Packaging Materials Based on Styrene-Isoprene-Styrene Triblock Copolymer Modified with Graphene.

This study presents the improved stabilization effects of graphene on a polymer substrate, namely a styrene-isoprene-styrene triblock copolymer (SIS) which creates opportunities for long-term applications and radiation processing. The added graphene has a remarkable activity on the protection of polymer against their oxidation due to the penetration of free macroradical fragments into the free interlayer space. The chemiluminescence procedure used for the evaluation of the progress of oxidation reveals the delaying effect of oxidative degradation by the doubling extension of oxidation induction time, when the material formulation containing graphene is oxidized at 130 °C. The pristine polymer that is thermally aged requires an activation energy of 142 kJ mol-1, while the modified material needs 148, 158 and 169 kJ mol-1, for the oxidative degradation in the presence of 1, 2 and, respectively, 3 wt% of graphene. The contribution of graphene content (1 wt%) on the stability improvement of SIS is demonstrated by the increase of onset oxidation temperature from 190 °C for neat polymer to 196 °C in the presence of graphene and to 205 °C for the polymer stabilized with graphene and rosemary extract. The addition of graphene into the polymer formulations is a successful method for enlarging durability instead of the modification of receipt with synthesis antioxidants. The presumable applications of these studied materials cover the areas of medical wear, food packaging, commodities, sealing gaskets and others that may also be included through the products for nuclear power plants.

Deep Regression Prediction of Rheological Properties of SIS-Modified Asphalt Binders.

The engineering properties of asphalt binders depend on the types and amounts of additives. However, measuring engineering properties is time-consuming, requires technical expertise, specialized equipment, and effort. This study develops a deep regression model for predicting the engineering property of asphalt binders based on analysis of atomic force microscopy (AFM) image analysis to test the feasibility of replacing traditional measuring estimate techniques. The base asphalt binder PG 64-22 and styrene-isoprene-styrene (SIS) modifier were blended with four different polymer additive contents (0%, 5%, 10%, and 15%) and then tested with a dynamic shear rheometer (DSR) to evaluate the rheological data, which indicate the rutting properties of the asphalt binders. Different deep regression models are trained for predicting engineering property using AFM images of SIS binders. The mean absolute percentage error is decisive for the selection of the best deep regression architecture. This study's results indicate the deep regression architecture is found to be effective in predicting the G*/sin δ value after the training and validation process. The deep regression model can be an alternative way to measure the asphalt binder's engineering property quickly. This study would encourage applying a deep regression model for predicting the engineering properties of the asphalt binder.

MoO3 Nanobelts Embedded Polypyrrole/SIS Copolymer Blends for Improved Electro-Mechanical Dual Applications.

This research endeavor aimed to develop thin film blends of polypyrrole (PPy) and poly (styrene-isoprene-styrene) (SIS) with MoO3 as a nanofiller for improved mechanical and electrical properties to widen its scope in the field of mechatronics. This study reports blends of polypyrrole (PPy) and poly (styrene-isoprene-styrene) (SIS) tri-block copolymer showing improved mechanical and electrical attributes while employing MoO3 nanobelts as nanofillers that additionally improves the abovementioned properties in the ensuing nanocomposites. The synthesis of PPy/SIS blends and MoO3/PPy/SIS nanocomposites was well corroborated with XRD, SEM, FTIR, and EDS analysis. Successful blending of PPy was yielded up to 15 w/w% PPy in SIS, as beyond this self-agglomeration of PPy was observed. The results showed a remarkable increase in the conductivity of insulating SIS copolymer from 1.5 × 10-6.1 to 0.343 Scm-1 and tensile strength up to 8.5 MPa with the 15 w/w% PPy/SIS blend. A further enhancement of the properties was recorded by embedding MoO3 nanobelts with varying concentrations of the nanofillers into 15 w/w% PPy/SIS blends. The mechanical strength of the polymeric nanocomposites was enhanced up to 11.4 MPa with an increase in conductivity up to 1.51 Scm-1 for 3 w/w% MoO3/PPy-SIS blends. The resultant product exhibited good potential for electro-mechanical dual applications.

