The present study explores solid-state cryomilling for the compounding of green composites. Herein, wood plastic composites (WPCs) composed of sawdust (SD) and poly(&epsilon:-caprolactone) (PCL) with various compositions were prepared. Two compounding techniques, namely, extrusion and cryomilling, were utilized to prepare WPC raw material pellets and powders, respectively, for comparison purposes. Flat pressing was further utilized to prepare WPC films for testing. Morphological, structural, thermal, mechanical, and surface wettability properties were investigated. Results indicate the advantages of cryomilling in producing WPCs. Scanning electron microscopy (SEM) along with optical micrographs revealed well ground SD particles and uniform distribution in the PCL matrix. Tensile strength and elongation at break of the composites declined with increasing SD content, however, the modulus of elasticity significantly increased. Water contact angles averaged less than 90&deg:, implying partial wetting. Visual observations and thermo-gravimetric analysis (TGA) indicated thermal stability of composites during processing. In conclusion, PCL/SD WPC is a potential candidate to replace conventional plastics for packaging applications. This would also provide a much better utilization of the currently undervalued wood waste resources.

Synthetic pollutants are a looming threat to the entire ecosystem, including wildlife, the environment, and human health. Polyhydroxyalkanoates (PHAs) are natural biodegradable microbial polymers with a promising potential to replace synthetic plastics. This research is focused on devising a sustainable approach to produce PHAs by a new microbial strain using untreated synthetic plastics and lignocellulosic biomass. For experiments, 47 soil samples and 18 effluent samples were collected from various areas of Punjab, Pakistan. The samples were primarily screened for PHA detection on agar medium containing Nile blue A stain. The PHA positive bacterial isolates showed prominent orange&ndash:yellow fluorescence on irradiation with UV light. They were further screened for PHA estimation by submerged fermentation in the culture broth. Bacterial isolate 16a produced maximum PHA and was identified by 16S rRNA sequencing. It was identified as Stenotrophomonas maltophilia HA-16 (MN240936), reported first time for PHA production. Basic fermentation parameters, such as incubation time, temperature, and pH were optimized for PHA production. Wood chips, cardboard cutouts, plastic bottle cutouts, shredded polystyrene cups, and plastic bags were optimized as alternative sustainable carbon sources for the production of PHAs. A vital finding of this study was the yield obtained by using plastic bags, i.e., 68.24 &plusmn: 0.27%. The effective use of plastic and lignocellulosic waste in the cultivation medium for the microbial production of PHA by a novel bacterial strain is discussed in the current study.

A growing common public interest in a more sustainable society drives efforts into the development of bio-based and biodegradable polymers. Such renewable polymers can replace conventional non-degradable polymers as the matrix for wood plastic composites (WPCs). However, despite ongoing advancements towards the implementation of these biocomposites, experience with biocomposite mechanical durability is limited. This comparative study investigated the mechanical stability of biocomposites based on polyhydroxyalkanoate (PHA) and wood flour at 50 wt% wood content in real-life in-service conditions, including indoor, outdoor and in soil environments. Polylactic acid (PLA) and polyethylene (PE) wood composites served as comparative reference materials. Aging studies over a 12-month period showed that PHA composites were mechanically stable under indoor conditions. A reduction in mechanical stability was observed for outdoor exposure but the composite property deterioration was independent of the polymer type. In soil, the biocomposites steadily degraded towards a complete loss in mechanical properties, in contrast to the PLA and PE based composites. Overall, the rate of water absorption and the rate of polymer biodegradation are principal factors controlling mechanical stability over time. These factors promote the formation of cracks and voids which in turn weaken the material performance under mechanical loading. Without such crack formation, the composites retained mechanical properties over the aging time. The results provide a basis for consideration of strategic applications of PHA-based WPCs in cases where sustained or time-constrained mechanical performance is required.

