APC Composite (Sweden)

Abstract In this research, a novel 3D printed core and natural fiber polyester composite skin based thick sandwich panel was developed as structural material for domestic and commercial infrastructure applications. The main objective of this research was to analyze how the carbon quantum dots (C‐dots) from agriculture waste strengthen the softer thermoplastic acrylonitrile butadiene styrene (ABS) core and overall sandwich panel's load bearing properties. The core of sandwich was prepared using additive manufacturing method whereas the skin was developed by hand layup method. According to the results the C‐dots of 20 phr into the ABS improved the compression properties of core in both flatwise and edgewise directions. A highest tensile and flexural strength of skin was observed to be 114 and 146 MPa respectively. The addition of C‐dots improved the load bearing effect and also restricts the deformation against load. This performance improved novel 3D printed core and bamboo fiber skin sandwich could be used as an alternative construction and building material where the commercial plywood and other forms of powder wood face damages via weather and termite issues.Highlights Higher filler volume of up to 20 phr of carbon quantum dots in acrylonitrile butadiene styrene (ABS) were developed Novel 3D printed thin walled core of 1 mm diameter was developed using carbon quantum dots and ABS. Bamboo fiber‐polyester skin with highest tensile strength of 114 MPa was developed. Improved flatwise compression and tensile strength were achieved for ABS core with 20 phr of Carbon quantum dots Flexural strength and edgewise compression properties were improved with 20 phr of Carbon quantum dots in ABS

Surface sizing agent (SSA) is a material used to improve the surface quality of the paper. It is one of the compulsory components in the paper-related industries to impart surface smoothness, printability, water resistivity and brightness. An environmental friendly surface sizing agent based on carboxymethyl cassava starch/polyurethane dispersion (CCS/PUD) blend had been developed. A local cassava starch (CS) was modified with anionic reagent, sodium monochloroacetate (SMCA) via etherification, in a presence of sodium hydroxide (NaOH) to form sodium carboxymethyl cellulose (CCS). Later CCS was blended with 30 wt% polyurethane dispersion (PUD) to enhance its water resistivity. The CCS/PUD blend was applied onto the surface of a hand-made paper prior to being tested and characterised. Fourier transform infrared analysis had verified the successful of etherification process by showing peaks at 3,400 cm-1, 1,635 cm-1 and 1,440 cm-1, corresponding to carboxymethyl substituent. The highest degree of substitution (0.76) was obtained from the system that used 6 g SMCA at fixed 1 : 7 CS : Water ratio and 4 mL NaOH. Meanwhile, CCS/PUD-coated paper had improved water resistivity corresponded to higher water contact angle at 73°, in comparison with the CCS-coated paper (62°) and the uncoated paper (40°). This was supported with low surface energy showed by CCS/PUD-coated paper (33.9 mJ/m2).

Mixed matrix membranes (MMMs) comprising polysulfone (PSF) Udel® P‐1700 and synthesized carbon molecular sieve (CMS) particles (<25 μm) have been fabricated and characterized. CMS were synthesized by using polyacrylonitrile (PAN) as polymer precursor. The casting process was performed at the processing temperature close to Tg of PSF in order to maintain the flexibility of polymer during film formation. This study investigated the effects of CMS loadings (10, 20, 30 and 35 wt%) on the morphology and the gas separation performance of PSF‐CMS MMMs. The fabricated MMMs were characterized using TGA, DSC, FESEM and single gas permeation test using high purity O2 and N2. Based on FESEM micrograph, a good polymer‐sieve adhesion was achieved in MMMs using the combination of PSF‐CMS even at high sieve loading (up to 35 wt%). The formation of 'sieve‐in‐the‐cage' morphology in PSF‐CMS MMMs has been minimized to a great extend by implementing casting procedure at the operating temperature close to the Tg of polymer matrix. The O2 and N2 permeability for MMMs were increased with increasing CMS loading; while at 20 wt% CMS loading the O2/N2 selectivity attain the highest value which is 5.97 with the O2 permeability of 7.9617 barrers.

The use of natural fibres instead of man made fibres, as reinforcements in thermoplastics, gives interesting alternatives for production of low cost and ecologically friendly composites. In this work different commercially available semi-finished natural fibre mat reinforced thermoplastics (NMT) composites have been studied. Mechanical properties and microstructure of different NMT composites were investigated and compared to conventional GMT (glass fibre mat reinforced thermoplastic) composites and pure polypropylene (PP). The study included also NMT composites manufacturing processing parameters as processing temperatures and pressure during compression moulding. The results showed that NMT composites have a high stiffness compared to pure polymer and the NMT with a high fibre content (50% by weight) showed even better stiffness than the GMT. The GMT composites had superior strength and impact properties compared to the NMT which might be due to the relatively low strength of the natural fibres but also to poor adhesion to the PP matrix. The NMT materials showed a large dependence on direction and are therefore believed to have more fibres oriented in one direction. The stronger direction (0°) of the NMT was in some cases as much as 45% better than the 90° direction.

CoC2O4.2 H2O has been precipitated by pouring ammonium oxalate solution into the Co(No3)2 solution in which very fine particles of WC are suspended. Then the mixture of carbide and cobalt oxalate after filtration, washing and drying, was reduced by hydrogen. The obtained mixed powder of carbide and cobalt was pressed at room temperature and sintered in hydrogen. The mechanical properties of the alloys of carbide and cobalt by this process were comparable to those of the alloys of carbide and cobalt by ball-milling process.