Exploring the influence of radiation crosslinking on high-performance hydrogenated acrylonitrile butadiene rubber and polyamide 12 based blends with special reference to heat and oil resistance

Design and Synthesis of Novel Bio-Based Polyester Elastomer with Tunable Oil Resistance

Polarity determines the oil resistance property of elastomers. In this work, three bio-based polyester elastomers (BPEs) with different mass fraction of ester groups (E) are designed and synthesized aiming to study the relationship of E and oil resistance performance, and to obtain bio-based elastomer materials with tunable oil resistance. Through adjusting the chain length of monomers, E of poly(ethylene glycol/1,3-propanediol/succinate/adipate/itaconate)(PEPSAI), poly(1,3-propanediol/1,4-butanediol/succinate/adipate/itaconate)(PPBSAI), and poly(1,3-propanediol/1,4-butanediol/sebacate/adipate/itaconate)(PPBSeAI) are ≈50.39%, 48.55%, and 39.68%, respectively. Results show that E has great influence on the oil resistance of BPEs. After being immersed in IRM-903# oil for 72 h at room temperature, the changes in mass and volume of BPEs decrease along with the increasing mass fraction of ester groups, indicating improved oil resistance performance. PEPSAI with the highest mass fraction of ester groups presents better oil resistance and lower Tg (better low-temperature resistance) than one of the most used commercial oil-resistant rubber nitrile rubber (N230S). Thus, this work provides a promising strategy to obtain bio-based oil resistant elastomers with practical value.

Thermoplastic mung bean starch/natural rubber/sericin blends for improved oil resistance

Oil resistant thermoplastic elastomers (TPE) were prepared using mung bean thermoplastic starch (MTPS) blending with rubbers and sericin. Sericin was incorporated into MTPS as a compatibilizer. MTPS with sericin (MTPSS) was blended with natural rubber (NR) and epoxidized NR (ENR). Sericin at 5% improved the tensile strength (10 MPa), elastic recovery (52%) and morphology of the MTPSS/ENR blend. The mechanical properties, elastic recovery and morphology of the MTPSS5/NR blend were improved by the addition of ENR. The MTPSS/ENR showed palm (28%) and motor oils (8%) swelling resistance because of the hydrophilicity of MTPS and high polarity of ENR. The MTPSS/ENR/NR showed gasoline swelling resistance (104%) because of the hydrophilicity of MTPS and low polarity of NR. FTIR confirmed a reaction between the -NH groups of sericin and the epoxy groups of ENR. This reaction improved the compatibility, mechanical properties, elastic recovery, morphology and oils swelling resistance of the blends.

Electron beam irradiation influencing the mechanical properties and water absorption of polycaprolactam (PA6) and polyhexamethylene adipamide (PA66)

It is known that polycaprolactam (PA6) and polyhexamethylene adipamide (PA66) are widely used industrial materials including in the irradiation industry. However, there is a lack of observation of irradiation effects on PA6 and PA66. In the current study, we firstly investigated mechanical and water absorption properties of PA6 and PA6 that were treated under irradiation doses of 200 kGy, 400 kGy, 800 kGy and 1600 kGy, respectively. The structure, mechanical properties and thermal properties of nylon after irradiation were characterized by mechanical property tests, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results indicated that the tensile strength of PA6 increased gradually while that of PA66 firstly increased and then decreased with the increase of irradiation dose. Additionally, the elongation at break of the two samples decreased obviously with the increase of irradiation dose. The water absorption of PA6 increased with the increase of irradiation dose; however, that of PA66 was almost constant regardless of irradiation. FTIR tests revealed that the carbonyl index of PA6 and PA66 increased with the increase of irradiation dose. SEM results illustrated that surface degradation of PA6 and PA66 occurred during the irradiation process.

Effect of Cross-Linking Degree of EPDM Phase on the Morphology Evolution and Crystallization Behavior of Thermoplastic Vulcanizates Based on Polyamide 6 (PA6)/Ethylene-Propylene-Diene Rubber (EPDM) Blends

As a special class of “green” elastomers, thermoplastic vulcanizates (TPVs) have been widely used in industries due to the combination of the excellent resilience of conventional elastomers and the easy recyclability of thermoplastics. Here, the morphology evolution of TPVs based on polyamide 6/ethylene-propylene-diene rubber (PA6/EPDM) blends was investigated by varying the content of the curing agent, phenolic resin (PF). With the incorporation of 6 wt% PF, the gel content of the EPDM phase reaches a high value of 49.6 wt% and a typical sea-island structure is formed with EPDM domain in a micro-nano size. The dynamic rheology behaviors of TPVs showed that with the curing degree of EPDM phase increasing, a denser network of EPDM particles is formed in PA6 matrix. Additionally, a lower crystal degree and crystal peak temperature are observed, indicating that there exists a growth restriction of PA6 crystal plate induced by a thinner plastic layer between the adjacent EPDM particles. However, the crystal form of PA6 is not changed with the increasing curing degree of the EPDM phase. This study provides an effective strategy to realize a new kind of TPVs, which can be easily introduced into industrial applications.