In food industry, a growing concern is the use of suitable packaging material (i.e., biodegradable coatings and films) with enhanced thermal, mechanical and barrier characteristics to prevent from contamination and loss of foodstuff. Biobased polymer resources can be used for the development of biodegradable bioplastics. To achieve this goal, biopolymers should be economic, renewable and abundantly available. Bioplastic packaging materials based on renewable biomass could be used as sustainable alternative to petrochemically-originated plastic materials. This review summarizes the recent advancements in biopolymer-based coatings and films for active food packaging applications. Microbial polymers (PHA and PLA), wood-based polymers (cellulose, hemicellulose, starch & lignin), and protein-based polymers (gelatin, keratin, wheat gluten, soy protein and whey protein isolates) were among the materials most widely exploited for the development of smart packaging films. These biopolymers are able to synthesize coatings and films with good barrier properties against food borne pathogens and the transport of gases. Biobased reinforcements e.g., plant essential oils and natural additives to bioplastic films improve oxygen barrier, antibacterial and antifungal properties. To induce the desired functionality the simultaneous utilization of different synthetic and biobased polymers in the form of composites/blends is also an emerging area of research. Nanoscale reinforcements into bioplastic packaging have also been reported to improve packaging characteristics ultimately increasing food shelf life. The development of bioplastic/biocomposite and nanobiocomposites exhibits high potential to replace nonbiodegradable materials with characteristics comparable to fossil-based plastics, additionally, giving biodegradable and compostable characteristics. The idea of utilization of renewable biomass and the implications of biotechnology can firstly reduce the burden from fossil-resources, while secondly promoting biobased economy.

Thesis (MScFor)--Stellenbosch University, 2020. | ENGLISH ABSTRACT: The South African Government is faced with numerous environmental, economic and social challenges. Invasive alien plants (IAPs) are environmental threats, which change the ecosystems they invade. The Working for Water (WfW) Programme is a pioneering environmental initiative working under the Department of Environmental Affairs (DEA), which aims to eradicate IAPs. The value-added industry (VAI) launched under the WfW Programme aims to use these cleared IAPs for economic benefits. Plastic pollution is another global and national environmental issue caused by increasing population and industrialization. Numerous organizations have created awareness pertaining to this issue and the importance and benefits of recycling plastic waste. The objective of this study was to assess the feasibility of producing wood plastic composites (WPCs) as a building material made from woody IAPs and recycled plastic for low cost buildings through a hypothetical small business initiative. WPCs can be deemed as green products since they use recycled material, renewable resources and minimize the impact they have on the environment. Small business development is being encouraged to address the national unemployment rate. A feasibility study was conducted to assess the success of a proposed small WPC business. The feasibility study assumed that the project would take place in the Western Cape and Acacia saligna sourced along the Berg River and recycled LLDPE plastic from Bellville would be used for production. A survey was conducted in the Kayamandi Township to study the living conditions of people living in the RDP houses and observe any infrastructural defects. This would help identify a potential building structure replacement made from WPC material. Based on the survey results, 14% of the respondents complained about defective ceiling boards thus, a potential building component was recognized. Another part of the study was to determine the economic and financial perspective of manufacturing WPC ceiling boards, whereby the procurement costs of the raw material including the harvesting, purchasing and transport of these raw materials was considered. Two WPC ceiling boards with different dimensions were proposed. Type A being 1 m2, with a thickness of 0.004 m (research prototype) and Type B with dimensions 3 m x 1.2 m x 0.004 m (commercial competitor) were proposed. Both options were found to be profitable for a small business initiative. The sample boards used for testing mechanical and physical properties exceeded the benchmark values of gypsum ceiling boards in all analysed properties. The results showed that Type B boards could potentially replace the currently used gypsum ceiling boards of the same dimensions. In addition, the