, ¹H NMR, GPC and viscosity measurement. It was shown that these synthesized oligomers have narrow molecular weight distribution and low intrinsic viscosity at 30°C. UV–vis spectra results showed that the G2‐ORs had sharp absorption bands at around 202 nm. The results of photosensitivities measurement indicated that the G2‐Macr shows the highest photosensitive than other hyperbranched oligomers in the absence of photoinitiator. In addition, these UV‐cured photosensitive G2‐ORs had good thermal properties. The solubilities of the synthesized hyperbranched oligomers were also examined. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Exfoliation of layered silicate facilitated by ring-opening reaction of cyclic oligomers in PET-clay nanocomposites

Ethylene terephthalate cyclic oligomers (ETCs) have been successfully polymerized to a high molecular weight poly(ethylene terephthalate) (PET) employing the advantages of the low viscosity of cyclic oligomers and lack of chemical emissions during polymerization. Using ring-opening polymerization of ETCs with organically modified montmorillonite (OMMT), we intend to ascertain the possibility of preparing high performance PET/clay nanocomposites. Due to the low molecular weight and viscosity, ETCs are successfully intercalated to the clay gallerys, what is evidenced by XRD showing a down-shift of basal plane peak of layered silicate along with TEM investigation. Subsequent ring-opening polymerization of ETCs in-between silicate layers yielded a PET matrix of high molecular weight along with high disruption of layered silicate structure and homogeneous dispersion of the latter in the matrix. Although co-existence of exfoliation and intercalation states of silicate layers after polymerization of ETCs rather than perfect exfoliation was observed, a dramatic increase in d-spacing along with fast polymerization presents us a great potential of cyclic oligomer process in producing a thermoplastic polymer-clay nanocomposites of extremely well-dispersed silicate nanoplatelets and the corresponding high performances.     

Thermal characterization of polylactides

Three important thermal characteristics of polylactides have been measured and discussed. These are glass transition temperature, melting temperature, and degradation behaviour. The glass transition temperatures at infinite molecular weight for - and -optical isomers were 58 and 57°C, respectively. Melting temperature for the crystalline -isomer was 184°C at infinite molecular weight. Number-average molecular weight, melt viscosity, differential scanning calorimetry, infra-red analysis and thermogravimetric analysis were used to study the degradation behaviour under different conditions. Polylactides were found to be highly sensitive to heat, especially at temperatures higher than 190°C. Most of the degradative reactions were thought to involve the highly concentrated ester bond on the main chain. These reactions included thermohydrolysis, depolymerization and cyclic oligomerization, intermolecular and intramolecular transesterifications. Low molecular weight compounds associated with the polymer seemed to play an important role in lowering the molecular weight at high temperatures, as well as the hydroxyl end group of the main chain. The compounds include water, monomers, oligomers, and polymerization catalysts. Removal of the non-polymeric contents and blocking the hydroxyl end-group enhanced the thermal stability of the polymers. The increased amount of the polymerization catalyst in the end product contributed to the degradative reactions.     

Effect of molecular weight distribution on polymer diffusion during film formation of two-component high-/low-molecular weight latex particles

We describe fluorescence resonance energy transfer (FRET) studies of film formation by a new type of two-component latex particles. These particles consist of a miscible blend of two components that have a similar composition but very different molecular weights. In our approach, we used sequential seeded emulsion polymerization to generate (in situ) a fraction of oligomer in poly(butyl acrylate-co-methyl methacrylate) P(BA-MMA) seed particles that contained a relatively high molecular weight (high-M) dye-labeled polymer. In this way we could systematically change the molecular weight distribution of polymer inside the particles. We varied the amount and the molecular weight of the oligomers. For latex films cast from these two-component particles, we studied the diffusion rate of the high molecular weight polymer by FRET. These measurements revealed that oligomers promoted diffusion rate during latex film formation (oligoplasticization). We analyzed our diffusion data in terms of the Fujita–Doolittle free-volume model and showed that higher molecular weight oligomers are less efficient as plasticizers. In separate experiments, oligomers with similar molecular weights as those in the two-component particles were introduced via latex blending. We compared oligoplasticization in latex blends films with that in the two-component particles films. Finally, we investigated the rheological behavior of the two-component polymers with compositions adjusted to have a common T_g (2 °C). The higher the molecular weight of the oligomer, the more that had to be added to achieve T_g = 2 °C. All of the oligomers were much shorter than the entanglement length and act as diluents of the entanglements in the high-M polymer. We found that incorporating larger amounts of oligomers with a higher molecular weight resulted in a more pronounced drop in polymer viscosity, associated with the decrease in the entanglement density.     

End-grafting of oligoesters based on terephthalic acid and linear diols for high solids coatings

Oligomers derived from terephthalic acid and 1,6-hexanediol or 1,10-decanediol have been chemically modified through end-grafting with succinic anhydride or trimellitic anhydride followed by glycidyl neodecanoate. The grafted oligomers are paste-like semisolids or viscous liquids at room temperature. As the grafted oligomers are heated, their viscosity goes down to a minimum, then up to a maximum, and then down again. Combined DSC, crossed polarizing microscopy, and wide-angle x-ray diffraction indicate that the grafted oligomers form crystalline domains dispersed in amorphous phase. The grafted oligomers are soluble in common organic solvents, such as toluene, at lower concentrations (<14-51 wt %) and form stable dispersions at higher concentrations. High solid coatings formulated with mel-amine or isocyanate resins gave glossy films with excellent combined hardness and impact resistance. © 1996 John Wiley & Sons, Inc.