This study explored the effect of multiple recycling on the dimensional stability of wood–plastic composite. For this purpose, the injection moulding parameters effective on dimensional stability were first optimized based on the response surface method. Optical scanning, melt flow index (MFI), and differential scanning calorimetry (DSC) tests were used to analyse the shrinkage and deformation of recycled samples. The obtained results revealed that some recycled samples were subjected to thermal changes during the grinding and injection moulding process. The MFI and DSC results showed that the high-density polyethylene thermoplastic used in the wood–plastic composite was broken with long chains. Also, thermal changes occurred during the grinding and injection moulding process. The samples recycled three times had the highest dimensional instability (2.8% of shrinkage values). Finally, with the reduction of DSC, the semi-crystalline structure changed to amorphous, and the samples recycled four and five times had 2.7% and 2.5% shrinkage percentage, respectively.
AcheampongJB, de AngelisM, KrauseA, MeinckenM.2021. The effect of raw material selection on physical and mechanical properties of wood plastic composites made from recycled LDPE and wood from invasive trees in South Africa. Wood Mater Sci Eng. 16(2):118–123. doi:10.1080/17480272.2019.1635207.
2.
AzadR, ShahrajabianH.2019. Experimental study of warpage and shrinkage in injection molding of HDPE/rPET/wood composites with multiobjective optimization. Mater Manuf Process. 34(3):274–282. doi:10.1080/10426914.2018.1512123.
3.
BenoitN, González-NúñezR, RodrigueD.2017. High density polyethylene degradation followed by closedloop recycling. Prog Rubber Plast Recycl Technol. 33(1):17–37. doi:10.1177/147776061703300102.
4.
ČermákR, ObadalM, PonížilP, PoláškováM, StoklasaK, LengálováA.2005. Injection-moulded α- and β-polypropylenes: I. Structure vs. processing parameters. Eur Polym J. 41(8):1838–1845. doi:10.1016/j.eurpolymj.2005.02.020.
5.
ChenT, BairdDG.2020. The influence of mehcanical recycling on the mechanical and thermal properties of thermotropic liquid crystalline polymer and glass fiber reinforced polyproplyene. Annual Technical Conference - ANTEC, Conference Proceedings 2(June); p. 562–566.
6.
ChenWC, NguyenMH, ChiuWH, ChenTN, TaiPH.2016. The effect of recycling on wood-fiber thermoplastic composites. Int J Adv Manuf Technol. 83(9–12):1873–1886. doi:10.1007/s00170-015-7683-0.
7.
ChiuHT, HuangJK, KuoMT, HuangJH.2018. Characterisation of PC/ABS blend during 20 reprocessing cycles and subsequent functionality recovery by virgin additives. J Polym Res. 25(124):1–8. doi:10.1007/s10965-018-1522-6.
8.
DerakhshandehM, HatzikiriakosSG.2012. Flow-induced crystallization of high-density polyethylene: the effects of shear and uniaxial extension. Rheol Acta. 51(4):315–327. doi:10.1007/s00397-011-0605-7.
9.
HamadK, KaseemM, DeriF.2013. Recycling of waste from polymer materials: an overview of the recent works. Polym Degrad Stab. 98(12):2801–2812. doi:10.1016/j.polymdegradstab.2013.09.025.
10.
HamaratI, KuramE, OzcelikB.2018. Investigation the mechanical, rheological, and morphological properties of acrylonitrile butadiene styrene blends with different recycling number content. Proc Inst Mech Eng Part E J Process Mech Eng. 232(4):449–458. doi:10.1177/0954408917717994.
11.
Janeschitz-KrieglH, RatajskiE.2005. Kinetics of polymer crystallization under processing conditions: transformation of dormant nuclei by the action of flow. Polymer (Guildf). 46(11):3856–3870. doi:10.1016/j.polymer.2005.02.096.
12.
JinH, Gonzalez-GutierrezJ, OblakP, ZupančičB, EmriI.2012. The effect of extensive mechanical recycling on the properties of low density polyethylene. Polym Degrad Stab. 97(11):2262–2272. doi:10.1016/j.polymdegradstab.2012.07.039.
13.
KajaksJ, KalninsK, NaburgsR.2018. Wood plastic composites (WPC) based on high-density polyethylene and birch wood plywood production residues. Int Wood Prod J. 9(1):15–21. doi:10.1080/20426445.2017.1410997.
14.
KhanjanzadehH, TabarsaT, ShakeriA, OmidvarA.2011. Effect of organoclay platelets on the mechanical properties of wood-plastic composites formulated with virgin and recycled polypropylene. Wood Mater Sci Eng. 6(4):207–212. doi:10.1080/17480272.2011.606915.
15.
KitayamaS, MiyakawaH, TakanoM, AibaS.2017. Multi-objective optimization of injection molding process parameters for short cycle time and warpage reduction using conformal cooling channel. Int J Adv Manuf Technol. 88(5–8):1735–1744. doi:10.1007/s00170-016-8904-x.
16.
KukaE, CiruleD, KajaksJ, AndersoneI, AndersonsB.2016. Wood plastic composites made with thermally modified birch wood residues. Int Wood Prod J. 7(4):225–230. doi:10.1080/20426445.2016.1214439.
17.
LeMC, BelhabibS, NicolazoC, VachotP, MousseauP, SardaA, DeterreR.2011. Pressure influence on crystallization kinetics during injection molding. J Mater Process Technol. 211(11):1757–1763. doi:10.1016/j.jmatprotec.2011.05.017.
18.
LellingerD, FloudasG, AligI.2003. Shear induced crystallization in poly(ϵ-caprolactone): effect of shear rate. Polymer (Guildf). 44(19):5759–5769. doi:10.1016/S0032-3861(03)00633-5.
19.
LiX, WeiQ, 2019. Numerical simulation on crystallization-induced warpage of injection-molded PP/EPDM part. J Polym Res. 26(228):1–11. doi:10.1007/s10965-019-1869-3.
20.
MontanesN, Quiles-CarrilloL, FerrandizS, FenollarO, BoronatT.2019. Effects of lignocellulosic fillers from waste thyme on melt flow behavior and processability of wood plastic composites (WPC) with biobased poly(ethylene) by injection molding. J Polym Environ. 27(4):747–756. doi:10.1007/s10924-019-01388-0.
21.
MukrasSMS.2020. Experimental-based optimization of injection molding process parameters for short product cycle time. Adv Polym Technol. 2020:1–15. doi:10.1155/2020/1309209.
22.
OblakP, Gonzalez-GutierrezJ, ZupančičB, AulovaA, EmriI.2016. Processability and rheological properties of extensively recycled high density polyethylene (HDPE). 33rd Danubia Adria Symp Adv Exp Mech. 114:194–195.
23.
TaghaviSK, ShahrajabianH, HosseiniHM.2018. Detailed comparison of compatibilizers MAPE and SEBS-g-MA on the mechanical/thermal properties, and morphology in ternary blend of recycled PET/HDPE/MAPE and recycled PET/HDPE/SEBS-g-MA. J Elastomers Plast. 50(1):13–35. doi:10.1177/0095244317698738.
24.
Twite-KabambaE, RodrigueD.2010. Rheological and molecular investigations of polyethylene degradation in a batch mixer. Int Polym Process. 25(4):297–303. doi:10.3139/217.2365.
ZhuoG, ZhangX, LiuY, WangM.2019. Effect of multiple recycling on properties of poplar fiber reinforced high density polyethylene wood-plastic composites. Mater Res Express. 6(12):125514. doi:10.1088/2053-1591/ab5742.