Simultaneous determination of the styrene unit content and assessment of molecular weight of triblock copolymers in adhesives by a size exclusion chromatography method.

The content of styrene units in nonhydrogenated and hydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers significantly influences product performance. A size exclusion chromatography method was developed to determine the average styrene content of triblock copolymers blended with tackifier in adhesives. A complete separation of the triblock copolymer from the other additives was realized with size exclusion chromatography. The peak area ratio of the UV and refraction index signals of the copolymers at the same effective elution volume was correlated to the average styrene unit content using nuclear magnetic resonance spectroscopy with commercial copolymers as standards. The obtained calibration curves showed good linearity for both the hydrogenated and nonhydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers (r = 0.974 for styrene contents of 19.3-46.3% for nonhydrogenated ones and r = 0.970 for the styrene contents of 23-58.2% for hydrogenated ones). For copolymer blends, the developed method provided more accurate average styrene unit contents than nuclear magnetic resonance spectroscopy provided. These results were validated using two known copolymer blends consisting of either styrene-isoprene-styrene or hydrogenated styrene-butadiene-styrene and a hydrocarbon tackifying resin as well as an unknown adhesive with styrene-butadiene-styrene and an aromatic tackifying resin. The methodology can be readily applied to styrene-containing polymers in blends such as poly(acrylonitrile-butadiene styrene).

Development of hot melt pressure sensitive adhesive for transdermal use and in vitro evaluation / 中国药学杂志

OBJECTIVE: To develop hot melt pressure sensitive adhesive (HMPSA) for transdermal use, and to investigate the in vitro drug release and permeation property of HMPSA based patches. METHODS: HMPSA was prepared using styrene-isoprene-styrene triblock copolymer (SIS), C5 petroleum resin hydrogenate, lanoline, liquid paraffin, dibutyl phthalate, 2, 6-ditertbutyl-cresol as material under orthogonal design. The formulation of HMPSA was screened using stickiness, melt temperature and vapor permeation rate as index. The in vitro drug release behavior and transdermal property of the optimized HMPSA were evaluated using a-asarone as model drug. RESULTS: The optimized formulation of HMPSA (HMPSA-OP) was followed as: SIS: C5 petroleum resin hydrogenate: lanoline: liquid paraffin: dibutylphthalate: 2, 6-ditertbutyl-cresol=100:140:20:40:20:2. HMPSA-OP had shown more rapid drug release than ordinary HMPSA. And the in vitro transdermal flux of HMPSA-OP was (4.75±0.84) μg · cm-2 · h-1, higher than that of ordinary HMPSA and acrylate PSA. CONCLUSION: The HMPSA-OP shows good property and was suitable to prepare transdermal patch.

Preparation of testosterone hot melt pressure sensitive adhesive transdermal patch / 中国药学杂志

OBJECTIVE: To prepare testosterone hot melt pressure sensitive adhesive (HMPSA) transdermal patch and investigate its percutaneous permeability in vitro. METHODS: The matrix of thermoplastic elastomer styrene-isoprene-styrene(SIS) hot melt pressure sensitive adhesive was used for testosterone transdermal patch. The percutaneous permeability through excised nude mice skin or porcine skin in vitro was conducted by Franz diffusion cells. Cumulative permeation quantity (Q) and steady state permeation rate (Jss) were evaluated to optimize drug loading capacity and enhancer. The optimal transdermal patches were compared with reference patches with regard to percutaneous behaviors using excised nude mice skin and porcine skin. RESULTS: The optimal formulation contained 2% testosterone, 6% transdermal enhancer isopropyl myristate(IPM). Its permeation behavior in vitro followed zero-order kinetics. The permeation behavior of the optimal patches was better than the reference patches for excised nude mice skin and porcine skin. CONCLUSION: SIS HMPSA has a broad application potential for transdermal drug delivery system.