Blends of poly(ε-caprolactone-b-lactic acid) and poly(lactic acid) for hot-melt applications

Hot-Melt and Pressure-Sensitive Adhesives Based on Styrene-Isoprene-Styrene Triblock Copolymer, Asphaltene/Resin Blend and Naphthenic Oil

Asphaltene/resin blend (ARB) extracted from heavy crude oil was used to modify poly(styrene-block-isoprene-block-styrene) (SIS) to make it an adhesive. There were prepared double and triple mixtures containing 10-60% SIS, 10-40% ARB, and 10-50% naphthenic oil used as an additional plasticizer. The viscoelasticity of the mixtures at 25 °C and 120 °C was studied, their flow curves were obtained, and the temperature dependences of the loss tangent and the components of the complex modulus were measured. In addition, the mixtures were used as hot-melt adhesives (HMAs) and pressure-sensitive adhesives (PSAs) in the shear, peel, and pull-off tests of the adhesive bonds that they formed with steel. Both naphthenic oil and ARB act as plasticizers for SIS and make it sticky. However, only the combined use of ARB and the oil allows for achieving the best set of adhesive properties of the SIS-based mixture. High-quality HMA requires low oil content (optimal SIS/ARB/oil ratio is 50/40/10, pull-off adhesion strength (τt) of 1990 kPa), whereas a lot of the oil is needed to give SIS characteristics of a PSA (SIS/ARB/oil is 20/40/40, τt of 100 kPa). At the same time, the resulting PSA can be used as a hot-melt pressure-sensitive adhesive (HMPSA) that has many times lower viscosity than HMA (13.9 Pa·s versus 2640 Pa·s at 120 °C and 1 s-1) but provides a less strong adhesive bond (τt of 960 kPa).

Biodegradable copolyester poly(butylene-co-isosorbide succinate) as hot-melt adhesives

We modified poly(butylene succinate) (PBS) with sugar-based monomer isosorbide to improve the bond strength between PBS and metal interfaces and thereby alleviate the environmental problems caused by nondegradable hot-melt adhesives. We analyzed the efficiency of different catalysts in the synthesis of poly(butylene-co-isosorbide succinate) (PBIS) copolyesters. The thermal stability, thermodynamic characteristics, and melting viscosity of PBIS copolyesters were systematically evaluated by characterization. The results indicate that isosorbide can greatly improve the bond strength of the interface between PBS and the iron plate when copolyesters are used as hot-melt adhesives.

Biodegradable PBIS copolyesters can be used as hot-melt adhesives and tailored by varying the isosorbide content.

An Analytical Method for Determining Residual Lactide in Polylactide by Gas Chromatography

An analytical method to determine the residual lactide in polylactide (PLA) was proposed using an internal standard method of gas chromatography (GC). PLA samples and diphenyl ether (DPE) as an internal standard were dissolved in dichloromethane, then PLA was precipitated in anhydrous alcohol. The residual lactide and DPE were extracted to alcohol for GC analysis. At room temperature, lactide could react with alcohol and change into ethyl lactoyl lactate (ELL), but the relative response factor of lactide versus DPE could be obtained through a numerical analysis method. Therefore, the residual lactide content could be quantitatively calculated in PLA. The relative standard deviation (RSD) of the measurements is not more than 7.0%, indicating that the method is suitably precise.

Improving interface adhesion of magnetic particle modified EVA hot melt adhesive through introduction of a thermodynamically compatible component

Fe₃O₄ particles were surface coated with a layer of polyvinyl acetate (PVAc), which could improve their compatibility with EVA composite hot melt adhesives and then further induce EVA segments to orientate.

Lactic Acid Yield Using Different Bacterial Strains, Its Purification, and Polymerization through Ring-Opening Reactions

Laboratory-scale anaerobic fermentation was performed to obtain lactic acid from lactose, using five lactic acid bacteria:Lactococcus lactis, Lactobacillus bulgaricus, L. delbrueckii, L. plantarum,andL. delbrueckii lactis. A yield of 0.99 g lactic acid/g lactose was obtained withL. delbrueckii, from which a final concentration of 80.95 g/L aqueous solution was obtained through microfiltration, nanofiltration, and inverse osmosis membranes. The lactic acid was polymerized by means of ring-opening reactions (ROP) to obtain poly-DL-lactic acid (PDLLA), with a viscosity average molecular weight (Mv) of 19,264 g/mol.