不同紫外波长对热塑性淀粉塑料表面的光交联改性研究

为有效提高热塑性淀粉塑料（TPS）的力学和耐水性能，本文提出用不同波长的紫外光照的方法来实现TPS表面的光交联改性。将光引发剂2,4,6?三甲基苯甲酰基二苯基氧化膦（TPO）的乙醇溶液涂覆于TPS表面后进行紫外光照射，研究了不同紫外光波长（254、308、365 nm）对TPS交联度、力学性能、动态力学性能、耐水性和吸湿性的影响。结果表明，与254 nm和365 nm紫外光照后的样品相比，308 nm光照后TPS样品的拉伸、弯曲和冲击强度最大，分别为4.1 MPa，2.7 MPa和96.8 kJ/m²;TPS中淀粉富集区的玻璃化转变温度（T_α）、甘油富集区的玻璃化转变温度（T_β）分别达最高为-37.48 ℃和50.32 ℃，表面接触角最大为75 °，吸水性能也得到显著改善，交联度结果证实此时形成了最佳的交联结构。     

Intensity enhancement of photoluminescent polyesters by photocrosslinking

A series of polyesters with alkylated triazole heterocyclic rings at the branches were designed and synthesized via the polycondensation reaction. The synthesized polyesters were examined with various spectroscopic methods such as Fourier transform IR, ¹H NMR and ¹³C NMR. The alkyl chain length at the branch was found to affect the thermal stability of the polyesters, which decreased with longer alkyl chain. These polyesters possessed an aggregation‐induced emission enhancement characteristic evidenced by the transformation of the clear solutions in tetrahydrofuran with weak greenish blue emission to cloudy solutions with enhanced blue emission when water was added to promote aggregation. Furthermore, enhancement in the photoluminescence intensity was observed when the polyesters underwent photocrosslinking upon UV irradiation and appeared as self‐assembled aggregates. The formation of aggregates in the water ? tetrahydrofuran solutions and after photocrosslinking was confirmed via TEM analysis. The SEM images showed that the photocrosslinked polyesters were highly porous which may enhance the π ? π stacking interaction that improved the photoluminescence intensity. © 2015 Society of Chemical Industry     

Synthesis and characterization of UV photocrosslinkable hydrogels with poly(N-vinyl-2-pyrrolidone): Determination of the network mesh size distribution

Hydrogels of poly(n-vinyl-2-pyrrolidone) were produced by UV irradiation of aqueous solutions of the polymer in presence of hydrogen peroxide, used as initiator. The mechanical and the nanostructural properties of the gels were characterized by a combination of experimental techniques including rheology, low field nuclear magnetic resonance spectroscopy (LF-NMR), and small angle X-ray scattering. Different irradiation doses as well as polymer and initiator concentrations were tested in the characterization. The study elucidates the relationship between different methods to estimate the mesh size of the gel polymeric network. Moreover, a novel correlation model was developed based on Chui and Scherer theories for the interpretation of LF-NMR dataset of polymer solutions and networks.     

阴图PS版感光层的光交朕

阴图ＰＳ版感光层的光交朕曹曙光，王仁祥，曹维孝（北京大学化学与分子工程学院，北京１００８７１）关键词重氮树脂；成膜树脂；阴图ＰＳ版；光交联阴图ＰＳ版感光层主要是由成膜树脂和感光树脂组成。感光树脂一般是二苯胺或取代二苯胺重氮树脂．成膜树脂类型较多。就成...     

Synthesis and properties of new polyamides based on a hydroxyethyl cinnamide extended from 3,5‐diaminobenzoic acid

A series of new aromatic polyamides containing cinnamide pendent units were prepared from 2′‐(cinnamide)ethyl‐3,5‐diaminobenzoate and various aromatic dicarboxylic acids by the direct polycondensation reaction, with triphenyl phosphite and pyridine as condensing agents. The polyamides were characterized by ¹H NMR, IR, and UV spectroscopy, and gel permeation chromatography. Their thermal stability was studied by thermogravimetric analysis in air, and differential scanning calorimetry. These polymers were readily soluble in polar aprotic solvents and can be cast from their solutions in flexible and tough films. Glass transition temperatures (T_gs) of these polyamides were observed in the range of 225–245°C. Their inherent viscosities varied from 0.77 to 1.12 dL/g that corresponded to weight–average and number–average molecular weights of 39,000–72,700 and 18,800–29,000, respectively. These polymers can be photochemically crosslinked. The photochemical aspects were revealed by means of UV–vis and IR analyses onto thin films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2013–2020, 2007     

光交联对HDPE凝胶量的影响

用安息香二甲醚和三(丙烯酰氧乙基)异氰尿酸酯(TAEIC)作为PE的光敏剂和助交联剂,研究了它们的用量、光照时间、交联温度,紫外光光强对PE交联度的影响。结果表明,安息香二甲醚是一种有效的光敏剂,引发效率较高;助交联剂可以提高交联效率;光照时间、紫外光光强和交联温度等对PE的交联度均有明显的影响。     