budgeted statement of profit or loss and comprehensive income showed a higher net profit after tax when compared to Type A boards. The mark-up percentages on cost of goods sold ensured that the selling prices per unit exceeded break-even prices resulting to selling prices (SP) of R90.16 and R120.76 for Type A boards and Type B boards per unit, respectively. This would allow the business to generate some profit. The net-present value (NPV) for the two board type investments were positive, however as a rule of thumb, the investment having the highest NPV value should be pursued. Therefore, the Type B boards would be recommended as a product to be sold in the small business. A sensitivity analysis was conducted to determine the effects of different input scenarios on the forecast break-even points. A change in selling price is highly sensitive as that determines the contribution margin of the business. | AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse regering word deur talle omgewings-, ekonomiese en maatskaplike uitdagings gekonfronteer. Indringerplante (indringerplante) is omgewingsbedreigings wat die ekosisteme wat hulle binnedring verander. Die Working for Water (WfW) -program is 'n baanbrekende omgewingsinisiatief wat onder die Departement van Omgewingsake (DEA) werk, met die doel om IAP's uit te wis. Die toegevoegde waarde-industrie (VAI) wat in die loop van die WfW-program van stapel gestuur is, is daarop gemik om hierdie skoongemaakte IAP's vir ekonomiese voordele te gebruik. Plastiese besoedeling is nog 'n wêreldwye en nasionale omgewingskwessie wat veroorsaak word deur toenemende bevolking en industrialisasie. Talle organisasies het bewustheid rakende hierdie kwessie en die belangrikheid en voordele van die herwinning van plastiekafval geskep. Die doel van hierdie studie was om die lewensvatbaarheid van die vervaardiging van houtplastiese komposiete (WPC's) as 'n boumateriaal wat van hardhoutagtige IAP's en herwinde plastiek vir lae koste geboue vervaardig word, te evalueer deur middel van 'n hipotetiese klein ondernemingsinisiatief. WPC's kan as groen produkte beskou word, aangesien dit herwinde materiaal, hernubare hulpbronne gebruik en die impak wat dit op die omgewing het, tot die minimum beperk. Die ontwikkeling van kleinsakeondernemings word aangemoedig om die nasionale werkloosheidsyfer aan te spreek. 'n Uitvoerbaarheidstudie is uitgevoer om die sukses van 'n voorgestelde klein WPC-onderneming te beoordeel. Die uitvoerbaarheidstudie het aanvaar dat die projek in die Wes-Kaap sou plaasvind en dat Acacia saligna langs die Bergrivier verkry word en dat herwinde LLDPE-plastiek uit Bellville vir produksie gebruik sou word. In die Kayamandi-township is 'n opname gedoen om die lewensomstandighede van mense wat in die Hop-huise woon, te ondersoek en infrastruktuurfoute op te spoor. Dit sal help om 'n moontlike vervanging van boustrukture uit WPC-materiaal te bepaal. Op grond van die resultate van die opname het 14% van die respondente gekla oor gebrekkige plafonborde, dus is 'n potensiële boukomponent erken. 'n Ander deel van die studie was om die ekonomiese en finansiële perspektief van die vervaardiging van WPC-plafonborde vas te stel, waardeur die verkrygingskoste van die grondstof, insluitend die oes, aankoop en vervoer van hierdie grondstowwe, oorweeg is. Twee WPC-plafonborde met verskillende afmetings is voorgestel. Tipe A is 1 m2, met 'n dikte van 0.004 m (navorsingsprototipe) en tipe B met afmetings 3 m x 1.2 m x 0.004 m (kommersiële mededinger). Daar is gevind dat beide opsies winsgewend is vir 'n klein ondernemingsinisiatief. Die monsterborde wat gebruik is vir die toets van meganiese en fisiese eienskappe het die normwaardes van gipsplafonborde in alle ontleed eienskappe oorskry. Die resultate het getoon dat tipe B-planke moontlik die huidige gebruikte gipsplafonborde van dieselfde afmetings kan vervang. Daarbenewens het die begrote staat van wins of verlies en omvattende inkomste 'n hoër netto wins na belasting getoon in vergelyking met Tipe A-direksies. Die winspersentasies op die koste van die verkoopte goedere het verseker dat die verkooppryse per eenheid gelykbreekpryse oorskry het, wat die verkooppryse (SP) van onderskeidelik R90.16 en R120.76 beloop het vir tipe A-borde en tipe B-borde per eenheid. Dit kan die onderneming 'n bietjie wins oplewer. Die netto huidige waarde (NPV) vir die twee boordtypebeleggings was positief, maar as 'n reël, moet die belegging met die hoogste NPV-waarde nagestreef word. Daarom word die tipe B-planke aanbeveel as 'n produk wat in die kleinsakeonderneming verkoop sal word. 'n Sensitiwiteitsanalise is uitgevoer om die gevolge van verskillende inset scenario's op die voorspelde gelykbreekpunte te bepaal. 'n Verandering in verkoopprys is baie sensitief, aangesien dit die bydrae van die onderneming bepaal. | Masters