Effect of Hyperbranched Polymers on Curing Behavior of UV Curable Inks in Inkjet Printing

A high quality and high resolution printing can be rapidly created by inkjet printing technology. Inkjet printing is one of the most economic printing methods and ink waste in this technique is very low. Inkjet process provides printing on any type of substrates. The UV curable inks are special types of printing inks that have been widely used in the last decades. The use of UV curable inks is more attractive in inkjet printing technology in comparison to other methods of printing. The most important advantage of UV curable inks in this method is that they are VOC-free and compatible and have good adhesion on many types of substrates. In this research, the effect of hyperbranched polymers on the curing behavior of UV curable inks was investigated. Two types of hyperbranched polymers with hydroxyl and fatty acid chain terminal groups were used in ink formulations. The effect of hyperbranched polymers on the curing behavior of UV curable ink was investigated by real-time FTIR analysis. The results showed that the hyperbranched polymers could improve curing process by increasing the conversion rate of the third curing stage. All ink formulations containing hyperbranched polymers showed higher conversion than a neat sample. The highest conversion was 77 % for the blend containing a hyperbranched polymer with hydroxyl end groups while the neat sample showed a final conversion of 55%. UV curable inks in inkjet process containing hyperbranched polymers with hydroxyl end groups showed a higher final conversion than neat sample

Correlation of nanostructural parameters and macromechanical behaviour of hyperbranched-modified polypropylene using time-resolved small-angle X-ray scattering measurements

Polypropylene (PP) is modified utilizing a poly(ester amide)-based hyperbranched polymer (PS). A maleic-modified PP is used to enhance the compatibility. Usual tensile experiments are carried out. The nanocrystalline structure is studied using small-angle X-ray scattering (SAXS) while a uniaxial mechanical load is simultaneously applied. SAXS patterns are analysed using procedures written in PV-WAVE. The chord distribution function (CDF) is calculated and nanostructural parameters such as long period (lp) and nanodeformation (ϵNano) are extracted. The correlations between macromechanical parameters and nanostructures are studied. Mechanical results show that PS has a plasticizing effect. Reactively blended samples demonstrate enhanced mechanical properties. SAXS patterns reveal a well-known structure of PP as a peculiar architecture of the nanostructure. Crystalline branching occurs in a geometry that is known as a mother–daughter crystal lamellar structure, also called a crosshatching structure. It is concluded that adding PS distorts the stacking of crystalline domains. The structural information from SAXS patterns in reciprocal space is visualized in real space in the calculated CDFs. The CDFs indicate that in simple blends, lp of the crystalline stacks increases compared to blank PP. Nevertheless, reactively blended samples show an increase of lp compared to blank PP; however, they possess smaller lp compared to simple blends

SAXS investigation of structure-property relationship of polypropylene/montmorillonite composites during load cycling

Polypropylene (PP) can hardly be reinforced by the layered silicate montmorillonite (MMT), but the material fatigue appears somewhat reduced. The probable reason is amplified competitive nucleation of the PP by MMT component. Utilizing small-angle X-ray scattering (SAXS) from synchrotron, we investigate the nanostructure evolution of the PP in straining experiments from neat PP and compatibilized composite materials. The compatibilizer is a styrene–ethylene/butylene–styrene copolymer (SEBS). Oriented injection-molded test bars are studied.The discrete SAXS probes variations of sizes and distances among those crystalline domains that are not placed at random. Crystallite dimensions and distances are documented for modeling purposes. The nanoscopic strain is computed from the distance variation and compared with the macroscopic strain. Differences between macroscopic and nanoscopic strain are observed. They require postulating regions with statistical placement of crystallites (poorly arranged region, PAR) in addition to the SAXS-probed well-arranged semi-crystalline entities (WAE). The extensibility of WAEs must be different from that of the PARs. In neat PP, the observed WAEs are well developed and stronger than the PARs. In the composites, the WAEs are made from thin and less extended crystalline domains. They are weaker than the PARs that appear reinforced. Thus, enclosing each MMT layer a PAR is formed, and the WAEs generated farther away remain imperfect. Consequently, in the composites, the narrow crystalline domains from the WAEs do not break into even smaller pieces, and the fatigue of the composites is lower than that of the neat P

An attempt to mechanistically explain the viscoelastic behavior of transparent epoxy/starch-modified ZnO nanocomposite coatings

International audienceThe effects of bare and starch-modified ZnO (ZnO-St) nanoparticles on viscoelastic and mechanical properties are studied by dynamic mechanical and tensile analyses. Transparent epoxy-based nanocomposite films are prepared by incorporating bare or starch-modified ZnO particles into the epoxy matrix. The results demonstrated that ZnO particles hindered the curing reactions and hence the final properties of the cured epoxy. As a result, glass-transition temperature (Tg) and crosslinking density demoted. However, starch as a surface modifier compensated for the undesired effects of ZnO in a way that by enhancing the curing reactions through autocatalytic mechanism, Tg and crosslinking density increased. The storage moduli for epoxy, epoxy/ZnO and epoxy/ZnO-St are accordingly as 13.84, 3.95 and 19.54 MPa. Therefore, the molecular weight between the entanglements is calculated as 0.2878, 1.0089 and 0.2039 in the same order. Moreover, considering the peaks of the tanδ diagrams, Tgs for epoxy, epoxy/ZnO and epoxy/ZnO-St are obtained as 95.95, 100.16 and 101.24 °C, respectively. Comparing epoxy/ZnO-St nanocomposite to epoxy, it can be inferred that the network becomes tougher in the elastic region and then becomes softer passing this region. Mechanistic sketches of epoxy network formation in the presence of bare and surface-treated nanoparticles are discussed

Transparent nanocomposite coatings based on epoxy and layered double hydroxide: Nonisothermal cure kinetics and viscoelastic behavior assessments

International audienceLayered double hydroxide (LDH) has a particular place in clay family because of its flame retardant action. The nanoplatelet-like structure of LDH makes possible development of polymer composites with cationic or anionic nature structures in which macromolecules are positioned in between nanoplatelet galleries. In this work, neat epoxy and its transparent nanocomposite coatings with sodium dodecylbenzene sulfonate (SDBS)-modified LDHs; Mg-Al and Zn-Al LDHs, were prepared and their cure kinetics and viscoelastic behavior were tracked through nonisothermal calorimetric and dynamic mechanical analyses. The higher progression of crosslinking in the epoxy network was observed for epoxy/Zn-Al LDH nanocomposites, while activation energy of cure reaction took a higher value for Mg-Al LDH-incorporated systems. Moreover, epoxy/Mg-Al LDH system revealed higher value of storage modulus and glass transition temperature thanks to larger galleries of Mg-Al nanoplatelets. Network formation in the presence of SDBS-modified Zn-Al LDH nanoplatelets was facilitated due to the action of Zn metal as an adduct with a lone-pair of oxygen atom of epoxy leading to an enhanced epoxy ring-opening. Viscoelastic behavior of transparent coatings containing Zn-Al LDH and Mg-Al LDH was studied through temperature-sweep test at various frequencies to compare the results of calorimetric and thermo-mechanical analyses

Epoxy/starch-modified nano-zinc oxide transparent nanocomposite coatings: A showcase of superior curing behavior

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Hyperbranched poly(ethyleneimine) physically attached to silica nanoparticles to facilitate curing of epoxy nanocomposite coatings

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