Synthesis,characterization and properties of photoresponsive polymers comprising photocrosslinkable pendant chalcone moieties

New methacrylate monomers, namely 4‐methacryloyloxyphenyl‐4′‐fluorostyryl ketone and 4‐methacryloyloxyphenyl‐4′‐ethylstyryl ketone comprising a free radical polymerizable group and a photocrosslinkable group, were synthesized by reacting the respective hydroxychalcones with methacryloyl chloride in the presence of triethylamine. The monomers were polymerized in the presence of ethyl methyl ketone (EMK) at 70 °C using benzoyl peroxide as the initiator. The chemical structures were characterized using various spectroscopic techniques: ultraviolet, Fourier transform infrared, ¹H NMR and ¹³C NMR. The thermal stability of the polymers was studied using thermogravimetric analysis in nitrogen atmosphere. Differential scanning calorimetry was used to determine the glass transition temperature of the homopolymers. Photocrosslinking of the synthesized homopolymers was investigated in solution. The two homopolymers were crosslinked within 10–15 min. After crosslinking, the homopolymers were insoluble in the same solvent. Copyright © 2006 Society of Chemical Industry     

酚醛树脂丙烯酸酯季铵盐感光性能的研究

通过凝胶生成率的测定,研究了紫外光引发剂：安息香（NB）、安息香乙醚（BE）、2,2－二乙氧基苯乙酮（DEAP）、二苯甲酮（BP）、2－丙基硫杂蒽酮（ITX）;交联型稀释性单体：二乙二醇二丙烯酸酯（DEDA）三乙二醇二丙烯酸酯（TEDA）、二乙二醇二甲基丙烯酸酯（DEDMA）、三乙二醇二甲基丙烯酸酯（TEDMA）、三羟甲基丙烷三丙烯酸酯（TMPTA）、三羟甲基丙烷三甲基丙烯酸酯（TMPTMA）;胺增效剂：乙基－4（二甲基氨基）苯甲酸酯（DEAB）等对水溶性酚醛树脂丙烯酸酯季铵盐（PreP)感光性能的影响。结果表明,ITX的光引发效率最高;交联型黧性单体中活性基团越多,反应活性越高,分子量越大,反应活性越差;二乙醇类与PreP的相容性比三羟甲基烃类的要好;胺增效剂能提高ITX的引发效率;PreP/DEDA=1/0.6(g/g),ITX为0.025mmol/g,DEAB为感光组分的2％,曝光60s,凝胶生成率可达到67.6%,延长曝光时间凝胶生成率增加。     

Photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) by the use of selected photoinitiators type I

This study investigated the photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) containing selected photoinitiators type I, known as α-cleavage photoinitiators. Photocrosslinking of PSA, especially of acrylic PSA, is well established crosslinking process using the UV radiation technology. UV-initiated crosslinking of acrylic PSA allows the synthesis of the wide range of UV-crosslinkable PSA with the interesting features. Especially, the important balances of properties such as adhesive and cohesive strength which are typically critical for the application performance can be achieved by this technology. The selection of suitable photoinitiator plays an important role to obtain the optimum properties of acrylic PSA including tack, peel adhesion, and shear strength. In this study, the investigations on different saturated conventional photoinitiators of type I for solvent-based PSA were carried out. The effects of photoinitiator concentration, UV crosslinking time and UV dose on the tack, peel strength, and shear strength were explored in detail for guiding the choice of photoinitiators to fabricate advanced PSA for industrial usage.     

Photocrosslinking of styrene–isoprene–styrene; effect of benzoin and ethylene glycol dimethacrylate on physical properties

Crosslinking reaction of polymer by ultraviolet (UV) irradiation has been important in industries. In this work, photocrosslinking of styrene–isoprene–styrene (SIS) triblock copolymer in the presence of benzoin photoinitiator and a dimethacrylate monomer as crosslinking agent was investigated. Curing of samples was initiated under UV irradiation. Benzoin was used as photoinitiator because it contains chromophore group that could absorb UV irradiation. Ethylene glycol dimethacrylate (EGDMA) was used as crosslinking agent, since it has alkene functional groups that could react with the alkene group of SIS. ATR-FTIR spectra of samples show that absorption band of double bond at 1500–1600?cm^?1 decreases after UV exposure. Increasing the concentration of benzoin (0.1–1?phr) and EGDMA (1–10?phr) leads to an increase in gel content and hardness, while swelling ratio decreases. After 5?min heating at 150?°C, about 20%wt of the unirradiated compound became insoluble, because heating of compound at 150?°C causes crosslinking reaction without any irradiation.