Reinforcement of Thermoplastic Starch Films with Cellulose Fibres Obtained from Rice and Coffee Husks

Cellulosic fibres from coffee(CF)and rice(RF)husks have been obtained applying chemical treatments and characterized as to their microstructure and thermal behaviour.These materials have been incorporated into glycerol plasticised thermoplastic starch(TPS)films obtained by melt blending and compression moulding at 1 wt%,5 wt%and 10 wt%.Microstructure,thermal behaviour and optical,tensile and barrier properties of the composites were analysed.Both kinds of micro-fibres improve the film stiffness while reduced the film stretchability.However,CF better maintained the film ductility at 1 and 5 wt%.A network of fine oriented fibres was observed on the surface of the films,while internal fibres exhibited a good adherence to the polymer network.The water vapour permeability of TPS films was not reduced in composites,although oxygen permeability was lowered by about 17%.Film transparency decreased by fibre addition in the UVVIS range.Thermal stability of composites was slightly higher than net TPS films.

Improvement of Concrete Properties and Reinforcing Steel Inhibition Using a Natural Product Admixture

The use of a natural white juice, taken from magrabe banana stem, as concrete admixture to improve mechanical and physicrvchemical properties of concrete has been studied. The compressive strength, bulk density the free lime liberated during hydration and the combined water content were determined. The results indicate that the admixture acts as a retarder in most cases and as accelerator in some ones. Also, the admixture effect on the corrosion resistance of the reinforcing steel against surrounding aggressive media has been investigated using galvanostatic polarization technique. The addition of 0.2% admixture leads to the more inhibition of the steel

A New Type Anticorrosion Coating for Ocean Reinforced Concrete Structures

Corrosion of reinforced concrete structures is a serious problem in ocean engineering. As an orientation of study, anticorrosion coating technique is developed and widely applied, but many problems need to be solved. LSW-2 type anticorrosion coating for maritime reinforced concrete structures is characterized by sea water resistance, salt fog resistance, moisture and heal resistance as well as impermeability to chlorions. The new type coating can be applied to wet concrete surface by conventional construction technique. It is a breakthrough in solving the above mentioned problem. The paper mainly introduces the test results, the property indices, coating procedure, construction technique and economic benefit of Ihe coating.

Plate reinforced square hollow section X-joints subjected to in-plane moment

The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specimens, moment-vertical displacement curves, moment-deformation of the chord, and strain strength distribution curves were presented. The effect of β and plate reinforcement types on in-plane flexural property of SHS X-joints was studied. Results show that punching shear of chord face disappears, brace material fracture appears and concave and convex deformation of chord decrease when either collar plates or doubler plates were welded on chord face. Moment-vertical displacement curves of all specimens have obvious elastic, elastic-plastic and plastic stages. As β increases, the in-plane flexural ultimate capacity and initial stiffness of joints of the same plate reinforcement type increase, but ductility of joints decreases. With the same β, the in-plane flexural initial stiffness and ultimate capacity of doubler plate reinforced joints, collar plate reinforced joints, and unreinforced joints decrease progressively. Thickness of reinforcement plate has no obvious effect on in-plane flexural initial stiffness and ultimate capacity of joints. As thickness of reinforcement plate increases, the ductility of reinforced X-joints decreases. The concave and convex deformation of every specimen has good symmetry;as β increases, the yield and ultimate deformation of chord decrease.

Covalently Crosslinked Networks from Telechelic Polycyclooctene with Reinforced Properties

Comprehensive Summary Introducing covalently crosslinked network to telechelic polymers can enable the formation of advanced polymeric materials with enhanced material properties.In this contribution,well-defined telechelic polymers bearing acetoacetate groups were synthesized via Ru-catalyzed ring-opening metathesis polymerization of cyclooctene in the presence of chain transfer agents.Given the unique feature of muti-site reactive acetoacetate end groups,several crosslinked networks were constructed using different crosslinkers under mild conditions.In the Michael addition reaction system,the introduction of di/trifunctional aliphatic acrylate as crosslinkers significantly enhanced the mechanical properties of the generated crosslinked network(tensile strength up to 27 MPa,elongation at break up to 500%).On the other hand,vitrimers with dynamic covalent crosslinked networks were accessed via transamination of vinylogous urethane reaction using telechelic polymers and tris(2-aminoethyl)amine.

Simultaneous Improvements of Thermal Stability and Mechanical Properties of Poly(propylene carbonate) via Incorporation of Environmental-friendly Polydopamine

Inspired by the photoprotection, radical scavenging of melanin together with versatile adhesive ability of mussel proteins, polydopamine（PDA） nanoparticles were successfully prepared and incorporated into environmentally friendly polymer, poly（propylene carbonate）（PPC） via solvent blending. The prepared composites exhibited excellent thermal stability in air and nitrogen atmosphere and extraordinary mechanical properties. The composites displayed eminent increase of temperature at 5% weight loss（T5%） by 30-100 K with 0.3 wt%-2.0 wt% loadings, meanwhile, the tensile strength and Young＇s modulus were significantly improved from 11.5 MPa and 553.7 MPa to 40.5 MPa and 2411.2 MPa, respectively. The kinetic calculation indicated that improvement of T5% is presumably derived from suppressing chain-end unzipping. The glass transition temperature（Tg） of the PPC/PDA composites increased by 8-10 K. This is probably due to hydrogen bonding interaction since the abundant proton donors along PDA chains would interact with proton acceptors like C = O and C―O―C in PPC which would cause restriction of segmental motion of PPC chains.