Thermoplastic Starch Prepared with Different Plasticizers: Relation between Degree of Plasticization and Properties

Ethylene glycol, glycerol, sorbitol, formamide, and urea were used as plasticizers for the preparation of thermoplastic starch（TPS） from corn starch. The properties of TPS were tested by analysis method. The results showed that TPSs were more highly plasticized with amines than alcohols. For the same type of plasticizer, the degree of plasticization decreased as the molecular weight of plasticizer increased. The relationship between plasticization degree and TPS properties was characterized and described by mechanical properties and water absorption. The experimental results showed that when the degree of plasticization increased, the tensile strength decreased and the elongation at breakage and water absorption increased.

Cellulose Acetate Thermoplastics with High Modulus, Dimensicnal Stability and Anti-migration Properties by Using CA-g-PLA as Macromolecular Plasticizer

Cellulose diacetate(CDA)can be melt processed to produce numerous and widely-used plastic products.However,due to the high glass transition temperature(Tg)of CDA,the addition of up to 30 wt%of micromolecular plasticizers is indispensable,which significantly reduces the dimensional stability and raises safety concerns from the migration of plasticizers.In this work,a series of CDA-graft poly(lactic acid)(CDA-g-PLA)copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyI groups of CDA.The resultant CDA-g-PLA copolymers possess adjustable degrees of substitution(DSpua)and side chain length(DPpLa)by controlling the reaction time and feed ratio.The Tgs and thermal flow temperatures(Ts)of CDA-g-PLA strongly depend on DPpA such as the Tgs decrease linearly with the increase of DPA.The CDA-g-PLA copolymers with the DPLA of 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers,because of their low Tfs of 170-215℃.More impressively.the CDA-g PLA can act as the macromolecular plasticizer.The obtained CDA/CDA-g-PLA has higher storage modulus,flexural modulus and Young's modulus than the commercial CDA plasticized with triethyl citrate.In addition,the CDA/CDA-g PLA exhibits high dimensional stabilty and anti-migration property.During a long term treatment at 80℃ and 60%humidity,the CDA/CDA-g-PLA can retain the initial shape.Therefore,this work not only proposes a facile method for achieving a direct thermoplastic processing of CDA,but also provides a macromolecular plasticizer for CDA to make lightweight,stable and safer biobased thermoplastics.

Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

Oxygen-flee copper （Cu） was successfully joined to carbon-fiber-reinforced thermoplastic （CFRTP, polyamide 6 with 20wt% carbon fiber addition） by friction lap joining （FLJ） at joining speeds of 200-1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 ram. It is the first time to report the joining of CFRTP to Cu by FLJ. As the joining speed increased, the tensile shear force （TSF） of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3 kN （ 15 mm in width）. Hydrogen bonding formed between the amide group of CFRTP and the thin Cu20 layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows： the joining area increased first and then decreased; the degra- dation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.