Sawdust Short Fiber Reinforced Epoxidized Natural Rubber: Insight on Its Mechanical, Physical, and Thermal Aspects

In this work,Epoxidized natural rubber/sawdust short fiber(ENR-50/SD)composites at different fiber content(5,10,15 and 20 phr)and size(fine size at 60–100μm and coarse size at 10–20 mm)were prepared using two-roll mill and electrical-hydraulic hot press machine respectively.Curing characteristics,water uptake,tensile,morphological,physical,and thermal properties of the composites were investigated.Results indicated that the scorch time and cure time became shorter whereas torque improved as SD content increase.Though the decline of tensile strength and elongation at break values,modulus,hardness and crosslinking density have shown enhancements with the increasing of SD content.The water uptake percentage of all samples has shown an increasing as SD content increase.However,the low SD content,particularly fine size have presented lower water uptake.The temperature of weight%loss(5 and 50 wt%loss)of 5 phr SD(low content)have recorded higher temperature compared to 20 phr SD(high content)in the rubber composites,which indicated higher thermal stability.The fine size of SD has recorded better overall properties than SD coarse size at same loading in the rubber composites.

Development of Biobased Poly(Lactic Acid)/Epoxidized Natural Rubber Blends Processed by Electrospinning: Morphological, Structural and Thermal Properties

This article reports the production of electrospun fibers from blends of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) solutions. The produced fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). SEM images showed the reduction in fiber size with ENR content of up to 25% in the mixture PLA/ENR. FTIR analysis revealed a possible interaction between carboxylic group of PLA and epoxi group of ENR. Thermal analysis showed the increase of the crystallinity fraction with ENR content and a decrease in thermal stability of eletrospun mats with the addition of ENR. The dynamic mechanical properties showed an enhancement of the stiffness of PLA/ENR blends with the increase of ENR content, which can support the production of interesting materials for tissue engineering based on renewable and biocompatible polymers. The reported properties indicate the possibility to use such fiber mats as potential materials in tissue engineering.

Sustainable shape memory polymers based on epoxidized natural rubber cured by zinc ferulate via oxa-Michael reaction

Although various shape memory polymers(SMPs)or diverse applications have been widely reported,the SMPs based on rubbers have been rarely realized due to the low triggering temperature of rubbers.In another aspect,the SMPs based on sustainable substances are highly desired for the growing shortage in fossil resources.In the present study,we accordingly developed the sustainable SMPs with tunable triggering temperature,based on natural rubber(NR)and ferulic acid(FA)as the raw materials.Specifically,the SMPs are based on a crosslinked network of epoxidized natural rubber(ENR)crosslinked by in situ formed zinc ferulate(ZDF)via oxa-Michael reaction.The excellent shape memory effect(SME)is found in these SMPs,as evidenced by the high fixity/recovery ratio and the tunable triggering temperature.With the incorpora-tion of natural halloysite nanotubes(HNTs),the stress and recovery rate of the SMPs are found to be tunable,which widens the application of this kind of SMPs.The combination of adoption of sustainable raw materials,and the excellent and tunable SME makes these SMPs potentially useful in many applications,such as various actuators and heat-shrinkable package materials.

Flexible,stretchable and magnetic Fe_(3)O_(4)@Ti_(3)C_(2)Tx/elastomer with supramolecular interfacial crosslinking for enhancing mechanical and electromagnetic interference shielding performance

Electromagnetic interference(EMI)and radiation of electronic devices are ubiquitous,which are potentially hazardous to the normal operation of electronic equipment and human health.MXenes are extremely attractive in the preparation of EMI shielding materials due to their excellent metallic conductivity and tunable surface chemistry.Herein,by virtue of the designed nanostructure and regulation of interface interactions,we fabricated flexible Fe_(3)O_(4)@Ti_(3)C_(2)Tx MXene/3,4-dihydroxyphenylacetic acid(DOPAC)-epoxidized natural rubber(ENR)elastomers(FMDE)with 3D segregated interconnected structures.The elaborately designed metalligand coordination crosslinking between Fe_(3)O_(4)nanoparticles and DOPAC ligand molecules provides strong interfacial interactions,resulting in significantly reinforced mechanical properties.Compared with Ti_(3)C_(2)Tx/ENR elastomers,the maximum tensile strength and toughness of FMDE are elevadted by~306%and 475%,respectively.Moreover,the 3D segregated conductive network constructed by Fe_(3)O_(4)@Ti_(3)C_(2)Tx nanoflakes resulted from volume exclusion effect of ENR latex and the introduction of magnetic Fe_(3)O_(4)nanoparticles with enhanced electromagnetic wave absorption greatly improved the EMI shielding performance of FMDE,exhibiting an excellent EMI shielding effectiveness of up to 58 dB in the X band(8.2–12.4 GHz)and stable EMI shielding capability during repeated deformations.This work provides a promising strategy for the design and manufacture of novel flexible EMI shielding materials.